Introduction 1Crash Workspace Guide Introduction 2 Overview and Definition Overview and Definition An overview of the SimXpert crash workspace is given here. Introduction SimXpert crash is a preprocessor for graphically preparing input data for LS-DYNA, an explicit dynamic software, used in applications such as crash, crush, and drop test simulations. Use of crash workspace allows users to work within one common modeling environment with other SimXpert workspaces such as Structures. Thus, for example, a model originally prepared for NVH, linear, or implicit nonlinear analysis can be easily used in explicit applications (crash). This dramatically reduces the time spent to build different models for implicit and explicit analysis and prevents you from making mistakes because of unfamiliarity between different programs. Theory A detailed theory of explicit analysis is outside the scope of this guide. However, it is important to understand the basics of the solution technique, since it is critical to many aspects of using the SimXpert crash workspace. If you are already familiar with explicit methods and how they differ from implicit methods, you may disregard this section. Method of Solution Although crash simulation software, including LS-DYNA uses the Explicit methods, a brief overview of both the Implicit and the Explicit Methods for the solution of dynamic response calculations is given below. Implicit Methods Most finite element programs use implicit methods to carry out a transient solution. Normally, they use Newmark schemes to integrate in time. If the current time step is step acceleration at the end of step n , a good estimate of the n + 1 will satisfy the following equation of motion: ext Ma' n + 1 + Cv' n + 1 + Kd' n + 1 = F n + 1 where: M C K ext Fn + 1 = = = = mass matrix of the structure damping matrix of the structure stiffness matrix of the structure vector of externally applied loads at step n+1 Introduction 3 Overview and Definition a' n + 1 v' n + 1 d' n + 1 n+1 = estimate of velocity at step n + 1 = estimate of displacement at step n + 1 = estimate of acceleration at step and the prime denotes an estimated value. The estimates of displacement and velocity are given by: d'n + 1 = d n + v n Δt + ( ( 1 – 2β )a n Δt ) ⁄ 2 + βa'n + 1 Δt v' n + 1 = v n + ( 1 – γ )a n Δt + γa'n + 1 Δt or 2 2 d'n + 1 = d * + βa'n + 1 Δt n * v' n + 1 = v n + γa' n + 1 Δt 2 where Δt is the time step, and β , and γ are constants. * * d n and v n are predictive and are based on values already calculated. The terms Substituting these values in the equation of motion results in Ma' n + 1 + C ( v* n + γa' n + 1 Δt ) + K ( d* n + βa' n + 1 Δt ) = F n + 1 or * * [ M + CγΔt + KβΔt ]a' n + 1 = F n + 1 – Cv n – Kd n 2 ext 2 ext The equation of motion may then be defined as M*a'n + 1 = F n + 1 residual The accelerations are obtained by inverting the M* matrix as follows: a'n + 1 = M* F n + 1 –1 residual This is analogous to decomposing the stiffness matrix in a linear static analysis. However, in dynamics, mass and damping terms are also present. 4 Overview and Definition Explicit Methods The equation of motion Ma n + Cv n + Kd n = F n can be rewritten as ext Ma n = F n – F n an = M Fn where: –1 ext int residual Fn Fn M ext int = = = = vector of externally applied loads vector of internal loads (e.g., forces generated by the elements and hourglass forces) Cv n + Kd n mass matrix The acceleration can be found by inverting the mass matrix and multiplying it by the residual load vector. In LS_DYNA, like any explicit finite element code, the mass matrix is lumped which results in a diagonal mass matrix. Since M is diagonal, its inversion is trivial, and the matrix equation is a set of independent equations for each degree of freedom, as follows: a ni = F ni residual ⁄ Mi The Leap-frog scheme is used to advance in time. The position, forces, and accelerations are defined at time level n , while the velocities are defined at time level n + 1 ⁄ 2 . Graphically, this can be depicted as: v n + 1 ⁄ 2 = v n – 1 ⁄ 2 + a n ( Δt n + 1 ⁄ 2 + Δt n – 1 ⁄ 2 ) ⁄ 2 d n + 1 = dn + v n + 1 ⁄ 2 Δt n + 1 ⁄ 2 Introduction 5 Overview and Definition n–1 d, F, a n–1§2 v n d, F , a n+1§2 v n+1 d, F , a time The Leap-frog scheme results in a central difference approximation for the acceleration, and is secondorder accurate in Δt . Explicit methods with a lumped mass matrix do not require matrix decompositions or matrix solutions. Instead, the loop is carried out for each time step as shown in the following diagram: Grid-Point Accelerations Leap-frog Integration in Time Grid-Point Velocities Grid-Point Displacements Element Formulation and Gradient Operator Element Stain Rates Constitutive Model and Integration Element Stresses Element Formulation and Divergence Operator Element Forces at Grid-Points CONTACT, Fluid-Structure Interaction, Force/Pressure boundaries + External Forces at Grid Points Explicit Time Step Implicit methods can be made unconditionally stable regardless of the size of the time step. However, for explicit codes to remain stable, the time step must subdivide the shortest natural period in the mesh. This means that the time step must be less than the time taken for a stress wave to cross the smallest element in the mesh. Typically, explicit time steps are 100 to 1000 times smaller than those used with implicit codes. However, since each iteration does not involve the costly formulation and decomposition of matrices, explicit techniques are very competitive with implicit methods. Because the smallest element in an explicit solution determines the time step, it is extremely important to avoid very small elements in the mesh. 6 Overview and Definition Courant Criterion Since it is impossible to do a complete eigenvalue analysis every cycle to calculate the timestep, an approximate method, known as the Courant Criterion, is used. This is based on the minimum time which is required for a stress wave to cross each element: Δt = SL/c where: Δt S L c = = = = Timestep Timestep scale factor (<1) Smallest element dimension Speed of sound in the element material For 1-D elements, the speed of sound is defined as: c = where: E⁄ρ E ρ = = Young’s modulus density Implicit vs. Explicit Analysis The time step for implicit solutions can be much larger than is possible for explicit solutions. This makes implicit methods more attractive for transient events that occur over a long time period and are dominated by low frequency structural dynamics. Explicit solutions are better for short, transient events where the effects of stress waves are important. There is, of course, an area where either method is equally advantageous and may be used. Explicit solutions have a greater advantage over implicit solutions if the time step of the implicit solution has to be small for some reason. This may be necessary for problems that include: • Material nonlinearity. A high degree of material nonlinearity may require a small time step for accuracy. • Large geometric nonlinearity. Contact and friction algorithms can introduce potential instabilities, and a small time step may be needed for accuracy and stability. • Those analyses where the physics of the problem demands a small time step (e.g. stress wave effects as in crash, crush, and impact analyses). Introduction 7 Overview and Definition • Material and geometric nonlinearity in combination with large displacements. Convergence in implicit methods becomes more difficult to achieve as the amount of nonlinearity for all types increases. Explicit Methods Have Increasing Advantages Over Implicit Methods as the Model Gets Bigger and Bigger. 8 Overview and Definition Parts and Geometry 9 Parts and Geometry 10 Parts and Geometry Parts and Geometry The geometry of the parts can be either created in SimXpert, or more likely imported from CAD program such as Catia, Pro/E. Units SimXpert interprets all dimensions and input data with respect to a system of units. It is important to set the appropriate units prior to importing any unitless analysis files (such as a Nastran Bulk Data file) or creating materials, properties, or loads. You can control the system of units by selecting Units Manager from the Tools menu. If you import a file that contains units, SimXpert will convert them into those specified in the Units Manager. Creating Geometry In the first release SimXpert has very limited geometry creation capabilities. It is possible to create curves and very simple surfaces. For the most part you will be importing geometry from an external source. The imported geometry can be edited in SimXpert Importing Geometry If the geometry of the part is available in a CATIA, parasolid, IGES, or STL file, it can be directly imported into the SimXpert Crash Workspace. Creating local coordinate systems Sometimes it is convenient to use local coordinate systems for specifying loads, and or boundary conditions. For example, a certain node may have a roller support placed in an inclined plane. A local Parts and Geometry 11 Parts and Geometry coordinate system with one of its axes normal to the inclined plane needs to be created and used to specify the fixity (SPC) of the displacement component along the direction normal to the inclined plane. CONSTRAINT Local coordinate systems can be in cartesian, cylindrical or spherical systems. Coordinate system created in SimXpert are represented by the following icons, corresponding to the method selected. Spherical Cylindrical Cartesian Coordinate System Cartesian Cylindrical Spherical Direction 1 x r r Direction 2 y Direction 3 z z φ 1-3 plane x-z (y=0) r-z ( θ =0) r- φ ( θ =0) θ θ You can create local coordinate systems by selecting Cartesian, Cylindrical, or Spherical from the Coordinate System group under the Geometry tab. There are numerous methods to create local coordinate systems in SimXpert: 12 Parts and Geometry 1. 3 Points: Three points are used to define the coordinate system. The first point corresponds to the location of origin. The second point defines the point on a specified axis and the third point defines a point in a specified plane. 2. Euler: Creates a coordinate system through three specified rotations about the axes of an existing coordinate system. 3. Normal: Creates a coordinate system with its origin at a point location on a surface. A specified axis is normal to the surface. 4. Two Vectors: Creates a coordinate system with its origin at a designated location and two of the coordinate frame axes are defined using vectors 5. Advanced: Location and orientation can be independently defined. There are 4 different ways to define the location of the origin of the coordinate system: Geometry, Point/Node, Coordinate System, and Center of Part. Further, the orientation can also be defined 3 ways: Global, Two Axes, and Coordinate System. Materials 13 Materials 14 Materials Materials SimXpert Crash Workspace supports most of the LS-DYNA material types, covering isotropic, anisotropic, orthotropic, and laminated material properties. These material properties can be dependent on temperature, strain, and strain rate. Here we briefly describe all the material types supported currently by the crash workspace. Please refer to “LS-DYNA Keyword Users’ Manual”, for a full description of all the LS-DYNA supported materials. Supported Materials MAT_ADD_EROSION This material model option provides a way of including failure in material models that do not allow failure and erosion. This option can also be applied to constitutive models with other failure and erosion criterion. Each of the criterion defined here is applied independently, and once any of them is satisfied, the element is deleted from further calculation. Field Title Desc TITLE_OPTION MID EXCL Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) for which this erosion definition applies. The Exclusion number. When any of the failure constants are set to the exclusion number, the associated failure criteria calculations are bypassed. For example, to prevent a material from going into tension, you may specify an unusual value for the exclusion number, e.g. 1234., set Pmin to 0.0 and all the remaining constants to 1234. The default value is 0.0, which eliminates all criteria from consideration that have their constants set to 0.0, or left blank. Pressure at failure, Pmin. Failure occurs when pressure is less than PFAIL PFAIL Materials 15 Materials Field SIGP1 SIGVM EPSP1 EPSSH SIGTH IMPULSE FAILTM Comments principal stress at failure, σmax. Failure occurs when the maximum principal stress exceeds SIGP1. Equivalent stress at failure, σvM. Failure occurs when the von Mises equivalent stress exceeds SIGVM. Principal strain at failure, εmax. Failure occurs when the maximum principal strain exceeds EPSP1. Shear strain at failure, γmax. Failure occurs when the maximum shear strain exceeds EPSSH. Threshold stress, σ0 (used in evaluating the Tuler-Butcher criterion) Stress impulse for failure, Kf. Failure occurs when the Tuler-Butcher criterion exceeds IMPULSE. Failure time. When the analysis time exceeds the failure time, the material is removed. Remarks: 1. This failure model only applies to the 2D and 3D solid elements with one point integration. See Also: • LS-DYNA Keyword User’s Manual MAT_ANISOTROPIC_ELASTIC This material model is used for modeling elastic anisotropic behavior of solids. Field Title Desc Contents Unique name identifying the material model. Optional description of the material model. 16 Materials Field TITLE_OPTION MID RO C11... C66 AOPT XP, YP, ZP A1, A2, A3 D1, D2, D3 V1, V2, V3 BETA REF Contents If selected, the material Title will be exported to LS-DYNA Material identification number. (Integer > 0) Mass density. Anisotropic constitutive matrix components Material axes option Coordinates for point P (for AOPT= 1 and 4) Components of a vector a (for AOPT=2) Components of a vector d (for AOPT=2) Components of a vector v (for AOPT= 3 and 4) Material angle in degrees (for AOPT= 3) Use Reference geometry to initialize the stress tensor See Also: • LS-DYNA Keyword User’s Manual MAT_BLATZ-KO_RUBBER This is used to model nearly incompressible continuum rubber. The Poisson’s ratio is fixed to 0.463 Field Title Desc TITLE_OPTION MID RO G REF Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Shear modulus Use reference geometry to initialize the stress tensor (0 =off; 1 = on) See Also: • LS-DYNA Keyword User’s Manual Materials 17 Materials MAT_CABLE_DISCRETE_BEAM This material model is used to define elastic cables realistically. Field Title Desc TITLE_OPTION MID RO E LCID F0 TMAXF0 TRAMP IREAD OUTPUT Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass density Young’s modulus (if value greater than zero), or stiffness (if value smaller than zero) Load curve Id for loading (engineering stress vs. engineering strain) Initial Tensile Force Time for which pre-tension force will be held Ramp-up time for pre-tension force Flag: If value greater than zero, use the value of OUTPUT from card 2. Flag = 1 to output axial strain Remarks: 1. The force, F generated by the cable is nonzero if the cable is in tension. The force is given by: F = max (F0 + KΔL, 0.) where K is the stiffness, and ΔL is the change in length. If E is greater than zero, K is defined as: K = (E X cross sectional area)/ (Initial length - offset) 2. A constant force element can be obtained by setting: F0 > 0, and K = 0 18 Materials 3. The cross section, and offset are defined on the *SECTION or *ELEMENT cards. For a slack cable, the offset should be input as a negative value. For an initial tensile force, the offset should be positive. 4. If a load curve is specified, the Young’s modulus will be ignored, and the load curve will be used instead. The points on the load curve are defined as engineering stress vs. engineering strain. The unloading behavior follows the loading. See Also: • LS-DYNA Keyword User’s Manual MAT_ELASTIC This LS-DYNA material model (001) is an isotropic elastic material available for beam, shell and solid elements. Field Title Desc TITLE_OPTION MID RO E PR DA DB Contents Unique name identifying the material model. Optional description of the material model. If selected, the material Title will be exported to LS-DYNA Material identification number. (Integer > 0) Mass density. Young’s modulus Poisson’s ratio Axial damping factor (used in Belytscho-Schwer beam type 2 only) Bending damping factor (used in Belytscho-Schwer beam type 2 only) Remarks: 1. The axial and bending damping factors are used to damp down numerical noise. The update of the force resultants, F i , and moment resultants, M i , includes the damping factors: Materials 19 Materials Fi n+1 n DA n+1⁄2 = F i + 1 + ------- ΔF i Δt Mi n+1 DB n n+1⁄2 = M i + 1 + ------- ΔM i Δt See Also: • LS-DYNA Keyword User’s Manual MAT_ELASTIC_FLUID This LS-DYNA material model (001) is an isotropic elastic material available for solid elements. Field Title Desc TITLE_OPTION MID RO E PR DA DB K VC CP Contents Unique name identifying the material model. Optional description of the material model. If selected, the material Title will be exported to LS-DYNA Material identification number. (Integer > 0) Mass density. Young’s modulus Poisson’s ratio Axial damping factor (used in Belytscho-Schwer beam type 2 only) Bending damping factor (used in Belytscho-Schwer beam type 2 only) Bulk Modulus (for fluid option) Tensor viscosity coefficient (between 0.1 and 0.5) Cavitation pressure (default = 1.0E+20) 20 Materials Remarks: 1. The axial and bending damping factors are used to damp down numerical noise. The update of the force resultants, F i , and moment resultants, M i , includes the damping factors: Fi n+1 n DA n+1⁄2 = F i + 1 + ------- ΔF i Δt Mi n+1 DB n n+1⁄2 = M i + 1 + ------- ΔM i Δt 2. Fluid like behavior is obtained with the following relationship between bulk modulus, K, and pressure rate, p: E K = ----------------------3 ( 1 – 2υ ) ·· p = – Kε ii A tensor viscosity VC, if used, which acts only on the deviatoric stresses See Also: • LS-DYNA Keyword User’s Manual MAT_ELASTIC_PLASTIC_THERMAL Temperature dependent material coefficients can be defined using this material type. A minimum of two temperature points are needed, and a maximum of eight can be defined. Field Title Desc TITLE_OPTION Comments Unique name identifying material model Optional description of the material model If selected material title option is used Materials 21 Materials Field MID RO YM_LC PR_LC A_LC SIGY_LC V_LC Mass Density of the material Comments Material identification number (Integer > 0) Load curve defining Young’s modulus Vs. Temperatures. Load curve defining Poisson’s raito Vs. Temperatures. Load curve defining the coefficent of thermal expansion Vs. Temperatures. Load curve defining Yield stressVs. Temperatures. Load curve defining the plastic hardening modulus Vs. Temperatures. See Also: • LS-DYNA Keyword User’s Manual MAT_ISOTROPIC_ELASTIC_PLASTIC Defines an isotropic plasticity material with isotropic hardening. This is a very low cost plasticity model, suitable for 3D solids and plane stress elements. If used in shell elements, this material model leads to inaccurate shell thickness updates and stresses after yielding. Field Name Desc Fields: MID RO G SIGY ETAN BULK Contents Unique name identifying the material model. Optional description of the material model. Material identification number. (Integer > 0) Mass density. Shear modulus. Yield Stress. Plastic hardening modulus Bulk modulus 22 Materials Remarks: 1. In the plane stress implementation for shell elements, a one-step radial return approach is used to scale the Cauchy stress tensor if the state of stress exceeds the yield surface. See Also: • LS-DYNA Keyword User’s Manual MAT_LOW_DENSITY_FOAM This material is used to model highly compressible low density foams. Its main applications are for seat cushions and padding on the Side Impact Dummies (SID). Optionally, a tension cut-off failure can be defined. Field Name Desc Fields: MID RO E LCID TC HU BETA Contents Unique name identifying the material model. Optional description of the material model. Material identification number. (Integer > 0) Mass density. Young’s modulus Load Curve Id for nominal stress versus strain Tension cut-off stress Hysteric unloading factor (between 0 and 1). Default is 1 (no energy dissipation) Decay constant (β) for creep in unloading Materials 23 Materials Field DAMP Contents Viscous damping coefficient (0.05< recommended value < 0.50) to model damping effects. LT. 0: the absolute value of DAMP is used as the load curve which defines the damping coefficient as a function of the maximum strain in compression εmax (see Remark 1). In tension, the damping constant is set to the value corresponding to the strain at 0. SHAPE FAIL Shape factor for unloading. Active for non-zero values of the Hysteric unloading factor (HU) Failure option, after cut-off stress reached. = 0, Tensile stress remains at cut-off value = 1, Tensile stress is reset to zero BVFLAG Bulk viscosity activation flag = 0, No bulk viscosity (recommended, default) = 1, Bulk viscosity active ED BETA1 KCON REF Young’s relaxation modulus Ed (optional), for rate effects. Optional Decay constant β1 Stiffness coefficient for contact interface stiffness. If undefined, the maximum slope in the stress vs. strain curve is used. Use Reference geometry to initialize the stress tensor. The reference geometry is defined by the keyword: *INITIAL_FOAM_REFERENCE_GEOMETRY. = 0, Off = 1, On Remarks: The compressive behavior is illustrated in Figure 1 where hysteresis on unloading is shown. This behavior under uniaxial loading is assumed not to significantly couple in the transverse directions. In tension the material behaves in a linear fashion until tearing occurs. Although the implementation may be somewhat unusual, it was motivated by Storakers (1986). The model uses tabulated input data for the loading curve where the nominal stresses are defined as a function of the elongations, εi , which are defined in terms of the principal stretches, λ i , as: εi = λi – 1 24 Materials The stretch ratios are found by solving for the eigenvalues of the left stretch tensor, V ij , which is obtained via a polar decomposition of the deformation gradient matrix, F ij . Recall that, F ij = R ik Ukj = V ik Rkj The update of Vij follows the numerically stable approach of (Taylor and Flanagan 1989). After solving for the principal stretches, we compute the elongations and, if the elongations are compressive, the corresponding values of the nominal stresses, τi are interpolated. If the elongations are tensile, the nominal stresses are given by τ i = Eε i and the Cauchy stresses in the principal system become τi σ i = --------λ i λk The stresses can now be transformed back into the global system for the nodal force calculations. Additional Remarks: 1. When hysteretic unloading is used the reloading will follow the unloading curve if the decay constant, β , is set to zero. If β is nonzero the decay to the original loading curve is governed by the expression: 1. – e – βt 2. The bulk viscosity, which generates a rate dependent pressure, may cause an unexpected volumetric response and, consequently, it is optional with this model. 3. The hysteretic unloading factor results in the unloading curve to lie beneath the loading curve as shown below. This unloading provide energy dissipation which is reasonable in certain kinds of foam. 4. Note that since this material has no effective plastic strain, the internal energy per initial volume is written into the output databases. 5. Rate effects are accounted for through linear viscoelasticity by a convolution integral of the form σ ij = r ∂ε kl g ijkl ( t – τ ) -------- dτ 0 ∂τ t where g ijkl ( t – τ ) is the relaxation function. The stress tensor augments the stresses determined from the foam. Consequently, the final stress, σ ij is taken as the summation of the two contributions: σ ij = σ ij + σ ij f r Materials 25 Materials Since we wish to include only simple rate effects, the relaxation function is represented by one term from the Prony series: N g ( t ) = α0 + given by, m=1 am e – βt g ( t ) = Ed e –β1 t This model is effectively a Maxwell fluid which consists of a damper and spring in series. We characterize this in the input by a Young's modulus, Ed , and decay constant, β 1 .The formulation is performed in the local system of principal stretches where only the principal values of stress are computed and triaxial coupling is avoided. Consequently, the one-dimensional nature of this foam material is unaffected by this addition of rate effects. The addition of rate effects necessitates twelve additional history variables per integration point. The cost and memory overhead of this model comes primarily from the need to “remember” the local system of principal stretches. Figure 1 Behavior of the Low Density Urethane Foam Model 6. The time step size is based on the current density and the maximum of the instantaneous loading slope, E, and ECON. If ECON is undefined the maximum slope in the loading curve is used instead. See Also: • LS-DYNA Keyword User’s Manual 26 Materials MAT_MOONEY_RIVLIN_RUBBER This LS-DYNA material is used to define material properties for a two-parameter material model for rubber. Field Name Desc Fields: MID PR RO A B REF Contents Unique name identifying the material model. Optional description of the material model. Material identification number. (Integer > 0) Poisson’s ratio. Mass density. Mooney Rivlin Constant, A Mooney Rivlin Constant, B Use Reference geometry to initialize the stress tensor =0, Off = 1, On SGL SW ST LCID Specimen Gauge length, l0 Specimen width Specimen thickness Load Curve Id defining the force versus actual length change (ΔL) in the gauge length. Remarks: The strain energy density function is defined as: W = A ( I – 3 ) + B ( II – 3 ) + C ( III –2 – 1 ) + D ( III – 1 ) 2 Materials 27 Materials C = 0.5A + B D = A(5ν - 2) + B(11ν -5)/(2(1 - 2ν)) ν = Poisson’s ratio 2(A + B) = Shear modulus of linear elasticity I, II, III are the three invariants of the Cauchy-Green Tensor The load curve definition that provides the uniaxial data should give the change in gauge length, Δ L , versus the corresponding force. In compression both the force and the change in gauge length must be specified as negative values. In tension the force and change in gauge length should be input as positive values. The principal stretch ratio in the uniaxial direction, λ 1 , is then given by L 0 + ΔL λ 1 = -----------------L0 with L0 being the initial length and L being the actual length. Alternatively, the stress versus strain curve can also be input by setting the gauge length, thickness, and width to unity (1.0) and defining the engineering strain in place of the change in gauge length and the nominal (engineering) stress in place of the force (Figure 2). 28 Materials Figure 2 Uniaxial Specimen for Experimental Data The least square fit to the experimental data is performed during the initialization phase and is a comparison between the fit and the actual input is provided in the printed file. It is a good idea to visually check to make sure that it is acceptable. The coefficients A and B are also printed in the Dyna output file. The stress versus strain curve can used instead of the force versus the change in the gauge length by setting the gauge length, thickness, and width to unity (1.0) and defining the engineering strain in place of the change in gauge length and the nominal (engineering) stress in place of the force (Figure 3). Figure 3 Experimental Data from Uniaxial Specimen See Also: • LS-DYNA Keyword User’s Manual Materials 29 Materials MAT_NONLOCAL Defines failure criterion to be dependent on the state of the material within a radius of influence which surrounds the integration point. With this failure model, the mesh size sensitivity of failure is greatly reduced, giving better convergence to a unique solution as the mesh is refined. Field Title Desc TITLE_OPTION MID PID P Q L NFREQ Comments Unique name identifying material model Optional description of the material model If selected material title option is used Non local Material identification number (Integer > 0) Part Id for non local material Exponent of weighting function. A typical value might be 8., depending on the choice of the value for L. Exponent of weighting function. A typical value might be 2. Characteristic length. This length should span a few elements Number of time steps before updating neighbors. Since the nearest neighbor search can add significant computational time, NFREQ should be set to value of 10 to 100. History variable Ids for non local treatment Coordinate of point on symmetry plane Coordinate of a point along the normal vector NL1,,, NL8 XC1, YC1, ZC1 XC2, YC2, ZC2 See Also: • LS-DYNA Keyword User’s Manual 30 Materials MAT_ORTHOTROPIC_ELASTIC This LS_Dyna material model (002) is an orthotropic elastic material available for solids, shells, and thick shells. Field Title Desc TITLE_OPTION MID RO EA EB EC PRBA PRCA PRCB GAB GBC GCA AOPT G SIGF XP, YP, ZP Contents Unique name identifying the material model. Optional description of the material model. If selected, the material Title will be exported to LS-DYNA Material identification number. (Integer > 0) Mass density. Young’s modulus in a-direction Young’s modulus in b-direction Young’s modulus in c-direction Poisson’s ratio (νba) Poisson’s ratio (νca) Poisson’s ratio (νcb) Shear modulus (Gab) Shear modulus (Gbc) Shear modulus (Gca) Material axis option Shear modulus for frequency dependent damping Limit stress for frequency independent frictional damping Coordinates for point P (for AOPT= 1 and 4) Materials 31 Materials Field A1, A2, A3 D1, D2, D3 V1, V2, V3 BETA REF Remarks: Contents Components of a vector a (for AOPT=2) Components of a vector d (for AOPT=2) Components of a vector v (for AOPT= 3 and 4) Material angle in degrees (for AOPT= 3) Use Reference geometry to initialize the stress tensor The material law that relates stresses to strains is defined as: C = T CL T ˜ ˜ ˜ ˜ where T is a transformation matrix, and C L is the constitutive matrix defined in terms of the material ˜ ˜ T constants of the orthogonal material axes, defined as: a , b , and c . The inverse of CL for the orthotropic case is ˜ 1- ν ba ν ca ----- – ------- – ------- 0 Ea Eb Ec ν ab 1 ν cb – ------- ----- – ------- 0 Ea Eb Ec CL ˜ –1 0 0 0 0 0 0 0 νac ν bc 1 – ------- – ------- ----Ea Eb Ec = 0 0 0 0 0 0 0 0 0 0 1-------- 0 G ab 10 -------- 0 G bc 0 10 -------G ca Note that ν ab ν ba ν ca ν ac ν cb ν bc ------- = ------- , ------- = -------, ------- = ------Ea Eb Ec E a Ec Eb 32 Materials The frequency independent damping is obtained by having a spring and slider in series as shown in the following sketch: G σ fric This option applies only to orthotropic solid elements and affects only the deviatoric stresses. See Also: • LS-DYNA Keyword User’s Manual MAT_PIECEWISE_LINEAR_PLASTICITY Defines elasto-plastic material with an arbitrary stress versus strain curve and arbitrary strain rate dependency. Also, failure based on a plastic strain or a minimum time step size can be defined. Field Name Desc Fields: MID E PR RO SIGY ETAN Contents Unique name identifying the material model. Optional description of the material model. Material identification number. (Integer > 0) Young’s modulus. (Real > 0.0 or blank) Poisson’s ratio. Mass density. Yield Stress. Tangent modulus (ignored if LCSS.GT. 0 is defined) Materials 33 Materials Field FAIL Failure Flag Contents LT. 0: User defined failure subroutine is called to determine failure EQ. 0.0: Failure not considered GT. 0.0: Plastic strain to failure. When the plastic strain reaches this value, the element is deleted from the calculation. TDEL C P LCSS Minimum time step size for automatic element deletion Strain rate parameter, C Strain rate parameter, P Load Curve Id or Table Id defining effective stress versus effective plastic strain. The tableId defined for each strain rate a value of load curve Id giving the stress versus effective plastic strain for that rate. Load Curve Id defining strain rate scaling effect on yield stress Formulation for rate effects =-1, Cowper-Symnods with deviatoric strain rate rather than total = 0, Scale yield stress = 1, Viscoplastic formulation Remarks: The stress strain behavior may be treated by a bilinear stress strain curve by defining the tangent modulus, ETAN. The most general approach is to use the table definition (LCSS) discussed below. Three options to account for strain rate effects are possible. 1. Strain rate may be accounted for using the Cowper and Symonds model which scales the yield stress with the factor LCSR VP · ε 1⁄p 1 + --- C · where, ε is the strain rate · ε = · · ε ij ε ij If VP=-1, the deviatoric strain rates are used instead. If the viscoplastic option is active, VP=1.0, and if SIGY is > 0 then the dynamic yield stress is computed from the sum of the static stress, 34 Materials σ y ( ε eff ) which is typically given by a load curve ID, and the initial yield stress, SIGY, multiplied by the Cowper-Symonds rate term as follows: p ·p σ y ( ε eff, ε eff ) s p σ y ( ε eff ) s p = · ε eff ------- + SIGY ⋅ C p 1⁄p where the plastic strain rate is used. If SIGY=0, the following equation is used instead where the static stress σ y ( ε eff ) must be defined by a load curve: p ·p σ y ( ε eff, ε eff ) s p σ y ( ε eff ) s p = · ε eff 1 + ------- C p 1⁄p This latter equation is always used if the viscoplastic option is off. 2. For complete generality a load curve (LCSR) to scale the yield stress may be input instead. In this curve the scale factor versus strain rate is defined. 3. If different stress versus strain curves can be provided for various strain rates, the option using the reference to a table (LCSS) can be used. See figure below. Materials 35 Materials Figure 4 Rate effects may be accounted for by defining a table of curves. If a table Id is specified a curve Id is given for each strain rate. Intermediate values are found by interpolating between curves. Effective plastic strain versus yield stress is expected. If the strain rate values fall out of range, extrapolation is not used; rather, either the first or last curve determines the yield stress depending on whether the rate is low or high, respectively. 4. A fully viscoplastic formulation is optional (variable VP) which incorporates the different options above within the yield surface. An additional cost is incurred over the simple scaling but the improvement in results can be dramatic. See Also: • LS-DYNA Keyword User’s Manual 36 Materials MAT_PLASTIC_KINEMATIC Defines elasto-plastic material with isotropic and kinematic hardening with or without rate effects. Field Name Desc Fields: MID E PR RO SIGY ETAN BETA Contents Unique name identifying the material model. Optional description of the material model. Material identification number. (Integer > 0) Young’s modulus. (Real > 0.0 or blank) Poisson’s ratio. Mass density. Yield Stress. Tangent modulus Hardening parameter = 0: Kinematic hardening = 1: Isotropic hardening 1 < BETA > 0: Combined hardening SRC SRP FS VP Strain rate parameter, C, for Cowper Symonds strain rate model. If zero, rate effects are ignored. Strain rate parameter, P, for Cowper Symonds strain rate model. If zero, rate effects are ignored. Failure strain for eroding elements Formulation for rate effects: = 0, Scale yield stress (default) = 1, Viscoplastic formulation Materials 37 Materials Remarks: Figure 5 Elastic-plastic behavior with kinematic and isotropic hardening where l0 and l are respectively undeformed and deformed lengths of uniaxial tension specimen, and Et is the slope of the bilinear stress vs. strain curve. Strain rate may be accounted for using the Cowper and Symonds model which scales the yield stress with the factor · ε 1⁄p 1 + --- C · where, ε is the strain rate 38 Materials · ε = · · ε ij ε ij A fully viscoplastic formulation is optional which incorporates the Cowper and Symonds formulation within the yield surface. Although an additional computational cost is incurred, the improvement in the results can be substantial. To ignore strain rate effects, set both SRC and SRP to zero. See Also: • LS-DYNA Keyword User’s Manual MAT_POWER_LAW_PLASTICITY Defines an isotropic plasticity material model with rate effects which uses a power law for hardening. Field Name Desc Fields: MID RO E PR K N SRC SRP Contents Unique name identifying the material model. Optional description of the material model. Material identification number. (Integer > 0) Mass density. Young’s modulus. (Real > 0.0 or blank) Poisson’s ratio. Strength coefficient Hardening exponent Strain rate parameter, C. If zero, rate effects are ignored. Strain rate parameter, P. If zero, rate effects are ignored. Materials 39 Materials Field SIGY VP Contents Yield Stress (optional). Generally this parameter is not necessary (See Remarks) Formulation for rate effects: = 0, Scale yield stress (default) = 1, Viscoplastic formulation Remarks: The yield stress, σy is a function of plastic strain, and obeys the following equation: σ y = k ε n = k ( ε yp + ε p ) n · where, ε yp is the strain rate to yield, and ε p is the effective plastic strain (logarithmic). The parameter SIGY governs how the strain to yield is identified. If SIGY is set to zero, the strain to yield is found by solving for the intersection of the linear elastic loading with the strain hardening equation: σ = Eε σ =kεn which gives the elastic strain at yield as: 1 ε yp E n −1 = k If SIGY is set to nonzero, and greater than 0.02 then: 1 ε yp σ n = y k 40 Materials Strain rate is accounted for using the Cowper-Symonds model which scales the yield stress with the following factor: ε 1+ C 1 P · where ε is the strain rate. A fully viscoplastic formulation is optional with this model which incorporates the Cowper-Symonds formulation within the yield surface. Although an additional cost is incurred, the improvement in results can be substantial. See Also: • LS-DYNA Keyword User’s Manual MAT_RIGID This material model is used to model parts made from rigid materials. Also, the coupling of a rigid body with MADYMO, and CAL3D can be defined via this material. Alternatively, a VDA surface can be attached as surface to model the geometry, e.g., for the tooling in metal-forming applications. Also, global and local constraints on the mass center can be optionally defined. Optionally, a local consideration for output and user-defined airbag sensors can be chosen. Field Title Desc TITLE_OPTION MID Contents Unique name identifying the material model. Optional description of the material model. If selected, the material Title will be exported to LS-DYNA Material identification number. (Integer > 0) Materials 41 Materials Field RO E PR N COUPLE ALIAS CMO Mass density Contents Young’s modulus. (Real > 0.0 or blank) Poisson’s ratio MADYMO3D coupling flag. Coupling Option VDA Surface alias Name Center of mass constraint option =1, Constraints applied in global directions =0, No constraints =-1, Constraints applied in local directions CON1 First constraint parameter =0, No constraints =1, Constrained x displacement =2, Constrained y displacement =3, Constrained z displacement =4, Constrained x and y displacements =5, Constrained y and z displacements =6, Constrained z and x displacements =7, Constrained x, y, and z displacements 42 Materials Field CON2 Second constraint parameter =0, No constraints =1, Constrained x rotation =2, Constrained y rotation =3, Constrained z rotation Contents =4, Constrained x and y rotations =5, Constrained y and z rotations =6, Constrained z and x rotations =7, Constrained x, y, and z rotations LCO A1-V3 Local coordinate system for output The components of two vectors a and v fixed in the rigid body for output. Remarks: 1. A rigid material provides a convenient way of turning one or more parts comprised of beams, shells, or solid elements into a rigid body. Approximating a deformable body as rigid is a preferred modeling technique in many real world applications. For example, an engine block in a car crash simulation can be treated as rigid. Elements belonging to a rigid material are bypassed in the element processing and no storage is allocated for storing history variables. Consequently, using a rigid material is very cost efficient. 2. The inertial properties are calculated from the geometry of the constituent elements and the density RO as specified on the MAT_RIGID. 3. The initial velocity of a rigid material is calculated from the initial velocity of the constituent grids. 4. A rigid body can be made up of disjoint meshes. All elements that are part of a rigid body will move together as one rigid, even if they are disjoint. 5. Motion control for a rigid material can be defined using the BOUNDARY_SPC entry. The SPC must be applied to one grid point only. 6. Load control for a rigid material can be defined using the FORCE and MOMENT entries. These loads can be applied to any grid point that belongs to the rigid body. The forces and moments acting on the grid points will be accumulated and applied to the rigid body. 7. If no constraints are specified for the rigid material (CMO=0) the nodes belonging to the rigid material are scanned to determine constraints of the rigid material in global directions. If constraints are specified for the rigid material (CMO equal to +1 or –1), the nodes belonging to the rigid material are not scanned Materials 43 Materials 8. Constraint directions for rigid materials (CMO equal to +1 or –1) are fixed, that is, not updated, with time. See Also: • LS-DYNA Keyword User’s Manual MAT_SEATBELT This material model is used to define the stretch characteristics and mass properties for seat belts. Field Title Desc TITLE_OPTION MID MPUL LLCID ULCID LMIN Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass per unit length Load curve Id for loading (Force vs. engineering strain) Load curve Id for unloading (Force vs. engineering strain) Minimum length for elements connected to slip rings and retractors Remarks: 1. The Load curves for loading and unloading should start at the origin (0, 0), and contain positive force and strain values only. The belt material is tension only, with zero forces being calculated whenever the strain becomes negative (compressive). The first nonzero point on the loading curve defines the initial yield point of the material. On unloading, the unloading curve is shifted along the strain axis until it crosses the loading curve at the yield point from which unloading starts. If the initial yield has not yet exceeded, or the origin of the (shifted) unloading curve is at negative strain, the original loading curve will be used for both loading and unloading. If the strain is less than the strain at the origin of the unloading curve, the belt is slack, and no force is generated. Otherwise, forces will be determined by the unloading curve for unloading, and reloading until the strain again exceeds yield after which the loading curve will again be used. 44 Materials 2. A small amount of damping is automatically included, to reduce high frequency oscillation. The damping force, D opposes the relative motion of the nodes, and is limited by stability: D = (0.1 X Mass X Relative velocity)/(Time step size) The magnitude of the damping force is limited to one-tenth of the force calculated from the force vs. strain relationship, and is zero when the belt is slack. Damping forces are not applied to elements attached to slip rings and retractors. See Also: • LS-DYNA Keyword User’s Manual MAT_SOIL_AND_FOAM This simple material model works similar to fluid. It should be used only in situations when soils and foams are confined within a structure or when geometric boundaries are present. Field Title Desc TITLE_OPTION MID RO G BULK A0, A1, A2 PC VCR Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Shear modulus Bulk modulus for unloading Yield function constants Pressure cut off for tensile fracture Volumetric crushing option: 0.0: on, 1.0: loading and unloading paths are the same Materials 45 Materials Field REF LCID Comments use reference geometry to initialize the pressure Load curve Id defining pressure vs. volumetric strain Remarks: 1. Pressure is positive in compression 2. Volumetric strain is given by the natural log of the relative volume and is negative in compression 3. Relative volume is the ratio of current volume to the initial volume at the start of the calculation 4. If the pressure drops below the cutoff value specified, it is reset to that value See Also: • LS-DYNA Keyword User’s Manual MAT_VISCOELASTIC This material model is used to define viscoelastic behavior for beams (Hughes-Liu), shells, and solids Field Title Desc TITLE_OPTION MID RO BULK G0 GI BETA Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Bulk modulus for unloading Short time shear modulus long time (Infinite) Shear modulus Decay constant Remarks: 1. The shear relaxation behavior is described by [Hermann and Peterson, 1968]: G ( t ) = GI + ( G0 – GI )e – βt 46 Materials See Also: • LS-DYNA Keyword User’s Manual MAT_HIGH_EXPLOSIVE_BURN This material model is used to input the detonation properties of high explosive materials. Field Title Desc TITLE_OPTION MID RO D PCJ BETA Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Detonation Velocity Chapman-Jouget pressure Beta burn flag 0: Beta and programmed burn 1: Beta burn only 2: Programmed burn only K G SIGY Bulk Modulus (Beta = 2) Shear Modulus (Beta = 2) Yield Stress (Beta = 2) See Also: • LS-DYNA Keyword User’s Manual Materials 47 Materials MAT_NULL The use of this material model allows equations of state without computing deviatoric stresses. Field Title Desc TITLE_OPTION MID RO PC MU TEROD CEROD YM PR Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Pressure Cutoff Dynamic Viscosity Coefficient Relative Volume for Erosion in Tension Relative Volume for Erosion in Compression Young’s Modulus (used for null beams and shells only) Poisson’s ratio (used for nul beams and shells only) See Also: • LS-DYNA Keyword User’s Manual 48 Materials MAT_ELASTIC_PLASTIC_HYDRO This material model is used to model an elastic-plastic hydrodynamic material. Field Title Desc TITLE_OPTION MID RO G SIGY EH PC FS LCID Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Shear Modulus Yield Stress Plastic hardening modulus Pressure Cutoff Failure strain for Erosion Load curve Id defining pressure vs. volumetric strain See Also: • LS-DYNA Keyword User’s Manual Materials 49 Materials MAT_ELASTIC_PLASTIC_HYDRO_SPALL This material model is used to model an elastic-plastic hydrodynamic material with spall to represent splitting, cracking, and failure under tensile loads. Field Title Desc TITLE_OPTION MID RO G SIGY EH PC FS A1 A2 SPALL LCID Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Shear Modulus Yield Stress Plastic hardening modulus Pressure Cutoff Failure strain for Erosion Linear Pressure Hardening Coefficient Quadratic Pressure Hardening Coefficient Spall Type Load curve Id defining pressure vs. volumetric strain See Also: • LS-DYNA Keyword User’s Manual 50 Materials MAT_STEINBERG This material model is used to model materials deforming at very high strain rate for use with solid elements. The yield strength is a function of temperature and pressure. Field Title Desc TITLE_OPTION MID RO G0 SIG0 BETA N GAMA SIGM B BP H F A TM0 Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Basic shear modulus Yield Stress, σ0 Parameter β, used in the equation defining Yield Strength Parameter n, used in the equation defininig Yield Strength Initial Plastic Strain γi σm Parameter b, used in the equation defininig Yield Strength Parameter b' , used in the equation defininig Yield Strength Parameter h, used in the equation defininig Yield Strength Parameter b, used in the equation defininig Yield Strength Atomic Weight Melting Temperature Materials 51 Materials Field GAM0 SA PC SPALL Comments Yield Stress equation Parameter, Gama_0 Melting Temperature equation Parameter, a Pressure Cutoff Spall Type 0: Default set to 2.0 1: P >= PC 2: if σmax >= -PC, element spalls and tension, p < 0, is never allowed 3: P< -PC, element spalls and tension, p < 0, is never allowed RP FLAG NMN NMX ECi Melting Temperature equation parameter, r' Set 1 for μ coefficients for the cold compression energy fit Optional minimum value for μ or η Optional maximum value for μ or η Cold Compression Energy coefficients See Also: • LS-DYNA Keyword User’s Manual 52 Materials MAT_STEINBERG_LUND This material model is used to input the properties of a Steinberg and Lund [1999].material model for including the strain rate effect. Field Title Desc TITLE_OPTION MID RO G0 SIG0 BETA N GAMA SIGM B BP H F Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Basic shear modulus Yield Stress, σ0 Parameter β, used in the equation defininig Yield Strength Parameter n, used in the equation defininig Yield Strength Initial Plastic Strain γi σm Parameter b, used in the equation defininig Yield Strength Parameter b' , used in the equation defininig Yield Strength Parameter h, used in the equation defininig Yield Strength Parameter b, used in the equation defininig Yield Strength Materials 53 Materials Field A TM0 GAM0 SA PC SPALL Atomic Weight Melting Temperature Comments Yield Stress equation Parameter, Gama_0 Melting Temperature equation Parameter, a Pressure Cutoff Spall Type 0: Default set to 2.0 1: P >= PC 2: if σmax >= -PC, element spalls and tension, p < 0, is never allowed 3: P< -PC, element spalls and tension, p < 0, is never allowed RP FLAG NMN NMX ECi UK C1 C2 YP YA YM Melting Temperature equation parameter, r' Set 1 for μ coeeficients for the cold compression energy fit Optional minimum value for μ or η Optional maximum value for μ or η Cold Compression Energy coefficients Activation Energy for rate dependent model Exponent prefactor in rate dependent model Coefficient of drag term rate dependent model Peierls stress for rate dependent model Ahtermal yield stress for rate dependent model Work hardening max for rate dependent model See Also: • LS-DYNA Keyword User’s Manual 54 Materials MAT_ISOTROPIC_ELASTIC_FAILURE This material model is used to define the properties of a non-iterative plasticity model with simple plastic strain failure criteria. Field Title Desc TITLE_OPTION MID RO G SIGY ETAN BULK EPF PRF REM Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Shear Modulus Yield Stress Plastic Hardening Modulus Bulk Modulus Plastic Failure Strain Failure Pressure Element Erosion option 0: Eroded at failure 1: no removal of element, (except if TERM = 1, and element time step size falls below Δt) TREM Δt for element removal 0: Δt is not considered 1: yes, if element time step size falls below Δt Materials 55 Materials See Also: • LS-DYNA Keyword User’s Manual MAT_SOIL_AND_FOAM_FAILURE This material model is used to define the material properties for a soil and foam model. This material model works similar to fluid, and should be used only in situations when soils and foams are confined within a structure or when geometric boundaries are present.In this material model, the material loses its ability to carry tension when the pressure exceeds the failure pressure. Field Title Desc TITLE_OPTION MID RO G BULK A0, A1, A2 PC VCR Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Shear Modulus Bulk Modulus for unloading Plastic Yield Function Constants Pressure Cutoff for Tensile Fracture Volumetric Crushing Option 0: On 1: Loading and unloading paths are the same 56 Materials Field REF Comments Use reference geometry to initialize pressure 0: Off 1:On LCID Load Curve Id defining pressure vs. volumetric strain See Also: • LS-DYNA Keyword User’s Manual MAT_JOHNSON_COOK The Johnson-Cook material model is a strain and temperature sensitive plasticity model. It is sometimes used for materials with a large variation in the strain rate, and/or undergoing softening due to plastic heating. Field Title Desc TITLE_OPTION MID RO G Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Shear Modulus Materials 57 Materials Field E PR DTF VP Comments Young’s Modulus (for shell elements only) Poisson’s Ratio (for shell elements only) Minimum Time step for Automatic Shell Element Deletion Formulation for Rate Effects 0: Scale Yield Stress 1: ViscoPlastic Formulation RATEOP Optional forms of strain-rate term: .EQ. 0: Log-Linear Johnson-Cook (default) .EQ. 1: Log-Quadratic Huh-Kang (2 parameters) .EQ. 2: Exponential Allen-Rule_jones .EQ. 3: Exponential Cowper-Symonds (2 parameters) A, B, N, C, M TM TR EPSO CP PC SPALL Constants to define the flow stress equation Melt Temperature Room Temperature Effective Plastic Strain Rate depends on Time Unit Specific Heat Pressure Cutoff (Pmin< 0.0) Spall Type 0: Default set to 2.0 1: P >= PC 2: if σmax >= -PC, element spalls and tension, p < 0, is never allowed 3: P< -PC, element spalls and tension, p < 0, is never allowed IT Plastic Strain Iteration 0: No Iteration 1: Accurative Iteration Solution Di C2/P Failure Parameters Optional strain-rate parameter for Huh-Kang (C2), or Cowper-Symonds (P) forms. 58 Materials See Also: • LS-DYNA Keyword User’s Manual MAT_PSEUDO_TENSOR This material model is used to define the properties a pseudo-tensor material model. This has been used to analyze buried steel reinforced concrete structures subjected to impulsive loadings. Field Title Desc TITLE_OPTION MID RO G PR SIGF A0 A1, A2 A0F A1F B1 PER Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Shear Modulus Poisson’s Ratio Tension Cutoff (Maximum Principal Stress at failure) Cohesion Pressure Hardening Coefficients Cohesion for failed material Pressure hardening coefficient for failed material Damage Scaling Factor Percent Reinforcement Materials 59 Materials Field ER PRR SIGY ETAN LCP LCR LCID Comments Young’s Modulus for Reinforcement Poisson’s Ratio for Reinforcement Initial Yield Stress Tangent Modulus/Plastic Hardening Modulus Load Curve Id defining rate sensitivity for principal material Load Curve Id defining rate sensitivity for reinforcement Load Curve defining Yield Stress (or scale factor) vs. effective plastic strains, damages, or pressures See Also: • LS-DYNA Keyword User’s Manual MAT_ORIENTED_CRACK Defines the properties of brittle materials failing due to large tensile stresses. Field Title Desc TITLE_OPTION MID RO E PR SIGY ETAN FS PRF Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Yield Stress Plastic Hardening Modulus Fracture Stress Fracture Pressure 60 Materials See Also: • LS-DYNA Keyword User’s Manual MAT_STRAIN_RATE_DEPENDENT_PLASTICITY Defines the properties of a strain rate dependent material. Field Title Desc TITLE_OPTION MID RO E PR VP Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Formulation for Rate Effects 0: Scale Yield Stress 1: Viscoplastic Formulation LC1 ETAN LC2 LC3 LC4 TDEL RDEF Load Curve Id for Yield Stress σ0 vs. effective strain rate Tangent Modulus Load Curve Id for Young’s Modulus vs. effective strain rate Load Curve Id for Tangent Modulus vs. effective strain rate Load Curve Id for von Mises stress at failure vs. effective strain rate Time Step Size for Automatic Element Deletion (shell elements only) Redefinition of failure curve 1: Effective plastic strain 2: Maximum principal stress Materials 61 Materials See Also: • LS-DYNA Keyword User’s Manual MAT_ORTHOTROPIC_THERMAL Defines the properties of a linear elastic material with temperature dependent orthotropic properties. Field Title Desc TITLE_OPTION MID RO EA, EB, EC PRBA, PRCA, PRCB GAB, GBC, GCA AA, AB, AC Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Moduli in the A, B and C direction Poisson’s Ratio in the ba, ca and cb directions Shear Moduli in the ab, bc and ca directions Coefficients of Thermal Expansion in the a, b, and c directions 62 Materials Field AOPT Material Axes option Comments 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of local c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal. 4: Locally orthotropic in cylindrical coordinate system with the material axis determined by a vector v, and an originating point, P, which defines the center line axis. This option is for solid elements only. XP YP ZP Ai Vi Di BETA REF X-coordinate of point p for AOPT=1 Y-coordinate of point p for AOPT=1 Z-coordinate of point p for AOPT=1 Component of Vector a, for AOPT=2 Component of Vector v, for AOPT=3 Component of Vector d, for AOPT=2 Material Angle (Degrees), for AOPT = 3 Use Reference Geometry to initialize stress tensor (0 = off; 1 = on) See Also: • LS-DYNA Keyword User’s Manual Materials 63 Materials MAT_COMPOSITE_DAMAGE Defines the properties of an orthrotropic material with optional brittle failure for composites. Field Title Desc TITLE_OPTION MID RO EA, EB, EC PRBA, PRCA, PRCB GAB, GBC, GCA KF Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Moduli in the A, B and C direction Poisson’s Ratio in the ba, ca and cb directions Shear Moduli in the ab, bc and ca directions Bulk Modulus of failed material 64 Materials Field AOPT Material Axes option Comments 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal. 4: Locally orthotropic in cylindrical coordinate system with the material axis determined by a vector v, and an originating point, P, which defines the centerline axis. This option is for solid elements only. XP YP ZP Ai Vi Di BETA SC XT YT YC ALPH SN SYX SZX X-coordinate of point p for AOPT=1 Y-coordinate of point p for AOPT=1 Z-coordinate of point p for AOPT=1 Component of Vector a, for AOPT=2 Component of Vector v, for AOPT=3 Component of Vector d, for AOPT=2 Material Angle Shear Strength, ab plane Longitudinal Tensile Strength, a-axis Transverse Tensile Strength, b-axis Transverse Compression Strength, b-axis Shear Stress Parameter for nonlinear term (0- 0.5) Normal Tensile Strength (solid elements only) Transverse Shear Strength (solid elements only) Transverse Shear Strength (solid elements only) See Also: • LS-DYNA Keyword User’s Manual Materials 65 Materials MAT_TEMPERATURE_DEPENDENT_ORTHOTROPIC Defines the properties of an orthotropic elastic material with arbitrary temperature dependency. Field Title Desc TITLE_OPTION MID RO Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material 66 Materials Field AOPT Material Axes option Comments 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal. 4: Locally orthotropic in cylindrical coordinate system with the material axis determined by a vector v, and an originating point, P, which defines the centerline axis. This option is for solid elements only. REF MACF Use Reference Geometry to initialize stress tensor (0 = off; 1 = on) Material axes change flag for brick element: =1 No Change; = 2 switch mateial axes a and b =3 switch material axes a and c ; =4 switch material axes b and c XP YP ZP Ai Vi Di BETA EA_LC, EB_LC, EC_LC PRBA_LC PRCA_LC PRCB_LC X-coordinate of point p for AOPT=1 Y-coordinate of point p for AOPT=1 Z-coordinate of point p for AOPT=1 Component of Vector a, for AOPT=2 Component of Vector v, for AOPT=3 Component of Vector d, for AOPT=2 Material Angle Load curve defining Young’s Moduli in the a, b and c directions, respecively, vs. Temperature Load curve defining Poisson’s Ratios in the ba directionsvs. Temperature Load curve defining Poisson’s Ratios in the ca directionsvs. Temperature Load curve defining Poisson’s Ratios in the cb directionsvs. Temperature Materials 67 Materials Field AA_LC, AB_LC, AC_LC GAB_LC GBC_LC GCA_LC Comments Load curves defining Coefficients of Thermal Expansion in the a, b, and c directions, respectively, vs. Temperature Load curve defining Shear modulus in the ab plane vs. Temperature Load curve defining Shear modulus in the bc plane vs. Temperature Load curve defining Shear modulus in the ca plane vs. Temperature See Also: • LS-DYNA Keyword User’s Manual MAT_GEOLOGIC_CAP_MODEL Defines the properties for geomechanical problems or materials like concrete. Field Title Desc TITLE_OPTION MID RO BULK G ALPHA THETA GAMMA BETA R Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Initial Bulk Modulus Initial Shear Modulus Failure Envelope Parameter Failure Envelope Linear coefficient Failure Envelope Exponential coefficient Failure Envelope Exponent Cap, surface axis ratio 68 Materials Field D W X0 C N PLOT FTYPE Hardening law exponent Hardening law coefficient Hardening Law Exponent Comments Kinematic Hardening Coefficient Kinematic Hardening Parameter Plotting Flag for LS-Taurus Formulation Flag 1: Soil or concrete 2: Rock VEC Vectorization Flag 0: Vectorized with a fixed number of iterations 1: Fully Iterative TOFF Tension Cutoff See Also: • LS-DYNA Keyword User’s Manual Materials 69 Materials MAT_HONEYCOMB Defines the properties for honeycomb and foam materials with real anisotropic behavior. Field Title Desc TITLE_OPTION MID RO E PR SIGY VF MU BULK Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Yield Stress for fully compacted Honeycomb Relative Volume at which Honeycomb is fully compacted Material Viscosity Coefficient Bulk Viscosity Flag 0: Bulk Viscosity Not Used 1: Bulk Viscosity Active and MU=0 LCA LCB Load Curve Id for (Sigma_aa vs. either Relative Volume or Volumetric Strain Load Curve Id for (Sigma_bb vs. either Relative Volume or Volumetric Strain (Default LCB = LCA) 70 Materials Field LCC LCS LCAB LCBC LCCA LCSR EAAU, EBBU, ECCU GABU, GBCU, GCAU AOPT Comments Load Curve Id for (Sigma_cc vs. either Relative Volume or Volumetric Strain (Default LCC = LCA) Load Curve Id for (shear stress vs. either Relative Volume or Volumetric Strain (Default LCS = LCA) Load Curve Id for (Sigma_ab vs. either Relative Volume or Volumetric Strain (Default LCAB = LCS) Load Curve Id for (Sigma_bc vs. either Relative Volume or Volumetric Strain (Default LCBC = LCS) Load Curve Id for (Sigma_ca vs. either Relative Volume or Volumetric Strain (Default LCCA = LCS) Load Curve Id for strain rate effects defining the scale factor vs. strain rate. The curves defined above are scaled using this curve. Elastic Moduli in uncompressed configuration in aa, bb, and cc directions Shear Moduli in uncompressed configuration in ab, bc, and ca planes Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. XP YP ZP Ai Di TSEF SSEF x-coordinate of point p, for AOPT = 1 y-coordinate of point p, for AOPT = 1 z-coordinate of point p, for AOPT = 1 Component of vector a, for AOPT = 2 Component of vector d, for AOPT = 2 Tensile Strain at Element Failure Shear Strain at Element Failure See Also: • LS-DYNA Keyword User’s Manual Materials 71 Materials MAT_RESULTANT_PLASTICITY Defines a resultant formulation material model, including elastoplastic behavior.for beam and shell elements, Field Title Desc TITLE_OPTION MID RO E PR SIGY ETAN Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Yield Stress Plastic Hardening Modulus (shell elements only) See Also: • LS-DYNA Keyword User’s Manual 72 Materials MAT_FORCE_LIMITED This material model allows the simulation of plastic hinge formation at the ends of a beam, using a curve definition (for Belytschko-Schwer beam only). Field Title Desc TITLE_OPTION MID RO E PR DF AOPT Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Damping Factor Axial Load Curve Option 0: Force vs. Strain 1: Force vs. Change in Length M1, M2,,,,, M8 LC1, LC2, ..., LC8 Applied end moment for force vs. strain/ or change in length curve. A minimum of one, and a maximum of eight must be defined. Load Curve Ids applied end moment Materials 73 Materials Field LPSi SFSi YMSi LPTi SFTi YMTi LPR SFR YMR Comments Load Curve Id for plastic moment vs. rotation about s-axis at node i Scale factor, plastic moment vs. rotation about s- axis at node i Yield moment about s- axis at node i for interaction calculations Load Curve Id for plastic moment vs. rotation about t-axis at node i Scale factor, plastic moment vs. rotation about t- axis at node i Yield moment about t- axis at node i for interaction calculations Load Curve Id for plastic torsional moment vs. rotation Scale factor for plastic torsional moment vs. rotation Torsional yield moment for interaction calculations See Also: • LS-DYNA Keyword User’s Manual MAT_SHAPE_MEMORY Defines the superplastic response present in shape memory alloys (SMA). Field Title Desc TITLE_OPTION MID RO E PR SIG_ASS Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Starting value for the forward phase transformation 74 Materials Field SIG_ASF SIG_SAS SIG_SAF EPSL ALPHA YMRT LC_ASS LC_ASF LC_SAS LC_SAF Comments Final value for the forward phase transformation Starting value for the reverse phase transformations Final value for the reverse phase transformation Recoverable strain or maximum residual strain Parameter Measuring the difference between material response in tension and compression Young’s Modulus for Martensite Load Curve Id for Starting value of forward phase transformation Load Curve Id for Final value of forward phase transformation Load Curve Id for Starting value of reverse phase transformations Load Curve Id for Final value of reverse phase transformation See Also: • LS-DYNA Keyword User’s Manual MAT_FRAZER_NASH_RUBBER_MODEL Defines rubber from uniaxial test data. Field Title Desc TITLE_OPTION MID Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Materials 75 Materials Field RO PR C100, C200, C300, C400, C110, C210, C010, C020 EXIT Mass Density of the material Poisson’s Ratio Strain Energy Parameters Comments Exit option of strain limit 0: Stop if limit exceeds 1: Continue even if limit exceeds EMAX EMIN REF Maximum Strain Limit Minimum Strain Limit Use Reference Geometry to initialize stress tensor 0: Off 1: On SGL SW ST LCID Specimen Gauge Length Specimen Width Specimen Thickness Load Curve Id defining Force vs. Actual Change in gauge Length See Also: • LS-DYNA Keyword User’s Manual 76 Materials MAT_LAMINATED_GLASS Defines layered glass including polymeric layers. Field Title Desc TITLE_OPTION MID RO EG PRG SYG ETG EFG EP PRP SYP ETP NUM_RFS F1, F2,, ..., FN Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus for Glass Poisson’s Ratio for Glass Yield Strength for Glass Plastic Hardening Modulus for Glass Plastic Strain at Failure for Glass Young’s Modulus for Polymer Poisson’s Ratio for Polymer Yield Strength for Polymer Plastic Hardening Modulus for Polymer Number of Integration Points of Material Integration Point Material Fi = 0: glass; Fi = 1: polymer Materials 77 Materials See Also: • LS-DYNA Keyword User’s Manual MAT_BARLAT_ANISOTROPIC_PLASTICITY Defines the properties of an anisotropic material behavior during forming processes. Field Title Desc TITLE_OPTION MID RO E PR K E0 N M A, B, C, F, G, H LCID Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Strength Coefficient Strain corresponding to initial yield Hardening exponent for yield strength Flow potential exponent in Barlat’s model Anisotropic Coefficients in Barlat’s model Load Curve Id defining effective Stress vs. effective Plastic Strain 78 Materials Field AOPT Material Axes option Comments 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by offsetting the material axes by an angle, OFFANG, from a line defined by the cross product of the vector v with the normal to the plane of a shell element, or mid surface of a brick element. BETA MACF Offset angle (for AOPT = 3) Material axes change flag for brick element: =1 No Change; = 2 switch mateial axes a and b =3 switch material axes a and c ; =4 switch material axes b and c XP YP ZP Ai Vi Di X-coordinate of point p for AOPT=1 Y-coordinate of point p for AOPT=1 Z-coordinate of point p for AOPT=1 Component of Vector a, for AOPT=2 Component of Vector v, for AOPT=3 Component of Vector d, for AOPT=2 See Also: • LS-DYNA Keyword User’s Manual Materials 79 Materials MAT_BARLAT_YLD96 Defines the properties of an anisotropic material behavior during forming processes, especially for aluminum alloys (only for shell elements only). Field Title Desc TITLE_OPTION MID RO E PR K E0 N ESRO M Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Strength Coefficient Strain corresponding to initial yield Hardening exponent for yield strength εSRO, in power law rate sensitivity Exponent, m for strain rate effects 80 Materials Field HARD Hardening option Comments <0: Absolute value defines the Load Curve Id 1:Powerlaw 2: Voce A Ci AX AY AZ0 AZ1 AOPT Flow Potential Exponent Equation parameters Equation parameter Equation Parameter Equation Parameter Equation Parameter Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by offsetting the material axes by an angle, OFFANG, from a line defined by the cross product of the vector v with the normal to the plane of the element. OFFANG blank1, blank2, blank3 Ai Vi Di Offset Angle for AOPT = 3 Blank Fields Component of Vector a, for AOPT=2 Component of Vector v, for AOPT=3 Component of Vector d, for AOPT=2 See Also: • LS-DYNA Keyword User’s Manual Materials 81 Materials MAT_FABRIC Defines the properties for airbag materials. Field Title Desc TITLE_OPTION MID RO EA EB EC PRBA, PRCA, PRCB GAB, GBC, BCA Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus, Longitudinal Direction Young’s Modulus, Transverse Direction Young’s Modulus, Normal Direction Poisson’s Ratio in ba, ca, and cb directions Shear Moduli in ab., bc, and ca directions 82 Materials Field CSE Comments Compressive Stress Elimination Option 0: Don’t Eliminate 1: Eliminate EL PRL LRATIO DAMP AOPT Young’s Modulus for Elastic Liner Poisson’s Ratio for Elastic Liner Ratio of linear thickness to total fabric thickness Rayleigh Damping Coefficient Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal. FLC FAC ELA LNRC Fabric Leakage coefficient Fabric Area Coefficient Effective Leakage Area for blocked fabric Liner Compression Flag 0: Off 1:On Materials 83 Materials Field FORM Comments Flag to modify Membrane Formulation for fabric material: 0: default 1: in variant Local Coordinate System 2: Green-Lagrange strain formulation 3: Large Strain with nonorthogonal material angles 4: Large Strainwith nonorthogonal material angles, and nonlinear material stress strain behavior. Define optional Load Curve Ids. FVOPT Fabric Venting Option 1: Wang-Nefske formulas for venting, through orifice, with no blockage. 2: Wang-Nefske formulas for venting through orifice, with blockage. 3: Graefe, Krummheurer, and Siejak [1990] Leakage formulas with no blockage. 4: Graefe, Krummheurer, and Siejak [1990] Leakage formulas with blockage. 5: Leakage formulas based on flow through a porous media, with no blockage. 6: Leakage formulas based on flow through a porous media, with blockage. TSRFAC blank1, blank2, blank3 Ai Vi Di BETA LCA LCB LCAB LCUA LCUB LCUAB LC_FLC Tensile Stress Cutoff Reduction factor Blank Fields Component of Vector a, for AOPT=2 Component of Vector v, for AOPT=3 Component of Vector d, for AOPT=2 Material Angle (Degrees), for AOPT=3 Load Curve Id for Stress vs. Strain along the a- axis Load Curve Id for Stress vs. Strain along the b- axis Load Curve Id for Stress vs. Strain in the ab plane Unload/Reload Curve Id for Stress vs. Strain along a- axis Unload/Reload Curve Id for Stress vs. Strain along b- axis Unload/Reload Curve Id for Stress vs. Strain in the ab plane Load Curve Id for Fabric Leakage Coefficient 84 Materials Field LC_FAC LC_ELA LC_TSR Comments Load Curve Id for Fabric Area Coefficient Load Curve Id for Effective Leakage Area for blocked fabric Load Curve Id for Tensile Stress Cutoff Reduction factor vs. Time See Also: • LS-DYNA Keyword User’s Manual MAT_PLASTIC_GREEN-NAGHDI_RATE This model is available for brick elements only. It is similar to MAT_PLASTIC_KINEMATIC, but uses the Green-Naghdi Rate formulation for the stress update. Field Title Desc TITLE_OPTION MID RO E PR SIGY ETAN SRC SRP BETA Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Yield Strength Plastic Hardening Modulus Strain Rate Parameter Strain Rate Parameter Hardening Parameter See Also: • LS-DYNA Keyword User’s Manual Materials 85 Materials MAT_3-PARAMETER_BARLAT This material model is designed for modeling sheets with anisotropic materials under plane stress conditions. Field Title Desc TITLE_OPTION MID RO E PR HR Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Hardening Rule 1: Linear 2: Exponential 3: Load Curve P1, P2 Material Parameters 86 Materials Field ITER Iteration Flag 0: Fully iterative 1: Fixed to 3 iterations M R00, R45, R90 LCID Epsilon_0 SPI AOPT Comments Exponent in Barlat’s yield surface Lankford Parameters Load Curve Id for hardening rule ε0 for determining initial yield stress for exponential hardening Parameter to redefine ε0 Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal. blank1, blank2, blank3 XP YP ZP Ai Vi Di BETA Blank Fields X-coordinate of point p for AOPT=1 Y-coordinate of point p for AOPT=1 Z-coordinate of point p for AOPT=1 Component of Vector a, for AOPT=2 Component of Vector v, for AOPT=3 Component of Vector d, for AOPT=2 Material Angle (Degrees), for AOPT=3 See Also: • LS-DYNA Keyword User’s Manual Materials 87 Materials MAT_TRANS_ANISO_ELASPLASTIC Simulates sheet forming processes with anisotropic material. Only transverse anisotropy can be considered. Field Title Desc TITLE_OPTION MID RO E PR SIGY ETAN R HLCID Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Yield Stress Plastic Hardening Modulus Anisotropic Hardening Parameter Load Curve Id for Effective Yield Stress vs. Effective Plastic Strain See Also: • LS-DYNA Keyword User’s Manual 88 Materials MAT_TRANS_ANISO_ELASPLASTIC_ECHANGE Simulates sheet forming processes with anisotropic material. Only transverse anisotropy can be considered. Field Title Desc TITLE_OPTION MID RO E PR SIGY ETAN R HLCID IDSCALE Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Yield Stress Plastic Hardening Modulus Anisotropic Hardening Parameter Load Curve Id for Effective Yield Stress vs. Effective Plastic Strain Load curve Id defining the scale factor for Young’s modulus change with respect to effective strain. Note: if EA, and COE are defined, this curve is not necessary. Coefficients (EA and ζ) defining Young’s modulus with respect to the effective strain. Note: if EA, and COE are defined, this curve is not necessary. EA, COE See Also: • LS-DYNA Keyword User’s Manual Materials 89 Materials MAT_BLATZ-KO_FOAM Defines the properties for rubber like foams of polyurethane. It is a simple one parameter model with a fixed Poisson’s ratio of 0.25. Field Title Desc TITLE_OPTION MID RO G REF Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Shear Modulus Use Reference Geometry to initialize stress tensor See Also: • LS-DYNA Keyword User’s Manual 90 Materials MAT_FLD_TRANSVERSELY_ANISOTROPIC Simulates sheet forming processes with anisotropic material. Only transverse anisotropy can be considered. Field Title Desc TITLE_OPTION MID RO E PR SIGY ETAN R HLCID LCIDFLD Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Yield Stress Plastic Hardening Modulus Anisotropic Hardening Modulus Load Curve Id defining Effective Yield Stress vs. Effective Plastic Strain Load Curve Id defining the Forming Limit Diagram (major vs. minor strain) See Also: • LS-DYNA Keyword User’s Manual Materials 91 Materials MAT_NONLINEAR_ORTHOTROPIC Defines an orthotropic nonlinear elastic material based on a finite strain formulation with initial geometry as the reference. Optional failure and stiffness properties are available. Field Title Desc TITLE_OPTION MID RO EAA, EBB, ECC PRBA, PRCA, PRCB GAB, GBC, GCA DT TRAMP ALPHA EFAIL Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus in the A, B and C directions Poisson’s Ratio in the ba, ca and cb directions Shear Modulus in the ab, bc and ca directions Temperature increment for stress stabilization Time to ramp up to the final temperature Thermal expansion coefficient Failure Strain LCIDA, LCIDB, LCIDC Load Curve Id for nominal stress vs. nominal strain in the a- , b-, and c-axes 92 Materials Field DTFAIL CDAMP AOPT Damping Coefficient Material Axes option Comments Timestep size criteria for element erosion 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal. blank1, blank2, blank3 Ai Vi Di BETA Blank Fields Component of Vector a, for AOPT=2 Component of Vector v, for AOPT=3 Component of Vector d, for AOPT=2 Material Angle (Degrees), for AOPT=3 LCIDAB, LCIDBC, LCIDCA Load Curve Id for nominal shear stress vs. nominal shear strain in the ab, bc, and ca plane See Also: • LS-DYNA Keyword User’s Manual Materials 93 Materials MAT_BAMMAN Defines a material with temperature and rate dependent plasticity. Field Title Desc TITLE_OPTION MID RO E PR T HC Ci Ai KAPPA Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Initial Temperature Heat Generation Coefficient Input parameters Initial value of state variable i Initial value of internal state variable 6 (κ) See Also: • LS-DYNA Keyword User’s Manual 94 Materials MAT_BAMMAN_DAMAGE Defines a material with temperature and rate dependent plasticity including damage in the modeling. Field Title Desc TITLE_OPTION MID RO E PR T HC Ci Ai N D0 FS Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Initial Temperature Heat Generation Coefficient Input parameter Initial value of state variable i Exponent in damage evaluation Initial Damage (porosity) Failure Strain for Erosion Materials 95 Materials See Also: • LS-DYNA Keyword User’s Manual MAT_CLOSED_CELL_FOAM Defines a low density, closed polyurethane foam for simulating impact limiters in automotive applications. Field Title Desc TITLE_OPTION MID RO E PR A, B, C P0 PHI GAMA0 LCID Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Factors a, b, and c for Yield Stress definition Initial Foam Pressure Ratio of Foam to Polymer Density Initial Volumetric Strain Load Curve Id defining vonMises Stress vs. Volumetric Strain See Also: • LS-DYNA Keyword User’s Manual 96 Materials MAT_ENHANCED_COMPOSITE_DAMAGE Defines the properties of an orthrotropic material with optional brittle failure for composites. This is an enhanced version of MAT_COMPOSITE_DAMAGE (MAT_022). Field Title Desc TITLE_OPTION MID RO EA EB EC PRBA, PRCA, PRCB GAB, GBC, GCA KF Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus, Longitudinal Direction Young’s Modulus, Transverse Direction Young’s Modulus, Normal Direction (NOT used) Poisson’s Ratio in the ba, ca, and cb planes (PRCA, PRCB NOT used) Shear Modulus in the ab, bc, and ca planes Bulk Modulus of failed material (NOT used) Materials 97 Materials Field AOPT Material Axes option Comments 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal. bl1, bl2, bl3 Ai MANGLE Vi Di DFAILM DFAILS TFAIL ALPH SOFT FBRT YCFAC DFAILT DFAILC EFS XC XT YC YT SC Blank Fields Components of Vector a, for AOPT=2 Material Angle (Degrees), for AOPT=3 Components of Vector v, for AOPT=3 Component of Vector d, for AOPT=2 Maximum Strain for matrix straining in tension/compression Maximum shear strain Timestep size criteria for element deletion Shear Stress Parameter for NonLinear Term Softening Reduction Factor Softening of fiber Tensile Strength Reduction Factor for compressive fiber strength, after matrix failure Maximum Strain for fiber in tension Maximum Strain for fiber in compression Effective Failure Strain Longitudinal Compression Strength Longitudinal Tensile Strength Transverse Compression Strength Transverse Tensile Strength Shear Strength, ab plane 98 Materials Field CRIT Comments Failure Criteria (Material Number) 54: Chang matrix failure criterion 55: Tsai-Wu matrix failure criterion BETA Weight Factor for Shear term in tensile fiber mode See Also: • LS-DYNA Keyword User’s Manual Materials 99 Materials MAT_LAMINATED_COMPOSITE_FABRIC Defines a composite material with unidirectional layers, complete laminates and woven fabrics (for shell elements only). Field Title Desc TITLE_OPTION MID RO EA EB EC PRBA Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus, Longitudinal Direction Young’s Modulus, Transverse Direction Young’s Modulus, Normal Direction (NOT used) Poisson’s Ratio in BA direction 100 Materials Field TAU1 GAMMA1 SLIMT1 SLIMC1 SLIMS AOPT Comments Stress limit of first slightly nonlinear part of Shear Stress vs. Shear Strain curve Strain limit of first slightly nonlinear part of Shear Stress vs. Shear Strain curve Factor to determine the minimum Stress Limit after Stress Maximum (fiber Tension) Factor to determine the minimum Stress Limit after Stress Maximum (fiber Compression) Factor to determine the minimum Stress Limit after Stress Maximum (Shear) Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal. TSIZE ERODS SOFT FS Time step size for Automatic Element Deletion Maximum Element Strain for Element Layer Failure Softening Reduction Factor in Crash front Failure Surface Type 1: Smooth surface Failure with Quadratic criteria for both fiber and transverse directions 0: Smooth surface Failure with Quadratic criteria for transverse direction, with a limiting value in the fiber direction -1: Faceted Failure surface XP YP X-coordinate of point p for AOPT=1 Y-coordinate of point p for AOPT=1 Materials 101 Materials Field ZP Ai Vi Di BETA E11C E11T E22C E22T GMS XC XT YC YT SC Comments Z-coordinate of point p for AOPT=1 Component of Vector a, for AOPT=2 Component of Vector v, for AOPT=3 Component of Vector d, for AOPT=2 Material Angle (Degrees), for AOPT=3 Strain at Longitudinal Compression Strength, a-axis Strain at Longitudinal Tensile Strength, a-axis Strain at Transverse Compression Strength, b-axis Strain at Transverse Tensile Strength, b-axis Strain at Shear Strength, ab plane Longitudinal Compression Strength Longitudinal Tensile Strength Transverse Compression Strength, b-axis Transverse Tensile Strength, b-axis Shear Strength, ab plane See Also: • LS-DYNA Keyword User’s Manual 102 Materials MAT_COMPOSITE_FAILURE_SHELL_MODEL Defines the properties of a composite material with failure properties (for shell elements only). Field Title Desc TITLE_OPTION MID RO EA EB EC PRBA, PRCA< PRCB GAB, GBC, GCA KF Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus, Longitudinal Direction Young’s Modulus, Transverse Direction Young’s Modulus, Normal Direction Poisson’s Ratio in ba, ca and cb directions Shear Moduli in ab, bc and ca directions Bulk Modulus of failed material Materials 103 Materials Field AOPT Comments 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal. MAFLAG XP YP ZP Ai Vi Di BETA TSIZE ALP SOFT FBRT SR SF XC XT YC YT SC Material Axes Flag (NOT active for shells) X-coordinate of point p for AOPT=1 and 4 Y-coordinate of point p for AOPT=1 and 4 Z-coordinate of point p for AOPT=1and 4 Component of Vector a, for AOPT=2 Component of Vector v, for AOPT=3, and 4 Component of Vector d, for AOPT=2 Material Angle (Degrees), for AOPT=3 Time step size for Automatic Element Deletion Nonlinear stress parameter Softening Reduction Factor in Crashfront Softening of fiber Tensile Strength Reduction Factor Softening Factor Longitudinal Compression Strength Longitudinal Tensile Strength Transverse Compression Strength, b-axis Transverse Tensile Strength, b-axis Shear Strength, ab plane See Also: • LS-DYNA Keyword User’s Manual 104 Materials MAT_COMPOSITE_FAILURE_SOLID_MODEL Defines the properties of a composite material with failure properties (for solid elements only). Field Title Desc TITLE_OPTION MID RO EA EB EC PRBA, PRCA< PRCB GAB, GBC, GCA KF Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus, Longitudinal Direction Young’s Modulus, Transverse Direction Young’s Modulus, Normal Direction Poisson’s Ratio in ba, ca and cb directions Shear Moduli in ab, bc and ca directions Bulk Modulus of failed material Materials 105 Materials Field AOPT Material Axes option Comments 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal. 4: Locally orthotropic in cylindrical coordinate system with the material axis determined by a vector v, and an originating point, P, which defines the centerline axis. This option is for solid elements only. MAFLAG Material Axes Change Flag 1: Default 2: Switch Axes a and b 3: Switch Axes a and c XP YP ZP Ai Vi Di BETA SBA SCA SCB XXC YYC X-coordinate of point p for AOPT=1 and 4 Y-coordinate of point p for AOPT=1 and 4 Z-coordinate of point p for AOPT=1and 4 Component of Vector a, for AOPT=2 Component of Vector v, for AOPT=3, and 4 Component of Vector d, for AOPT=2 Material Angle (Degrees), for AOPT=3 In Plane Shear Strength Transverse Shear Strength Transverse Shear Strength Longitudinal Compression Strength, x-axis Transverse Compression Strength, b-axis 106 Materials Field ZZC XXT YYT ZZT Comments Normal Compression Strength, c-axis Longitudinal Tensile Strength, x-axis Transverse Tensile Strength, b-axis Normal Tensile Strength, c-axis See Also: • LS-DYNA Keyword User’s Manual MAT_ELASTIC_WITH_VISCOSITY Simulates the forming of glass products at high temperatures. Field Title Desc TITLE_OPTION MID Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Materials 107 Materials Field RO V0 A, B, C LCID PRi Ti Vi Ei ALPHAi Temperatures Viscosity coefficients Mass Density of the material Comments Load Curve Id defining factor for viscosity vs. temperature Corresponding Viscosity coefficients Corresponding Young’s moduli coefficients Corresponding thermal expansion coefficients See Also: • LS-DYNA Keyword User’s Manual MAT_ELASTIC_WITH_VISCOSITY_CURVE Simulates the forming of glass products at high temperatures.Load curves are used to represent the temperature dependence of Poisson’s ratio, Young’s modulus, the coefficient of thermal expansion, and the viscosity. Field Title Desc TITLE_OPTION MID RO V0 Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material 108 Materials Field A, B, C LCID PR_LC YM_LC A_LC V_LC V_LOG Viscosity coefficients Comments Load Curve Id defining factor for viscosity vs. temperature Load curve defining Poisson’s ratio as a function of temperature Load curve defining Young’s modulus as a function of temperature Load curve defining the coefficient of thermal expansion as a function of temperature Load curve defining the viscosity as a function of temperature Falg for the form of V_LC. If V_LOg =1, the value specified in V_LC is the natural logarithm of the viscosity. If V_LOg =0, the value is the viscosity. See Also: • LS-DYNA Keyword User’s Manual MAT_KELVIN-MAXWELL_VISCOELASTIC A classic Kelvin-Maxwell material model for modeling viscoelastic bodies, like foams. Field Title Desc TITLE_OPTION MID RO BULK GO GI DC Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Bulk Modulus (elastic) Short time Shear Modulus Long time Shear Modulus Maxwell decay constant or Kelvin relaxation constant Materials 109 Materials Field FO Formulation option 0: Maxwell 1: Kelvin SO Strain output option Comments 0: Maximum principal Strain occurring during the calculation 1: Maximum magnitude of principal Strain occurring during the calculation 2: Maximum Effective Strain occurring during the calculation See Also: • LS-DYNA Keyword User’s Manual MAT_VISCOUS_FOAM A material to represent the Confor Foam on the ribs of EuroSID side impact dummy (valid only for solid elements under compressive load). Field Title Desc TITLE_OPTION MID RO E1 N1 V2 E2 Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Initial Young’s Modulus Exponent in power law for Young’s Modulus Viscous Coefficient Elastic Modulus for viscosity 110 Materials Field N2 PR Poisson’s Ratio Comments Exponent in power law for viscosity See Also: • LS-DYNA Keyword User’s Manual MAT_CRUSHABLE_FOAM A material model for modeling crushable foam with optional damping and tension cutoff. Field Title Desc TITLE_OPTION MID RO E PR LCID TSC DAMP Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Load Curve Id defining Yield Stress vs. Volumetric Strain Tensile Stress Cutoff Rate sensitivity via damping coefficient See Also: • LS-DYNA Keyword User’s Manual Materials 111 Materials MAT_RATE_SENSITIVE_POWERLAW_PLASTICITY A strain rate sensitive elasto-plastic material model with a power law hardening. Field Title Desc TITLE_OPTION MID RO E PR K M N E0 VP Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Material Constant Strain Hardening Coefficient Strain Rate Sensitivity Coefficient Initial Strain Rate Formulation for Rate Effects 0: Scale Yield Stress 1: ViscoPlastic Formulation EPSO Factor to Normalize Strain (Time Units) 1: Seconds 1e-006 : Milliseconds 1e-006 : Microseconds 112 Materials Field LCID_K LCID_M LCID_N Comments Load Curve Id defining material constant K vs. Effective Plastic Strain Load Curve Id defining material constant M vs. Effective Plastic Strain Load Curve Id defining material constant N vs. Effective Plastic Strain See Also: • LS-DYNA Keyword User’s Manual MAT_MODIFIED_ZERILLI_ARMSTRONG A rate and temperature sensitive plasticity material model, sometimes used in ordinance design calculations. Field Title Desc TITLE_OPTION MID RO G E0 N TROOM PC Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Shear Modulus Factor to normalize strain rate Exponent for bcc metal Room Temperature Pressure Cutoff Materials 113 Materials Field SPALL Spall Type 1: Minimum Pressure Limit 2: Maximum Principal Stress 3: Minimum Pressure Cutoff Ci EFAIL VP Coefficients for flow stress Failure Strain for Erosion Formulation for Rate Effects 0: Scale Yield Stress 1: ViscoPlastic Formulation Bi Gi BULK Comments Coefficients for polynomial representation of temperature dependency of flow stress yield Coefficient for defining Heat Capacity and temperature dependency of Heat Capacity Bulk Modulus (for shell elements only) See Also: • LS-DYNA Keyword User’s Manual 114 Materials MAT_LINEAR_ELASTIC_DISCRETE_BEAM A material model for linear elastic beams by using six springs each acting along one of its six degrees of freedom. The two nodes that define the beam can be coincident to give a zero length beam, or offset to give a finite length beam. Field Title Desc TITLE_OPTION MID RO TKR, TKS, TKT RKR, RKS, RKT TDR, TDS, TDT RDR, RDS, RDT FOR, FOS, FOT MOR, MOS, MOT Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Translational Stiffness along local ar-, s-, and t- axes respectively Rotational Stiffness about local r-, s-, and t- axes respectively Translational viscous damping along local r-, s-, and t- axes respectively Rotational viscous damping about local r-, s-, and t- axes respectively Pre-load forces in r-, s- and t-directions repectively (optional) Pre-load moments in r-, s- and t-directions repectively (optional) See Also: • LS-DYNA Keyword User’s Manual Materials 115 Materials MAT_NONLINEAR_ELASTIC_DISCRETE_BEAM A material model for nonlinear elastic and nonlinear viscous beams by using six springs each acting along one of its six degrees of freedom. The two nodes that define the beam can be coincident to give a zero length beam, or offset to give a finite length beam. Field Title Desc TITLE_OPTION MID RO LCIDTR, LCIDTS, LCIDTT LCIDRR, LCIDRS, LCIDRT LCIDTDR, LCIDTDS, LCIDTDT LCIDRDR, LCIDRDS, LCIDRDT FOR, FOS, FOT MOR, MOS, MOT Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Load Curve Id defining Translational Force along the r-, s-, and t- axes vs. Translational Displacement Load Curve Id defining Rotational Moment about the r-, s-, and t- axes vs. Rotational Displacement Load Curve Id defining Translational Damping Force along the r-, s-, and t- axes vs. Translational Velocity Load Curve Id defining Rotational Damping Force the r-, s-, and t- axes axis vs. Rotational Velocity Pre-load forces in r-, s- and t-directions repectively (optional) Pre-load moments in r-, s- and t-directions repectively (optional) See Also: • LS-DYNA Keyword User’s Manual 116 Materials MAT_NONLINEAR_PLASTIC_DISCRETE_BEAM A a material model for nonlinear elastoplastic, linear viscous behavior of beams by using six springs each acting along one of its six degrees of freedom. The two nodes that define the beam can be coincident to give a zero length beam, or offset to give a finite length beam. Field Title Desc TITLE_OPTION MID RO TKR, TKS, TKT RKR, RKS, RKT TDR, TDS, TDT RDR, RDS, RDT LCPDR, LCPDS, LCPDT LCPMR, LCPMS, LCPMT Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Translational Stiffness along local r-, s-, and t- axes respectively Rotational Stiffness about local r-, s-, and t- axes respectively Translational viscous damping along local r-, s-, and t- axes respectively Rotational viscous damping about local r-, s-, and t- axes respectively Load Curve Id for Yield Force vs. Plastic Displacement along local r-, s-, and t- axes respectively Load Curve Id for Yield Moment vs. Plastic Rotation about local r-, s-, and t- axes respectively Materials 117 Materials Field FFAILR, FAILS, FAILT MFAILR, MFAILS, MFAILT UFAILR, UFAILS, UFAILT TFAILR, TFAILS, TFAILT FOR, FOS, FOT MOR, MOS, MOT Comments Failure Parameters corresponding to Force Fr, Fs, Ft Failure Parameters corresponding to Moment Mr, Ms, Mt Failure Parameters corresponding to Displacement Ur, Us, Ut Failure Parameters corresponding to Rotation θr, θs, θt Pre-load forces in r-, s- and t-directions repectively (optional) Pre-load moments in r-, s- and t-directions repectively (optional) See Also: • LS-DYNA Keyword User’s Manual MAT_SID_DAMPER_DISCRETE_BEAM A material model for side impact dummy, using a damper that is not adequately taken care of by the nonlinear force versus relative velocity curves. Field Title Desc TITLE_OPTION MID Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) 118 Materials Field RO ST D R H K C C3 STF RHOF C1 C2 LCIDF LCIDD S0 NUM_RFS ORFLOCi ORFRADi SFi DCi Mass Density of the material Piston Stroke Piston Diameter Orifice Radius Orifice Controller Position Damping Constant Discharge Coefficient Comments Coefficient for fluid inertia term Stiffness Coefficient (piston bottom out) Fluid Density Coefficient of linear velocity term Coefficient of quadratic velocity term Load Curve Id defining Force vs. Piston Displacement Load Curve Id defining Damping Coefficient vs. Piston Displacement Initial Displacement Number of Orifice Location Orifice Location of the i-th orifice, relative to the fix end Orifice Radius of the i-th orifice Scale factor on calculated force for the i-th orifice Linear viscous damping coefficient (after damper bottoms out in tension or compression) for the i-th orifice See Also: • LS-DYNA Keyword User’s Manual Materials 119 Materials MAT_HYDRAULIC_GAS_DAMPER_DISCRETE_BEAM A special element that represents a combined hydraulic and gas-filled damper with a variable orifice coefficient. This material can only be used as a discrete beam element. Field Title Desc TITLE_OPTION MID RO C0 N P0 PA AP KH LCID FR SCLF CLEAR Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Length of Gas Column Adiabatic constant Initial gas Pressure Atmospheric Pressure Piston Cross-Section Area Hydraulic Constant Load Curve Id Defining Orifice Area vs. Element Deletion Return factor on orifice force Scale factor on Force Clearance See Also: • LS-DYNA Keyword User’s Manual 120 Materials MAT_CONCRETE_DAMAGE A material model for analyzing buried steel reinforced concrete structure with impulsive loading. Field Title Desc TITLE_OPTION MID RO E PR SIGF A0, A0Y Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Maximum principal Stress at Failure Cohesion and Cohesion for Yield Materials 121 Materials Field A1, A2 A1Y, A2Y A1F, A2F B1 B2 B3 PER ER PRR SIGY ETAN LCP LCR LAMBDAi ETAi Comments Pressure Hardening Coefficients Pressure Hardening Coefficients for yield limit Pressure Hardening Coefficients Failed Material) Damage Scaling Factor Damage Scaling Facto for uniaxial tensile path Damage Scaling Facto for triaxial tensile path Percent Reinforcement Young’s Modulus for Reinforcement Poisson’s Ration for Reinforcement Initial Yield Stress Tangent Modulus/Plastic hardening Modulus Load Curve Id giving rate sensitivity for principal material Load Curve Id giving rate sensitivity for reinforcement Tabulated Damage functions Tabulated Scale Factors See Also: • LS-DYNA Keyword User’s Manual 122 Materials MAT_LOW_DENSITY_VISCOUS_FOAM A material model for low density urethane foam with high compressibility, and with rate sensitivity characterized by a relaxation curve. Field Title Desc TITLE_OPTION MID RO E LCID TC HU BETA DAMP SHAPE FAIL Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Load Curve Id for nominal Stress vs. Strain Tension Cutoff Stress Hysteretic Unloading Factor between 0 to 1 Decay constant to model creep in unloading Viscous coefficient Shape factor for unloading Failure Option after Cutoff Stress 1: Tensile stress remains at cutoff value 2: Tensile stress is reset to zero Materials 123 Materials Field BVFLAG Bulk Viscosity activation Flag 0: No 1: Active KCON LCID2 BSTART TRAMP NV NUM_RFS GI1 BETAI1 REF Comments Stiffness coefficient for contact interface stiffness Load Curve Id of relaxation curve Fit Parameter Optional ramp time for loading Number of terms in fit Number of viscoelastic constants Optional relaxation modulus for rate effect Optional decay constant Use Reference Geometry to initialize stress tensor 0: Off 1: On See Also: • LS-DYNA Keyword User’s Manual MAT_ELASTIC_SPRING_DISCRETE_BEAM A model for elastic springs with damping to be combined and represented with a discrete beam element. Field Title Desc Comments Unique name identifying material model Optional description of the material model 124 Materials Field TITLE_OPTION MID RO E K F0 D CDF TDF FLCID HLCID Ci DLE GLCID Comments If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Elastic loading and unloading stiffness Optional initial force Optional viscous damping coefficient Compressive displacement at failure Tensile displacement at failure Load Curve Id defining Yield Force vs. Deflection for nonlinear behavior Load Curve Id defining Force vs. Relative Velocity for nonlinear behavior Damping Coefficients Scale factor for time unit Load Curve Id defining Scale Factor vs. Deflection for Load Curve Id (HLCID) See Also: • LS-DYNA Keyword User’s Manual MAT_BILKHU/DUBOIS_FOAM A material model to simulate isotropic crushable foams using uniaxial and triaxial test data. Field Title Desc Comments Unique name identifying material model Optional description of the material model Materials 125 Materials Field TITLE_OPTION MID RO YM LCPY LCUYS VC PC VPC TC VTC LCRATE PR KCON ISFLG Comments If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Load Curve Id defining Yield Pressure vs. Volumetric Strain Load Curve Id defining uniaxial Yield Stress vs. Volumetric Strain Viscous Damping Coefficient Pressure Cutoff Variable Pressure Cutoff as a fraction of pressure yield value Tension Cutoff for uniaxial tensile stress Variable Tension Cutoff as a fraction of uniaxial compressive yield strength Load Curve Id defining Scale Factor for the previous yield curves, dependent upon the volumetric strain vs. Volumetric plastic Strain Poisson coefficient applying to both elastic and plastic deformations Stiffness coefficient for contact interface stiffness. If undefined, one third of Young’s Modulus (YM) is used.. Tensile response flag (active only if negative abscissa are present in the load curve LCUYS). .EQ. 0: load curve abscissa in tensile region correspond to volumetric strain. .EQ. 1: load curve abscissa in tensile region correspond to effective strain. See Also: • LS-DYNA Keyword User’s Manual 126 Materials MAT_GENERAL_VISCOELASTIC A general viscoelastic Maxwell model used for modeling dense continuum rubber and solid explosives. Field Title Desc TITLE_OPTION MID RO BULK PCF Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Elastic Bulk Modulus Tensile Pressure elimination flag (for solid elements only) 1: yes (Tensile Pressure reset to zero) 0: no (Tensile Pressure NOT reset to zero) EF Elastic Flag 1: Elastic layer 0: Viscoelastic layer LCID NT BSTART TRAMP LCIDK Load Curve Id for deviatoric behavior Number of terms in shear fit Parameter for resetting the exponents in the Relaxation Curve Optional Time ramp for loading Load Curve ID defining the bulk behavior Materials 127 Materials Field NTK BSTARTK TRAMPK NUM_RFS GIi BETAIi KIi BETAKIi Number of terms in bulk Fit Parameter for bulk Comments Optional ramp time for bulk loading number of viscoelastic constants Optional shear relaxation modulus for the i-th term Optional shear Decay Constant for the i-th term Optional bulk Relaxation Modulus for the i-th term Optional bulk Decay Constant for the i-th term See Also: • LS-DYNA Keyword User’s Manual MAT_HYPERELASTIC_RUBBER A general hyperelastic rubber material model, combined optionally with linear viscoelasticity. Field Title Desc TITLE_OPTION Comments Unique name identifying material model Optional description of the material model If selected material title option is used 128 Materials Field MID RO PR N Mass Density of the material Poisson’s Ratio Constants to solve for 1: Solve for C10, C01 Comments Material identification number (Integer > 0) 2: Solve for C10, C01, C11, C20, C02 3: Solve for All constants (C10, C01, C11, C20, C02, and C30) NV G SIGF SGL SW ST LCID1 DATA Number of Prony series terms in fit Shear Modulus Limit stress for frequency independent, frictional, Damping Specimen gauge length Specimen Width Specimen Thickness Load Curve Id defining Force vs. Actual Change in gauge Length Type of experimental data 0:Uniaxial LCID2 BSTART TRAMP Ci NUM_RFS GIi BETAIi Load Curve Id of relaxation curve Fit Parameter Optional ramp time for loading Material Constants Number of viscoelastic constants Optional Shear Relaxation Modulus for the i-th term Optional Decay Constants for the i-th term See Also: • LS-DYNA Keyword User’s Manual Materials 129 Materials MAT_OGDEN_RUBBER An Ogden rubber material model, combined optionally with linear viscoelasticity. Field Title Desc TITLE_OPTION MID RO PR N Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Poisson’s Ratio Order to fit the Ogden model NV G SIGF SGL SW ST Number of Prony series terms in fit Shear Modulus Limit stress for frequency independent, frictional, Damping Specimen gauge length Specimen Width Specimen Thickness 130 Materials Field LCID1 DATA Type of experimental data 1:Uniaxial 2:Biaxial LCID2 BSTART TRAMP MUi ALPHAi NUM_RFS GIi BETAIi Comments Load Curve Id defining Force vs. Actual Change in Length Load Curve Id of relaxation curve Fit Parameter Optional ramp time for loading i-th Shear Modulus i-th Exponent Number of viscoelastic constants i-th Optional Shear Relaxation Modulus i-th Optional Decay Constant See Also: • LS-DYNA Keyword User’s Manual MAT_SOIL_CONCRETE An efficient soil and concrete material model. Field Title Desc TITLE_OPTION MID RO G Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Shear Modulus Materials 131 Materials Field K LCPV LCYP LCFP LCRP PC OUT Bulk Modulus Comments Load Curve Id defining Pressure vs. Volumetric Strain Load Curve Id defining von Mises Stress vs. Pressure Load Curve Id defining Plastic Strain at which fracture starts vs. Pressure Load Curve Id defining Plastic Strain at which residual strength is released vs. Pressure Pressure Cutoff Output option for plastic strain 0: Volumetric 1: Deviatoric B FAIL Residual strength factor after cracking Failure flag 0: No 1: Element Erodes when Pressure reached failure pressure 2: No tension in element when Pressure reached failure pressure See Also: • LS-DYNA Keyword User’s Manual 132 Materials MAT_HYSTERETIC_SOIL A nested surface material model with five superimposed layers of elasto-perfectly plastic material, each with its own elastic moduli and yield values. Field Title Desc TITLE_OPTION MID RO K0 P0 B A0, A1, A2 DF RP LCID SCLF DIL_A DIL_B DIL_C DIL_D Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Bulk Modulus Pressure Cutoff Exponent for pressure sensitive moduli Yield Function Constants Damping Factor Reference Pressure Load Curve Id defining Shear Stress vs. Shear Strain Scale Factor o apply on shear stress in LCID Dilation Parameter A Dilation Parameter B Dilation Parameter C Dilation Parameter D Materials 133 Materials Field GAMi PINIT Shear Strains (if LCID is zero) Pressure sensitivity flag: .EQ. 0: Use current pressure Comments .EQ. 1: Use pressure from initial stress state .EQ. 2: Use initial “plane stress”pressure .EQ. 3: Use compressive initial vertical stress TAUi Shear Stresses (if LCID is zero) See Also: • LS-DYNA Keyword User’s Manual MAT_RAMBERG_OSGOOD A simple material model of shear behavior, and can be used for seismic analysis. Field Title Desc TITLE_OPTION MID RO GAMY TAUY ALPHA R BULK Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Reference Shear Strain Reference Shear Stress Stress coefficient Stress exponent Elastic Bulk Modulus 134 Materials See Also: • LS-DYNA Keyword User’s Manual MAT_PLASTICITY_WITH_DAMAGE An elasto-visco-plastic material with an arbitrary stress versus strain curve and arbitrary strain rate dependency. Damage, in this model, is considered before rupture occurs. Field Title Desc TITLE_OPTION MID RO E PR SIGY ETAN EPPF TDEL C, P LCSS LCSR EPPFR VP Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Yield Stress Tangent Modulus Plastic Strain, at which material softening begins Minimum time step size for Automatic Element Deletion Strain Rate Parameters Load Curve Id defining Effective Stress vs. Effective Plastic Strain Load Curve Id defining Strain Rate Scaling Effect on Yield Stress Plastic Strain at which material ruptures Formulation for Rate Effects 0: Scale Yield Stress 1: Viscoplastic Formulation Materials 135 Materials Field LCDM NUMINT Comments Load Curve Id defining nonlinear damage curve No. of through thickness integration points which must fail before the element is deleted See Also: • LS-DYNA Keyword User’s Manual MAT_PLASTICITY_WITH DAMAGE_ORTHO_RCDC An elasto-visco-plastic material with an arbitrary stress versus strain curve and arbitrary strain rate dependency. This includes an orthotropic damage model (only for shell elements). Field Title Desc TITLE_OPTION MID RO E PR SIGY ETAN EPPF TDEL Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Yield Stress Tangent Modulus Plastic Strain, at which material softening begins Minimum time step size for Automatic Element Deletion 136 Materials Field C, P LCSS LCSR EPPFR VP Strain Rate Parameter Comments Load Curve Id defining Effective Stress vs. Effective Plastic Strain Load Curve Id defining Strain Rate Scaling Effect on Yield Stress Plastic Strain at which material ruptures Formulation for Rate Effects 0: Scale Yield Stress 1: Viscoplastic Formulation NUMINT LCDM ALPHA BETA GAMMA D0 B LAMDA DS L No. of through thickness integration points which must fail before the element is deleted Load Curve Id defining nonlinear damage curve Parameter α Parameter β Parameter γ Parameter D0 Parameter b Parameter λ Parameter Ds Optional characteristic element length for this material. See Also: • LS-DYNA Keyword User’s Manual Materials 137 Materials MAT_FU_CHANG_FOAM A material such as low and medium density foams, for hysteric unloading behaviors. Rate effects can be included in this material model. Field Title Desc TITLE_OPTION MID RO E ED TC FAIL Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Young’s Relaxation Modulus for rate effect Tension Cutoff Stress Failure option after Cutoff Stress is reached 0: Tensile Stress Remains at cutoff 1: Tensile Stress Resets to Zero DAMP TBID Viscous Coefficient Table Id for nominal Stress vs. Strain 138 Materials Field BVFLAG Bulk Viscosity activation Flag 0: No 1: Active SFLAG Strain Rate Flag 0: True strain 1: Engineering strain RFLAG Strain Rate evaluation flag 0 : First principal direction Comments 1 : Principal strain rates for each principal direction 2: Volumetric strain rate TFLAG Tensile Stress Evaluation Flag 0: Linear 1: Input via Load Curves with the tensile response corresponding to negative values of stress and strain PVID SRAF Load Curve Id defining Pressure vs. Volumetric Strain Strain Rate averaging flag 0: Weighted running average 1: Average of the last twelve values REF User reference geometry to initialize the stress tensor.: .EQ. 0: OFF .EQ. 1: ON HU D0, N0, C0, Ni, Ci AIJ, SIJ MINR MAXR SHAPE Hysteric unloading factor between 0 and 1 (default = 1, i.e. no energy dissipation). Material Constants Material Constants Minimum strain rate of interest Maximum strain rate of interest Shape factor for unloading. Active for nonzero values of the hysteric unloading factor HU. Materials 139 Materials See Also: • LS-DYNA Keyword User’s Manual MAT_WINFRITH_CONCRETE A smeared crack, smeared rebar, material model (only for the 8-noded single integration point continuum element). Field Title Desc TITLE_OPTION MID RO TM PR UCS UTS FE Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Tangent Modulus of Concrete Poisson’s Ratio Uniaxial Compression Strength Uniaxial Tensile Strength Depends on value for RATE If RATE = 0, FE is Fracture Energy per unit area in opening crack If RATE = 1, FE is crack width at which crack-normal tensile stress becomes zero ASIZE E YS Aggregate size (radius) Young’s Modulus for rebar Yield Stress for rebar 140 Materials Field EH UELONG RATE Hardening Modulus for rebar Comments Ultimate elongation before rebar fails Rate effects Flag 0: Included (MAT_0 84) 1: Turned off (MAT_0 85) CONM CONL CONT LCID Factor to convert model mass units to kg Factor to convert model length units to meters (if CONM .GT. 0) Factor to convert model time units to seconds Defining Pressure vs. Volumetric Strain See Also: • LS-DYNA Keyword User’s Manual Materials 141 Materials MAT_WINFRITH_CONCRETE_REINFORCEMENT A rebar reinforcement material model (material type 84). Reinforcement quantity is defined as the ratio of the cross-sectional area of steel, relative to the cross-sectioanl area of concrete in the element (or layer). Field Title Desc TITLE_OPTION MID RO TM PR UCS UTS FE Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Tangent Modulus of Concrete Poisson’s Ratio Uniaxial Compression Strength Uniaxial Tensile Strength Depends on value for RATE If RATE = 0, FE is Fracture Energy per unit area in opening crack If RATE = 1, FE is crack width at which crack-normal tensile stress becomes zero 142 Materials Field ASIZE E YS EH UELONG RATE Aggregate size (radius) Young’s Modulus for rebar Yield Stress for rebar Hardening Modulus for rebar Comments Ultimate elongation before rebar fails Rate effects Flag 0: Included (MAT_0 84) 1: Turned off (MAT_0 85) CONM CONL CONT LCID EID1 EID2 INC XR YR ZR Factor to convert model mass units to kg Factor to convert model length units to meters (if CONM .GT. 0) Factor to convert model time units to seconds Defining Pressure vs. Volumetric Strain First element Id in group Last element Id in group Element increment for genaration X-reinforcement quantity (for bars running parallel to global x-axis) Y-reinforcement quantity (for bars running parallel to global y-axis) Z-reinforcement quantity (for bars running parallel to global z-axis) PID AXIS Part Id of reinforced elements Axis normal to layer: .EQ. 1: A and B are parallel to global Y and Z, respectively .EQ. 2 A and B are parallel to global X and Z, respectively .EQ. 3: A and B are parallel to global X and Y, respectively COOR RQA RQB Coordinate location of layer (X-coordinate if AXIS = 1, Y-Coordinate if AXIS = 2, Z-Coordinate if AXIS = 3) Reinforcement quantity (A) Reinforcement quantity (B) Materials 143 Materials See Also: • LS-DYNA Keyword User’s Manual MAT_ORTHOTROPIC_VISCOELASTIC A viscoelastic material model (only for shell elements). Field Title Desc TITLE_OPTION MID RO EA EB EC VF K G0 GINF BETA Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus in Longitudinal Direction Young’s Modulus in Transverse Direction Young’s Modulus in Normal Direction Volume fraction for viscoelastic material Elastic Bulk Modulus Short time Shear Modulus Long time Shear Modulus Decay Constant 144 Materials Field PRBA, PRCA, PRCB GAB, GBC, GCA AOPT Comments Poisson’s Ratio in the ba, ca and cb directions Shear Moduli in the ab, bc and ca directions Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal. MANGLE blank1, blank2, blank3 Ai Vi Di Material Angle (Degrees), for AOPT=3 Blank Fields Component of Vector a, for AOPT=2 Component of Vector v, for AOPT=3 Component of Vector d, for AOPT=2 See Also: • LS-DYNA Keyword User’s Manual Materials 145 Materials MAT_CELLULAR_RUBBER A material model for a cellular rubber with confined air pressure, combined with linear viscoelasticity. Field Title Desc TITLE_OPTION MID RO PR N SGL SW ST LCID C10, C01, C11, C20, C02 P0 PHI IVS G BETA Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Poisson’s Ratio Order or fit Specimen Gauge Length Specimen Width Specimen Thickness Load Curve Id defining the Force vs. Actual Change in gauge Length Material Constants Initial Air Pressure Ratio of cellular rubber to rubber density Initial Volumetric Strain Optional shear relaxation modulus, G, for rate effects Optional Decay Constant 146 Materials See Also: • LS-DYNA Keyword User’s Manual MAT_MTS This MTS material model, developed by Maudlin, Davidson, and Henninger [1990], is used for applications involving high pressures, large strains, and high strain rates. This model uses dislocation mechanics and provides an understanding of the plastic deformation process in ductile materials. Field Title Desc TITLE_OPTION MID RO SIGA SIGI SIGS SIG0 BULK HF0, HF1, HF2 SIGSO Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Dislocation interaction with long-range barriers Dislocation interaction with interstitial atoms Dislocation interaction with solute atoms NOT used Bulk Modulus (for shell elements) Dislocation generation material constants Saturation Threshold stress at 0 degrees K Materials 147 Materials Field EDOTSO, EDOTO, EDOTI, EDOTS BURG CAPA BOLTZ SM0, SM1, SM2 G0, GOI, GOS PINV, QINV, PINVI, QINVI, PINVS., QINVS., ALPHA RHOCPR TEMPRF EPSO Reference Strain rates Magnitude of Burgers vector Material Constant, A Boltzmann’s constant, k Shear Modulus Constants Comments Normalized activation energies Material Constants Product of density and specific heat Initial Element Temperature Factor to normalize strain rate See Also: • LS-DYNA Keyword User’s Manual MAT_PLASTICITY_POLYMER An elasto-plastic material model with arbitrary stress versus strain curve, and arbitrary strain rate dependency. Field Title Desc TITLE_OPTION Comments Unique name identifying material model Optional description of the material model If selected material title option is used 148 Materials Field MID RO PR C, P LCSS LCSR EFTX Mass Density of the material Poisson’s Ratio Strain Rate Parameters Comments Material identification number (Integer > 0) Load Curve Id defining Effective Stress vs. Total Effective Strain Load Curve Id defining Strain Rate Scaling effect on Yield Stress Failure Flag 0: Failure determined by Maximum tensile strain 1: Failure determined only by tensile strain in local x direction 2: Failure determined only by tensile strain in local y direction DAMP RATEFAC LCFAIL Stiffness proportional damping ratio Filtering factor for strain rate effect Load Curve Id defining variation of Failure strain with Strain rate See Also: • LS-DYNA Keyword User’s Manual MAT_ACOUSTIC Defines the properties of materials used to track low pressure waves in acoustic media, like air or water (only for acoustic pressure elements). Field Title Desc TITLE_OPTION Comments Unique name identifying material model Optional description of the material model If selected material title option is used Materials 149 Materials Field MID RO C BETA CF Mass Density of the material Sound Speed Damping Factor Cavitation Flag 0: Off 1: On ATMOS GRAV XP, YP, ZP XN, YN, ZN Atmospheric Pressure Comments Material identification number (Integer > 0) Gravitational Acceleration constant Coordinates of free surface point Direction cosines of free surface normal vector See Also: • LS-DYNA Keyword User’s Manual 150 Materials MAT_SOFT_TISSUE Defines a transversely isotropic hyperelastic material that represents biological soft tissue such as ligaments, tendons, and fascia. Field Title Desc TITLE_OPTION MID RO Ci XK XLAM FANG XLAMO FAILSF FAILSM Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Hyperelastic Coefficients Bulk Modulus Stretch ratio at which fibers are straightened Fiber angle in local shell coordinate system (shell elements only) Initial fiber stretch stretch ratio for ligament fibers at failure (shell elements only). If zero, failure is not considered. stretch ratio for surrounding matrix material at failure (shell elements only). If zero, failure is not considered. Materials 151 Materials Field FAILSHR Comments Shear strain at failure of a material point (shell elements only). If zero, failure is not considered. This failure value is independent of FAILSF and FAILSM. 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. AOPT AX, AY, AZ BX, BY, BZ LAX, LAY, LAZ MACF Components of first material axis point/vector Components of second material axis point/vector Component of fiber orientation vector (Brick elements only) Material axes change flag for brick element: =1 No Change; = 2 switch mateial axes a and b =3 switch material axes a and c ; =4 switch material axes b and c See Also: • LS-DYNA Keyword User’s Manual 152 Materials MAT_SOFT_TISSUE_VISCO A transversely isotropic hyperelastic material model that represents biological soft tissue such as ligaments, tendons, and fascia. This model has a viscoelastic option activating a six-term Prony series kernel for the relaxation function. Field Title Desc TITLE_OPTION MID RO Ci XK XLAM FANG XLAMO Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Hyperelastic Coefficients Bulk Modulus Stretch ratio at which fibers are straightened Fiber angle in local shell coordinate system (shell elements only) Initial fiber stretch Materials 153 Materials Field AOPT Comments 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. AX, AY, AZ BX, BY, BZ LAX, LAY, LAZ Si Ti Components of first material axis point/vector Components of second material axis point/vector Component of fiber orientation vector (Brick elements only) Spectral strengths for prony series relaxation kernel Characteristic time for prony series relaxation kernel See Also: • LS-DYNA Keyword User’s Manual MAT_ELASTIC_6DOF_SPRING_DISCRETE_BEAM A material model for simulating the effects of nonlinear elastic and nonlinear viscous beams using six springs each acting along one of it six degrees-of-freedom. Field Title Desc TITLE_OPTION MID RO TPIDR Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Part Id governing the Translational motion in the local r direction (If zero, no force is computed in this direction) 154 Materials Field TPIDS TPIDT RPIDR RPIDS RPIDT Comments Part Id governing the Translational motion in the local s direction (If zero, no force is computed in this direction) Part Id governing the Translational motion in the local t direction (If zero, no force is computed in this direction) Part Id governing the Rotational motion about the local r direction (If zero, no moment is computed in this direction) Part Id governing the Rotational motion about the local s direction (If zero, no moment is computed in this direction) Part Id governing the Rotational motion about the local t direction (If zero, no moment is computed in this direction) See Also: • LS-DYNA Keyword User’s Manual MAT_INELASTIC_SPRING_DISCRETE_BEAM A material model for elastoplastic springs, with damping to be represented with discrete beam elements. A yield force versus deflection is used which can vary in tension and compression. Field Title Desc TITLE_OPTION MID RO K F0 D Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Elastic Loading/Unloading Stiffness Optional initial force Optional viscous damping coefficient Materials 155 Materials Field CDF TDF FLCID HLCID C1, C2 DLE GLCID Comments Compressive displacement at failure Tensile Displacement at failure Load Curve Id defining Yield Force vs. Plastic Displacement Load Curve Id defining Force vs. Relative Velocity Damping Coefficients Scale Factor for time unit Load Curve Id defining a Scale Factor vs. Deflection for Load Curve Id, HLCID See Also: • LS-DYNA Keyword User’s Manual MAT_INELASTIC_6DOF_SPRING_DISCRETE_BEAM A material model for nonlinear inelastic and nonlinear viscous beams using six springs each acting along one of it six degrees-of-freedom. Field Title Desc TITLE_OPTION MID RO TPIDR TPIDS TPIDT Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Part Id governing the Translational motion in the local r direction (If zero, no force is computed in this direction) Part Id governing the Translational motion in the local s direction (If zero, no force is computed in this direction) Part Id governing the Translational motion in the local t direction (If zero, no force is computed in this direction) 156 Materials Field RPIDR RPIDS RPIDT Comments Part Id governing the Rotational motion about the local r direction (If zero, no moment is computed in this direction) Part Id governing the Rotational motion about the local s direction (If zero, no moment is computed in this direction) Part Id governing the Rotational motion about the local t direction (If zero, no moment is computed in this direction) See Also: • LS-DYNA Keyword User’s Manual MAT_BRITTLE_DAMAGE A material model with anisotropic brittle damage characteristics, used mainly for concrete but can be applied for a variety of brittle materials. Field Title Desc TITLE_OPTION MID RO E PR TLIMIT SLIMIT FTOUGH SRETEN VISC Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Tensile Limit Shear Limit Fracture Toughness Shear Retention Viscosity Materials 157 Materials Field FRA_RF E_RF YS_RF EH_RF FS_RF SIGY Comments Fraction of reinforcement in section Young’s Modulus of Reinforcement Yield Stress of Reinforcement Hardening Modulus of Reinforcement Failure Strain of Reinforcement Compressive Yield Stress See Also: • LS-DYNA Keyword User’s Manual MAT_GENERAL_JOINT_DISCRETE_BEAM Defines the properties of a general joint constraining any combination of degrees of freedom between two nodes. Field Title Desc TITLE_OPTION MID RO TR Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Translational Constraint Code along r-axis 0: Free 1:Fixed 158 Materials Field TS Comments Translational Constraint Code along s-axis 0: Free 1:Fixed TT Translational Constraint Code along t-axis 0: Free 1:Fixed RR Rotational Constraint Code about r-axis 0: Free 1:Fixed RS Rotational Constraint Code about s-axis 0: Free 1:Fixed RT Rotational Constraint Code about t-axis 0: Free 1:Fixed RPST RPSR Penalty stiffness scale factor for translational constraints Penalty stiffness scale factor for rotational constraints See Also: • LS-DYNA Keyword User’s Manual Materials 159 Materials MAT_SIMPLIFIED_JOHNSON_COOK A material model used for problems where the strain rates vary over a large range. In this model, thermal effect and damage are ignored and maximum stress is directly limited since thermal softening is not available. Field Title Desc TITLE_OPTION MID RO E PR VP Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Formulation for Rate Effects 0: Scale Yield Stress 1: Viscoplastic Formulation A, B, N, C PSFAIL SIGMAX SIGSAT EPSO Parameters used in the Johnson-Cook flow stress equation Effective Plastic Strain at Failure Maximum Stress obtained from Work Hardening before rate effects are added Saturation Stress Effective Plastic Strain rate See Also: • LS-DYNA Keyword User’s Manual 160 Materials MAT_SIMPLIFIED_JOHNSON_COOK_ORTHO_DAMAGE Defines the properties of a material used for problems where the strain rates vary over a large range. Orthotropic damage is included as a means for treating failure in aluminum panels (only for shell elements with multiple through thickness integration points). Field Title Desc TITLE_OPTION MID RO E PR VP Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Formulation for Rate Effects 0: Scale Yield Stress 1: Viscoplastic Formulation EPPFR LCDM NUMINT A, B, N, C PSFAIL SIGMAX SIGSAT EPSO Plastic Strain at which the material ruptures Load Curve Id defining nonlinear damage curve No. of through thickness integration points which must fail before element is deleted Parameters used in the Johnson-Cook flow stress equation Effective Plastic Strain at Failure Maximum Stress obtained from Work Hardening before rate effects are added Saturation Stress Effective Plastic Strain rate Materials 161 Materials See Also: • LS-DYNA Keyword User’s Manual MAT_SPOTWELD A material model for spotweld modeled with beam element type 9, and solid element type 1. Field Title Desc TITLE_OPTION MID RO E PR SIGY ET DT TFAIL EFAIL NRR NRS NRT MRR MSS MTT NF Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Initial Yield Stress Hardening Modulus Time Step Size for Mass Scaling Failure Time (Ignored if value is zero) Effective Plastic Strain at Failure Axial force resultant NrrF (or Maximum Axial Stress σrrF) at failure Force resultant NrsF (or Maximum Shear Stress τF) at failure Force resultant NrtF at failure Torsional moment resultant MrrF at failure Moment resultant MssF at failure Moment resultant MttF at failure No. of force vectors stored for filtering 162 Materials See Also: • LS-DYNA Keyword User’s Manual MAT_SPOTWELD_DAMAGE-FAILURE A material model used in spotweld, modeled with beam element type 9, and solid element type 1. Damage parameters are also included in this model. Field Title Desc TITLE_OPTION MID RO E PR SIGY ET DT TFAIL EFAIL NRR NRS NRT MRR Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Initial Yield Stress Hardening Modulus Time Step Size for Mass Scaling Failure Time (Ignored if value is zero) Effective Plastic Strain at Failure Axial force resultant NrrF (or Maximum Axial Stress σrrF) at failure Force resultant NrsF (or Maximum Shear Stress τF) at failure Force resultant NrtF at failure Torsional moment resultant MrrF at failure Materials 163 Materials Field MSS MTT NF RS OPT Comments Moment resultant MssF at failure Moment resultant MttF at failure No. of force vectors stored for filtering Rupture Strain Failure Option 0: Resultant based failure 1: Stress based failure computed from resultant (Toyota) 2: User subroutine to determine failure 3: Notch stress based failure (beam weld only) 4: Stress intensity factor at failure (beam weld only) 5: Structural stress at failure (beam weld only) FVAL Failure parameter: .EQ. 3: Notch stress value at failure (σKF) .EQ. 4: Stress intensity factor value at failure (KeqF) .EQ. 5: Structural stress value at failure (σSF) .EQ. 6: Number of cycles that that failure condition must be met to trigger beam deletion. .EQ. 9: Number of cycles that that failure condition must be met to trigger beam deletion. Note: Values of -2, -1, 0, 1, 2, 7 - Not used TRUE_T BETA True weld thickness. This optional value is available for solid element failure by OPT = 0, 1, 7, or -2. Damage model decay rate. See Also: • LS-DYNA Keyword User’s Manual MAT_SPOTWELD_DAIMLERCHRYSLER A material model used in spotweld, modeled with solid element type 1, with type 6 hour glass control. Special Damage parameters are used in this model. 164 Materials Field Title Desc TITLE_OPTION MID RO E PR DT TFAIL EFAIL NF RS TRUE_T CON_ID Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Time Step Size for Mass Scaling Failure Time (Ignored if value is zero) Effective Plastic Strain at Failure Number of failure function evaluations stored for filtering by time averaging. Rupture Strain True weld thickness for hexahedron solid weld element. Connection Id of *DEFINE_CONNECTION See Also: • LS-DYNA Keyword User’s Manual Materials 165 Materials MAT_GEPLASTIC_SRATE_2000a Defines properties for the General Electric’s commercially available thermoplastics subjected to high strain rates. This model features variation of yield stress dependent upon strain rate, cavitation effects of rubber modified material, and automatic element deletion for either ductile or brittle materials. Field Title Desc TITLE_OPTION MID RO E PR RATESF EDOTO ALPHA LCSS LCFEPS LCFSIG LCE Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Constant in plastic strain rate equation Reference Strain Rate Pressure Sensitive Factor Load Curve Id (or Table Id) for post Yield Stress behavior vs. Strain Load Curve Id for Plastic failure Strain vs. Strain Rate Load Curve Id for Maximum principal failure Stress vs. Strain Rate Load Curve Id for Unloading Moduli vs. Plastic Strain See Also: • LS-DYNA Keyword User’s Manual 166 Materials MAT_HYPERBOLIC_SIN Defines properties for modeling materials with temperature and rate dependent plasticity. Field Title Desc TITLE_OPTION MID RO E PR T HC VP Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Initial Temperature Heat Generation Coefficient Formulation for Rate Effects 0: Scale Yield Stress 1: Viscoplastic Formulation ALPHA, N, A, Q, G EPSO Material constitutive constants Effective plastic strain rate See Also: • LS-DYNA Keyword User’s Manual Materials 167 Materials MAT_ANISOTROPIC_VISCOPLASTIC Defines an anisotropic viscoplastic material that is applied to either shell or brick elements. The material constants may be input directly, or by stress-strain data. If stress-strain data is provided, a least squares fit will be performed to determine the constants. Field Title Desc TITLE_OPTION MID RO E PR SIGY FLAG LCSS Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Initial Yield Stress Flag for material parameters Load Curve Id for Effective Stress vs. Effective Plastic Strain 168 Materials Field ALPHA α distribution hardening: =0: Kinematic hardening = 1: Isotropic hardening QRi, CRi QXi, CXi VK, VM R00/F R45/G R90/H L, M, N AOPT Comments Isotropic Hardening Parameters Kinematic Hardening Parameters Viscous Material Parameters R00 for shell, or F for solid R45 for shell, or G for solid R90 for shell, or H for solid Parameters (for solid elements only Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal. 4: Locally orthotropic in cylindrical coordinate system with the material axis determined by a vector v, and an originating point, P, which defines the centerline axis. This option is for solid elements only. FAIL Failure flag: .LT. 0: user defined failure subroutine to determine failure. .EQ. 0: failure is not considered .GT. 0: Plastic strain to failure. When the plastic strain reaches this value, the element is deleted from calculation. Materials 169 Materials Field NUMINT MACF Comments Number of integration point which must fail before element is deleted.. If zero, all points must fail. This option applies to shell elements only. Material axes change flag: =1 No Change; = 2 switch mateial axes a and b =3 switch material axes a and c ; =4 switch material axes b and c XP, YP, ZPP Ai Vi Di BETA Coordinates of point p, for AOPT=1 Component of Vector a, for AOPT=2 Component of Vector v, for AOPT=3 Component of Vector d, for AOPT=2 Material Angle (Degrees), for AOPT=3 See Also: • LS-DYNA Keyword User’s Manual 170 Materials MAT_ANISOTROPIC_PLASTIC This anisotropic plastic material model is a simplified version of the MAT_ANISOTROPIC_VISCOPLASTIC model. This model applies to shell elements only. Field Title Desc TITLE_OPTION MID RO E PR SIGY LCSS QRi, CRi QXi, CXi R00/F R45/G R90/H Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Initial Yield Stress Load Curve Id for effective Stress vs. effective plastic Strain Isotropic Hardening Parameters Kinematic Hardening Parameters R00 for shell or F for solid R45 for shell or G for solid R90 for shell or H for solid Materials 171 Materials Field S11, S22, S33, S12 AOPT Material Axes option Comments Yield Stress in the x, y, z and xy direction, respectively 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal. 4: Locally orthotropic in cylindrical coordinate system with the material axis determined by a vector v, and an originating point, P, which defines the centerline axis. This option is for solid elements only. XP, YP, ZP Ai Vi Di BETA Coordinates of point p, for AOPT=1 Components of Vector a, for AOPT=2 Components of Vector v, for AOPT=3 Components of Vector d, for AOPT=2 Material Angle (Degrees), for AOPT=3 See Also: • LS-DYNA Keyword User’s Manual 172 Materials MAT_DAMAGE_1 Defines properties for a continuum damage mechanics material model which includes anisotropy and viscoplasticity. This model is applied to shell, thick shell and brick elements. Field Title Desc TITLE_OPTION MID RO E PR SIGY LCSS LCDM Qi, Ci EPSD Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Initial Yield Stress Load Curve Id for effective Stress vs. effective plastic Strain Load Curve Id defining nonlinear damage (for FLAG = -1) Isotropic Hardening Parameters Damage Threshold, rd Materials 173 Materials Field S EPSR DC FLAG Damage Material Constant Comments Plastic strain at which material ruptures Critical Damage valueDc Flag for Localization -1: Anisotropic damage 0: No calculation of localization due to damage 1: Flag those elements where local stabilization occurs VK, VM R00/F R45/G R90/H L, M, N AOPT Viscous Material Parameter R00 for shell or F for solid R45 for shell or G for solid R90 for shell or H for solid Parameters (for solid elements only Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal. 4: Locally orthotropic in cylindrical coordinate system with the material axis determined by a vector v, and an originating point, P, which defines the centerline axis. This option is for solid elements only. XP, YP, ZP Ai Vi Coordinates of point p, for AOPT=1 Component of Vector a, for AOPT=2 Component of Vector v, for AOPT=3 174 Materials Field Di BETA Comments Component of Vector d, for AOPT=2 Material Angle (Degrees), for AOPT=3 See Also: • LS-DYNA Keyword User’s Manual MAT_DAMAGE_2 Defines properties for an elastic viscoplastic material model combined with the continuum damage mechanics. This model is applied to shell, thick shell and brick elements. Field Title Desc TITLE_OPTION MID RO E PR SIGY ETAN FAIL Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Yield Stress Tangent Modulus Failure flag =0: Failure due to plastic strain not considered > 0: Plastic strain to failure considered. When the plastic strain reaches this value, the element is deleted from calculation. Materials 175 Materials Field TDEL C, P LCSS LCSR EPSD S DC Strain Rate Parameters Comments Minimum time step for Automatic Element Deletion Load Curve Id defining effective Stress vs. effective plastic Strain Load Curve Id defining Strain Rate Scaling Effect on Yield Stress Damage Threshold, rd Damage Material Constant Critical Damage valueDc See Also: • LS-DYNA Keyword User’s Manual MAT_ELASTIC_VISCOPLASTIC_THERMAL Defines properties for an elastic viscoplastic material with thermal effects. Field Title Desc TITLE_OPTION MID RO E PR Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio 176 Materials Field SIGY ALPHA LCSS QRi, CRi QXi, CXi C, P LCE LCPR LCSIGY LCR LCX LCALPH LCC LCP Initial Yield Stress Comments Coefficient of thermal expansion Load Curve Id for effective Stress vs. effective plastic Strain Isotropic Hardening Parameters Kinematic Hardening Parameters Viscous Material Parameters Load Curve Id defining Young’s Modulus vs. Temperature Load Curve Id defining Poisson’s Ratio vs. Temperature Load Curve Id defining Initial Yield Stress vs. Temperature Load Curve Id defining for Parameters QR1 and QR2 vs. Temperature Load Curve Id defining for Parameters QX1 and QX2 vs. Temperature Load Curve Id defining Coefficient of thermal expansion vs. Temperature Load Curve Id defining scaling Viscous material parameter C vs. Temperature Load Curve Id defining scaling Viscous material parameter P vs. Temperature See Also: • LS-DYNA Keyword User’s Manual Materials 177 Materials MAT_JOHNSON_HOLMQUIST_CERAMICS Defines properties for a material used to model ceramics, glass and other brittle materials. Field Title Desc TITLE_OPTION MID RO G A B C M N EPSI T SFMAX HEL PHEL BETA Di K1, K2 Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Shear Modulus Intact normalized strength parameter Fractured normalized strength parameter Strength Parameter (for strain rate dependence) Fracture strength parameter (Pressure exponent) Intact strength parameter (Pressure exponent) Reference Strain Rate Maximum Tensile Strength Maximum normalized Fractured Strength Hugoniot elastic limit Pressure component at the at Hugoniot elastic limit Fraction of elastic energy loss converted to hydrostatic energy Parameters for plastic strain to fracture First and Second pressure coefficients 178 Materials Field K3 FS Failure Criteria Comments Elastic Constant (Note that K1 is the bulk modulus) <0: Fails if (p* + t*) is negative (tensile failure) 0: No failure >0: Fails if strain exceeds FS See Also: • LS-DYNA Keyword User’s Manual MAT_JOHNSON_HOLMQUIST_CONCRETE This material model is used for concrete under high strain rates, large strains and high pressure. Field Title Desc TITLE_OPTION MID RO G A B C N Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Shear Modulus Normalized Cohesive Strength Normalized Pressure Hardening Strain rate coefficient Pressure Hardening Exponent Materials 179 Materials Field FC T EPSO EFMIN SFMAX PC UC PL UL D1, D2 K1, K2, K3 FS Comments Quasi-static uniaxial compressive strength Maximum Tensile hydrostatic pressure Reference Strain Rate Plastic strain before fracture Maximum Fractured Strength Crushing Pressure Crushing Volumetric Strain Locking Pressure Locking Volumetric Strain Damage Constants Pressure Constants Failure Type See Also: • LS-DYNA Keyword User’s Manual MAT_FINITE_ELASTIC_STRAIN_PLASTICITY An elasto-plastic material model with arbitrary stress-strain curve and arbitrary strain rate dependency. This material model uses a finite strain formulation allowing large elastic strains before yielding. Field Title Desc TITLE_OPTION MID RO Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material 180 Materials Field E PR SIGY ETAN FAIL Young’s Modulus Poisson’s Ratio Yield Stress Tangent Modulus Failure Flag Comments <0: User defined failure subroutine is called to determine failure =0: Failure is not considered. >0: Plastic strain to failure. When plastic strain reaches this value, the element is deleted from calculation. TDEL C, P LCSS LCSR Minimum time step size for automatic element deletion Strain Rate Parameters Load Curve Id for effective Stress vs. effective plastic Strain Load Curve Id defining Strain Rate Effect on Yield Stress See Also: • LS-DYNA Keyword User’s Manual MAT_LAYERED_LINEAR_PLASTICITY Defines a layered elastoplastic material with an arbitrary stress-strain curve and arbitrary strain rate dependency. Field Title Desc Comments Unique name identifying material model Optional description of the material model Materials 181 Materials Field TITLE_OPTION MID RO E PR SIGY ETAN FAIL Comments If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Yield Stress Tangent Modulus Failure Flag <0: User defined failure subroutine is called to determine failure =0: Failure is not considered. >0: Plastic strain to failure. When plastic strain reaches this value, the element is deleted from calculation. TDEL C, P LCSS LCSR Minimum time step size for automatic element deletion Strain Rate Parameters Load Curve Id for effective Stress vs. effective plastic Strain Load Curve Id defining Strain Rate Effect on Yield Stress See Also: • LS-DYNA Keyword User’s Manual MAT_UNIFIED_CREEP Defines properties of a material for elastic creep behavior. Field Title Desc TITLE_OPTION Comments Unique name identifying material model Optional description of the material model If selected material title option is used 182 Materials Field MID RO E PR A N M Mass Density of the material Young’s Modulus Poisson’s Ratio Stress Coefficient Stress Exponent Time Exponent Comments Material identification number (Integer > 0) See Also: • LS-DYNA Keyword User’s Manual MAT_COMPOSITE_LAYUP Defines the elastic response of composite layups that have an arbitrary number of layers through the shell thickness. Field Title Desc TITLE_OPTION MID RO EA Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus, a Direction Materials 183 Materials Field EB EC PRBA, PRCA, PRCB GAB, GBC, GCA AOPT Young’s Modulus, b Direction Young’s Modulus, c Direction Comments Poisson’s Ratio in the ba, ca and cb directions Shear Moduli in the ab, bc and ca directions Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal. 4: Locally orthotropic in cylindrical coordinate system with the material axis determined by a vector v, and an originating point, P, which defines the centerline axis. This option is for solid elements only. XP, YP, ZP Ai Vi Di BETA Coordinates of point p for AOPT=1 and 4 Component of Vector a, for AOPT=2 Component of Vector v, for AOPT=3 and 4 Component of Vector d, for AOPT=2 Material Angle (Degrees), for AOPT=3 See Also: • LS-DYNA Keyword User’s Manual 184 Materials MAT_COMPOSITE_MATRIX Defines the properties of materials used for the elastic response of composites where pre-integration is used to compute the extensional, bending, and coupling stiffness coefficients (available only for Belytschko-Tsay resultant shell formulation). Field Title Desc TITLE_OPTION MID RO Cij Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Coefficient of Stiffness Matrix Materials 185 Materials Field AOPT Material Axes option Comments 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal. 4: Locally orthotropic in cylindrical coordinate system with the material axis determined by a vector v, and an originating point, P, which defines the centerline axis. This option is for solid elements only. XP, YP, ZP Ai Vi Di BETA Coordinates of point p for AOPT=1 and 4 Component of Vector a, for AOPT=2 Component of Vector v, for AOPT=3 and 4 Component of Vector d, for AOPT=2 Material Angle (Degrees), for AOPT=3 See Also: • LS-DYNA Keyword User’s Manual 186 Materials MAT_COMPOSITE_DIRECT Defines properties for a material used for the elastic response of composites where pre-integration is used to compute the extensional, bending, and coupling stiffness coefficients (available only for BelytschkoTsay resultant shell formulation). Field Title Desc TITLE_OPTION MID RO Cij Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Coefficient of Stiffness Matrix See Also: • LS-DYNA Keyword User’s Manual Materials 187 Materials MAT_GENERAL_NONLINEAR_6DOF_DISCRETE_BEAM Defines the properties of a very general spring and damper. The beam is based on MAT_SPRING_GENERAL_NONLINEAR option. This model includes additional unloading options. Field Title Desc TITLE_OPTION MID RO KT KR UNLDOPT OFFSET Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Translational stiffness for unloading option 2.0 Rotational Stiffness for unloading option 2.0 Unloading Option Offset Factor (between 0 and 1) 188 Materials Field DAMPF LCIDTR, LCIDTS, LCIDTT LCIDRR, LCIDRS, LCIDRT LCIDTUR, LCIDTUS, LCIDTUT LCIDRUR, LCIDRUS, LCIDRUT LCIDTDR, LCIDTDS, LCIDTDT LCIDRDR, LCIDRDS, LCIDRDT LCIDTER, LCIDTES, LCIDTET LCIDRER, LCIDRES, LCIDRER UTFAILR, UTFAILS, UTFAILT WTFAILR, WTFAILS, WTFAILT UCFAILR, UCFAILS, UCFAILT WCFAILR, WCFAILS, WCFAILT IUR, IUS< IUT IWR, IWS, IWT Damping factor for stability Comments Load Curve Id defining Translational Force resultant along r, s, t axes respectively vs. Translational Displacement. Load Curve Id defining Rotational Moment about r, s, t axes vs. Rotational Displacement. Load Curve Id defining Translational Force resultant along r, s, t axes vs. Translational Displacement during unloading Load Curve Id defining Rotational Moment about r, s, t axes vs. Rotational Displacement during unloading. Load Curve Id defining Translational Damping Force along r, s, t axes vs. relative Translational Velocity. Load Curve Id defining Rotational Damping Moment about r, s, t axes vs. relative Rotational Velocity. Load Curve Id defining Translational Damping Force scale factor vs. relative Displacement along r, s, t axes Load Curve Id defining Rotational Damping Moment scale factor vs. relative Displacement along r, s, t axes Translational Displacement along r, s, t at failure in Tension Rotational Displacement about r, s, t at failure in Tension Translational Displacement along r, s, t at failure in Compression Rotational Displacement about r, s, t at failure in Compression Initial Translational Displacement along r, s, t directions Initial Rotational Displacement about r, s, t axes See Also: • LS-DYNA Keyword User’s Manual Materials 189 Materials MAT_GURSON Defines the material properties for the Gurson dilational plastic material model (available only for shell elements). Field Title Desc TITLE_OPTION MID RO E PR SIGY N Q1, Q2 FC F0 EN SN FN ETAN Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Yield Stress Exponent in power law Parameters Critical void volume fraction Initial void volume fraction Mean nucleation strain Standard deviation SN of the normal distribution of εN Void Volume Fraction of nucleating particles Hardening Modulus 190 Materials Field ATYP Hardening Type 1: Power Law 2: Linear 3: 8 points curve FF0 Li FFi LCSS LCLF NUMINT LCF0 LCFC LCFN VGTYP Failure void volume fraction Element Length Value Comments Corresponding failure void volume fraction Load Curve id defining effective Stress vs. effective plastic Strain Load Curve Id defining Failure Void Volume Fraction vs. Element Length No of through thickness integration points which must fail before element is deleted Lod curve Id defining initial void volume fraction f0 vs. element length. Lod curve Id defining initial void volume fraction fN vs. element length. Lod curve Id defining initial void volume fraction f0 vs. element length. Type of void growth behavior: .EQ. 0: void growth in tension, and void contraction in compression, but never below f0 (default). .EQ. 1: void growth in tension only. .EQ. 2: void growth in tension, and void contraction in compression, even below f0. See Also: • LS-DYNA Keyword User’s Manual Materials 191 Materials MAT_GURSON_RCDC Defines the material properties for the Gurson model with Wilkins Rc-Dc (for shell elements only). Field Title Desc TITLE_OPTION MID RO E PR SIGY N Q1, Q2 FC F0 EN SN FN Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Yield Stress Exponent in power law Parameters Critical void volume fraction Initial void volume fraction Mean nucleation strain Standard deviation SN of the normal distribution of εN Void Volume Fraction of nucleating particles 192 Materials Field ETAN ATYP Hardening Modulus Hardening Type 1: Power Law 2: Linear 3: 8 points curve FF0 Li FFi LCSS LCLF NUMINT ALPHA BETA GAMMA D0 B LAMBDA DS L Failure void volume fraction Element Length Value Comments Corresponding failure void volume fraction Load Curve id defining effective Stress vs. effective plastic Strain Load Curve Id defining Failure Void Volume Fraction vs. Element Length No of through thickness integration points which must fail before element is deleted Parameter α for Rc-Dc Model Parameter β for Rc-Dc Model Parameter γ for Rc-Dc Model Parameter D0 for Rc-Dc Model Parameter b for Rc-Dc Model Parameter λ for Rc-Dc Model Parameter ds for Rc-Dc Model Characteristic element length for Rc-Dc Material See Also: • LS-DYNA Keyword User’s Manual Materials 193 Materials MAT_GENERAL_NONLINEAR_1DOF_DISCRETE_BEAM Defines the material properties for a very general spring and damper. The beam is based on MAT_SPRING_GENERAL_NONLINEAR option and is a one dimensional version of 6DOF_DESCRETE_BEAM. This model includes additional unloading options. Field Title Desc TITLE_OPTION MID RO K UNLDOPT OFFSET DAMPF LCIDT LCIDTU LCIDTD LCIDTE UTFAIL Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Translational stiffness for unloading option 2 Unloading option Offset to determine permanent set upon unloading if the UNLDOPT equals to 3. Damping factor for stability Load Curve Id defining Translational Force along the axis vs. relative Translational Displacement. Load Curve Id defining Translational Force along the axis vs. relative Translational Displacement, during unloading Load Curve Id defining Translational Damping Force along the local axis vs. relative Translational Velocity. Load Curve Id defining Translational Damping Force scale factor along the local axis vs. relative Displacement. Translational displacement at failure in tension 194 Materials Field UCFAIL IU Comments Translational displacement at failure in compression Initial translational displacement along the axis See Also: • LS-DYNA Keyword User’s Manual MAT_HILL_3R Defines the properties for the Hill’s planar anisotropic material model with 3 R values. Field Title Desc TITLE_OPTION MID RO E PR Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Materials 195 Materials Field HR Hardening Rule 1: Linear 2: Exponential 3: Load Curve P1, P2 R00, R45, R90 LCID Epsilon_0 SPI AOPT Material Parameters Lankford parameters Comments Load Curve Id for the hardening rule ε0 for determining initial yield stress for exponential hardening Parameter to redefine ε0 Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal. blank1, blank2, blank3 Ai Vi Di BETA Blank Fields Component of Vector a, for AOPT=2 Component of Vector v, for AOPT=3 Component of Vector d, for AOPT=2 Material Angle (Degrees), for AOPT=3 See Also: • LS-DYNA Keyword User’s Manual 196 Materials MAT_MODIFIED_PIECEWISE_LINEAR_PLASTICITY Defines an elasto-plastic material with an arbitrary stress versus strain curve and arbitrary strain rate dependency (available only for shell elements). Field Title Desc TITLE_OPTION MID RO E PR SIGY ETAN FAIL TDEL C, P LCSS LCSR VP EPSTHIN EPSMAJ NUMINT Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Yield Stress Tangent Modulus Failure flag Minimum time step size for automatic element deletion Strain Rate Parameters Load Curve Id defining effective Stress vs. effective plastic Strain Load Curve Id defining Strain Rate scaling effect on Yield Stress Formulation for Rate Effects Thinning Plastic Strain at Failure Major Plastic Strain at Failure No. of through thickness integration points that must fail before element is deleted See Also: • LS-DYNA Keyword User’s Manual Materials 197 Materials MAT_PLASTICITY_COMPRESSION_TENSION Defines an isotropic elastic-plastic material allowing different yield stress versus plastic strain curves in compression and tension. Field Title Desc TITLE_OPTION MID RO E PR C, P FAIL TDEL LCIDC LCIDT Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Strain Rate Parameters Failure Flag Minimum time step size for automatic element deletion Load Curve Id defining Yield Stress vs. effective Plastic Strain in compression Load Curve Id defining Yield Stress vs. effective Plastic Strain in tension 198 Materials Field LCSRC LCSRT SRFLAG Comments Optional load curve Id defining strain rate scaling effect on yield stress when the material is in compression Optional load curve Id defining strain rate scaling effect on yield stress when the material is in tension Formulation for rate effects: .EQ. 0: Total strain rate ; .EQ. 1: Deviatoric strain rate LCFAIL PC PT PCUTC PCUTT PCUTF Load curve Id defining failure strain vs. strain rate Compressive mean stress (pressure) at which the yield stress follows the Load Curve ID, LCIDC Tensile mean stress (pressure) at which the yield stress follows the Load Curve ID, LCIDT Pressure cut-off in compression Pressure cut-off in tension Pressure cut-off flag: 0 = inactive ; 1 = active K NUM_RFS GI1 BETAI1 (optional) bulk modulus for the viscoelastic material. If nonzero, a Kelvin type will be used. Number of terms used for shear relaxationmodulus/shear decay constant (optional) shear relaxation modulus for the i-th term (optional) shear decay constant for the i-th term See Also: • LS-DYNA Keyword User’s Manual Materials 199 Materials MAT_MODIFIED_HONEYCOMB Defines the properties for aluminum honeycomb crushable foam materials with anisotropic behavior. Field Title Desc TITLE_OPTION MID RO E PR SIGY VF MU BULK Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Yield Stress Relative volume at which honeycomb is fully compacted Material viscosity coefficient Bulk Viscosity Flag 0: Not used 1: Active and MU=0 200 Materials Field LCA Load Curve ID, defining: Comments >0: Stress along a- axis vs. strain along a-axis <0: Yield stress vs. the angle off the material axis is degrees LCB Load Curve ID, defining: >0: Stress along b- axis vs. strain along b-axis <0: the strong axis stress vs. volumetric strain LCC Load Curve ID, defining: >0: Stress along c- axis vs. strain along c-axis <0: the wreak axis stress vs. volumetric strain LCS Load Curve ID, defining: >0: Shear Stress vs. shear strain <0: the damage curve defining the shear stress multiplier as a function of the shear strain component LCAB Load Curve ID, defining: >0: Shear Stress-ab vs. shear strain-ab <0: the damage curve defining the shear stress-ab multiplier as a function of the shear strain-ab LCBC Load Curve ID, defining: >0: Shear Stress-bc vs. shear strain-bc <0: the damage curve defining the shear stress-bc multiplier as a function of the shear strain-bc LCCA Load Curve ID, defining: >0: Shear Stress-ca vs. shear strain-ca <0: the damage curve defining the shear stress-ca multiplier as a function of the shear strain-ca LCSR EAAU, EBBU, ECCU GABU, GBCU, GCAU Load Curve ID of Strain Rate effect scale factor vs. Strain Rate Elastic Moduli in the a-, b-, and c- directions, in uncompressed configuration Shear Moduli in the ab, bc, ca planes in uncompressed configuration Materials 201 Materials Field AOPT Material Axes option Comments 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal. 4: Locally orthotropic in cylindrical coordinate system with the material axis determined by a vector v, and an originating point, P, which defines the centerline axis. This option is for solid elements only. MSCF Material axes change flag: 1 = no change (default) ; 2 = switch material axes a and b 3 = switch material axes a and c ; 4 = switch material axes b and c XP YP ZP Ai Di TSEF SSEF VREF X-coordinate of point p for AOPT=1 Y-coordinate of point p for AOPT=1 Z-coordinate of point p for AOPT=1 Component of Vector a, for AOPT=2 Component of Vector d, for AOPT=2 Tensile Strain at Element Failure Shear Strain at Element Failure Relative volume at which the reference geometry is stored (for solid elements 1, 2, 3, 4, 10) 202 Materials Field TREF SHDFLG Comments Element timestep size at which the reference geometry is stored Flag defining treatment of damage from curves LCS, LCAB, LCBC, and LCBC (relevant only if LCA < 0): .EQ. 0: damage reduces shear stress every time step .EQ. 1: damage = (shear stress)/(undamaged shear stress) See Also: • LS-DYNA Keyword User’s Manual MAT_ARRIBA_BOYCE_RUBBER Defines the material properties for hyperelastic rubber combined optionally with linear viscoelasticity. Field Title Desc TITLE_OPTION MID RO K G N Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Bulk Modulus Shear Modulus Number of statistical links Materials 203 Materials Field LCID TRAMP NT NUM_RFS GIi BETAIi Comments Load Curve id defining Relaxation curve for shear Optional ramp time for loading Number of Prony series terms in fit Number of viscoelastic constants Optional i-th shear Relaxation Modulus i Optional i-th shear Decay Constant See Also: • LS-DYNA Keyword User’s Manual MAT_HEART_TISSUE Defines the material properties for heart tissue as described in the paper by Guccione, McCulloch and Waldman [1991]. This model is transversely anisotropic. Field Title Desc TITLE_OPTION MID RO C, B1, B2, B3 Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Material Coefficients 204 Materials Field P AOPT Pressure in muscle tissue Material Axes option Comments 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal. 4: Locally orthotropic in cylindrical coordinate system with the material axis determined by a vector v, and an originating point, P, which defines the centerline axis. This option is for solid elements only. MACF Material axes change flag: 1 = no change (default) ; 2 = switch material axes a and b 3 = switch material axes a and c ; 4 = switch material axes b and c XP, YP, ZP Ai Vi Di BETA Coordinates of point p for AOPT=1 and 4 Component of Vector a, for AOPT=2 Component of Vector v, for AOPT=3 and 4 Component of Vector d, for AOPT=2 Material Angle (Degrees), for AOPT = 3 See Also: • LS-DYNA Keyword User’s Manual Materials 205 Materials MAT_LUNG_TISSUE Defines the material properties for a hyperelastic material model for heart tissue combined optionally with linear viscoelasticity. Field Title Desc TITLE_OPTION MID RO K C, DELTA, ALPHA, BETA, C1, C2 LCID TRAMP NT NUM_RFS GIi BETAIi Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Bulk Modulus Material Coefficients Relaxation curve for shear Optional ramp time for loading Number of Prony series terms in fit Number of viscoelastic constants Optional i-th shear Relaxation Modulus Optional i-th shear Decay Constant See Also: • LS-DYNA Keyword User’s Manual 206 Materials MAT_SPECIAL_ORTHOTROPIC This material model defines the properties for a material model developed for the Belytschko-Tsay and the C0 triangle shell elements. It is based on a resultant stress formulation. In plane behavior is treated separately from bending in order to model perforated materials such as television shadow masks. Field Title Desc TITLE_OPTION MID RO YS EP EiiP NUijP GijP EiiB NUijB G12B Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Yield Stress Plastic Hardening Modulus Young’s Modulus (in-plane) in i- direction Poisson’s Ratio in plane ij Shear Modulus in Plane ij Young’s Modulus (Bending) in i-direction Poisson’s Ratio (Bending) in ij plane Shear Modulus (Bending) in 12 plane Materials 207 Materials Field AOPT Material Axes option Comments 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal. blank i Ai Vi Di BETA Blank Field Component of Vector a, for AOPT=2 Component of Vector v, for AOPT=3 Component of Vector d, for AOPT=2 Material angle (degrees), for AOPT = 3 See Also: • LS-DYNA Keyword User’s Manual 208 Materials MAT_MODIFIED_FORCE_LIMITED This material model is an extension of MAT_FORCE_LIMITED (MAT_029). In addition to plastic hinge and collapse mechanisms, yield moments may be defined as a function of axial force. The moment transmitted by the hinge is defined by a moment-plastic rotation relationship. Materials 209 Materials 210 Materials Field Title Desc TITLE_OPTION MID RO E PR Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Materials 211 Materials Field DF AOPT Damping Factor Axial load curve option 0: Force vs. Strain 1: Force vs. change in length YTFLAG ASOFT M1, M2, ..., M8 LC1, LC2, ..., LC8 LPSi SFSi YMSi LPTi SFTi YMTi LPR SFR YMR LYSi SYSi LYTi SYTi LYR LYS HMS1_i LPMS1_i HMS2_i LPMS2_i HMT1_i LPMT1_i HMT2_i LPMT2_i Flag to allow beam to yield Axial elastic softening factor Applied End Moments Comments Load Curve Ids corresponding to applied end moments Load Curve Id for plastic moment vs. rotation about s-axis at node i Scale factor, plastic moment vs. rotation about s- axis at node i Yield moment about s- axis at node i for interaction calculations Load Curve Id for plastic moment vs. rotation about t-axis at node i Scale factor, plastic moment vs. rotation about t- axis at node i Yield moment about t- axis at node i for interaction calculations Load Curve Id for plastic torsional moment vs. rotation Load Curve Id for Scale factor vs. rotation Torsional Yield moment for interaction calculation Load Curve Id for yield moment vs. axial force along axis s at node i Load Curve Id for Scale factor applied to corresponding load curve LYSi Load Curve Id for yield moment vs. axial force along axis t at node i Load Curve Id for Scale factor applied to corresponding load curve LYTi Load Curve Id for yield moment vs. axial force for the torsional axis Load Curve Id for the Scale factor applying to LYR Hinge moments for s axis at node 1 for hinge i Load Curve Id for plastic moment vs. plastic rotation for HMS1_i Hinge moments for s axis at node 2 for hinge i Load Curve Id for plastic moment vs. rotation for HMS2_i Hinge moments for t axis at node 1 for hinge i Load Curve Id for plastic moment vs. rotation for HMT1_i Hinge moments for t axis at node 2 for hinge i Load Curve Id for plastic moment vs. rotation for HMT2_i 212 Materials Field HMR_i LPMR_i Comments Hinge moment for the torsional axis for hinge i Load Curve Id for plastic moment vs. plastic rotation for HMR_i See Also: • LS-DYNA Keyword User’s Manual MAT_VACUUM Defines the properties for a dummy material representing a vacuum in a multi-material Euler/ALE model. Field Title Desc TITLE_OPTION MID KW_OPTION Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Title optional keywords See Also: • LS-DYNA Keyword User’s Manual Materials 213 Materials MAT_RATE_SENSITIVE_POLYMER Defines the properties for simulating an isotropic ductile polymer with strain rate effects. It uses uniaxial test data. Field Title Desc TITLE_OPTION MID RO E PR D0 N Z0 q Omega Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Reference Strain Rate (D0) Exponent for inelastic strain rate Initial hardness of material (Z0) Parameter used in the constitutive equation Maximum internal stress See Also: • LS-DYNA Keyword User’s Manual 214 Materials MAT_TRANSVERSELY_ANISOTROPIC_CRUSHABLE_FOAM Defines the properties for extruded foam material that is transversely anisotropic, crushable, and of low density with no significant Poisson effect. Field Title Desc TITLE_OPTION MID RO E11, E22 E12 G K I11 I22 I12 I23 Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Elastic Moduli in the 1(axial) and 2 (transverse) direction Elastic shear Modulus in the axial-transverse plane (E12 = E13) Shear Modulus Bulk Modulus for Contact Stiffness Load Curve Id for Nominal Axial Stress vs. Volumetric Strain Load Curve Id for Nominal Transverse Stress vs. Volumetric Strain (I22= I33) Load Curve Id for Shear Stress components 12 and 31 vs. Volumetric Strain (I22= I31) Load Curve Id for Shear Stress components 23 vs. Volumetric Strain Materials 215 Materials Field IAA NY ANG MU AOPT Comments Load Curve Id for Nominal stress vs. Volumetric strain at angle, ANG, relative to the material axis Flag for symmetric yield surface Angle corresponding to Load Curve Id, IAA Damping factor Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. ISCL MSCF Load Curve Id for the strain rate scale factor vs. volumetric strain rate. The yield rate is scaled by the value specified by the load curve. Material axes change flag: 1 = no change (default) ; 2 = switch material axes a and b 3 = switch material axes a and c ; 4 = switch material axes b and c XP YP ZP Ai Vi Di X-coordinate of point p for AOPT=1 Y-coordinate of point p for AOPT=1 Z-coordinate of point p for AOPT=1 Component of Vector a, for AOPT=2 Components of vector v (for AOPT = 3 or 4) Component of Vector d, for AOPT=2 See Also: • LS-DYNA Keyword User’s Manual 216 Materials MAT_WOOD Defines the material properties for a transversely isotropic material (available only for solid elements). Field Title Desc TITLE_OPTION MID RO Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Materials 217 Materials Field NPLOT Plotting Option 1: Parallel damage 2: Perpendicular damage ITER IRATE Comments Number of plasticity algorithm iterations Rate effects option 0: Turn off 1: Turn on HARD IFAIL Perfect plasticity override Erosion perpendicular to the ground 0: No 1: Yes IVOL Erode on negative volume or strain increments greater than 0.01 =0 No (default) ; =1 Yes EL ET GLT GTR PR XT XC YT YC SXY SYZ GF1_I GF2_I BFIT DMAX_I GF1_r GF2_r Parallel Normal Modulus Perpendicular Normal Modulus Parallel Shear Modulus (GLT=GLR) Perpendicular Shear Modulus Poisson’s Ratio Parallel Tensile Strength Parallel Compressive Strength Perpendicular Tensile Strength Perpendicular Compressive Strength Parallel Shear Strength Perpendicular Shear Strength Parallel Fracture Energy in Tension Parallel Fracture Energy in Shear Parallel softening Parameter Parallel Maximum Damage Perpendicular Fracture Energy in Tension Perpendicular Fracture Energy in Shear 218 Materials Field DFIT DMAX_r FLPAR FLPARC POWPAR FLPER FLPERC POWPER NPAR CPAR NPER CPER AOPT Comments Perpendicular Softening Parameter Perpendicular Maximum Damage Parallel Fluidity Parameter for Tension and Shear Parallel Fluidity Parameter for Compression Parallel Power Perpendicular Fluidity Parameter for Tension and Shear Perpendicular Fluidity Parameter for Compression Perpendicular Power Parallel Hardening initiation Parallel Hardening Rate Perpendicular Hardening initiation Perpendicular Hardening Rate Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. MACF Material axes change flag: =1 No Change; = 2 switch mateial axes a and b =3 switch material axes a and c ; =4 switch material axes b and c BETA XP YP ZP Ai Di Vi Material angle in degrees (for AOP = 3) X-coordinate of point p for AOPT=1 Y-coordinate of point p for AOPT=1 Z-coordinate of point p for AOPT=1 Component of Vector a, for AOPT=2 Component of Vector d, for AOPT=2 Components of vector v( for AOP = 3 and 4) Materials 219 Materials See Also: • LS-DYNA Keyword User’s Manual MAT_WOOD_PINE Defines the material properties for a transversely isotropic material (available only for solid elements). This model has default material properties for yellow pine. Field Title Desc TITLE_OPTION MID RO NPLOT Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Plotting Option 1: Parallel damage 2: Perpendicular damage ITER Number of plasticity algorithm iterations 220 Materials Field IRATE Rate effects option 0: Turn off 1: Turn on HARD IFAIL Perfect plasticity override Comments Erosion perpendicular to the ground 0: No 1: Yes IVOL Erode on negative volume or strain increments greater than 0.01 =0 No (default) ; =1 Yes MOIS TEMP QUAL_T QUAL_C UNITS Percentage moisture content Temperature Quality Factor Option in Tension Quality Factor Option in Compression Units Option 0: GPa, mm, msec, Kg/mm3, KN 1: MPa, mm, msec, g/mm3, N 2: MPa, mm, sec, Mg/mm3, N 3:Psi, inch, sec, lb-sec2/inch4, lb. IQUAL Apply quality factors perpendicular to grain 0: Yes 1: No Materials 221 Materials Field AOPT Material Axes option Comments 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. MACF Material axes change flag: =1 No Change; = 2 switch mateial axes a and b =3 switch material axes a and c ; =4 switch material axes b and c BETA XP YP ZP Ai Di Vi Material angle in degrees (for AOP = 3) X-coordinate of point p for AOPT=1 Y-coordinate of point p for AOPT=1 Z-coordinate of point p for AOPT=1 Component of Vector a, for AOPT=2 Component of Vector d, for AOPT=2 Components of vector v( for AOP = 3 and 4) See Also: • LS-DYNA Keyword User’s Manual 222 Materials MAT_WOOD_FIR Defines the material properties for a transversely isotropic material (available only for solid elements). This model has default material properties for Douglas Fir. Field Title Desc TITLE_OPTION MID RO NPLOT Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Plotting Option 1: Parallel damage 2: Perpendicular damage ITER IRATE Number of plasticity algorithm iterations Rate effects option 0: Turn off 1: Turn on HARD Perfect plasticity override Materials 223 Materials Field IFAIL Comments Erosion perpendicular to the ground 0: No 1: Yes IVOL Erode on negative volume or strain increments greater than 0.01 =0 No (default) ; =1 Yes MOIS TEMP QUAL_T QUAL_C UNITS Percentage moisture content Temperature Quality Factor Option in Tension Quality Factor Option in Compression Units Option 0: GPa, mm, msec, Kg/mm3, KN 1: MPa, mm, msec, g/mm3, N 2: MPa, mm, sec, Mg/mm3, N 3:Psi, inch, sec, lb-sec2/inch4, lb. IQUAL Apply quality factors perpendicular to grain 0: Yes 1: No AOPT Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. MACF Material axes change flag: =1 No Change; = 2 switch mateial axes a and b =3 switch material axes a and c ; =4 switch material axes b and c 224 Materials Field BETA XP YP ZP Ai Vi Di Comments Material angle in degrees (for AOP = 3) X-coordinate of point p for AOPT=1 Y-coordinate of point p for AOPT=1 Z-coordinate of point p for AOPT=1 Component of Vector a, for AOPT=2 Components of vector v( for AOP = 3 and 4) Component of Vector d, for AOPT=2 See Also: • LS-DYNA Keyword User’s Manual MAT_PITZER_CRUSHABLE_FOAM Defines the properties for a material model that simulates isotropic crushable foams with strain rate effects. It uses uniaxial and triaxial data. Field Title Desc TITLE_OPTION MID RO K G PR TY SRTV LCPY Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Bulk Modulus Shear Modulus Poisson’s Ratio Tension Yield Young’s Modulus Load Curve Id defining pressure vs. volumetric strain Materials 225 Materials Field LCUYS LCRS VC DFLG Comments Load Curve Id defining uniaxial stress vs. volumetric strain Load Curve Id defining Strain rate Scale Factor vs. Volumetric Strain rate Viscous Damping Coefficient Density Flag 0:Use Initial Density value 1: Use Current Density value See Also: • LS-DYNA Keyword User’s Manual 226 Materials MAT_SCHWER_MURRAY_CAP_MODEL Defines the material properties for a three invariant extension of MAT_GEOLOGIC_CAP_MODEL (MAT_025) that also includes viscoplasticity for rate effects and damage mechanics to model strain softening. Field Title Desc TITLE_OPTION MID RO SHEAR BULK GRUN SHOCK PORE Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Shear Modulus Bulk Modulus Gruneisen Ratio Shock Velocity Parameter Flag for Pore Collapse 0: Yes 1: Constant Bulk Modulus Materials 227 Materials Field ALPHA, THETA, GAMMA, BETA EFIT, FFIT ALPHAN, CALPHA R0 X0 IROCK Shear Failure Parameters Comments Dilitation damage mechanics parameters Kinematic strain hardening parameters Initial Gap Surface ellipticity, R Initial Gap Surface J1 (mean stress) axis intercept Material Flag 0: Soils (cap can contact) 1: Rock/Concrete SECP AFIT, BFIT, RDAM0 W, D1, D2 NPLOT EPSMAX CFIT, DFIT TFAIL FAILFL DBETA, DDELTA VPTAU ALPHA1 THETA1, GAMMA1, BETA1 ALPHA2 THETA2, GAMMA2, BETA2 Shear Enhanced Compaction Ductile damage mechanics parameters Plastic volume strain parameters History variable post-processed as effective plastic strain Maximum permitted strain increment Brittle damage parameters Tensile Failure Stress Failure Flag (failed element) Rounded Vertices Parameters Viscoplastic Relaxation time Parameter Torsional scaling parameters Triaxial extension scaling parameters See Also: • LS-DYNA Keyword User’s Manual 228 Materials MAT_1DOF_GENERALIZED_SPRING Defines the properties for a linear spring or damper that allows different degrees-of-freedom at two nodes to be coupled with linear spring and/or damper. Field Title Desc TITLE_OPTION MID RO K C SCLNi DOFNi CIDi Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Spring Stiffness Damping Constant Scale Factor on force at node i Active dof at node i Local coordinate system Id at node 1 and node 2 respectively See Also: • LS-DYNA Keyword User’s Manual Materials 229 Materials MAT_FHWA_SOIL Defines the material properties for an isotropic material with damage for solid elements. The model has a modified Mohr-Coulomb surface for determining pressure dependent peak shear strength. Field Title Desc TITLE_OPTION MID RO NPLOT SPGRAV RHOWAT VN, GAMMAR ITERMAX K G PHIMAX AHYP COH ECCEN AN ET Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Plotting option Specific gravity of soil Density of water Viscoplastic parameters Maximum number of plastic iterations Bulk Modulus Shear Modulus Peak Shear strength (friction) angle (degrees) Coefficient A for modified Drucker-Prager surface Cohesion shear strength at zero confinement (overburden) Eccentricity parameter Strain hardening percent of PHIMAX where nonlinear effects start Strain hardening amount of nonlinear effects 230 Materials Field MCONT PWD1 PWSK PWD2 PHIRES DINT VDFM DAMLEV EPSMAX Moisture content in soil Comments Parameter for pore water effects on Bulk Modulus Skeleton Bulk Modulus Parameter for pore water effects on the effective pressure Minimum internal frictional angle (radians) Volumetric strain at initial threshold damage Void formation energy Level of damage that will cause element deletion Maximum principal failure strain See Also: • LS-DYNA Keyword User’s Manual MAT_FHWA_SOIL_NEBRASKA Defines the material properties for a soil model with default property values for soils used at the University of Nebraska. Default units are in millimeter, milliseconds and kilograms. Field Title Desc TITLE_OPTION MID FCTIM FCTMAS FCTLEN Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Factor to multiply milliseconds by to get desired time unit Factor to multiply Kg by to get desired mass unit Factor to multiply mm by to get desired length unit See Also: • LS-DYNA Keyword User’s Manual Materials 231 Materials MAT_GAS_MIXTURE Defines the material properties for a material model that simulates gas mixture and works in conjunction with the multi-material ALE formulation. Field Title Desc TITLE_OPTION MID IADIAB Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Flag for turning adiabatic compression logic ON/OFF 0 = ON ; 1 = OFF RUNIV CVi MOLi CPi Universal gas constant in per-mole unit Heat Capacity at constant volume for upto eight different gases in per-mass unit gas (If RUNIV = 0 or blank) Molecular weight of each ideal gas in the mixture (mass-unit/molde) (if RUNIV is nonzero) Heat Capacity at constant pressure for upto eight different gases in permass unit gas (If RUNIV = 0 or blank) 232 Materials Field Bi Ci Comments First order coefficient for a temperature dependent heat capacity at constant pressure for up to eight different gases (If RUNIV = 0 or blank) Second order coefficient for a temperature dependent heat capacity at constant pressure for up to eight different gases (If RUNIV = 0 or blank) See Also: • LS-DYNA Keyword User’s Manual MAT_CFD Defines the material properties for a material model that allows constant, isotropic fluid properties to be defined for the incompressible/low-Mach CFD solver. Field Title Desc TITLE_OPTION MID RHO MU K CP BETA TREF Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Fluid Density Fluid Viscosity Thermal Conductivity Heat Capacity Coefficient of expansion Reference Temperature Materials 233 Materials Field GX, GY, GZ DIFFi Diffusivity for Species i Comments Gravitational acceleration in the X, Y, Z direction See Also: • LS-DYNA Keyword User’s Manual MAT_CFD_CONSTANT Defines the material properties for a material model that allows constant, isotropic fluid properties to be defined for the incompressible/low-Mach CFD solver. Field Title Desc TITLE_OPTION MID RHO MU K CP BETA TREF GX, GY, GZ DIFFi Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Fluid Density Fluid Viscosity Thermal Conductivity Heat Capacity Coefficient of expansion Reference Temperature Gravitational acceleration in the X, Y, Z direction Diffusivity for Species i 234 Materials See Also: • LS-DYNA Keyword User’s Manual MAT_DESHPANDE_FLECK_FOAM Defines the material properties for aluminum foam, used as a filler material in aluminum extrusions to enhance the energy absorbing capability of the extrusion. Field Title Desc TITLE_OPTION MID RO E PR ALPHA GAMMA, ALPHA2, BETA, SIGP EPSD DERFI Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Parameter to Control Shape of yield surface Equation parameters Densification strain Type of derivation in Material subroutine 0: Numerical 1: Analytical CFAIL Failure Strain See Also: • LS-DYNA Keyword User’s Manual Materials 235 Materials MAT_COMPOSITE_MSC Defines the material properties for a material model to simulate the progressive failure analysis for composite materials consisting of unidirectional and woven fabric layers. Field Title Desc TITLE_OPTION MID RO EA EB EC PRBA, PRCA, PRCB GAB, GBC, GCA Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus - longitudinal direction Young’s Modulus - transverse direction Young’s Modulus - through thickness direction Poisson’s Ratio in ba, ca, and cb directions Shear Stress in ab bc, and ca directions 236 Materials Field AOPT Material Axes option Comments 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. MACF Material Axes change flag: = 1 no change (default) = 2, switch material axes a and b = 3, switch material axes a and c = 4, switch material axes b and c XP YP ZP Ai Vi Di BETA SAT SAC SBT SBC SCT SFC SFS SAB, SBC, SCA SFFC X-coordinate of point p for AOPT=1 Y-coordinate of point p for AOPT=1 Z-coordinate of point p for AOPT=1 Component of Vector a, for AOPT=2 Component of Vector v, for AOPT=3 Component of Vector d, for AOPT=2 Layer in-plane rotational Angle (degrees) Longitudinal Tensile Strength Longitudinal Compressive Strength Transverse Tensile Strength Transverse Compressive Strength Through thickness Tensile Strength Crush Strength Fiber mode shear strength Matrix mode Shear Strength in ab bc, and ca planes Scale factor for residual compressive strength Materials 237 Materials Field AMODEL Material Model 1: Unidirectional layer model 2: Fabric layer model PHIC E_LIMT S_DELM OMGMX ECRSH EEXPN CERATE1 AM1 Coulomb friction angle Element eroding axial strain Comments Scale factor for delamination criteria Limit damage parameter for elastic modulus Limit compressive volume strain for element eroding Limit tensile volume strain for element eroding Coefficient for strain rate dependent strength properties Coefficient for strain rate softening property for fiber in a direction See Also: • LS-DYNA Keyword User’s Manual 238 Materials MAT_COMPOSITE_MSC_DMG Defines the material properties for a material model to simulate the progressive failure analysis for composite materials consisting of unidirectional and woven fabric layers. Field Title Desc TITLE_OPTION MID RO EA EB EC PRBA, PRCA, PRCB GAB, GBC, GCA Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus - longitudinal direction Young’s Modulus - transverse direction Young’s Modulus - through thickness direction Poisson’s Ratio in ba, ca, and cb directions Shear Stress in ab bc, and ca directions Materials 239 Materials Field AOPT Material Axes option Comments 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. MACF Material Axes change flag: = 1 no change (default) = 2, switch material axes a and b = 3, switch material axes a and c = 4, switch material axes b and c XP YP ZP Ai Vi Di BETA SAT SAC SBT SBC SCT SFC SFS Sij SFFC X-coordinate of point p for AOPT=1 Y-coordinate of point p for AOPT=1 Z-coordinate of point p for AOPT=1 Component of Vector a, for AOPT=2 Component of Vector v, for AOPT=3 Component of Vector d, for AOPT=2 Layer in-plane rotational Angle (degrees) Longitudinal Tensile Strength Longitudinal Compressive Strength Transverse Tensile Strength Transverse Compressive Strength Through thickness Tessile Strength Crush Strength Fiber mode shear strength Transverse Shear Strength ij Scale factor for residual compressive strength 240 Materials Field AMODEL Material Model 1: Unidirectional 2: Fabric PHIC E_LIMT S_DELM OMGMX ECRSH EEXPN CERATEi Coulomb friction angle Element eroding axial strain Comments Scale factor for delamination criteria Limit damage parameter for elastic modulus Limit compressive volume strain Limit tensile volume strain Coefficient for strain rate dependent strength parameter, axial moduli, shear moduli, transverse moduli See Also: • LS-DYNA Keyword User’s Manual MAT_MODIFIED_CRUSHABLE_FOAM Defines the material properties for a material model to simulate crushable foam with optional damping, tension cutoff and strain rate effects. Unloading is fully elastic. Tension is treated as elastic-perfectlyplastic at the tension cutoff value. Field Title Desc TITLE_OPTION MID RO Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Materials 241 Materials Field E PR TID TSC DAMP NCYCLE SRCLMT Young’s Modulus Poisson’s Ratio Comments Load Curve Id defining Yield Stress vs. Volumetric Strain Tensile Stress Cutoff Rate sensitivity via damping coefficient Number of cycles to determine volumetric strain rate Strain rate change limit See Also: • LS-DYNA Keyword User’s Manual MAT_QUASILINEAR_VISCOELASTIC Defines the properties for a material model to simulate a quasi-linear, isotropic, viscoelastic material which represents biological soft tissue such as brain, kidney, etc. Field Title Desc TITLE_OPTION MID RO K LC1 Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Bulk Modulus Load Curve Id for the Relaxation function in shear 242 Materials Field LC2 N GSTART M S0 Comments Load Curve Id for the instantaneous Elastic response in shear No. of Prony series terms in fit Starting value for least square fit No. of terms used to determine the instantaneous elastic response Strain output option to be plotted as component 7 in LS-TAURUS 0: Maximum principal strain 1: Maximum Magnitude of principal strain 2: Maximum Effective strain E_MIN E_MAX GAMA1, GAMA2 KF Minimum strain rate used to generate the load curve fron Ci Maximum strain rate used to generate the load curve fron Ci Material failure parameters Material failure parameter that controls the enclosed by the failure surface. .LE 0, ignore failure criterion. .GE. 0, use actual K value for failure criterion. EH FORM Damage parameter Formulation of Model. =0 original model by Fung which relaxes to a zero stress state as time approaches to infinity. = 1 Alternative model which relaxes to the quasistatice elastic response C1 to C6 Coefficients of the instanteneous elastic response in compression and tension See Also: • LS-DYNA Keyword User’s Manual Materials 243 Materials MAT_HILL_FOAM Defines the properties for a material model to simulate a highly compressible foam based on strain energy function, proposed by Hill. This model takes Poisson’s ratio effects into account. Field Title Desc TITLE_OPTION MID RO K N MU LCID FITTYPE Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Bulk Modulus Material constant Damping coefficient Load Curve Id defining Force per unit area vs. Stretch Ratio Type of fit 1: Uniaxial 2: Biaxial LCSR R M Load Curve Id defining uniaxial (or biaxial, depending on FITTYPE) Stress ratio vs. Transverse Stretch Ratio Mullinus effect model r coefficient Mullinus effect model m coefficient See Also: • LS-DYNA Keyword User’s Manual 244 Materials MAT_VISCOELASTIC_HILL_FOAM Defines the properties for a material model to simulate a highly compressible foam based on strain energy function, proposed by Hill. with extensions to include large strain viscoelasticity proposed by Feng and Hallquist [2002]. Field Title Desc TITLE_OPTION MID RO K N MU LCID FITTYPE Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Bulk Modulus Material constant Damping coefficient Load Curve Id defining Force per unit area vs. Stretch Ratio Type of fit 1: Uniaxial 2: Biaxial LCSR LCVE NT GSTART Load Curve Id defining uniaxial (or biaxial, depending on FITTYPE) Stress ratio vs. Transverse Stretch Ratio Load Curve Id defining the Relaxation function in shear No. of Prony series terms in fit Starting value for least square fit See Also: • LS-DYNA Keyword User’s Manual Materials 245 Materials MAT_LOW_DENSITY_SYNTHETIC_FOAM Defines the properties of rate independent low density foams exhibiting considerably reduced properties in the loading-unloading curve after the first loading cycle. Field Title Desc TITLE_OPTION MID RO E LCID1 LCID2 HU BETA DAMP SHAPE FAIL Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Load Curve Id defining nominal Stress vs. Strain for the first loading cycle Load Curve Id defining nominal Stress vs. Strain for loading cycles after the first loading cycle is completed Hysteric unloading factor between 0 and 1 Decay constant to model creep in unloading Viscous coefficient Shape factor for unloading Failure option after cutoff stress 0: Tensile Stress remains at cutoff 1: Tensile Stress resets to zero 246 Materials Field BVFLAG Bulk viscosity activation flag 0: No 1: Active ED BETA1 KCON REF Comments Optional Young’s relaxation modulus for rate effects Optional decay constant Stiffness coefficient for contact interface stiffness Use reference geometry to initialize stress tensor 0: Off 1: On TC RFLAG Tension Cutoff Stress Rate type for input: = 0, LCID1 and LCID2 should be input as functions of true strain rate = 1, LCID1 and LCID2 should be functions of engineering strain rate DIRT Strain rate averaging flag: = 0, use weighted running average .LE. 0, average the last eleven values .GT. 0, average over the last DIRT time units K GAMA1, GAMA2 EH Material failure parameters Damage parameter See Also: • LS-DYNA Keyword User’s Manual MAT_LOW_DENSITY_SYNTHETIC_FOAM_ORTHO Defines the properties of rate independent low density foams exhibiting considerably reduced properties in the loading-unloading curve after the first loading cycle. This material model considers any orthotropic behavior after the first loading and unloading cycle of the material in the orthogonal directions. Materials 247 Materials Field Title Desc TITLE_OPTION MID RO E LCID1 LCID2 HU BETA DAMP SHAPE FAIL Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Load Curve Id defining nominal Stress vs. Strain for the first loading cycle Load Curve Id defining nominal Stress vs. Strain for loading cycles after the first loading cycle is completed Hysteric unloading factor between 0 and 1 Decay constant to model creep in unloading Viscous coefficient Shape factor for unloading Failure option after cutoff stress 0: Tensile Stress remains at cutoff 1: Tensile Stress resets to zero 248 Materials Field BVFLAG Bulk viscosity activation flag 0: No 1: Active ED BETA1 KCON REF Comments Optional Young’s relaxation modulus for rate effects Optional decay constant Stiffness coefficient for contact interface stiffness Use reference geometry to initialize stress tensor 0: Off 1: On TC RFLAG Tension Cutoff Stress Rate type for input: = 0, LCID1 and LCID2 should be input as functions of true strain rate = 1, LCID1 and LCID2 should be functions of engineering strain rate DIRT Strain rate averaging flag: = 0, use weighted running average .LE. 0, average the last eleven values .GT. 0, average over the last DIRT time units K GAMA1, GAMA2 EH Material failure parameters Damage parameter See Also: • LS-DYNA Keyword User’s Manual Materials 249 Materials MAT_SIMPLIFIED_RUBBER/FOAM Defines the properties of a rubber amd foam model defined by a single uniaxial load curve or by a family of curves at discrete strain rates. Field Title Desc TITLE_OPTION MID RO KM MU G SIGF REF Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Linear Bulk Modulus Damping coefficient Shear Modulus Limit stress for frequency independent, frictional, damping Use Reference Geometry (defined in *INITIAL_FOAM_REFERENCE_GEOMETRY) to initialize the stress tensor. 0 = ON ; 1 = OFF Tensile Poisson’s ratio. = 0 indicates that PR/BETA will serve as Poisoon’s ratio for both tension and compression in shells. Otherwise, PR/BETA will serve as Poisoon’s ratio for compression in shells. PRTEN SGL SW ST Specimen Gauge Length Specimen Width Specimen Thickness 250 Materials Field LCID TENSION Comments Load Curve Id defining Force vs. Actual change in gauge length Parameter to control rate effect -1: Rate effects are treated for loading either in tension or in compression (but not for unloading) 0: Rate effects are treated for loading compressive loading only 1:Rate effects are treated identically for tension and compressive loading only RTYPE Strain rate type 0: True 1: Engineering AVGOPT Averaging option to determine strain rate (to reduce numerical noise) 0: Simple average of twelve time steps 1: Running 12-point average PR/BETA If value is between 0.0 and 0.5 (exclusive), the value give here is taken as Poisson’s ratio. If value is exactly 0.0 (zero), an incompressible rubber like behavior is assumed, and a value of 0.495 is used inside the software. If zero Poisson’s ratio is desired, use a small value such as 0.001 for PR. Material failure parameter that controls the enclosed by the failure surface. .LE 0, ignore failure criterion. .GE. 0, use actual K value for failure criterion. K GAMA1, GAMA2 EH Material failure parameters Damage parameter See Also: • LS-DYNA Keyword User’s Manual Materials 251 Materials MAT_SEISMIC_BEAM Defines the properties of a material characterized by lumped plasticity to be developed at the ‘node 2’ end of Belytschko-Schwer beams. The plastic yield surface allows interaction between the two moments and the axial force. Field Title Desc TITLE_OPTION MID RO E PR AOPT Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Axial force option 0: Axial Load Curves are Collapse Load vs. Strain NE. 0: Axial Load Curves are Collapse Load vs. Change in Length 252 Materials Field FTYPE Comments Formulation type for interaction 1: Parabolic coefficients 2: Japanese Code, axial force and major axis bending DEGRADE Flag for degrading moment behavior 0 = behavior as in previous versions 1 = Fatigue-type moment-rotation behavior 2 = FEMA-type moment-rotation behavior IFEMA Flag for input of FEMA thresholds = 0 No inputs ; 1 = Input of rotation thresholds only =2 Input of rotation and axial strain thresholds LCPMS SFS LCPMT SFT LCAT SFAT LCAC SFAC Load Curve Id for Plastic Moment vs. Rotation about s at node 2 Scale factor on s -moment at node 2 Load Curve Id for Plastic Moment vs. Rotation about t at node 2 Scale factor on t -moment at node 2 Load Curve Id for axial tensile yield force vs. total tensile strain (or elongation, see AOPT option) Scale factor for axial tensile force Load Curve Id for axial compressive force vs. strain/elongation Scale factor for axial compressive force ALPHA, BETA, Parameters to define yield surface GAMMA, DELTA, A, B FOFFS SIGY D W TF TW PR1 - PR4 TS1 - TS4 CS1 - CS4 Force offset for Yield Surface Yield Stress Depth of section used for interaction curve Width of section used for interaction curve Flange Thickness of section used for interaction curve Web Thickness of section used for interaction curve Plastic rotation thresholds 1 to 4 Tensile axial strain hresholds 1 to 4 Compressive axial strain hresholds 1 to 4 Materials 253 Materials See Also: • LS-DYNA Keyword User’s Manual MAT_SOIL_BRICK Defines the properties of clay like soils accurately. Field Title Desc TITLE_OPTION MID RO RLAMDA, RKAPPA, RIOTA, RBETAi RMU RNU RLCID TOL PGCL SUB-INC BLK GRAV Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Material coefficient Shape factor coefficient Poisson’s ratio Load Curve Id referring to a curve defining up to ten pairs of ‘string-length’ vs. G/Gmax points.up to 10 points of string-length vs. Gmax User defined tolerance for convergence checking Pre consolidation ground level User defined strain increment size Elastic bulk stiffness of the soil Gravitational acceleration 254 Materials Field THEORY Comments Version of material subroutine used 0 (default) = 1995 version (vectorized) ; 4 = 1995 version (unvectorized) RVHNH XSICRIT, ALPHA RVH RNU21 ANISO_4 Anisotropy parameter Anisotropy parameters Anisotropy ratio (Ev/Eh) Anisotropy ratio (ν2/ν1) Anisotropy parameter See Also: • LS-DYNA Keyword User’s Manual MAT_DRUCKER_PRAGER Defines the properties of materials such as soils modeled with the modified Drucker-Prager yield surface. Field Title Desc TITLE_OPTION MID RO GMOD RNU RKF Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Elastic Shear Modulus Poisson’s ratio Failure surface shape parameter Materials 255 Materials Field PHI CVAL PSI STR_LIM GMODDP PHIDP CVALDP PSIDP GMODGR PHIGR CVALGR PSIGR Angle of friction (radians) Cohesive Value Dilation angle (radians) Comments Factor for calculating minimum shear strength of material which is calculated as STR_LIM*CVAL Depth at which shear modulus is correct Depth at which friction angle is correct Depth at which cohesive value is correct Depth at which dilation angle is correct Gradient at which shear modulus increases with depth Gradient at which friction angle increases with depth Gradient at which cohesive value increases with depth Gradient at which dilation angle increases with depth See Also: • LS-DYNA Keyword User’s Manual 256 Materials MAT_RC_SHEAR_WALL Defines the properties of materials to model cyclic shear loading of reinforced concrete walls (available only for shell elements). Field Title Desc TITLE_OPTION MID RO E PR TMAX Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Ultimate shear stress Materials 257 Materials Field Fc PREF FYIELD SIG0 UNCONV ALPHA FT ERIENF A, B, C, D, E F Yi Ti AOPT Percent reinforcement Yield stress of reinforcement Overburden stress Comments Unconfirmed compressive strength of Concrete Unit conversion factor, to compute ultimate tensile stress of Concrete Shear span factor Cracking stress in direct tension Young’s Modulus for reinforcement Hysteresis constants to determine shape of the hysteresis loops Strength gradient factor Shear strain points on stress vs. strain curve Shear stress points on stress vs. strain curve Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. XP YP ZP Ai Vi Di BETA X-coordinate of point p for AOPT=1 Y-coordinate of point p for AOPT=1 Z-coordinate of point p for AOPT=1 Component of Vector a, for AOPT=2 Component of Vector v, for AOPT=3 Component of Vector d, for AOPT=2 Layer in-plane rotational Angle See Also: • LS-DYNA Keyword User’s Manual 258 Materials MAT_CONCRETE_BEAM Defines an elasto-plastic material with an arbitrary stress-strain curve and arbitrary strain rate dependency. Also, failure based on plastic strain or a minimum time step can be defined. Field Title Desc TITLE_OPTION MID RO E PR SIGY ETAN C, P FAIL TDEL LCSS LCSR Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Young’s Modulus Poisson’s Ratio Yield Stress Tangent Modulus Strain Rate Parameters Failure Flag Minimum time step size for automatic element deletion Load Curve Id defining Effective Stress vs. Effective Plastic Strain in compression Load Curve Id defining Strain rate effects on Yield Stress Materials 259 Materials Field NOTEN No-tension flag 0: Takes tension 1: Does not take Tension Comments 2: Takes tension upto value given by TENCUT (Tension cutoff) TENCUT SDR Tension cutoff stress Stiffness degradation factor See Also: • LS-DYNA Keyword User’s Manual MAT_GENERAL_SPRING_DISCRETE_BEAM Defines the properties of materials with elastic and elastoplastic springs with damping to be represented by discrete beam elements using six springs, each acting along one of the six local degrees-of-freedom. 260 Materials For elastic behavior, use a load curve of yield force or moment versus displacement or rotation. For inelastic case, use a load curve of yield force or moment versus plastic deflection or rotation. Materials 261 Materials 262 Materials Field Title Desc TITLE_OPTION MID RO DOFi TYPEi Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Active degree-of-freedom Behavior 0: Elastic 1: Inelastic Ki Di CDFi TDFi FLCIDi Elastic loading/unloading stiffness Optional viscous damping coefficient Compressive displacement at failure Tensile displacement at failure Load Curve Id defining Force (or Moment) vs. Displacement for nonlinear elastic (TYPE1 = 0). For inelastic behavior, this curve defines the yield force vs. plastic deflection. Load Curve Id defining Force vs. Relative Velocity Damping coefficients Scale factor for time unit Load Curve Id defining scale factor vs. deflection for HLCIDi HLCIDi C1_i, C2_i DLEi GLCIDi See Also: • LS-DYNA Keyword User’s Manual Materials 263 Materials MAT_SEISMIC_ISOLATOR Defines the properties of materials used as sliding and elastometric seismic isolation bearings. This material model uses a bi-directional coupled plasticity theory (available only for discrete beam elements). Field Title Desc TITLE_OPTION MID RO A, GAMMA, BETA DISPY STIFFV ITYPE Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Non dimensional variable Yield displacement Vertical stiffness Type 0: Sliding 1: Elastomeric PRELOAD DAMP MXi MYi FMAX Vertical preload Damping ratio Moment factor at end i in local x direction Moment factor at end i in local y direction Maximum dynamic friction coefficient 264 Materials Field DELF AFRIC RADX RADY RADB STIFFL STIFFTS FORCEY ALPHA STIFFT DFAIL FMAXYC FMAXXT FMAXYT YLOCK Comments Difference between maximum and Static Friction coefficient Velocity multiplier in sliding friction equation Radius for sliding in local x direction Radius for sliding in local y direction Radius of retaining ring Stiffness for lateral contact against retaining ring Stiffness for tensile vertical response (sliding) Yield force Ratio of post and pre yielding stiffness Stiffness for tensile vertical response (elastomeric) Lateral displacement at which isolator fails Maximum dynamic friction coefficient in compression in local y-direction Maximum dynamic friction coefficient in tension in local x-direction Maximum dynamic friction coefficient in tension in local y-direction Stiffness locking the local y- displacement (optional in single axis sliding) See Also: • LS-DYNA Keyword User’s Manual Materials 265 Materials MAT_JOINTED_ROCK Defines the properties of jointed rocks. Field Title Desc TITLE_OPTION MID RO GMOD RNU RKF PHI CVAL PSI STR_LIM NPLANES Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Mass Density of the material Elastic Shear Modulus Poisson’s ratio Failure surface shape parameter Angle of friction (radians) Cohesive Value Dilation angle (radians) Factor for calculating minimum shear strength of material which is calculated as STR_LIM*CVAL No of joint planes 266 Materials Field ELASTIC Flag for Elastic Behavior 0: Non elastic 1: Elastic LCCPDR LCCPT LCCJDR LCCJT LCSFAC GMODDP PHIDP CVALDP PSIDP GMODGR PHIGR CVALGR PSIGR DIPi STRIKEi CPLANEi FRPLANEi TPLANEi SHRMAXi LOCALi Comments Load Curve Id for extra cohesion for parent material (dynamic relaxation) Load Curve Id for extra cohesion for parent material (transient) Load Curve Id for extra cohesion for joints (dynamic relaxation) Load Curve Id for extra cohesion for joint material (transient) Load Curve Id giving factor on Strength vs. Time Depth at which shear modulus is correct Depth at which friction angle is correct Depth at which cohesive value is correct Depth at which dilation angle is correct Gradient at which shear modulus increases with depth Gradient at which friction angle increases with depth Gradient at which cohesive value increases with depth Gradient at which dilation angle increases with depth Angle (degrees) of plane below the horizontal Plan view angle (degrees) of downhill vector drawn on the plane Cohesion for shear behavior on plane i Friction angle for shear behavior on plane i Tensile strength across plane i Maximum shear stress on plane i DIP and STRIKE Coordinate System flag 0: with respect to Global axes 1: with respect to element local axes See Also: • LS-DYNA Keyword User’s Manual Materials 267 Materials MAT_SPRING_ELASTIC Defines the properties of a translational or rotational elastic spring placed between two nodes. Only one degree of freedom is connected. Field Title Desc TITLE_OPTION MID K Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Elastic Stiffness (Translational or Rotational) See Also: • LS-DYNA Keyword User’s Manual MAT_DAMPER_VISCOUS Defines the properties of translational and rotational dampers located between two nodes. Only one degree of freedom is connected. Field Title Desc TITLE_OPTION MID DC Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Damping Constant (Force/Displacement rate or Moment/Rotation rate) 268 Materials See Also: • LS-DYNA Keyword User’s Manual MAT_SPRING_ELASTOPLASTIC Defines the properties of discrete springs providing an elastoplastic translational or rotational spring with isotropic hardening located between two nodes. Only one degree of freedom is connected. Field Title Desc TITLE_OPTION MID K KT FY Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Elastic Stiffness (Translational or Rotational) Tangent Stiffness Yield Force or Moment See Also: • LS-DYNA Keyword User’s Manual Materials 269 Materials MAT_SPRING_NONLINEAR_ELASTIC Defines the properties of discrete springs providing a nonlinear elastic translational or rotational spring with arbitrary force versus displacement and moment versus rotation data. Only one degree of freedom is connected. Field Title Desc TITLE_OPTION MID LCD LCR Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Load Curve Id defining Force vs. Displacement or Moment vs. Rotation Load Curve Id defining Scale factor on Force or Moment as a function of relative velocity, or rotational velocity respectively See Also: • LS-DYNA Keyword User’s Manual 270 Materials MAT_DAMPER_NONLINEAR_VISCOUS Defines the properties of discrete dampers providing a viscous translational or rotational damper with arbitrary force versus velocity or a moment versus rotational velocity data. Only one degree of freedom is connected. Field Title Desc TITLE_OPTION MID LCDR Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Load Curve Id defining the Force vs. rate of Displacement or Moment vs. rate of Rotation relationship See Also: • LS-DYNA Keyword User’s Manual MAT_SPRING_GENERAL_NONLINEAR Defines the properties of discrete springs providing a general nonlinear translational or rotational spring with arbitrary loading and unloading data. It also considers hardening or softening. Only one degree of freedom is connected. Field Title Desc TITLE_OPTION Comments Unique name identifying material model Optional description of the material model If selected material title option is used Materials 271 Materials Field MID LCDL LCDU BETA TYI CYI Comments Material identification number (Integer > 0) Loading Curve Id for Force vs. Displacement or Moment vs. Rotation Unloading Load Curve Id for Force vs. Displacement or Moment vs. Rotation Hardening parameter Initial Yield force in tension Initial Yield force in compression See Also: • LS-DYNA Keyword User’s Manual MAT_SPRING_MAXWELL Defines the properties of discrete springs providing a three Parameter Maxwell Viscoelastic translational or rotational spring. Only one degree of freedom is connected. Field Title Desc TITLE_OPTION MID K0 KI BETA TC Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Short term stiffness Long term stiffness Decay constant Cutoff time. After this time a constant force/moment transmitted 272 Materials Field FC COPT Time implementation option 0: Incremental time change 1: Continuous time change See Also: • LS-DYNA Keyword User’s Manual MAT_SPRING_INELASTIC Comments Force/Moment after cutoff time Defines the properties of discrete springs and dampers providing an inelastic tension or compression only, translational or rotational spring. Field Title Desc TITLE_OPTION MID LCFD KU CTF Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Load Curve Id defining the Force/Torque vs. Displacement/Twist relationship Unloading Stiffness Flag for compression/tension -1: Tension only 1: Compression only (Default CTF value is 0, which is same as 1) See Also: • LS-DYNA Keyword User’s Manual Materials 273 Materials MAT_SPRING_TRILINEAR_DEGRADING Defines the properties of concrete shear walls under seismic loading modelled as discrete elements. It represents cracking of the concrete, yield of the reinforcement, and overall failure. Field Title Desc TITLE_OPTION MID DEFL1 F1 DEFL2 F2 DEFL3 F3 FFLAG Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Deflection at point where concrete cracks Force corresponding to DEFL1 Deflection at reinforcement yield Force corresponding to DEFL2 Deflection at complete failure Force corresponding to DEFL3 Failure Flag See Also: • LS-DYNA Keyword User’s Manual 274 Materials MAT_SPRING_SQUAT_SHEARWALL Defines the properties of squat shear walls modelled as discrete elements. This material model allows concrete cracking, reinforcement yield, and ultimate strength, followed by degradation of strength, leading finally to collapse. Field Title Desc TITLE_OPTION MID A14, B14, C14, D14, E14 LCID FSD Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Material coefficient Load Curve Id referencing the maximum strength envelope curve Sustained strength reduction factor See Also: • LS-DYNA Keyword User’s Manual Materials 275 Materials MAT_SPRING_MUSCLE Defines the properties for discrete springs and dampers. This is a Hill-type muscle model with activation. Field Title Desc TITLE_OPTION MID L0 VMAX SV A FMAX TL TV FPE LMAX KSH LCID_SV LCID_A LCID_TL LCID_TV LCID_FPE Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Initial muscle length Maximum CE shortening velocity Scale factor for Vmax vs. Active State Scale factor for Activation Level vs. Time function Peak isometric force Scale factor for Active tension vs. length function Scale factor for Active tension vs. velocity function Scale factor for Force vs. length function, for parallel elastic element Relative length at FPE=FMAX Constant governing the exponential rise of FPE Load Curve Id defining Vmax vs. active state Load Curve Id defining Active level vs. Time function Load Curve Id defining Active tension vs. Length function Load Curve Id defining Active tension vs. velocity function Load Curve Id defining Force vs. Length function See Also: • LS-DYNA Keyword User’s Manual 276 Materials MAT_THERMAL_ISOTROPIC Defines isotropic thermal properties of materials in coupled structural/thermal and thermal only analyses. Field Title Desc TITLE_OPTION MID TRO TGRLC TGMULT TLAT HLAT HC TC Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Thermal Density Thermal generation rate value Thermal generation rate multiplier Phase chnage temperature Latent heat Heat capacity Thermal conductivity See Also: • LS-DYNA Keyword User’s Manual MAT_THERMAL_ORTHOTROPIC Defines orthotropic thermal properties in coupled structural/thermal and thermal only analyses. Materials 277 Materials Field Title Desc TITLE_OPTION MID TRO TGRLC TGMULT AOPT Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Thermal Density Thermal generation rate value Thermal generation rate multiplier Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. TLAT HLAT Phase chnage temperature Latent heat 278 Materials Field K1, K2, K3 XP YP ZP Ai Di Comments Thermal conductivity in local x, y and z, respectively X-coordinate of point p for AOPT=1 Y-coordinate of point p for AOPT=1 Z-coordinate of point p for AOPT=1 Component of Vector a, for AOPT=2 Component of Vector d, for AOPT=2 See Also: • LS-DYNA Keyword User’s Manual MAT_THERMAL_ISOTROPIC_TD Defines temperature dependent isotropic thermal properties in coupled structural/thermal and thermal only analyses. Field Title Desc TITLE_OPTION MID TRO TGRLC Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Thermal Density Thermal generation rate value Materials 279 Materials Field TGMULT TLAT HLAT LC_C LC_K Phase chnage temperature Latent heat Comments Thermal generation rate multiplier Load Curve defining Heat capacity (C) Vs. Temperature Load Curve defining Thermal Conductivity (K) Vs. Temperature See Also: • LS-DYNA Keyword User’s Manual MAT_ORTHOTROPIC_TD Defines temperature dependent orthotropic thermal properties in coupled structural/thermal and thermal only analyses. 280 Materials Field Title Desc TITLE_OPTION MID TRO TGRLC TGMULT AOPT Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Thermal Density Thermal generation rate value Thermal generation rate multiplier Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by vectors below. LC_C LC_KX LC_KY LC_KZ XP YP ZP Ai Di Load Curve defining Heat capacity Vs. Time Load Curve defining Thermal conductivity in local X Vs. Time Load Curve defining Thermal conductivity in local Y Vs. Time Load Curve defining Thermal conductivity in local Z Vs. Time X-coordinate of point p for AOPT=1 Y-coordinate of point p for AOPT=1 Z-coordinate of point p for AOPT=1 Component of Vector a, for AOPT=2 Component of Vector d, for AOPT=2 See Also: • LS-DYNA Keyword User’s Manual Materials 281 Materials MAT_THERMAL_ISOTROPIC_PHASE_CHANGE Defines temperature dependent isotropic properties with phase changes in coupled structural/thermal and thermal only analyses. Field Title Desc TITLE_OPTION MID TRO TGRLC TGMULT LC_C LC_K SOLT LIQT LH Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Thermal Density Thermal generation rate value Thermal generation rate multiplier Load Curve defining Heat capacity Vs. Temperature Load Curve defining Thermal conductivity Vs. Temperature Solid Temperature Liquid Temperature Latent Heat 282 Materials See Also: • LS-DYNA Keyword User’s Manual MAT_THERMAL_ISOTROPIC_TD_LC Defines temperature dependent isotropic thermal properties by specifying a load curve in coupled structural/thermal and thermal only analyses. Field Title Desc TITLE_OPTION MID TRO TGRLC TGMULT HCLC TCLC TGRLCID Comments Unique name identifying material model Optional description of the material model If selected material title option is used Material identification number (Integer > 0) Thermal Density Thermal generation rate value Thermal generation rate multiplier Load Curve Id specifying Heat capacity vs. Temperature Load Curve Id specifying Thermal conductivity vs. Temperature Load Curve Id specifying Thermal generation rate curve number See Also: • LS-DYNA Keyword User’s Manual Properties 273 Properties 274 Properties Properties Overview Typical properties include cross-sectional properties of beam elements, thicknesses of plate and shell elements, element integration rules, and hourglass controls. Properties are assigned to the elements of a specified part or element type, either directly to the elements, or indirectly through the part to which the elements belong. Element Types and Associated Properties Thin Shell Elements Two-dimensional elements, commonly referred to as plate and shell elements, are used to represent areas in your model where one of the dimensions is small in comparison to the other two. As shown Figure 1 the thickness is substantially less than dimensions a or b. Figure 1 Typical Plate Element ELEMENT_SHELL - General-purpose plate elements (4-noded) capable of carrying in plane force, bending forces, and transverse shear force. The triangular element is defined by repeating the third for the fourth node. This family of elements are the most commonly used shell elements in the SimXpert crash element library. These are the element types generated by the Automesher. Properties 275 Properties *SECTION_SHELL - The thin shell elements are commonly referred to as the plate and shell elements within SimXpert. Their properties, are defined using the *SECTION_SHELL entry. The format of the *SECTION_SHELL entry is as follows: 276 Properties Field SECID ELFORM Element formulation options = 1: Hughes-Liu = 2: Belytscho-Tsay = 3: BCIZ triangular shell = 4: C0 triangular shell = 5: Belytscho-Tsay membrane = 6: S/R Hughes-Liu = 8: Belytscho-Leviathan shell Contents Section ID, to be referred by parts = 9: Fully integrated Belytscho-Tsay membrane = 10: Belytscho-Wong-Chiang = 11: Plane stress (x-y plane) = 12: Fast (co-rotational) Hughes-Liu = 13: Plane strain (x-y plane) = 14: Axisymmetric solid (y-axis of symmetry) - area weighted = 15: Axisymmetric solid (y-axis of symmetry) - volume weighted = 16: Fully integrated shell element = 17: Fully integrated DKT triangular shell element = 18: Fully integrated DK quadrilateral/triangular shell element = 20: Fully integrated linear assumed strain C0 shell = 21: Fully integrated linear assumed strain (5 DOF per node) C0 shell = 22: Linear shear panel element (3 DOF per node) SHRF NIP Shear correction factor (value of 5/6 is recommended for solid plate) Number of through thickness integration points Properties 277 Properties Field PROPT Printout options Contents = 0: Average resultants and fiber lengths = 1: resultants at plan points and fiber lengths = 3: Resultants, stresses at all points, fiber lengths QR Quadrature rule LT 0.: Absolute value is used as the Quadrature rule EQ. 0.: Gauss Rule (up to five points permitted) EQ. 1.: Trapezoidal Rule ICOMP Flag for orthotropic/anisotropic layered composite material model = 0: Homogeneous =1: Composite SETYP 2D solid element type (defined for ELFORM 13, 14, and 15) = 1: Lagrangian = 2: Eulerian (single material with voids) = 3: ALE T1 T2, T3, T4 NLOC MAREA IDOF Shell thickness at node 1 Shell thickness at nodes 2, 3, and 4 respectively Location of reference surface normal to s axis (Hughes-Liu elements: ELFORM = 1 or 6) Nonstructural mass per unit area Applies to shell element types 25 and 26. .EQ. 1(default): The thickness field is continuous across the element edges for metal-forming applications. .EQ. 2: The thickness field is discontinuous across the element edges. This is necessary for applications such as crashworthiness where shell intersections, sharp included angles, and non-smooth deformations exist. EDGSET AFAC BFAC Edge node set, required for shell type seatbelts. Smoothing weight factor - simple average (No smoothing if value is -1.) Smoothing weight factor - volume weighting 278 Properties Field CFAC DFAC EFAC START END AAFAC DX, DY ISPLINE IDILA IRID Contents Smoothing weight factor - isoparametric Smoothing weight factor - equipotential Smoothing weight factor - equilibrium Start time for smoothing End time for smoothing ALE advection factor Normalized dilatation parameters of the kernel function in X and Y directions respectively Replaces choice for the EFG kernel functions definition in *CONTROL_EFG. Replaces choice for the normalized dilation parameter definition in *CONTROL_EFG. Integration Rule Id (User defined) The element coordinate systems for the shell element is shown in Figure 2. The orientation of the element coordinate system is determined by the order of the connectivity for the nodes. The element z-axis, often referred to as the positive normal, is determined using the right-hand rule. Therefore, if you change the order of the nodal connectivity, the direction of this positive normal also reverses. This rule is important to remember when applying pressure loads or viewing the untransformed element forces or stresses. Untransformed directional element stress plots may appear strange when they are displayed by the postprocessor in SimXpert because the normals of the adjacent elements may be inconsistent. Remember that components of forces, moments, and element stresses are always output in the element coordinate system. Figure 2 Thin Shell Element Geometry and Coordinate Systems See Also: • LS-DYNA Keyword User’s Manual Properties 279 Properties Thick Shell Elements If the thickness dimension of your component is small, but not too small, in comparison to the other two, dimensions, you can model it with thick shell elements. Figure 3 Typical Plate Element *ELEMENT_TSHELL - Eight noded thick shell element useful for modeling thick plated components. Unlike the thin shell element, *ELEMENT_SHELL which represents the plate through the middle surface, and thickness, the 8-noded thick shell element represents plate as a hexahedron, the first four nodes representing the bottom surface, and the last four nodes representing the top surface. The thick 280 Properties shell wedge element is defined by repeating the third for the fourth node, and repeating the seventh for the eighth node . Figure 4 Thick Shell Element Connectivity Properties 281 Properties SECTION_TSHELL The properties of the thick shell elements are defined using the *SECTION_TSHELL entry. The format of the *SECTION_TSHELL entry is as follows: Field SECID ELFORM Element formulation options Contents Section ID, to be referred by parts = 1: 1point reduced integration (Default) = 2: Selective reduced 2X2 in plane integration = 3: Assumed strain 2X2 in plane integration SHRF NIP PROPT Shear correction factor (a value of 5/6 recommended for solid section plate) Number of through thickness integration points. (If NIP = 0, the Default value of 2 is used) Printout options = 0: Average resultants and fiber lengths = 1: resultants at plan points and fiber lengths = 3: Resultants, stresses at all points, fiber lengths 282 Properties Field QR Quadrature rule Contents LT 0.: Absolute value is used as the Quadrature rule EQ. 0.: Gauss Rule (up to five points permitted) EQ. 1.: Trapezoidal Rule ICOMP Flag for orthotropic/anisotropic layered composite material model = 0: Homogeneous =1: Composite IRID B1 Integration Rule Id (User defined) Material angle (β1) at first integration point. This angle is measured with respect to the element edge n1-n2. The orientation of the element coordinate system is determined by the order of the connectivity for the nodes. The element z-axis (the thickness direction) often referred to as the positive normal to the face connected by nodes n1, n2, n3, and is determined using the right-hand rule (cross product of edge vectors n1-n2 and n1-n3). Therefore, if you change the order of the nodal connectivity, the direction of this positive normal also reverses. This rule is important to remember when applying pressure loads or viewing the untransformed element forces or stresses. Untransformed directional element stress plots may appear strange when they are displayed by the postprocessor in SimXpert because the normals of the adjacent elements may be inconsistent. Remember that components of forces, moments, and element stresses are always output in the element coordinate system. See Also: • LS-DYNA Keyword User’s Manual Three-Dimensional Elements Whenever you need to model a structure that does not behave as a bar or plate structure under the applied loads, you need to use one or more of the three-dimensional elements. The three-dimensional elements are commonly referred to as solid elements. Typical engineering applications of solid elements include engine blocks, brackets, and gears. The Solid Elements in the Crash Workspace Include the Following: 1. 8 noded hexahedron 2. 6 noded pentahedron (degenerated from the 8-node hexahedron, by repeating node 4 for the last four nodes (n1, n2, n3, n4, n4, n4, n4, n4, n4) 3. 4 noded tetrahedron (degenerated from the 8-node hexahedron, by repeating node 5 for the sixth node, and repeating node 7 for the eighth node (n1, n2, n3, n4, n5, n5, n6, n4, n6) Properties 283 Properties 4. 10 noded tetrahedron Figure 5 Solid Elements 284 Properties SECTION_SOLID The properties of the solid elements are entered on the *SECTION_SOLID form shown below: Field Title SECID Unique name identifying the section. Section ID, to be referred by parts Contents Properties 285 Properties Field ELFORM Element formulation options Contents = 0: 1 point co-rotational for *MAT_MODIFIED_HONEYCOMB = 1: Constant stress solid element (Default) = 2: Fully integrated S/R solid = 3: Fully integrated quadratic 8 node element with nodal rotations = 4: S/R quadratic tetrahedron with nodal rotations = 5: 1 point ALE = 6: 1 point Eulerian = 7: 1 point Eulerian ambient = 8: acoustic = 9: 1 point co-rotational for *MAT_MODIFIED_HONEYCOMB = 10: 1 point tetrahedron = 11: 1 point ALE multi-material element = 12: 1 point integration with single material and void = 13: 1 point nodal sure tetrahedron for bulk forming = 14: 8 point acoustic = 15: 2 point pentahedron element = 16: 5 point 10 noded tetrahedron = 18: 8 point enhanced strain solid element for linear statics only AET Ambient element type (foe ELFORM = 7, 11 or 12) = 3: pressure outflow = 4: pressure inflow (Default for ELFORM = 7) AFAC BFAC CFAC Smoothing weight factor - simple average (if value is -1, smoothing turned off) Smoothing weight factor - volume weighting Smoothing weight factor - isoparametric 286 Properties Field DFAC START END AAFAC DX, DY, DZ ISPLINE End time for smoothing Start time for smoothing ALE advection factor Contents Smoothing weight factor - equipotential Normalized dilatation parameters of the kernel function in X, Y, and Z directions respectively Replaces choice for the EFG kernel functions definition in *CONTROL_EFG.. .EQ. 0: Cubic spline function (default) .EQ. 1: Quadratic spline function .EQ. 2: Cubic spline function with cubic shape IDILA Replaces choice for the normalized dilation parameter definition in *CONTROL_EFG.. .EQ. 0: Maximum distance based on the background elements .EQ. 1: Maximum distance based on the sourounding nodes IEBT Essential boundary condition treatment: .EQ. 1: Full transformation method .EQ. -1: w/o transformation .EQ. 2: Mixed transformation method .EQ. 3: Coupled FEM/EFG method .EQ. 4: Fast transformation method .EQ. -4: w/o transformation .EQ. 5: Fluid particle method for E.O.S and *MAT_ELASTIC_FLUID materials Properties 287 Properties Field IDIM Domain integration method: Contents .EQ. 1: Local boundary integration (default) .EQ. 2: Two-point gauss integration .EQ. 3: Improved gauss integration for IEBT = 4 or -4 TOLDEF Deformation tolerance for the activation of adaptive EFG Semi-Lagrangian and Eulerian kernel. = 0.0: Lagrangian kernel > 0.0: Semi-Lagrangian <0.0: Eulerian kernel. See Also: • LS-DYNA Keyword User’s Manual One-Dimensional Elements A one-dimensional element is one in which the properties of the element are defined along a line or curve. Typical applications for the one-dimensional element include trusses, beams, and stiffeners. One- 288 Properties dimensional elements discussed in this chapter include 3D beams, trusses, 2D axisymmetric shells, and 2D plane strain beam elements. Figure 6 Beam Elements SECTION_BEAM Properties 289 Properties The properties of the one dimensional elements are entered on the *SECTION_BEAM form shown below: Field SECID ELFORM Element formulation options Contents Section ID, to be referred by parts = 1: Hughes-Liu with cross section integration (Default) = 2: Belytscho-Schwer resultant beam = 3: Truss resultant = 4: Belytscho-Schwer full cross-section integration = 5: Belytscho-Schwer tubular beam full cross-section integration = 6: Discrete beam/cable = 7: 2D plane strain shell element (xy plane) SHRF Shear factor (5/6 recommended for rectangular section beam) 290 Properties Field QR Contents Quadrature rule or rule number for user defined integration rule = 1: 1 point integration = 2: 2X2 Gauss quadrature (default beam) = 3: 3X3 Gauss quadrature = 4: 3X3 Lobatto quadrature = 5: 4X4 Gauss quadrature = -n: where the absolute value of n is the number of the user defined rule. CST Cross section type (Not needed for truss, resultant beam, discrete beam, and cable elements) = 0: rectangular = 1 Tubular (circular only) = 2 Arbitrary (User defined integration rule) SCOOR NSM TS1 TS2 TT1 TT2 NSLOC NTLOC IRID Location for triad for tracking the rotation of the discrete beam element Nonstructural mass per unit length Beam thickness (for CST = 0.0, 2.0), or Outer diameter (CST=1.0) in s direction at node 1 Beam thickness (for CST = 0.0, 2.0), or Outer diameter (CST=1.0) in s direction at node 2 Beam thickness (for CST = 0.0, 2.0), or Outer diameter (CST=1.0) in t direction at node 1 Beam thickness (for CST = 0.0, 2.0), or Outer diameter (CST=1.0) in t direction at node 2 Location of reference surface normal to s axis (for Hughes-Liu beam elements only) Location of reference surface normal to t axis (for Hughes-Liu beam elements only) Integration Rule Id (User defined) See Also: • LS-DYNA Keyword User’s Manual Properties 291 Properties Discrete Elements Discrete elements in SimXpert Crash comprise of spring and damper elements used between two nodes, or a node and ground. SECTION_DISCRETE The properties of the discrete elements are entered on the *SECTION_DISCRETE form shown below: Field SECID DRO Displacement/Rotation Option: Contents Section ID, to be referred by parts =0 for translational spring or damper =1 for torsional spring or damper KD V0 CL FD CDL TDL Dynamic magnification vector Test velocity Clearance Failure deflection (twist, for DRO = 1. Negative for compression, positive for tension Deflection (twist, for DRO = 1) limit in compression Deflection (twist, for DRO = 1) limit in tension See Also: • LS-DYNA Keyword User’s Manual Seatbelt Elements Seat belt elements are elements with single degree of freedom, connecting two nodes. 292 Properties SECTION_SEATBELT The properties of the seat belt elements are entered on the *SECTION_SEATBELT form shown below: Field SECID Contents Section ID, to be referred by parts See Also: • LS-DYNA Keyword User’s Manual Mass Elements Mass elements are used to defined lumped masses to nodes. In SimXpert crash workspace, the mass associated with the mass elements are assigned directly to the mass element, and hence no properties are needed to be created. See Also: • LS-DYNA Keyword User’s Manual Element Integration SimXpert crash Workspace normally uses the recommended integration through thickness of beams and shell elements. However, you can use other through-thickness integration rules using • *INTEGRATION_BEAM for defining through thickness integration rules for the beam elements • *INTEGRATION_SHELL for defining through thickness integration rules for both the thin and thick shell elements. See Also: • LS-DYNA Keyword User’s Manual Properties 293 Properties Hourglassing The advantage of the reduced integration elements is that the strains and stresses are calculated at the location that provide optimal accuracy, the so-called Barlow points. The reduced integration elements also tend to underestimate the stiffness of the element which often gives better results in a typically overly-stiff finite element analysis displacement method. An additional advantage is that the reduced number of integration points decreases CPU time and storage requirements. The disadvantage is that the reduced integration procedure may admit deformation modes that cause no straining at the integration points. These zero-energy modes cause a phenomenon called “hourglassing,” where the zero energy mode starts propagating through the mesh, leading to inaccurate solutions. This problem is particularly severe in first-order quadrilaterals and hexahedrals. To prevent these excessive deformations, an additional artificial stiffness is added to these elements. In this so-called hourglass control procedure, a small artificial stiffness is associated with the zero-energy modes. This procedure is used in many of the solid and shell elements in SimXpert crash Workspace Use the *HOURGLASS keyword data to define hourglass and bulk viscosity properties which are referenced via the HGID in the *part command. . Figure 7 Hourglassing See Also: • LS-DYNA Keyword User’s Manual 294 Properties Meshing and Element Creation 293 Meshing and Element Creation 294 Meshing and Element Creation Meshing and Element Creation Modeling Guidelines Finite element modeling in many ways is more like an art than a science since the quality of the results is dependent upon the quality of your model. One of the more common errors that a beginning finite element analyst makes in modeling is to simply simulate the geometry rather than to simulate both the geometry and the physical behavior of the real structure. The following modeling guidelines are provided to put a little more science back into the art of finite element modeling: • Choosing the right element. • Mesh transitions. The above guidelines are by no means complete; however, they do serve as a good starting point. There is no better substitute for good modeling than experience. It is also good modeling practice to simulate and validate a new capability or a feature that you have not used before with a small prototype model before applying this feature to your production model. Model verification techniques are covered in Quality Checks, 297. SimXpert contains a large library of structural elements. In many situations several elements are capable of modeling the same structural effects. The criteria for the selection of an element may include its capabilities (for example, whether it supports anisotropic material properties), the amount of time required to run an analysis (in general, the more DOF an element has, the longer it runs), and/or its accuracy. In many cases the choice of the best element for a particular application may not be obvious. For example, in the model of a space frame, you may choose to use truss elements if bending or torsional stiffness is unimportant or to use the beam elements with axial, bending and torsional stiffness. You may even choose to represent the members with built-up assemblies of plate or solid elements. The choice of which type and number of elements to use depends primarily on your assessment of the effects that are important to represent in your model and on the speed and accuracy you are willing to accept. In this context, it is critical that you have a fairly good idea of how the structure will behave prior to generating your finite element model. The best source of such insight is usually experience with similar structures or components. In other words, understanding the load path is crucial in the selection of the appropriate element. In addition, a few hand calculations can usually provide a rough estimate of stress intensities. Such calculations are always recommended. If you do not have a fairly good idea of how the structure will behave, you may be misled by incorrect results due to errors or incorrect assumptions in your input data preparation. The following guidelines are provided to help you in selecting the “right” element for your task. Meshing and Element Creation 295 Meshing and Element Creation Avoid highly skewed elements (see Figure 1). The angle α should be as close to 90 degrees as possible. α Figure 1 Highly Skewed Element Aspect ratio is defined as l ⁄ ω (length/width). Very high aspect ratio (see Figure 2) should also be avoided in areas where there is a high stress gradient. l ω Figure 2 Element with High Aspect Ratio Warping is a measure of the amount the element deviates from being planar (see Figure 3). Element warping should be minimized. Element Mid-Plane Figure 3 Highly Warped Element Mesh Transitions Mesh transition can be a complicated subject. It may simply be used to refine the mesh in a particular area, connect different element types (for example, a CBAR element to a solid element), or provide transitions required to model the geometry of the structure. Two guidelines for mesh transitions are as follows: 1. Never place a mesh transition in an area of interest or in an area where there is a large variation in stress. 2. Mesh transitions should be located away from the areas of interest in a region. 296 Meshing and Element Creation Due to incompatibilities between finite element types, any transition between different element types (even a transition from quadrilateral to a triangular elements) can result in local stress anomalies. Normally, these stress anomalies are localized and dissipate quickly as you move away from the transition. However, a problem arises when the transition occurs in an area of interest. In this case, the local stress rises (or decreases) due to the effect of the transition; in other words, the results may be conservative (or non-conservative) in an area near a transition. However, if this localized stress variation occurs away from areas of interest, the increase (or decrease) in stress caused by the transition should cause no concern. • Transition from a Coarse Mesh to a Fine Mesh The transition from a coarse mesh to a fine mesh, or vice versa, may not always be an easy task. One common method of performing a transition is to use an intermediate belt of triangular elements as shown in Figure 4. Q4 Q4 Q4 Q4 Q4 T3 T3 Q4 T3 Q4 T3 T3 Q4 T3 Q4 Q4 Figure 4 Mesh Transition Mesh Control Before you create elements, you should first specify a default mesh size by selecting Element Options from the Elements menu. Mesh sizes can also be set interactively using Mesh Size from the Elements menu. In addition you can also define hard points on curves or surfaces to ensure that a node is placed at that location. You do this using Create Hard Points from the Geometry menu. Mesh should have high density in areas of large stress gradients. Meshing Automeshing You can use the selections under Automeshing to create multiple elements on geometry. • Automesh - Used to create quadrilateral and triangular plate/shell elements on surfaces. • Solid Mesher - Used to create a tetrahedral mesh inside bounding surfaces • Interactive Mesh Size - Interactively modifies the number of elements along a selected curve Meshing and Element Creation 297 Meshing and Element Creation Manual Meshing You can use the selections under Manual Meshing to create mesh without having surfaces. • 2-3-4 Line Mesh - Creates a mapped mesh by selecting 2,3, or 4 bounding curves. User can modify the number of elements to be created on each curve. Set or modify the mesh elements parameters using Params button from the pick menu. • 3-4 Point Mesh - Creates mesh between the 3 or 4 selected points. You can specify the number of elements to be created between each pair of selected points. Points should be selected in a circular manner. • Drag Mesh - Creates a solid or shell mesh by dragging elements or nodes along a specified vector or curve. • Flange Creation - Creates a flange by dragging selected nodes through a specified width and angle. • Linear Solid Mesh - Creates solid elements between two groups of shell elements. • Refine Mesh - Refines the selected mesh region to specified edge length, while maintaining element connectivity with congruent elements. • Spin Mesh - Creates solid or shell elements by rotating shell elements or nodes through a specified angle about a vector. Merge Coincident Nodes Nodes along common edges of adjoining geometry entities need to match. If these nodes are not coincident, your model will have free edges or faces at these points. Always merge coincident nodes before analyzing your model using Merge Coincident Nodes from the Node menu. Quality Checks Free Edges You can check that your model has completed merging coincident nodes by displaying free edges in your model. In Figure 5 the model is shown with free edges displayed by selecting Highlight FE Boundary from the View menu.The picture on the left shows the model with a solid horizontal line running through the middle. This indicates that a free edge exists there and the top and bottom are not connected. The 298 Meshing and Element Creation picture on the right shows the model after the coincident nodes have been merged. The model is now one continuos piece. I Free (unconnected) edge Before After Figure 5 Free Edge Check - Before and After Merge Coincident Nodes Consistent Plate Normals You can check the orientation of your plate elements using the Normals selection from the Element menu. When the pick box appears, in the Mode list, click Show Normal then click All. In Figure 6 you can see that these elements do not have consistent normals. Figure 6 Inconsistent Normals Meshing and Element Creation 299 Meshing and Element Creation You can enforce consistent normals by now clicking Fix Normal in the Mode list and then selecting a reference element with the desired normal direction. You could also click Rev. Normal and then select the elements on which to reverse normals. Figure 7 Consistent Normals To turn off the display of normal vectors click Hide Normal in the Mode list then click All. Element Shape Checks The types of quality checks that SimXpert can perform on shell elements can be seen on the following form. It is accessed by selecting Quality/Quality from the Elements menu. • Warp check: Evaluates how far out of plane the element ‘bends’. Warp is computed by determining the angle between the normals of 2 triangular regions superimposed on the element. This check is also applicable to quad faces of solid elements. • Taper check: Compares the ratios of the lengths of opposite edges of an element. • Skew check: Compares the maximum angles between the element diagonals. 300 Meshing and Element Creation • Interior Angle check: Evaluates the interior angles measured at each of the four (or 3) corner nodes. If any element exceeds minimum or maximum tolerance levels specified for an element check, it is considered to have failed that test. SimXpert can compute a Quality Index which is a weighted composite of all the selected quality checks. You can toggle the display of the Quality Index from the Bottom Block by selecting Fringes On/Off from the FE-Grafix menu. Elements that violate any of the activated quality criteria will be displayed in magenta. Those elements color-coded red to orange have marginal quality. You can further investigate which specific tests your elements may be failing by selecting the individual quality measure from the FE-Qual Meshing and Element Creation 301 Meshing and Element Creation menu and your display will update accordingly. The following image shows the model now color-coded based on Warpage. Once again, failed elements are shown in magenta. Elements with a high value that does not exceed the threshold are color-coded red or orange. Tools to Help Fix Poorly Shaped Elements • Manual - Element / Quality / Manual Fix - allows you to select a node and drag it to a new location. Element color coding will change in real time to feed back how the element’s quality is changing. Click the middle mouse button to finalize the new nodal location. 302 Meshing and Element Creation • Mesh Quality - Element / Quality / Quick Quality - allows you to select elements for mesh quality enhancement then select desired parameters as shown below: • Fast Shell Enhancing attempts to fix failed elements only. Once they pass all selected criteria, no further enhancement is attempted. • Slow Shell Enhancing attempts to fix failed elements and also to further improve all selected elements. • All passes except Warp Enhancing will maintain nodes on the FE-Surface. Warp Enhancing will move the node (within the specified tolerance) normal to the surface to decrease the warping. Loads and Boundary Conditions 303 Loads and Boundary Conditions 304 Loads and Boundary Conditions Loads and Boundary Conditions This chapter describes the loads and boundary conditions available when performing analysis with the SimXpert crash workspace. Each of the load types discussed may be applied to your model individually, or in any combination. Supported Load and Constraint Types Most often, boundary conditions are imposed in the form of constraints on selected degrees of freedom on the model. Typically, several degrees of freedom are constrained to ground, using Single Point Constraints (SPC) boundary conditions. Besides single-point constraints, crash workspace provides a method of creating linear constraint relationships between several degrees of freedom. A third type of boundary conditions is the contact boundary condition for specifying that certain regions of the structure might be touching or separating during the simulation process. Contact boundary condition is an important feature of the crash workspace. This section discusses the single-point and multiple-point constraints. The rigid elements are discussed under Meshing, and the Contact is discussed under the section on contact. Single-Point Constraints A Single-Point Constraint (SPC) is a constraint that is applied to a single degree of freedom, which may be either a component of motion at a node or the displacement of a scalar point. The primary applications for single-point constraints are: 1. To tie a structure to ground. 2. To apply symmetric or anti symmetric boundary conditions by restraining the degrees of freedom that must have a zero value to satisfy symmetry or anti symmetry. Symmetry is discussed in the Modeling Guide. 3. To remove degrees of freedom that are not used in the structural analysis (that is, are not connected to any structural elements or otherwise joined to the structure). SPC BC • *BOUNDARY_SPC constraints usually specified at model boundaries to define rigid support points. These can also be used to apply an enforced nonzero displacement. Directions are in the applicable nodal coordinate system. Loads and Boundary Conditions 305 Loads and Boundary Conditions • *CONSTRAINED_LINEAR_OPTION defines linear constraint equation between displacements and rotations defined in global (OPTION =GLOBAL), or local (OPTION =LOCAL) coordinate system. The constraint equation is generally of the form: C u k k =1 n k = C0 where uk are the displacements/rotations, and Ck are the user defined coefficients. Nodal BC • FORCE and MOMENT -- Concentrated forces and moments, which are applied directly to nodes. The magnitude is entered directly. The direction is defined by selecting an appropriate degree-of-freedom (DOF) code. The node or nodes to which forces or moments are to be applied, can be selected directly or via node set. Follower forces and moments can also be applied. The temporal variation of the force or moment can be defined by using a load versus time curve (LCID). • Boundary Sliding Plane -- Boundary conditions at nodes on symmetry planes defined by creating the symmetry plane. • Boundary Temperature -- Temperature Boundary Conditions at nodes for thermal loading, or temperature dependent materials. • Initial Temperature -- Defines initial nodal temperatures. These can be applied either directly to the nodes, or via node set. • Initial Foam Reference Geometry -- Defines reference configuration for the geometry of the foam material for initialization of stresses in the foam. • Boundary Prescribed Motion -- Defines imposed (nonzero) nodal motion (velocity, acceleration, or displacement) on nodes, node sets, or rigid bodies. Element BC • Load Shell -- Distributed pressure load applied to shell or thick shell elements, or element set. • Load Beam -- Distributed traction load along any local axis of beam elements or a set of beams. • Initial Strain Shell -- Applies initial strains to shell elements. • Initial Stress Shell -- Applies initial stresses to shell elements. • Initial Stress Beam-- Applies initial stresses to beam elements. • Initial Stress Solid -- Applies initial stresses to solid elements. • Initial Volume Fraction -- Defines initial volume fraction for different materials in multi-material ALE, or in single material and void models. • Initial Momentum -- Defines initial momentum for depositing in solid elements, to simulate impulse loading. 306 Loads and Boundary Conditions Load Segment • Applies distributed pressure load over a triangular or quadrilateral segment defined by four nodes, over each segment in a segment set. Global BC • BOUNDARY_CYCLIC -- Defines nodes in boundary planes for cyclic symmetry • BOUNDARY_PRESCRIBED_MOTION -- Defines imposed (nonzero) nodal motion (velocity, acceleration, or displacement) on nodes, node sets, or rigid bodies. • CONSTRAINED_ADAPTIVITY -- Defines adaptive constraints to constrain nodes to the midpoint along edges of shell elements. • CONSTRAINED_GENERALIZED_WELD_BUTT -- Defines butt welds. Weld failures include both plastic and brittle failures. Coincident nodes are permitted, provided local coordinates are defined. • CONSTRAINED_EULER_IN_EULER -- Defines coupling between materials in two overlapping, and geometrically identical multi-materials Eulerian mesh sets. It also allows frictional contact between two or more Eulerian materials. • CONSTRAINED_GLOBAL -- Defines a global boundary constraint plane • CONSTRAINED_INTERPOLATION -- Defines an interpolation constraint whereby the motion of a single dependent node is interpolated from the motion of a set of independent nodes. • CONSTRAINED_POINTS -- Defines constraint between two points with the specified coordinates connecting two shell elements at locations other than nodal points. • CONSTRAINED_RIGID_BODIES -- Defines rigid body stoppers, to conveniently control the motion of rigid tooling in metal forming applications. • CONSTRAINED_RIGID_BODY_STOPPERS -- Defines the merger of two rigid bodies • CONSTRAINED_SHELL_TO_SOLID -- Defines a tie (constraint) between the edge of a shell and solid elements. • CONSTRAINED_TIE_BREAK -- Defines a tie (constraint) between the edge of a shell and solid elements enabling local release as a function of plastic strain at the shell elements surrounding the interface nodes. • CONSTRAINED_TIED_NODES_FAILURE -- Defines a tied (constrained) node set with failure based on plastic strains. • CONSTRAINED_JOINT_STIFFNESS -- Defines translational and rotational joint stiffness. Options include FLEXION-TORSION, GENERALIZED, and, TRANSLATIONAL. • INITIAL_DETONATION -- Defines points to initiate high explosive detonations in parts • INITIAL_GAS_MIXTURE -- Defines initial temperature and density of different gas species in *MAT_GAS_MIXTURE for the simulation of gas mixtures. • INITIAL_VELOCITY -- Defines initial nodal velocities using node set IDs. • INITIAL_VEHICLE_KINEMATICS -- Defines initial kinematical information such as orientation, yaw, pitch, and roll axes for a vehicle. Loads and Boundary Conditions 307 Loads and Boundary Conditions • INITIAL_VELOCITY_RIGID_BODY -- Defines the initial translational and rotational velocities at the center of gravity for a rigid body. This input overrides all other velocity input for the rigid body and the nodes which define the rigid body. • INITIAL_VELOCITY_GENERATION -- Defines initial velocity for rotating and translating bodies. • INITIAL_VOID -- Defines initial voided part set or part numbers. • INITIAL_VOLUME_FRAC_GEOMETRY-- Defines initial volume fraction of different materials in multi-material ALE, or in single material and void models. • Load Blast-- Defines an airblast function for the application of pressure loads due to explosives in conventional weapons. • Load Body-- Defines body force loads due to prescribed base acceleration or angular velocity using global axes definition. This load applies to all nodes in the model unless a part subset is specified via the *LOAD_BODY_PARTS keyword. • Load Body Generalized-- Defines body force loads due to prescribed base acceleration, or a prescribed angular velocity over a subset of the model. The subset is defined by using nodes. • Load Body Parts-- Defines body force loads for nodes belonging to selected parts. • Load Brode-- Defines brode function for application of pressure loads due to explosives. • Load Density Depth -- Defines density versus depth for gravity loading for analyzing submerged and underground structures. • Load Mask-- Defines distributed pressure load over a three dimensional shell part. The pressure is applied to a subset of elements that lie within a fixed global box and lie either outside or inside of a closed curve in space which is projected onto the surface. • Load Rigid Body-- Defines concentrated nodal force to a rigid body. The force is applied at the center of mass, or a moment is applied around a global or local axis. • Load SSA-- Defines a simple way of loading the structure to account for the effects of primary explosion and the subsequent bubble oscillations. • Load SuperPlastic Form -- Defines loads for superplastic forming analysis. • Load Thermal Constant-- Defines nodal temperatures that remains constant (during the duration of the analysis) or thermally loading a structure for structural analysis. • Load Thermal Load Curve -- Defines uniform (throughout the model) nodal temperatures that can vary (in time) according to a load curve. • Load Thermal Variable -- Defines nodal sets giving the temperature that varies during the duration of the analysis. • Airbag - Defines an airbag or control volume, providing a way of defining the thermodynamic behavior of the gas flow into the airbag, and a reference configuration for the fully inflated bag. The available thermodynamic relationships include: Simple Pressure Volume, Simple Airbag Model, Adiabatic Gas Model, Wang Nefske, Wang Nefske Jetting, Wang Nefske Multiple Jetting, Load Curve, Linear Fluid, Hybrid, Hybrid Jetting, and Hybrid Chemkin. • Airbag Interaction -- Defines two connected airbags which vent into each other. 308 Loads and Boundary Conditions • Airbag Reference Geometry -- Defines airbag reference geometry LBC Sets Loads and boundary conditions can be grouped into sets. The applied loads can be applied independently or in combination. To group your applied loads into load sets select Create LBC Set from the BC menu. Supply a name for your LBC set, then select the desired loads and boundary conditions. Contact 309 Contact 310 Contact Contact Overview The simulation of many physical problems requires the ability to model the contact phenomena. This includes analysis of interference fits, rubber seals, tires, crash, and manufacturing processes among others. The analysis of contact behavior is complex because of the requirement to accurately track the motion of multiple geometric bodies, and the motion due to the interaction of these bodies after contact occurs or breaks. This includes representing the friction between surfaces and heat transfer between the bodies if required. The numerical objective is to detect the motion of the bodies, apply a constraint to avoid penetration, and apply appropriate boundary conditions to simulate the frictional behavior and heat transfer. This section gives an overview of the methods used in the SimXpert crash Workspace for handling contact. Contact problems can be classified as one of the following types of contact. • Deformable-Deformable contact between single (self-contact), or multiple two- and three- dimensional deformable bodies. • Rigid - Deformable contact between a deformable body and a rigid body, for two- or three- dimensional cases. • Tied contact in two and three dimensions. This is a general capability for tying (bonding) two deformable bodies, or a deformable body and a rigid body, to each other. Contact problems involve a variety of different geometric and kinematic situations. Some contact problems involve small relative sliding between the contacting surfaces, while others involve large sliding. Some contact problems involve contact over large areas, while others involve contact between discrete points. The approach adopted by SimXpert crash Workspace to model contact can be used to handle most contact problems. Contact Methodology This section gives an overview of the methods used in the SimXpert crash Workspace for handling contact. Constraint Method One side of the contact interface is called the slave side, and the other is designated as the master side. Nodes lying in those surfaces are respectively referred to as the slave nodes and the master nodes. Constraints are imposed on the global equations by a transformation of the displacement components of the slave nodes along the contact interface. To keep the efficiency of the explicit time integration scheme, the mass is lumped to the extent that only the global degrees of freedom of each master node are lumped. Impact and release conditions are imposed to ensure the conservation of momentum. If the mesh in the master surface zone is finer than the slave surface zone, master nodes can penetrate through the slave surface without resistance, and create incorrect solution, especially if the interface pressures are too high. Better choice of master and slave zoning would minimize such errors in some Contact 311 Contact cases. However, in some modeling situations (e.g. modeling of airbags in automotive crash applications) good zoning in the initial configuration may be poor zoning later as the deformation progresses. Penalty Method The penalty method places normal interface springs between all penetrating nodes and the contact surface. Momentum is conserved exactly without the necessity of imposing impact and release conditions. Currently there are three formulations of the penalty algorithm. Standard Penalty Formulation: In this formulation, the interface stiffness is chosen to be approximately of the same order of magnitude as the stiffness of the interface element normal to the interface. If interface pressures become large, unacceptable penetration may occur. The usual remedy of scaling up the penalty stiffness, and scaling down the time step size increase the cost of the simulation. Soft Constraint Penalty Formulation: In this formulation, in addition to the master and slave contact stiffness, an additional stiffness (called the stability contact stiffness) which is based on the stability (Courant’s criterion) of the local system comprised of two masses (segments) connected by a spring is added. The stability contact stiffness kcs is calculated as: kcs = 0.5. SOFSCL. m*. (1/(Δtc(t)) where, SOFSCL is the Soft Constraint Penalty Scale factor, m* is a function of the mass of the slave node and the master nodes, and Δtc is set to the initial solution time step. Segment-based Penalty Formulation: This formulation uses a slave segment-master segment approach instead of the slave node-master segment approach. It is especially very efficient for airbag self-contact during inflation and complex contact conditions. Accounting for Shell Thickness Shell thickness effects as well as change in thicknesses are accounted for in the crash Workspace. Contact Damping Viscous contact damping can be added to all contact options including single surface contact. It allows to damp out oscillations normal to the contact surfaces during metal forming operations, and it also works effectively in removing high frequency noise in problems involving impact. Friction Friction in crash Workspace is based on a Coulomb formulation See “LS-DYNA Theory Manual” for a complete description of the friction formulation. 312 Contact Tied Contact Tied contact or tied interfaces provides a convenient way of modeling with dissimilar (non congruent) meshes across an interface. This can often decrease the amount of effort required to generate meshes since it eliminates the need to match nodes across common faces of parts. Contact Types Different types of contact may be defined in SimXpert crash. Some of the most common contact types are listed here. Refer to the “LS-DYNA Keyword User’s Manual” for a more complete and detailed description. • Automatic Nodes to Surface • Automatic Single Surface • Automatic One way Surface to Surface • Automatic Surface to Surface • Nodes to Surface • Surface to Surface • Tied Nodes to Surface Contact 313 Contact • Tied Shell Edge to Surface • Tied Surface to Surface • Airbag Single Surface • Rigidwall Geometric Flat • Rigidwall Geometric Cylinder • Rigidwall Geometric Sphere Contact Parameters A list of the most common contact parameters are described here. Refer to the “LS-DYNA Keyword User’s Manual” for a more complete and detailed description. Variable FS FD DC VC VDC PENCHK BT DT SFS SFM SST MST SFST SFMT FSF vs.F CF FRAD HTC GCRIT GMAX Static coefficient of friction Description Dynamic coefficient of friction Exponential decay coefficient Coefficient for viscous friction Viscous damping coefficient in percent critical Small penetration option in contact search. Birth time of contact (contact surface becomes active at this time) Death time of contact (contact surface is deactivated at this time) Scale factor on default slave penalty stiffness. Scale factor on default master penalty stiffness Optional thickness for slave surface (overrides true thickness) Optional thickness for master surface (overrides true thickness) Scale factor for slave thickness (scales true thickness) Scale factor for master thickness (scales true thickness) Coulomb friction scale factor Viscous friction scale factor Thermal conductivity of fluid between the slide surfaces Radiation factor between the slide surfaces Heat Transfer conductance for close gaps Critical gap. Use Heat Transfer conductance defined (HTC) for gap thickness less than the value of GCRIT No thermal contact if gap is greater than GMAX 314 Contact Variable CD_FAC SOFSCL LCIDAB MAXPAR EDGE DEPTH BSORT FRCFRQ PENMAX THKOPT SHLTHK SNLOG ISYMB I2D3D SLDTHK SLDSTF Description A multiplier used on the element characteristic distance for the search algorithm. Scale factor for constraint forces of soft constraint option Load Curve Id defining thickness of airbag (used in airbag contacts) Maximum parametric coordinate in segment search. Edge to edge penetration check Option to search depth in automatic contact Number of cycles between bucket sorts Number of cycles between contact force updates for penalty contact formulations Maximum penetration distance Thickness option Shell thickness option Option to enable/disable shooting node logic in thickness offset contact Symmetric plane option (set to 1, to retain the correct boundary conditions in models with symmetry.) Segment searching option Solid element thickness (a nonzero positive value activates the contact thickness offsets in the contact algorithm where offsets apply) Solid element stiffness (a nonzero positive value overrides the bulk modulus taken from the material model referenced by the solid element) Flag to improve implicit convergence behavior at the expense of creating some sticking, if parts attempt to separate Option to allow/ignore initial penetrations Flag for initial penetration compensation Bucket sorting frequency Load Curve Id defining bucket sorting frequency vs. time Number of segments to track for each slave node Number of iterations for initial penetration checking IGAP IGNORE trackpen bucket lcbucket nseg2trac initiator Simulation 315 Simulation 316 Time Step Control Time Step Control During the solution a new time step is estimated by taking the minimum value over all the elements in the model: Δt n+1 = a ⋅ min{Δt1, Δt2 , Δt3,..., ΔtN } where, N is the number of elements, and a is the scale factor. For stability reasons the scale factor a is typically set to a value of 0.90 (default) or smaller. Time Step for Solid Elements A critical time step size, Δte, is computed for solid elements from: Δte = { Q + (Q Le 2 1/ 2 + c2) } where, c is the adiabatic speed of sound, Q is a function of the bulk viscosity coefficients C0 and C1. For elastic materials with a constant bulk modulus c can be computed as: c= E (1 − υ ) (1 + υ )(1 − 2υ ) ρ where, E, ν, and ρ are respectively the Young’s modulus, Poisson’s ratio, and density. C1c + C0 Le ε kk for ε kk < 0 Q= for ε kk ≥ 0 0 where, Le is a characteristic length calculated as the minimum altitude (for 4-node tetrahedrons), or the ratio of the element volume to the area of the largest face (for 8-node hexahedra) Time Step for Shell Elements For the shell elements, the time step size is given by: Δte = Ls c Simulation 317 Time Step Control where, Ls is the characteristic length, and c is the speed of sound: c= E ρ (1 −ν 2 ) Three user options exist for selecting the characteristic length Ls. In the first (default) option, Ls is given by: e Ls = (1 + β ) As max( L1 , L2 , L3 , (1 − β ) L4 ) where, β = 0 for quadrilateral, and 1 for triangular shell elements, As is the area, and Li (i = 1, 2, 3, 4) is the length of the sides defining the shell elements. In the second option, the following more conservative value is used for Ls: Ls = (1 + β ) As max( D1 , D2 ) where, Di (i = 1, 2) is the length of the diagonals. The third option, which provides the largest time step size, and is often used for triangular shell elements with very small altitudes uses the following expression for Ls: (1 + β ) As , min( L1 , L2 , L3 , L4 + β 1020 ) Ls = max max( L1 , L2 , L3 ,(1 − β ) L4 ) Time Step for Beam and Truss Elements For the Hughes-Liu beam and truss elements, the time step size is given by: Δt e = L c 318 Time Step Control where, L is the length of the element, an c is the speed of sound calculated as: c= E ρ The Belytscho beam also uses smaller of the values given by: Δt e = and L c Δt e = .5L 3 1 + 2 c 3I 2 12 I + AL AL where, I and A are the maximum value of the moment of inertia, and the area of the beam cross section respectively. Time Step for Discrete Elements For spring elements there is no wave propagation speed c to calculate the critical time step size. However, based on the maximum eigenvalue of the spring with the nodal masses M1, M2 attached to the nodes connected to the spring, the critical time step size can be computed as: Δte = 2 2M 1M 2 k ( M1 + M 2 ) Simulation 319 Output Control Output Control The Control and the database options are used to set solution and output options for the analysis. 320 Control Control The Control options are used to set solution options such as analysis duration (*CONTROL_TERMINATION), adaptive meshing (*CONTROL_ADAPTIVE), parallel processing (*CONTROL_PARALLEL), and output options such as energy (*CONTROL_ENERGY), output interval (*CONTROL_OUTPUT). Refer to the LS-DYNA Keyword user’s Manual for a complete list of the Control cards and options. These control options can be set, and or changed from the SimXpert crash Workspace. Many of these options have default settings which work pretty well in most situations. However, a set of standard or user selected control options can be imported from an existing LS-DYNA keyword file, for use either on an as-is basis, or to be selectively modified in the crash workspace GUI. Database The LS-DYNA Database options define options for output files containing results information for post processing. For example, the use of the *DATABASE_BINARY_D3_PLOT card lets you select the time interval (DT) between output for the d3plot files. Refer to the “LS-DYNA Keyword User’s Manual” for a complete list of the database cards and options. These database options can be set, and or changed from the SimXpert crash Workspace. Many of these options have default settings which work pretty well in most situations. However, a set of standard or user selected control options can be imported from an existing LS-DYNA keyword file, for use either on an as-is basis, or to be selectively modified in the crash workspace GUI. Simulation 321 Perform the Simulation Perform the Simulation To perform the analysis, export an LS-DYNA keyword file (File -> Export -> Dyna Model). This will create a keyword input file which can then be used to perform the simulation with LS-DYNA on a computer where it is installed. Manually Invoking LS-DYNA As a part of SimXpert Installation, the LS-DYNA Analysis Code solver is installed in a subdirectory under the main installation directory and can be invoked directly. Should you need to manually invoke LS-DYNA, run the executable found under the SimXpert installation directory. To invoke LS-DYNA from Linux32: <INSTALLROOT>/Nastran/md2009/dyna/linux32/run_dytran jid=jobid.key iam=simxcr From Linux64: <INSTALLROOT>/Nastran/md2009/dyna/linux64/run_dytran jid=jobid.key iam=simxcr From Windows32: <INSTALLROOT>/Nastran/md2009/dyna/win32/run_dytran jid=jobid.key iam=simxcr From Windows64: <INSTALLROOT>/Nastran/md2009/dyna/win64/run_dytran jid=jobid.key iam=simxcr where jobid.key is a LSDYNA input deck. For Linux32, the default INSTALLROOT Path for SimXpert R4 is /msc/SimXpert/R4 For Linux64, the default INSTALLROOT Path for SimXpert R4 is /msc/SimXpert_x64/R4 For Windows32/64, the default INSTALLROOT Path for SimXpert R4 is C:\MSC.Software\SimXpert\R4 322 Perform the Simulation Example - Crushing of a Thin Square Tube 323 Example - Crushing of a Thin Square Tube 324 Crushing of a Thin Square Tube Crushing of a Thin Square Tube Problem Description A square cross section thin tube is to be simulated for crushing by a rigid wall moving with an initial velocity toward one end of the tube, while the other end is fixed. The basic FEA model containing the nodes and the elements is imported from a Nastran input file. Complete the crush model with materials, sections, boundary conditions, loads, and analysis and output options for performing the crush simulation. Some Key Data: Cross-section of the tube: Length of the tube: Thickness of the tube: Weight of the rigid wall: 69.954 mm X 69.954 mm 320 mm 1.2 mm 0.4 ton Initial velocity of the rigid wall: 5646 mm/sec Steps: Following are the steps to complete the crush model. 1. Launch SimXpert Select Structures as the Workspace 2. Select the Solver Card as the GUI Options Tools -> Options -> GUI Options Select Solver Card Click Apply 3. Set the Units for the model Click Units Manager Click Standard Units Select mm, t, s as the units for Length, Mass, and Time respectively Click OK Click OK Example - Crushing of a Thin Square Tube 325 Crushing of a Thin Square Tube 4. Import the FEA mesh from a MSC.Nastran input file File -> Input -> Nastran ... Select the file, square_tube_nast.bdf Hint: You can find the above file in the PartFiles folder under the help folder in the SimXpert installation directory. Click Open Close the (pop-up) Notepad window (nastran.err - Notepad) The imported FEA mesh represents a quarter model of the thin square tube. Figure 1 Quarter model of a square section tube 5. Switch the workspace to crash: Set workspace to crash 6. Create the material: Materials and Properties-> MAT [1 to 20] -> [003]MAT_PLASTIC_KINEMATIC Enter steel as the Title for the material Enter value for RO: 7.85E-9 326 Crushing of a Thin Square Tube Enter value for E: 1.994E5 Enter value for PR: 0.30 Enter value for SIGY: 3.366E2 Enter value for ETAN: 1 Enter value for BETA: 1 Click OK 7. Create properties for the shell elements: Materials and Properties-> Section -> SECTION_SHELL Select 2 for ELFORM Enter value for SHRF: 1. Enter value for NIP: 3 Note: Hit the Enter key, after typing 3 for NIP. Otherwise, the change will not be made. Enter value for T1: 1.2 Enter value for T2: 1.2 Enter value for T3: 1.2 Enter value for T4: 1.2 Click OK 8. Assign property and material to the part: Right click on the (part) PSHELL... in the Model Browser Click Properties on the pop-up window Double click on the SECID data box, and click Select Select SECTION_SHELL_1 from the Select a PSECTION form Click OK Double click on the cell below MID, and click Select Select steel from the Select a Material form Click OK Set the value for ADPOPT to 1 Click Modify Click Exit 9. Create the boundary conditions for the tube: Example - Crushing of a Thin Square Tube 327 Crushing of a Thin Square Tube LBCs -> LBC -> SPC -> Boundary SPC Make sure all six DOFs are checked-in (selected) Click Store Click Exit Pick all the nodes on the bottom of the tube Click Done on the Pick panel This fixes the bottom edge of the tube against all translations and rotations. 328 Crushing of a Thin Square Tube Top edge z-symmetry edge x-symmetry edge Bottom edge (fixed) Figure 2 Boundary conditions for the tube model Example - Crushing of a Thin Square Tube 329 Crushing of a Thin Square Tube LBCs -> LBC -> SPC -> Boundary SPC Check in DOFX, DOFRY, DOFRZ Click Store Click Exit Pick all the nodes on the x-symmetry edge, except the node on the bottom edge. Click Done on the Pick panel This imposes the symmetric boundary condition on the x-symmetry edge. LBCs -> LBC -> SPC -> Boundary SPC Check in DOFZ, DOFRX, DOFRY Click Store Click Exit Pick all the nodes on the z-symmetry edge, except the node on the bottom edge. Click Done on the Pick panel This imposes the symmetric boundary condition on the z-symmetry edge. 10. Create a constrained node set on all the nodes on the top edge: Nodes/Elements ->Elements -> Create -> Rigid -> Constrained Node Set Set DOF to 2 Click Store Click Exit Pick all the nodes on the top edge Click Done on the Pick panel 11. Create mass elements to represent the rigid wall: Elements -> Create -> 1 Noded -> Element Mass Enter value for MASS: 0.01 Click Store Click Exit Pick all the nodes on the top edge, except two nodes where the symmetry edges meet the top edge. Click Done on the Pick panel 330 Crushing of a Thin Square Tube Elements -> Create -> 1 Noded -> Element Mass Enter value for MASS: 0.005 Click Store Click Exit Pick the two nodes where the symmetry edges meet the top edge Click Done on the Pick panel 12. Create the initial velocity on the top nodes: LBCs -> LBC -> Nodal BC-> Initial Velocity Enter value for VY: -5646 Click on Define App Region Pick all the nodes on the top edge Click Create 13. Create an auto single surface contact: LBCs -> Contact-> Automatic -> Auto Single Surface Click OK on the Auto Single Surface form 14. Select the dyna control options: Parameters -> Control -> [A to C] -> CONTROL ADAPTIVE Enter value for ADPFREQ: 1.E-4 Enter value for ADPTOL: 5 Select value for ADPOPT: 2 Enter value for MAXLVL: 2 Enter value for ADPSIZE: 0 Click OK Control -> [N to Z] -> CONTROL TERMINATION Enter value for ENDTIME: 3.E-3 Click OK Control -> [D to H] -> CONTROL ENERGY Select value for HGEN: 2 Select value for RWEN: 2 Select value for SLNTEN: 2 Select value for RYLEN: 1 Example - Crushing of a Thin Square Tube 331 Crushing of a Thin Square Tube Click OK Control -> [N to Z] -> CONTROL OUTPUT Select value for NPOPT: 1 Select value for NEECHO: 3 Click OK Control -> Title ->TITLE Enter value for Title: Crushing of a thin square tube Click OK 15. Select the dyna database options: Database -> OPC -> DATABASE BINARY option Enter valuEnter value for DT_D3PLOT: 1.E-4 Check in the IOPT select box, and set its value to 1 Click OK Database -> OPC -> DATABASE option Enter value for DT_GLSTAT: 2.E-5 Enter value for DT_MATSUM: 2.E-5 Click OK 16. Save the SimXpert database: File -> Save As Enter name for the file: square_tube_crush Click Save 17. Run the Simulation: Rght-click on Simulations Enter name for Fle name: square_tube_crush Click Save 18. Exit from SimXpert: File -> Exit 19. Post-process the Results in ls-prepost 332 Crushing of a Thin Square Tube Figure 3 Von Mises Stress at Time = 0.003