Rutman_2000

March 17, 2018 | Author: abo029 | Category: Cartesian Coordinate System, Deformation (Mechanics), Bending, Stiffness, Geometry
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(c)2000 American Institute of Aeronautics & Astronautics or Published with Permission of Author(s) and/or Author(s)' Sponsoring Organization.AOO-45051 2000-01-5585 Fastners Modeling for MSC.Nastran Finite Element Analysis Alexander Rutman and Adrian Viisoreanu The Boeing Company John A. Parady, Jr. MSC. Software Corportation 2000 World Aviation Conference October 10-12, 2000 San Diego, CA ' For Advancing Mobility f Land Sea Air and Space^ 1 The Engineering Society AM A A American Institute of Aeronautics and Astronautics 370 L'Enfant Promenade, S.W. Washington, D.C. 20024 INTERNATIONAL SAE International 400 Commonwealth Drive Warrendale, PA 15096-0001 U.S.A. For permission to copy or republish, contact the American Institute of Aeronautics and Astronautics or SAE International. (c)2000 American Institute of Aeronautics & Astronautics or Published with Permission of Author(s) and/or Author(s)' Sponsoring Organization. Published by the American Institute of Aeronautics and Astronautics (AIAA) at 1801 Alexander Bell Drive, Suite 500, Reston, VA 22091 U.S.A., and the Society of Automotive Engineers (SAE) at 400 Commonwealth Drive, Warrendale, PA 15096 U.S.A. Produced in the U.S.A. Non-U.S. purchasers are responsible for payment of any taxes required by their governments. Reproduction of copies beyond that permitted by Sections 107 and 108 of the U.S. Copyright Law without the permission of the copyright owner is unlawful. The appearance of the ISSN code at the bottom of this page indicates SAE's and AlAA's consent that copies of the paper may be made for personal or internal use of specific clients, on condition that the copier pay the per-copy fee through the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923. This consent does not extend to other kinds of copying such as copying for general distribution, advertising or promotional purposes, creating new collective works, or for resale. Permission requests for these kinds of copying should be addressed to AIAA Aeroplus Access, 4th Floor, 85 John Street, New York, NY 10038 or to the SAE Publications Group, 400 Commonwealth Drive, Warrendale, PA 15096. Users should reference the title of this conference when reporting copying to the Copyright Clearance Center. ISSN #0148-7191 Copyright © 2000 by The Boeing Company. Published by American Institute of Aeronautics and Astronautics, Inc. and SAE International with permission. Copyright ©2000 by MSC.Software Corporation. Published by American Institute of Aeronautics and Astronautics Inc. and SAE International with permission. All AIAA papers are abstracted and indexed in International Aerospace Abstracts and Aerospace Database. All SAE papers, standards and selected books are abstracted and indexed in the Global Mobility Database. Copies of this paper may be purchased from: AlAA's document delivery service Aeroplus Dispatch 1722 Gilbreth Road Burlingame, California 94010-1305 Phone: (800) 662-2376 or (415) 259-6011 Fax:(415)259-6047 or from: SAExpress Global Document Service c/o SAE Customer Sales and Satisfaction 400 Commonwealth Drive Warrendale, PA 15096 Phone: (724) 776-4970 Fax: (724)776-0790 SAE routinely stocks printed papers for a period of three years following date of publication. Quantity reprint rates are available. No part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without the prior written permission of the publishers. Positions and opinions advanced in this paper are those of the author(s) and not necessarily those of SAE or AIAA. The author is solely responsible for the content of the paper. A process is available by which discussions will be printed with the paper if it is published in SAE Transactions. As a rule. So. Considering each fastener requires the creation of additional nodes and elements. These models more realistically represent not only structural parts but also their interaction including fastener joints. The proposed procedure is free of those limitations.(c)2000 American Institute of Aeronautics & Astronautics or Published with Permission of Author(s) and/or Author(s)' Sponsoring Organization. the accuracy of the finite element analysis is influenced much by the fastener representation in the model. Published by SAE International and the American Institute of Aeronautics and Astronautics. Software Corporation. It cannot be used for other joint configurations and for joints with larger number of connected plates. Parady.Software Corporation Copyright 2000 by The Boeing Company. The procedure is based on definition of independent components of a fastener joint flexibility. ABSTRACT INTRODUCTION The distribution of loads between the components of a structural assembly depends not only on their dimensions and material properties but also on the stiffness of fasteners connecting the components. the trend for creation of more detailed models has arisen. the distribution of loads between structural parts depends not only on the parts dimensions and mechanical properties of selected materials. Jr. This paper describes an approach designed specifically for joints with connected plates modeled by shell elements located at plates mid planes. MSC.e. Copyright 2000 by MSC. With developing models more closely representing structures but still consisting of plate elements. As a rule. and their assembly to represent a complete plate-fastener system of the joint. these formulae consider the combination of mechanical and geometric properties of a fastener and joined plates. they share the common grid points. or springs. with permission. such as bolts and rivets. The widely used method of fastener joints modeling is the joining of co-linear or co-planar finite elements of connected structural parts with elastic elements representing fasteners.Nastran and provides a user friendly and efficient tool that creates fasteners connecting a selected group of nodes. With increase of computers speed along with the volume of available memory.Patran utility that automates the fasteners modeling was written and is described in the paper. Inc. but also on the stiffness of connecting elements. these parts are connected in large models rigidly. A new MSC. the joined .Nastran Finite Element Analysis Alexander Rutman and Adrian Viisoreanu The Boeing Company John A. The stiffness of these elastic elements. The common practice in aircraft structural analysis is the creation of large finite element models with a coarse mesh with further extraction of separate parts along with applied loads for hand analysis or for preparation of more detailed models. It takes advantage of the CBUSH element formulation in MSC. 2000-01-5585 Fasteners Modeling for MSC. i. it is obvious the manual use of this procedure is practically impossible for large models of aircraft structures that could have thousands of fasteners. The application of this approach is limited by single shear joint of two plates or symmetric double shear joint of three plates. Inc. The proposed modeling technique differs from the traditional approach where all the connected plates are modeled coplanar. The traditional approach is based on calculating a single spring rate for a particular combination of fastener and plate properties. Published by SAE International and the American Institute of Aeronautics and Astronautics. However. is calculated using formulae developed by empirical or semi-empirical methods. with permission. Their application is usually limited to single shear and double shear symmetric joints. analysis of each component. where Ecf . STIFFNESS OF FASTENER JOINT 1 plate 2nd plate ) 3rd plate st Fastener =l A di / 1 ———— —————— j 4th plate I— I 1L Figure 1. translational fastener bearing stiffness.compression modulus of plate / material. the practical use of this method showed some of its disadvantages. Combination of these elements represents the complete work of a fastener joint. which will be discussed later. The fastener translational bearing flexibility at plate / C btf. rotational fastener bearing stiffness. elements are no longer located in the same plane. . In a fastener joint (Figure 1) the following stiffness components are considered: translational plate bearing stiffness. the plates slide relative to each other.Nastran and an example of a model with fasteners. The bearing deformations caused by this relative rotation are assumed distributed linearly along the plate thickness . Combined fastener and plate translational bearing flexibility at plate / Cbtj = Cbtpj + Cbtfj Under load. The approach to 3-dimensional modeling of fastener joints is based on definition of each deformation component contributing to a joint flexibility and modeling them by corresponding finite elements. This paper presents an updated method for the finite element modeling of fastener joint for MSC. The translational bearing flexibility of plate / is: 1 Combined translational bearing stiffness at plate / 1 The relative rotation of the plate and fastener creates a moment in the plate-fastener interaction (Figure 2). Following the aerospace industry common analysis practice.(c)2000 American Institute of Aeronautics & Astronautics or Published with Permission of Author(s) and/or Author(s)1 Sponsoring Organization.Patran utility for fastener joints modeling. The procedure for modeling of fastener joints for detailed finite element models with non-coplanar joined parts was described in the paper presented at the First MSC Conference for Aerospace Users [1]. >=cf p. the single elastic element cannot fully reflect the work of a fastener joint. Fastener joint.compression modulus of fastener material. This causes the translational bearing deformations of joined plates and a fastener. In this case. the friction between joint parts was not taken into account. The method does not consider the effect of fastener pretension and fit. Some relative displacements in the model of a fastener joint were limited to ensure the compatibility of deformations. fastener shear stiffness.thickness of plate /. where ECp. fastener bending stiffness. However. . It also describes a new MSC. rotational plate bearing stiffness. = P l. tp. Rotational bearing stiffness definition.xdF = Ecp<px2dx Moment in the plate-fastener contact caused by the plate deformation Elastic bearing stiffness of a plate and fastener at contact surface. = Stiffness of a dx thick slice of plate / is: =EcPidx The bearing stiffness is modeled by elastic elements.3 The fastener rotational bearing flexibility at plate / C ^' = -^-r Combined fastener and plate rotational bearing flexibility at plate / Figure 2. MODELING OF A FASTENER JOINT Load on dx thick slice of plate / caused by the plate bearing deformation j Modeling of a fastener joint is illustrated here using MSC. <P .angle of relative rotation of the plate and fastener. The shear and bending stiffness of a fastener are represented by a beam element.M~ F .(c)2000 American Institute of Aeronautics & Astronautics or Published with Permission of Author(s) and/or Author(s)' Sponsoring Organization.Nastran. Compatibility of displacements of a fastener and connected plates at the joint. REPRESENTATION OF A FASTENER JOINT =x<pEcpdx Moment of cF force about the plate /center line Idealization of a plate-fastener system includes the following: • • • dM . Bending and shear stiffness of a fastener shank. The presented method creates the plate-fastener system illustrated in Figure 3. . Combined rotational bearing stiffness at plate / S 1 br. C br.coordinate along the plate thickness. = Cbrpj + Cbrfi 8 = X(p where x . A x Pi 72 2 dx The rotational bearing flexibility of plate / r -V Uhn 12 ". but shown offset for clarity. NOTES: • CBAR element • Orientation vector is parallel to Y axis of fastener coordinate system •REAR element • Dependent DOF's are ijk •Arrow points to dependent node •CBUSH element •Stiffness DOF's 2356 •X axis is aligned with fastener axis Nodes Npj and Nfj are coincident. Fastener joint modeling.(c)2000 American Institute of Aeronautics & Astronautics or Published with Permission of Author(s) and/or Author(s)' Sponsoring Organization. The analysis coordinate system of all nodes is the fastener coordinate system. X axis of fastener coordinate system . w Figure 3. However it is difficult to interpret CELAS2 A fastener is modeled by CBAR or CBEAM elements [2] with corresponding PBAR or PBEAM cards for properties definition. All CBAR or CBEAM elements representing the same fastener reference the same PBAR or PBEAM card [2] with following properties: • • MID to reference the fastener material properties. i. The plates mid planes stay parallel to each other under the load. An example of CBAR element and its properties definition for .e.9 The fastener joint model was designed under the following assumptions: • The plates are incompressible in transverse direction. MODELING OF INTERACTION BETWEEN FASTENER AND JOINED PLATES These goals are reached by using REAR elements. COMPATIBILITY OF DISPLACEMENTS IN THE JOINT 32 • Area factors for shear of circular section /C. Fastener cross-sectional area element forces. The bearing stiffness is presented as translational stiffness in direction of axes normal to the head to stay parallel to the first plate mid plane under the load.64 Torsional constant assumed in the example that the fastener axis is parallel to x-axis of corresponding coordinate system. An alternative form of CBAR properties definition is presented in Table 2. a separate set of grid points coincidental with corresponding plate grid points (Figure 3) is created.fastener diameter. Planes under the fastener heads stay parallel to the plate mid planes under the load. This set also includes grid points located on intersection of the fastener axis and outer surfaces of the first and last connected plates. It is also assumed in this example (Figure 3) that the fastener axis is parallel to the x-axis of the corresponding coordinate system. FASTENER MODELING fastener axis and defining the fastener shear plane and rotational stiffness about the same axes. Moments of inertia of the fastener cross section / r = / 2 = .(c)2000 American Institute of Aeronautics & Astronautics or Published with Permission of Author(s) and/or Author(s)' Sponsoring Organization. The bearing stiffness of a fastener and connected plates is defined in Section "Stiffness of fastener joint". It also prevents the fastener movement as a rigid body. An alternative method for the bearing stiffness modeling using CELAS2 elements is shown in Table 4. For correct definition of a fastener shear plane and its axial direction. For the modeling of the bearing stiffness. For the CBAR or CBEAM elements connectivity. but 4 CELAS2 elements are required to replace one CBUSH element. The middle RBAR cards support the first two . An example of the bearing stiffness modeling using the CBUSH and PBUSH cards is given in Table 3. = K2 = 0. The first RBAR card forces the plane under the fastener The interaction between a fastener and plate results in bearing deformation of all parts of the joint on their surfaces of contact. fastener is shown in Table 1. Each pair of coincident grid points. the plate node and corresponding fastener node.375" dia. The CELAS2 card accomplishes both functions. a coordinate system with one of its axis parallel to the fastener axis must be defined in the bulk data. two sets of coincident grid points mentioned above are used. Definition of a fastener using CBEAM and PBEAM cards is similar to that shown in Table 2 for CBAR and PBAR • • with small differences described in Reference [2]. This coordinate system must be used as analysis coordinate system for both sets of grid points. An example of a group of RBAR elements satisfying the above compatibility conditions is given in Table 5. The connectivity card CBUSH must be accompanied by PBUSH card defining the stiffness. is connected by CBUSH element [2] or combination of CELAS2 elements with equal translational stiffness along the axes normal to the fastener axis and equal rotational stiffness about the same axes. It is f where df . 314 315 GA 905 1005 . . 5005 6005 GB 1005 2005 . . .2E3 Table 3.9 Table 1. The last card forces the plane under the other head of the fastener to stay parallel to the last plate mid plane. CBUSH CBUSH EID 210 PID 12 GA 1005 GB 2005 GO/X1 X2 X3 CID 0 PBUSH PBUSH PID 12 "K" K Kl K2 1. . . Example RBAR cards for compatibility of displacements in the joint. . CBAR CBAR PBAR PBAR EID 21 PID 206 Cl PID GA GB 2011 XI 206 MID 2 1011 A . . . 156 56 Table 5.0 12 El X2 0.0 Kl 112 0.6E7 K3 1. . .6E7 5. assume that plates are incompressible.0 NSM Fl F2 11 9.0 J E2 X3 0. 6005 915 CNA 123456 123456 . 123456 123456 CNB CMA CMB 1456 156 . .2E3 Gl 1005 1005 1005 1005 Cl 2 3 5 6 G2 2005 2005 2005 2005 C2 2 3 5 6 Table 4. . . .6E7 1. They also guarantee zero relative rotation of plates keeping them parallel to each other. . . . Example CBUSH and PBUSH cards. REAR REAR REAR . .375 Table 2.0 K2 0. CELAS2 CELAS2 CELAS2 CELAS2 CELAS2 EID 210 211 212 213 K 1.7E-4 D2 C2 0. . . . .6E7 K4 K5 5. . . . . . . . They keep the constant distance between the plate mid planes. assumptions. Example PBARL card. . .2E3 5. .(c)2000 American Institute of Aeronautics & Astronautics or Published with Permission of Author(s) and/or Author(s)' Sponsoring Organization. . . . .9 0. . .e. . REAR REAR EID 310 311 . . . Example CBAR and PBAR cards.2E3 K6 5. . . PEARL PBARL PID MID 2 NSM GROUP TYPE ROD 206 DIM1 . i.11 Dl 1. . Example CELAS2 cards. . . . . . 25". Example of finite element model with fasteners. The inner plate is loaded by a distributed load of 5000 pound/in. The thickness is 0. . The model is constrained at outer plates.2" for inner plate. the combined plates and fastener bearing deformations. The bulk data file is given in Appendix. The results of analysis are in good agreement with the expected behavior of the joint under load.15" for outer plates and 0. The fastener diameter is 0. Outer plates Inner plate 5. The modeled structure consists of three aluminum plates and two titanium fasteners.(c)2000 American Institute of Aeronautics & Astronautics or Published with Permission of Author(s) and/or Author(s)' Sponsoring Organization.00+03 5. MODELING EXAMPLE A symmetric double shear joint was modeled as an example (Figure 4). The displacements at a fastener location consist of the fastener movement as a rigid body. Constraints Figure 5 presents the analysis results.00+03 ^ Distributed Load Fasteners Figure 4. and the fastener bending and shear deformation. (c)2000 American Institute of Aeronautics & Astronautics or Published with Permission of Author(s) and/or Author(s)1 Sponsoring Organization. . Displacements of example finite element model. 135 1235 135 Undeformed model Deformed model Fastener bending and shear deformation Rigid elements (RBAR's) Fastener before deformation Fastener after deformation Inner plate bearing deformation Outer plate bearing deformation Figure 5. This relative rotation results in nonuniform distribution of bearing stress through the plate thickness. In the structure. Comparison of results obtained by two modeling techniques. COMPARISON OF MODELING TECHNIQUES To compare the modeling technique described in this paper with one developed in Reference [1] the finite element model with fine mesh was created (Figure 6).(c)2000 American Institute of Aeronautics & Astronautics or Published with Permission of Author(s) and/or Author(s)' Sponsoring Organization. The fine mesh was employed to show deformation of fasteners and particularly the joined plates. The fastener deformation causes change of angle between fastener and plate or in other words their relative rotation. Deformation of joint modeled using proposed techniques Reactions Inner plate Fastener before deformation Fastener after deformation P/2 Fasteners Applied loads P/2 Plates deform only in their planes Deformation of joint modeled using Reference Ml techniques Figure 6. . the moment is reacted by loads on the plate contact surfaces and does not cause the plates local bending. The plates bending moments in the P/2 P/2 Figure 7. The resultant load transferred through the contact area between the fastener and plate consists of a force in the plate mid plane and out-of-plane moment. plates have clear out-of-plane deformations.Patran utility for modeling of fastener joints is applied to a group of nodes selected by user in the model area where the group of fastener joints must be created. the data input forms (Graphical User Interface) and an example of fastener joint modeling using this utility. The proposed modeling technique takes this phenomenon into account ensuring the plates mid planes stay parallel to each other under load. UTILITY DESCRIPTION Extraction of plate nodes for connection by fastener The MSC. If the Reference [1] technique is employed. the joined plates slide along each other due to combined plates and fastener translational bearing deformation and the fastener bending and shear deformation. Figure 7 illustrates the behavior of a fastener joint modeled using the both discussed techniques. Plates in the joint modeled using the proposed technique have only in-plane deformations. This is reached by use of rigid elements RBAR's connecting the plate nodes at the fastener location and forcing them to keep the same angle of rotation during the deformation. The modeling technique presented in Reference [1] assumes that plates follow locally the fastener deformation. This model is the same example model presented in previous section with the only difference in mesh density.PATRAN UTILITY This section presents the algorithm of the newly developed MSC. Fastener before deformation Fastener after deformation Deformed model Undeformed model Under the load.Patran utility. It means the fastener guides the connected plates and it results in bending of plates and interference between them. Fine mesh finite element model for comparison of modeling techniques. MSC. Outer plate fastener-plate contact are distributed through the model structural parts and causes additional stresses not existing in real structure. The fastener length chosen by user should be bigger than the longest fastener but smaller than the distance from any of subgroup nodes to grid points not belonging to the subgroup to avoid creation of undesirable elements. To take these phenomena into account the thickness and modulus of elasticity for bearing stiffness analysis are calculated as weighted average of plates adjacent to node /\L: II i=1 k=1 where X . The criterion for node subgroups creation: the distance between any two nodes of the subgroup must be smaller than or equal to the fastener length supplied by user. Epi . the thickness of plate elements adjacent to the fastener can be different.average plate modulus at node NP!.thickness of element k adjacent to node The program performs an alignment check before computing the direction of the X-axis. the X-axis of the fastener coordinate system is always directed along the fastener axis.(c)2000 American Institute of Aeronautics & Astronautics or Published with Permission of Author(s) and/or Author(s)' Sponsoring Organization. The direction of X-axis of the fastener coordinate system is defined as weighted average of normals of all elements adjacent to the fastener nodes: n n/ Thickness and material properties of plate elements using a subgroup node for connectivity are extracted from the MSC. . n . Nk . Fasteners with different diameters or material cannot be combined in one group. The procedure assumes that fasteners in considered group have the same diameter and material. This coordinate axis will be addressed as reference axis of the fastener coordinate system. This condition can influence not only the user's definition of fastener length but also the selection of initial group of nodes..number of plates adjacent to node NPI. The program extracts sub-groups of nodes from the entire group. . To reduce the number of coordinate systems in the model. the program either selects one of previously defined coordinate systems or creates a new one. t'k .number of plate nodes NP!. Each sub-group is associated with one fastener.distance between centroid of element k and node A/p. If the user selects the manual option the program requires ID of one of previously defined coordinate systems and ID of coordinate axis parallel to the fastener axis.average plate thickness at node NPI. With the automatic option. Moduli of elasticity for those elements can also differ if the influence of temperature distribution along the structure is considered in the analysis.modulus of element k adjacent to node HI . If the angle between normal of element k adjacent to node / and normal of element 1 adjacent to node 1 is greater than 90°. E'k . R'k . . Plate properties Fastener Coordinate System Two options of the fastener coordinate system definition are available to the user: manual and automatic. the program checks the MSC.length of vector Nk . If connected structural parts include tapered plates. If the automatic option is chosen.distance from node NP! to centroid of element / adjacent to node Npi. R. then direction of normal of element k is reversed for computational purposes.X-axis vector.Patran database for existing coordinate systems that could be used to define the orientation of the current fastener with the following test: NP. 14 k=1 —t where tpl . In this case separate groups of nodes must be selected.Patran database and do not require the user's input. NP!.normal of element /. 10 . NFn.X axis vector of existing coordinate system C/D. it is possible that some plate nodes. as shown in Figure 3.3 Pi -cf S4 = 0 E 14 \ OP . Z0) parallel to the reference axis of the fastener coordinate system. . If a PBAR property card with same data already exists. The orientation vector of the CBAR elements is given by one of axes normal to the reference axis of the fastener coordinate system. NH2(see Figure 3). Each fastener is represented by a group of CBAR elements. For fasteners not located on symmetry planes. Two other axes of the fastener coordinate system must be in plane normal to the fastener axis. Zi .0. a fastener located on the intersection of the two symmetry planes has 77 = 0. Fastener-plate interface CBUSH elements created between plate nodes NPi and their corresponding fastener nodes A/F/ represent fastener-plate interface.. 77 = 0. the program creates the fastener head node NH1 at distance tp1 / 2 from node NF1 and fastener node NH2 at distance tpn from node NFn along the fastener axis. If an existing coordinate system satisfying the above test is found. A/F..*' n Y - ~ n n where X:.coordinates of plate nodes A/P|.5 for the fasteners located on the symmetry plane. the program uses it to define the axis of the current fastener.5 is used. program stops and the corresponding message is displayed. a . 77 = 0. X j X X . Y. Y0. +£ i] cf 11 . The program creates CBAR elements between nodes NH1. Alignment of plate nodes When different structural parts are modeled separately and sometimes by different modelers. the program defines the fastener axis as passing through point (X0. Calculation of CBAR elements section properties is described in Section "Modeling of a fastener joint".vector product of X} and X . An example of expressions for the CBUSH stiffness coefficients when the fastener axis is parallel to X-axis of the fastener coordinate system: S1 =0 S2 = S3 = -op. Creation of fastener nodes The new fastener nodes NFI are created as duplicates of corresponding plate nodes NPi. and torsional constant of fasteners located on symmetry planes are multiplied by coefficient 77. the program associates the current CBAR to the existing property. In addition to these nodes. If the deviation of plate nodes exceeds the established tolerance.. Coordinates of the new coordinate system origin are II The symmetry coefficient 77 is used to scale the properties of fasteners located on symmetry planes. The analysis coordinate system of all fastener nodes is the fastener coordinate system. Modeling of fasteners I.25. when only quarter of the structure is modeled.tolerance angle. moments of inertia. Otherwise a new PBAR record is created. Otherwise a new coordinate system is created and committed to the database. .. Model symmetry <sina X where X. default value 1°. rj = 1. are not collinear. For structures with two symmetry planes. Area. If the maximum deviation of those nodes normally to the fastener direction is smaller than the tolerance established by user. which should be connected by a single fastener. . If the structure has one symmetry plane and only half of the structure is modeled. For other fasteners located on symmetry planes..(c)2000 American Institute of Aeronautics & Astronautics or Published with Permission of Author(s) and/or Author(s)' Sponsoring Organization. Patran database. This coordinate plane is indicated by perpendicular to its coordinate axis. the user is not required to supply any additional information. On the symmetry coefficient panel the user has three choices: • 1. the user must identify the coordinate system with one of coordinate planes coplanar with the symmetry plane. then the current CBUSH element is associated with the existing property. If the manual 12 .CBUSH stiffness coefficients (Reference [2]) The program then checks the MSC. • • If the fasteners are on a symmetry plane (Figure 9). the degrees of freedom already constrained by symmetry are eliminated from the dependant set of the RBAR elements. The fasteners will be created only between nodes located not further from each other than the established by user maximum fastener length.for fasteners not located on symmetry planes (Figure 8).Patran utility.25 . MSC. The fastener diameter and material are self-explanatory. The fastener material listbox (Figure 8) contains all the materials currently defined in the MSC.PATRAN INPUT PANEL method has been chosen. 0. When the automatic option was selected.(c)2000 American Institute of Aeronautics & Astronautics or Published with Permission of Author(s) and/or Author(s)' Sponsoring Organization. When the fastener axis is on the intersection of two symmetry planes (Figure 10). Figure 8 shows the input form for the MSC. as it is usually done in majority of input forms. In this case.for fasteners belonging to one plane of symmetry (Figure 9). Otherwise a new PBUSH record is created. Two other axes are in symmetry planes. the user must to identify the coordinate system with one axis collinear wit intersection line. 0. the program either selects an existing coordinate system according to established criterion or creates a new one.for fasteners located on the intersection of symmetry planes (Figure 10).Patran database for existence of a property card PBUSH with the same data. Compatibility of displacements Compatibility of displacements in the fastener joint is enforced by REAR elements.5 . The starting ID of the new nodes and elements can be selected. The user has to identify the region where fasteners will be created by giving the program the list of plate nodes. Where S1-6 . If the fastener is on a symmetry plane. The RBAR elements are created as shown in Figure 3.0 . When the fastener is on intersection of two symmetry planes identification of coordinate system is not required and the fastener axis selection panel is dimmed (Figure 10). It is not necessarily the program will use all this nodes for connection by fasteners. If such PBUSH record is found. The user has two options for the fastener coordinate system definition: manual and automatic. the user is required not only identify the existing coordinate system as a fastener coordinate system but also to tell the program which axis of the system is parallel to the fastener axis. The fastener material must be created before this utility is executed. 25 Select Sjfm.— length MatertaJ Fastener axis manually selected Fastener Axis Method . Node alignment tolerance Symmetry panel Fastener diameter Node Alignment Toterance (Deg. Help Starting Node to .25 j Select Moct«s 11 Mode 2:10:41 Selected plate nodes „ Auto Execute ! Select Nodes Node2:10:4l Figure 8..O Symmetry Coefficient ' '• -. 13 .Patran utility panel when fasteners are on symmetry plane. Wane Mormal : .5 I J0.) \ PS.J1108 ID of first new fastener node -*\~~~~~~~ element Starting £)e»n to jiSO pos Starting Bern ID . MSC.(c)2000 American Institute of Aeronautics & Astronautics or Published with Permission of Author(s) and/or Author(s)' Sponsoring Organization.Patran utility input panel when fasteners are not on symmetry plane.i Automatic Select fastener Axis Coord 3.)] SiS——————— Symmetry Coefficient I Jl-0 I » 0. MSC. Apply Cancel Figure 9.-.__ ID of first new fastener Node Alignment Tolerance (Deg.Coord 0.2? Coordinate axis normal to symmetry plane Fastener not to exceed length Fastener Information Fastener material 'CMS! Diam«ter i^^. EXAMPLE OF MSC. Fastener Axis M<ftho<J S«?tecf Fastener Axis The fastener axis is X-axis of local coordinate system 1..1 -v™ « /"™y<««««^ Coordinate axis parallel with the intersection of the two symmetry planes Fastener Information Diameter Length Aluminum Place Figure 11.2S I Select Fastener Axis jCoordO.* Auto Execute j select Nodes II Node 2:10:41 Apply Cancel Figure 10.5 . Starting Node ID |:10S Starting Bern ID Figure 11 shows a fragment of example model consisting of three plates made from different materials. The shown plate nodes were selected for connection by a fastener. 14 . Degrees of freedom of CBUSH and REAR elements refer to the same local coordinate system 1. Node Alignment Tolerance (DegJ Symmetry coefficient J-1. Example model before fastener creation. MSC.. I 0. .Patran utility panel when fasteners are on intersection of two symmetry planes.0 ' \ J0. Figure 12 shows the fastener created between the three selected nodes. Example model with created fastener. Figure 12.PATRAN UTILITY APPLICATION Show Description..(c)2000 American Institute of Aeronautics & Astronautics or Published with Permission of Author(s) and/or Author(s)1 Sponsoring Organization. O. P. CA 1998 2. The MacNeal-Schwendler Corporation. Rutman.D. Los Angeles.com adrian. MS K89-04 Wichita.Software Corporation 1000 Main Street #190 Grapevine. 1997 MSC.5 Quick Reference Guide. MS 9U-RF Seattle.O. Ph. CONTACT Alexander Rutman. KS 67277 Adrian Viisoreanu. D. Jr. Kogan. A. Parady. B.rutman @ boeing.E Sr.com 15 .Nastran Version 70.parady@mscsoftware. J. CA. Box 3707.viisoreanu@boeing. Principal Engineer The Boeing Company P. Los Angeles. WA 98124-2207 alexander.(c)2000 American Institute of Aeronautics & Astronautics or Published with Permission of Author(s) and/or Author(s)' Sponsoring Organization. Proceedings of The First MSC Conference for Aerospace Users. REFERENCES 1. Application Engineer MSC.com John A. Multi-Spring Representation of Fasteners for MSC/NASTRAN Modeling. Principal Engineer The Boeing Company P. Box 7730. Ph. TX 76051 Phone:817-481-4812 john.. 15 1 37 39 43 1 39 43 47 38 42 38 42 46 CQUAD4 CQUAD4 CQUAD4 CQUAD4 CQUAD4 CQUAD4 CQUAD4 CQUAD4 CQUAD4 $ 10 11 12 13 14 15 16 17 18 2 2 2 2 2 2 2 2 2 37 39 43 60 62 66 61 63 67 49 51 55 61 63 67 73 75 79 51 55 59 63 67 71 75 79 83 39 43 47 62 66 70 63 67 71 $ Elements and Element Properties for region : pbar.2 $ 2 72 8 9 1 36 2 2 . YES $ Elements and Element Properties for region : pshell. YES 0 NO -1 10.2 12 14 18 11 15 19 1 11 15 19 25 27 31 15 19 23 27 31 35 1 14 18 22 15 19 23 $ Elements and Element Properties for region : pshell. 2000 at $ 12:37:02. $ ASSIGN OUTPDT2 = 'dsh_new_course. UNIT = 12 $ $ Linear Static Analysis.NOCOMPS. REAL) =ALL STRESS (SORT1.4 16 .-! PARAM PRTMAXIM $ PSHELL $ CQUAD4 CQUAD4 CQUAD4 CQUAD4 CQUAD4 CQUAD4 $ PSHELL $ CQUAD4 CQUAD4 CQUAD4 -1 3. APPENDIX. REAL) =ALL SPCFORCES (SORT1. 1.op2'. REAL) =ALL OLOAD (SORT1.5 ) on May 26. BILIN) =ALL $ $ BEGIN BULK $ $ PARAM POST PARAM PATVER PARAM AUTOSPC PARAM INREL PARAM ALTRED PARAM COUPMASS PARAM K6ROT PARAM WTMASS PARAM. VONMISES.1 $ 1 1 2 3 4 5 6 1 1 1 1 1 1 1 . BULK DATA FILE FOR EXAMPLE MODEL $ NASTRAN input file created by the MSC MSC/NASTRAN input file $ translator ( MSC/PATRAN Version 8. BILIN) =ALL FORCE (SORT1.(c)2000 American Institute of Aeronautics & Astronautics or Published with Permission of Author(s) and/or Author(s)' Sponsoring Organization. REAL. REAL. Database $ SOL 101 TIME 600 CEND $ SEALL = ALL SUPER = ALL TITLE = MSC/NASTRAN job created on 17-Feb-OO at 17:37:42 ECHO = NONE MAXLINES = 999999999 $ SUBCASE 1 $ Subcase name : Tension SUBTITLE=Tension SPC = 2 LOAD = 2 DISPLACEMENT (SORT1. 0. 0. 1. 0. 3. 0.175 . -1. 1. 1. 0.175 . -1.5 0. 1. 0. 1.175 . 0. 0. 1.175 -.5 0. 0. -1. 1. 0. $ Referenced Material Records $ $ Material Record : aluminum $ Description of Material : Date: 03-Feb-OO $ MAT1 1 1. 4.5 3.. 0. .5 1. 1.. 3.5 1.175 -. 23 35 1.5 3. 0. 3.175 -. 0.5 3. 22 23 1.175 .5 1. 1.175 . 0.175 -. 3.05+7 .175 -. A B $ Elements and Element Properties for region $ PBARL + $ CBAR CBAR CBAR CBAR CBAR CBAR CBAR CBAR $ pbar. 1. 0. 0. 0. 0. 0. 1. 0. 0. 0. 0.5 1. 0.175 -. -1. 0.175 .5 4. -1.175 .5 3.5 3.33 $ Time: 15:39:23 $ Material Record : titanium $ Description of Material : Date: 08-Feb-OO $ MAT1 2 1. 1. 0.5 0. 0. 3. -1.175 . 0. 0. 0. -1.175 -.175 0. 1. 0. 1. 3. 0.175 .175 .175 -.175 . 0.5 3.175 . 0.5 1. 1.5 1. 0. 1. 1.175 0. 0. -1. -1.175 .3 $ Time: 17:45:11 $ Nodes of the Entire Model $ GRID GRID GRID GRID GRID GRID GRID GRID GRID GRID GRID GRID GRID GRID GRID GRID GRID GRID GRID GRID GRID GRID GRID GRID GRID GRID GRID GRID GRID GRID GRID GRID GRID GRID GRID GRID GRID GRID GRID GRID 11 12 14 15 18 19 22 23 25 27 31 35 36 37 38 39 42 43 46 47 49 51 55 59 60 61 62 63 66 67 70 71 73 75 79 83 84 85 86 87 1. 1.5 3. 0. -1. 1. 1. 0.6+7 . 0. 0. . 0.175 . 1. -1. 1. $ PBAR $ CBAR + CBAR + $ 4 27 A 28 B 1 4 1 4 1 1.(c)2000 American Institute of Aeronautics & Astronautics or Published with Permission of Author(s) and/or Author(s)' Sponsoring Organization. 3.175 -.5 0.5 3. 3. 1. 0.175 -.5 5 C . -1. 0. 0. 1. 1.5 3. 4. 0. 11 11 1. 0. 1.125 19 20 21 22 23 24 25 26 2 5 5 5 5 5 5 5 5 ROD 84 86 85 87 92 89 96 91 85 87 89 91 84 95 86 99 1. 17 . 0. 1783.25 -. 0. $ Bearing Stiffnesses $ 6 7 31 32 33 34 35 36 K K 7 6 7 7 6 7 1267925.175 -. 0. -5000.25 -.175 . -5000. 1 . 1. 1. 39 15 63 43 19 67 84 85 89 86 87 91 4226. 950943. -5000.5 3.1267925.25 $ Loads for Load Case : Tension $ 2 2 ^ 1. $ Compatibility Conditions $ 41 42 43 44 45 46 92 39 15 63 96 43 39 15 63 95 43 19 123456 123456 123456 123456 123456 123456 123456 123456 3456 345 345 45 3456 345 345 45 REAR 47 REAR 48 $ $ ENDDATA 19 67 67 99 18 .25 . 3 1 $ Displacement Constraints of Load Set : spc_2 $ 1 2 37 $ Displacement Constraints of Load Set : spc_l $ 3 135 36 37 49 $ Displacement Constraints of Load Set : spc_3 $ 4 15 60 61 73 $ Distributed Loads of Load Set : Tension $ 1 1 27 28 FYE FYE FR FR 0. .5 1.5 3 3 0. GRID GRID GRID GRID GRID GRID $ SPCADD $ LOAD $ SPC1 $ SPC1 $ SPC1 $ PLOAD1 PLOAD1 $ PBUSH PBUSH $ CBUSH CBUSH CBUSH $ CBUSH CBUSH CBUSH $ REAR REAR REAR REAR $ REAR REAR 89 91 92 95 96 99 1 . -. 4226. 950943. -5000. 1783. 0. 0.(c)2000 American Institute of Aeronautics & Astronautics or Published with Permission of Author(s) and/or Author(s)' Sponsoring Organization. 0.
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