MechanismsProf.dr.ing. Csaba Antonya
[email protected] DATR Lectures, lab, project Lectures 3h: Friday 13.30 – 16.20, venue: G P 3/H P 13 Laboratory work / Project: Mechanical Engineering Wednesday 11.40- 13.20, venue G P 3 / L II 10 Automotive Engineering Wednesday 13.30- 15.10, venue G P 3 / L II 10 Final grade: Project – (33%) Exam (theory and application) – (66%) MECHANISMS 2 Lecture1 DATR Subjects - Lecture I Introduction. Objectives of this course. History of Mechanism and Machine Science Study of mechanisms: analysis and synthesis Study of mechanisms: structure, kinematics, dynamics Examples MECHANISMS 3 Lecture1 DATR The principal objectives of this course are: To develop your understanding of the fundamentals of kinematics and dynamics of mechanisms. Gain experience using computer software to facilitate the design and analysis of simple and complex mechanisms. Gain practical working knowledge, through design project of some common linkages. MECHANISMS 4 Lecture1 DATR Course Objectives In this course, we will study the motion of mechanisms and machines (kinematics) Mobility Displacement, velocity and acceleration analysis Understand the behavior of existing designs Design of mechanisms Gears Cams MECHANISMS Machine elements are assumed to be rigid 5 Lecture1 DATR Course Outline • Introduction & Formal Definitions • Linkage & Mobilities • Kinematics: Position Analysis • Velocity and Acceleration Analysis • Dynamics • Graphical and Analytical Linkage Synthesis • Gears • Cam Design MECHANISMS 6 Lecture1 DATR Definition of Mechanism A device that transforms motion to some desirable pattern 4 D C 3 B 1 2 A Oscillation motion of the piston translate to rotational motion MECHANISMS of the crank shaft (engine) Rotational motion of the crank shaft translates to Oscillation motion of the piston (pump) 7 Lecture1 DATR Mechanism Analysis and Synthesis Analysis Synthesis Analysis – given a mechanism, perform kinematics and kinetics analysis Establishing the structural, kinematic and dynamic characteristics MECHANISMS Synthesis - design a new mechanism to perform a desired function 8 Lecture1 DATR Literature Talabă, D., Mecanisme articulate. Proiectare asistată de calculator, Ed.Univ. Transilvania, 2004. Alexandru, P. ş.a, Proiectarea funcţională a mecanismelor. Editura Lux Libris. 1999 Antonya, Cs., Simularea grafică a sistemelor de corpuri, Ed.Univ. Transilvania, 2004. Erdman, A. G., Sandor, G. N., Kota, S., Mechanism Design: Analysis and Synthesis, Prentice Hall, 2001. Haug, J.E., Computers Aided Kinematics and Dynamics of Mechanical System, vol. I. Allyn and MECHANISMS Bacon, 1989. Jalon, J.G., Bayo, E., Kinematic and Dynamic Simulation of Multibody Systems – The real time challenge, Springer-Verlag, 1994. 9 Lecture1 DATR Literature Uicker, J.J. Jr., Pennock, G.R. and Shigley J.E. Theory of Machines and Mechanisms, Oxford University Press, 2011 Myska, David H. Machines & Mechanisms: applied kinematic analysis, 2nd Ed., Prentice Hall, 2002 Shabana, A. A., Dynamics of Multibody Systems, Cambridge University Press, 2005 Waldron, Kenneth J. and Kinzel, Gary L., MECHANISMS Kinematics, Dynamics, and Design of Machinery, John Wiley & Sons, Inc, 2004. 10 Lecture1 DATR History of Mechanism and Machine Science Archimedes (ca. 287–212 BC) systematized the design of simple machines and the study of their functions Contributed greatly to the theory of the lever, screw, and pulley, although he did not invent any of these machines. He is the founder of statics MECHANISMS and of hydrostatics, and his machine designs fascinated subsequent writers 11 Lecture1 DATR History of Mechanism and Machine Science Heron of Alexandria (10–85 AD) wrote many books on Mathematics, Geometry and Engineering, which were in use till the medieval times. His most important invention was the Aeolipile, the first steam turbine. Other inventions include automated machines for MECHANISMS temples and theaters, surveying instruments, and military machines and weapons. 12 Lecture1 DATR History of Mechanism and Machine Science Agustin de Betancourt (1758–1824), together with Jose Maria de Lanz, is known as co-author of “Essai sur la composition des machines” (1808), considered to be the first modern treatise on machines and the first book that contains a proposal for the MECHANISMS classification of mechanisms based on criteria of transformation of motion. 13 Lecture1 DATR History of Mechanism and Machine Science Franz Reuleaux (1829-1905) developed a system for classifying kinematic mechanisms and created hundreds of models to embody his basic MECHANISMS machine elements. 14 Lecture1 DATR Kinematics (History) André-Marie Ampère (1775-1836) first used the word Cinematique (French), from the Greek word for motion, describes the study of motion without regard to forces. Later Cinematique anglecized to kinematics and germanized to kinematik. MECHANISMS 15 Lecture1 DATR Kinematics (History) • Robert Willis (1800-1875), Prof. of natural philosophy at the University of Cambridge, England, summarized the task of mechanical synthesis. – Five different ways to obtain relative motions between input and output links: 1. Rolling contact 2. Sliding contact MECHANISMS 3. Linkages 4. Wrapping connectors (belts, chains) 5. Tackle (rope or chain hoists) 16 Lecture1 DATR Kinematics (History) • Reuleaux (1829-1905), published Theoretitiche Kinematik in 1875, translated into English by Alexander Kennedy (1847- 1928) – This text became the foundation of modern kinematics. • Reuleaux defined six basic mechanical components. 1. The link 2. The wheel MECHANISMS 3. The cam 4. The screw 5. The ratchet (intermittent-motion devices) 6. The belt 17 Lecture1 DATR http://www.iftomm.org International Federation for the Promotion of Mechanism and Machine Science Technical Committee for Biomechanical Engineering Technical Committee for Computational Kinematics Technical Committee for Gearing and Transmissions Technical Committee for Linkages and Mechanical Controls Technical Committee for Micromachines Technical Committee for Multi-body Dynamics Technical Committee for Reliability Technical Committee for Robotics and Mechatronics MECHANISMS Technical Committee for Rotordynamics Technical Committee for Sustainable Energy Systems Technical Committee for Transportation Machinery Technical Committee for Tribology Technical Committee for Vibrations 18 Lecture1 MECHANISMS DATR 19 Lecture1 DATR MECHANICS Science dealing with motion DIVISIONS OF MECHANICS Statics – Deals with systems which are not changing with time. Dynamics – Deals with systems which are changing with time. MECHANISMS Lecture1 DATR DIVISIONS OF DYNAMICS KINEMATICS – Deals with Motion and Time THE STUDY OF MOTION WITHOUT REGARD TO FORCES (Kinema – Greek Word – Motion) KINETICS (DYNAMICS) – Deals with Motion, Time and Forces. THE STUDY OF MOTION AND ITS CAUSES (forces, mass, MECHANISMS inertia) Statics Kinematics Dynamics STRUCTURE MECHANISM MACHINE Lecture1 DATR Theory of mechanisms Structure of mechanisms Kinematics of mechanisms MECHANISMS Dynamics of mechanisms 22 Lecture1 DATR Examples MECHANISMS 23 Lecture1 DATR Examples MECHANISMS 24 Lecture1 MECHANISMS DATR 25 Lecture1 MECHANISMS DATR 26 Lecture1 MECHANISMS DATR 27 Lecture1 MECHANISMS DATR 28 Lecture1 MECHANISMS DATR 29 Lecture1 MECHANISMS DATR 30 Lecture1 MECHANISMS DATR 31 Lecture1 DATR Steering mechanisms(Ackerman) MECHANISMS Curs Mecanisme Lecture1 DATR Suspension mechanisms MECHANISMS 33 Lecture1 DATR Windshield Wipers MECHANISMS 34 Lecture1 DATR Engine MECHANISMS 35 Lecture1 MECHANISMS DATR 36 Lecture1 DATR Full car model MECHANISMS 37 Lecture1 DATR Software tools MSC Software: ADAMS (Automatic Dynamic Analysis of Mechanical Systems) MECHANISMS 38 Lecture1 DATR Software tools SIMPACK – INTEC GmbH MECHANISMS 39 Lecture1 DATR Software tools LMS Virtual.Lab Motion MECHANISMS 40 Lecture1 DATR Software tools SimMechanics – MATLAB Mathworks MECHANISMS 41 Lecture1 DATR Software tools alaska Technical University of Chemnitz, Germany AUTOLEV OnLine Dynamics Inc., United States AutoSim Mechanical Simulation Corp., United States AVL EXCITE AVL, Austria CAMeL-View IXtronics GmbH, Germany COMPAMM CEIT, Spain Dynawiz Concurrent Dynamics International Hyperview Motionview Altair Engineering, United States MapleSim Maplesoft, Canada MECANO Samtech, Belgium MBDyn Politecnico di Milano, Italy MBSoft Universite Catholique de Louvain, Belgium NEWEUL University of Stuttgart, Germany RecurDyn Function Bay Inc., Korea RoboAnalyzer Avon Enterprises, India Robotran Universite Catholique de Louvain, Belgium SAM Artas Engineering Software, The Netherlands SD/FAST PTC, United States SimCreator Realtime Technologies Inc., United States MECHANISMS SimMechanics The Mathworks, United States SPACAR University of Twente, The Netherlands TRUE True-World, France Universal Mechanism Bryansk State Technical University, Russia Working Model Knowledge Revolution, United States 42 Lecture1 DATR Definitions - MACHINE Machines are mechanical devices used to accomplish work, to transfer or transform energy to do useful work. An assemblage of parts that transmit forces, motion and energy in a predetermined manner modifies mechanical energy and transmits it in a more useful form MECHANISMS 43 Lecture1 DATR Definitions - MECHAMISN A mechanism is a heart of a machine. It is the mechanical portion of the machine that has the function of transferring motion and forces from a power source to an output. Mechanism is a system of rigid elements (linkages) arranged and connected to transmit motion and/or force in a predetermined fashion. Mechanism consists of linkages and joints. MECHANISMS In contrast: Structure – a single body with no motion / combination of bodies with no relative motion 44 Lecture1 DATR Mechanism and machine parts or links move with respect to one another, because adjacent links are connected by articulations called joints (kinematic pair) A link is assumed to be completely rigid MECHANISMS 45 Lecture1 DATR Classification of Mechanisms Based on the nature of output speed Uniform motion mechanism - Equal Displacement For Equal Time Interval All Gear Drives Non-uniform motion mechanism Unequal Displacement For Equal MECHANISMS Time Interval Examples : Linkage Mechanisms Cam Mechanisms 46 Lecture1 DATR Components of Mechanisms Link / element Kinematic pairs / joints Kinematic chain MECHANISMS 47 Lecture1 DATR Four-Bar Linkage MECHANISMS 48 Lecture1 DATR The Slider-Crank Mechanism Input link, Coupler link, crank connecting rod Output link, piston (slider) MECHANISMS 49 Lecture1 DATR Categories of Mechanisms Function generation mechanisms Output is a specified function of input Motion generation mechanisms The orientation of the object is important, rigid body guidance Path generation mechanisms MECHANISMS A point on a link moves on a specified path 50 Lecture1 DATR Function Generation Mechanisms A function generator is a linkage in which the relative motion between links connected to the ground is of interest. MECHANISMS A four-bar hand actuated wheelchair brake mechanism 51 Lecture1 DATR Function Generation Mechanisms Function Generation Mechanisms MECHANISMS A four-bar drive linkage for a lawn sprinkler 52 Lecture1 DATR Function Generation Mechanisms A four-bar function generation mechanism to lower an attic stairway. MECHANISMS A four-bar function generation mechanism to operate an artificial hand used for gripping. 53 Lecture1 DATR Motion Generation Mechanisms In motion generation, the entire motion of the coupler link is of interest (rigid body guidance). 2 Moving 3 joints Fixed pivot points 4 MECHANISMS Rollerblade brake system 54 Lecture1 DATR Motion Generation Mechanisms MECHANISMS Four-bar automobile hood linkage design 55 Lecture1 DATR Motion Generation Mechanisms Six bar 5 Six bar 3 2 4 5 1 6 4 1 6 3 2 MECHANISMS Lift platform Microwave carrier to assist people on wheelchair 56 Lecture1 DATR Path generation mechanisms In path generation, we are concerned only with the path of a tracer point and not with the motion (rotation) of the coupler link. MECHANISMS Crane – straight line motion 57 Lecture1 DATR Straight line Mechanisms MECHANISMS 58 Lecture1 DATR Straight line Mechanisms MECHANISMS 59 Lecture1