Computer Aided Analysis Of Rigid And Flexible Mechanical Systems

This book contains the edited version of the lectures presented at the NATO ADVANCED STUDY INSTITUTE on "COMPUTER AIDED ANALYSIS OF RIGID AND FLEXIBLE MECHANICAL SYSTEMS". held in Troia. Portugal. from the 27 June to 9 July. 1993. and organized by the Instituto de Engenharia Mecanica. Instituto Superior Tecnico. This ASI addressed the state-of-art in the field of multibody dynamics. which is now a well developed subject with a great variety of formalisms. methods and principles. Ninety five participants. from twenty countries. representing academia. industry. government and research institutions attended this Institute. This contributed greatly to the success of the Institute since it encouraged the interchange of experiences between leading scientists and young scholars and promoted discussions that helped to generate new ideas and to defme directions of research and future developments. The full program of the Institute included also contributed presentations made by participants where different topics have been explored. Such topics include: formulations and numerical aspects in rigid and flexible mechanical systems; object-oriented paradigms; optimal design and synthesis; robotics; kinematics; path planning; control; impact dynamics; and several application oriented developments in weapon systems. vehicles and crash worthiness. These papers have been revised and will be published by Kluwer in a special issue of the Journal of Nonlinear Dynamics and in a forthcoming companion book. This book brings together. in a tutorial and review manner. a comprehensive summary of current work and is therefore suitable for a wide range of interests.

This volume contains the edited version of selected papers presented at the Nato Advanced Study Institute on "Computer Aided Analysis of Rigid and Flexible Mechanical Systems", held in Portugal, from the 27 June to 9 July, 1994. The present volume can be viewed as a natural extension of the material addressed in the Institute which was published by KLUWER in the NATO ASI Series, Vol. 268, in 1994. The requirements for accurate and efficient analysis tools for design of large and lightweight mechanical systems has driven a strong interest in the challenging problem of multibody dynamics. The development of new analysis and design formulations for multi body systems has been more recently motivated with the need to include general features such as: real-time simulation capabilities, active control of machine flexibilities and advanced numerical methods related to time integration of the dynamic systems equations. In addition to the presentation of some basic formulations and methodologies in dynamics of multibody systems, including computational aspects, major applications of developments to date are presented herein. The scope of applications is extended to vehicle dynamics, aerospace technology, robotics, mechanisms design, intermittent motion and crashworthiness analysis. Several of these applications are explored by many contributors with a constant objective to pace development and improve the dynamic performance of mechanical systems avoiding different mechanical limitations and difficult functional requirements, such as, for example, accurate positioning of manipulators.

The chapters of this book summarize the lectures delivered du ring the NATO Advanced Study Institute (ASI) on Computational Methods in Mechanisms, that took place in the Sts. Constantin and Elena Resort, near Varna, on the Bulgarian Coast of the Black Sea, June 16-28, 1997. The purpose of the ASI was to bring together leading researchers in the area of mechanical systems at large, with special emphasis in the computational issues around their analysis, synthesis, and optimization, during two weeks of lectures and discussion. A total of 89 participants from 23 count ries played an active role during the lectures and sessions of contributed papers. Many of the latter are being currently reviewed for publication in specialized journals. The subject of the book is mechanical systems, Le. , systems composed of rigid and flexible bodies, coupled by mechanical means so as to constrain their various bodies in a goal-oriented manner, usually driven under computer con trol. Applications of the discipline are thus of the most varied nature, ranging from transportation systems to biomedical devices. U nder normal operation conditions, the constitutive bodies of a mechanical system can be consid ered to be rigid, the rigidity property then easing dramatically the analysis of the kinematics and dynamics of the system at hand. Examples of these systems are the suspension of a terrestrial vehicle negotiating a curve at speeds within the allowed or recommended limits and the links of multiaxis industrial robots performing conventional pick-and-place operations.

This enhanced fourth edition of Dynamics of Multibody Systems includes an additional chapter that provides explanations of some of the fundamental issues addressed in the book, as well as new detailed derivations of some important problems. Many common mechanisms such as automobiles, space structures, robots and micromachines have mechanical and structural systems that consist of interconnected rigid and deformable components. The dynamics of these large-scale multibody systems are highly nonlinear, presenting complex problems that in most cases can only be solved with computer-based techniques. The book begins with a review of the basic ideas of kinematics and the dynamics of rigid and deformable bodies before moving on to more advanced topics and computer implementation. The book's wealth of examples and practical applications will be useful to graduate students, researchers and practising engineers working on a wide variety of flexible multibody systems.

The International Union of Theoretical and Applied Mechanics (IUTAM) initiated and sponsored an International Symposium on Optimization of Mechanical Systems held in 1995 in Stuttgart, Germany. The Symposium was intended to bring together scientists working in different fields of optimization to exchange ideas and to discuss new trends with special emphasis on multi body systems. A Scientific Committee was appointed by the Bureau of IUTAM with the following members: S. Arimoto (Japan) EL. Chernousko (Russia) M. Geradin (Belgium) E.J. Haug (U.S.A.) C.A.M. Soares (Portugal) N. Olhoff (Denmark) W.O. Schiehlen (Germany, Chairman) K. Schittkowski (Germany) R.S. Sharp (U.K.) W. Stadler (U.S.A.) H.-B. Zhao (China) This committee selected the participants to be invited and the papers to be presented at the Symposium. As a result of this procedure, 90 active scientific participants from 20 countries followed the invitation, and 49 papers were presented in lecture and poster sessions.

A systematic treatment of current crashworthiness practice in the automotive, railroad and aircraft industries. Structural, exterior and interior design, occupant biomechanics, seat and restraint systems are dealt with, taking account of statistical data, current regulations and state-of-the-art design tool capabilities. Occupant kinematics and biomechanics are reviewed, leading to a basic understanding of human tolerance to impact and of the use of anthropometric test dummies and mathematical modelling techniques. Different types of restraining systems are described in terms of impact biomechanics. The material and structural behaviour of vehicle components is discussed in relation to crash testing. A variety of commonly used techniques for simulating occupants and structures are presented, in particular the use of multibody dynamics, finite element methods and simplified macro-elements, in the context of design tools of increasing complexity, which can be used to model both vehicles and occupants. Audience: An excellent reference for researchers, engineers, students and all other professionals involved in crashworthiness work.