CRASHWORTHINESS ANALYSIS AND DESIGN USING RIGID-FLEXIBLE MULTIBODY DYNAMICS WITH APPLICATION TO TRAIN VEHICLES

SUMMARY Di⁄erent formulations based on multibody dynamics are shown to be suitable for the development of a methodology for the impact simulation and crashworthiness design of railway vehicles. The proposed design methodology comprises di⁄erent computer-aided tools of increasing complexity and accuracy which can be used with greater advantage and eƒciency in the di⁄erent design stages of railway stock. In general, the crashworthiness design methods and associated multibody dynamic tools which are presented in this paper require information to be obtained from numerical or experimental crush tests of specific structural components, subassemblies and critical energy absorption devices normally located in car extremities. This hybrid feature lends to the present design process various eƒciency gains as a result of a better understanding of the crash and di⁄erent collapse mechanisms and ease of use. To access the merits of the present methodologies some new designs are discussed and the application of the proposed numerical tools is illustrated for di⁄erent structural configurations of car extremities. A formulation for the sensitivity analysis and optimization of planar constrained mechanical systems is also presented. An example of crashworthiness design of an end underframe model of a railway car is solved to demonstrate the use of the methodology. The interest in railway transportation has significantly increased for economical and environmental reasons. In fact, with the advent of high-speed trains, the railway has become a very promising and attractive means of transportation for mass transit and commuter and longdistance travelling. There is now an increasing awareness of the costs of railway accidents, in terms of human su⁄ering in general and property damage. This situation has encouraged operators, manufacturers and research institutions to join e⁄orts in the development of new design capabilities taking into account impact conditions with the aim to significantly reduce damage costs and human injuries and fatalities. This involves an e⁄ort towards a better understanding of the mechanics of railway collisions including more accurate evaluation of impact loads which, in turn, allows the development of new crashworthy railway car extremities with reduced uncertainty margins and with maximal energy absorption characteristics. During the last twenty-five years, computer-aided analysis of crashworthiness and structural impact has received considerable attention and is now emerging as a powerful methodology