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Railway Vehicle Dynamics, Multibody Systems, and Bifurcation Analysis

DLR’s Vehicle System Dynamics group has a long tradition in the computational analysis of railway vehicles’ dynamics. The group’s main focus used to be on the development of software tools for the efficient analysis of general mechanical systems with a special emphasis on the dynamics of ground vehicles like automobiles, railway vehicles and aircraft landing gears. The respective research activities culminated in the general multibody system software Simpack which provides a highly specific and sophisticated wheel– rail module for the dynamic analysis of all types of railway vehicles. The palette starts with tramways or streetcars and goes via freight cars up to high speed passenger cars – single cars as well as complete trains under arbitrary track conditions are analysable. Nowadays, the group’s main research topics have changed a bit. Concerning railway vehicles, these are devoted now to modern concepts of mechatronic wheelsets resulting in independently rotating wheels actively steered by a torque–control algorithm. This concept has already been implemented and verified on a test roller rig. Also, the modelling of elastic wheelsets and rails extends conventional simulation models of wheel–rail systems in order to reach mid–frequency behaviour (up to ca. 500Hz). Besides a more exact analysis of high velocity running behaviour, the possibility of simulating more precisely wear and corrugation of the tracks and polygonisation of the wheels or the noise emission of the wheel–rail interface is one of the final aims of this project. A third major topic is about the crosswind stability of railway vehicles. And, finally, some of the recently developed effective methods of computational bifurcation analysis are enhanced especially with respect to a robust applicability to mechanical systems being of industrial relevance – like railway vehicles. After a short introduction of simulation models of arbitrary railway vehicles basing on a multibody system (MBS) approach and allowing for a virtual design process, the major part of this paper is about the bifurcation analysis of railway vehicles. Here, the application on ‘realistic’, i.e. complex and sophisticated simulation models is a fundamental concern. Virtual design of railway vehicles