Limit Cycle Behaviour and Chaotic Motions of Two-Axle Freight Wagons with Friction Damping

Abstract

Simulation results for two-axle freight wagons were found to beextremely sensitive to minor changes of some input parameters. Thereforethe influence of non-linearities in the model – especially frictiondamping – on the running behaviour of the wagon is investigated. After adescription of the vehicle model and the basic running behaviour abrief introduction into differences between linear an non-linear systemsis given. A typical bifurcation diagram for railway vehicle dynamicsis presented. For different wheel-rail geometries limit cycle diagramsare calculated. Furthermore phase diagrams at different speeds areshown. Attractors with a `broad band structure' which indicate chaoticbehaviour can be observed. The chaotic content of the oscillations is,however, restricted to small changes of the amplitude of the limitcycles. The conclusion is therefore that the observed behaviourmentioned above is due to co-existing stable attractors rather than tochaotic behaviour.