ABSTRACT
The vehicle is considered as a multi-rigid-body system with 17 degrees of freedom. During the wheel/rail impact when the wheelset lateral displacement is greater than the wheel flange clearance, the vehicle/track coupling model is considered. The rail is modelled as an Euler-Bernoulli beam extended to infinity and discretely supported by sleepers. The lateral and torsional vibration of the rail is taken into account. Two propositions for searching the Hopf bifurcation point of the system are given. The stability is an important dynamic problem for railway vehicle systems. Since the railway vehicles are nonlinear systems, their stability problems are more complicated than linear systems, bifurcations or even chaos of the systems should be studied. It is supposed that collision between wheel and rail occurs when the wheelset lateral displacement is greater than the wheel flange clearance. The chaotic motion is preliminary discovered and the transition to chaos is possibly duo to the quasi-periodic solution.
