A transient dynamic study of the self-excited vibration of a railway wheel set-track system induced by saturated creep forces

Two dynamic models of a wheel set-track system on a tight curved track and on a straight track are established, in which the friction coupling between the wheel and rail is taken into account. Both the transient dynamic and complex eigenvalue analyses are performed to study the unstable transient dynamics and stability of the wheel set-track system. It is assumed that in the models creep forces between wheels and rails are saturated, that is, approximately equal to the normal forces multiplied by the dynamic coefficients of friction. The simulation results demonstrate that the saturated creep force can induce self-excited vibration of the wheel set-track system. The normal contact force between the wheel and rail fluctuates at the same frequency as the wheel and rail vibrate when the self-excited vibration occurs. And the fluctuation frequency of the normal contact force falls into the range of 60-500 Hz, which corresponds to the frequency range of rail corrugation. This phenomenon indicates that the self-excited vibration of the wheel set-track system may be a main cause of rail corrugation occurrence. Parameter sensitivity analysis shows that the stiffness and damping of the rail fastener have important influences on the oscillation amplitude of the normal contact force. Bringing the friction coefficient below a certain level and increasing the damping of the rail fastener can suppress rail corrugation.