LAUSR

This study focuses mainly on the mechanism of wheelset longitudinal dynamics which has often been neglected. By analysing the process of wheel/rail rolling contact, taking into account of the wheelset longitudinal vibration, a wheel/rail longitudinal friction model combining an elastic spring and a viscous damper coupled with a friction element and incorporating both frequency and amplitude dependence is proposed to capture the characteristics of wheel/rail longitudinal vibration and the differences between small and large creepage. At small creepage, the characteristics of the wheel/rail longitudinal friction model are influenced by the excitation frequency and the amplitude of creepage. This influence is incorporated into a dynamical analysis of a wheel/rail longitudinal friction model coupled with a single-wheelset longitudinal dynamical model. The results show that once the wheelset longitudinal vibration has been stimulated under external excitation at small creepage, the wheelset longitudinal natural frequency will be dominant, with other frequencies making a very small contribution in comparison. This will cause a sudden increase in vibration amplitude, which may lead to wheel/rail nonlinear adhesion–slip vibration at large creepage.