Investigation of the effect of vertical dynamics on friction induced torsional vibration and rail corrugation

It was found that rail corrugation mainly occurs on the inner rails of curved tracks, and this phenomenon can be explained with the theoretical model of friction induced torsional vibration of wheelsets under the assumption that outer wheel tends to roll steadily while inner wheel tends to slide and trigger friction induced torsional vibration. This assumption, however, has not been verified yet. In this research, a wheel/rail model on a curved track including the nonlinear friction-creepage characteristics is developed. Instantaneous analysis results show that the torsional angular velocity of wheelset varies periodically as the wheelset negotiates curved tracks. The results of modal analysis further indicate that friction induced torsional vibration is generated on inner wheel and that the assumption is reasonable. On the other hand, a test rig can introduce longitudinal creepage is developed. The measurement results show the existence of longitudinal creepage results in corrugations, indicating that friction induced torsional vibration could cause rail corrugation. Furthermore, the simultaneous measurements of torsional angular velocity and vertical force can disclose the correlation between vertical dynamics and friction induced torsional vibration, indicating that vertical dynamics can affect friction induced torsional vibration that may result in rail corrugation.