The effect of yaw damper performance degradation on carbody hunting of high-speed trains

The yaw damper is an integral and pivotal component in guaranteeing the carbody hunting stability of high-speed trains (HSTs). However, it is reported that the occurring incidences of low-frequency carbody hunting frequently have been observed in HSTs, a predicament attributed to the degradation of yaw damper performance resulting from the obstruction of the damping valve by foreign particulates. Given these circumstances, the objective of this study is to investigate the impact of yaw damper performance degradation on the intricate phenomenon of carbody hunting motion. A HST dynamic model is developed, incorporating a detailed physical parameter model of the yaw damper, which enables the reproduction of abnormal low-frequency swaying arising from the deterioration in yaw damper performance. The findings of this study demonstrate that the obstruction of the damping valve significantly augments the damping force and dynamic stiffness of the yaw damper, thereby potentially instigating the occurrence of severe low-frequency hunting motion and consequent deterioration in the ride comfort of HSTs.