Dynamic characteristics of disc brake systems of a high-speed train with wheel polygonal wear

The brake system is a key component of a high-speed train, which suffers intense wheel-rail interactions caused by wheel polygonal wear (WPW) in realistic working conditions. To explore the dynamic characteristics of the disc brake systems with WPW, a rigid-flexible coupled vehicle dynamics model is proposed. The developed model systematically takes into account the flexible deformation of brake components and wheelsets, measured WPW and non-linear factors such as wheel-rail interaction, disc-pad friction and non-linear damping characteristics. It allows the dynamic behaviors of the vehicle brake system in service to be accurately and effectively revealed. The model is verified using line test data, and then the dynamic characteristics of disc brake systems with WPW are investigated in details. The results show that for vehicle speed below 80 km/h and depths of WPW below 0.04 mm, the effect of WPW on the vibration of the caliper is slight. However, as vehicle speed and wear depth continue to rise, the vibration of the caliper increases noticeably. Furthermore, the effects of vehicle speed and wear depth on brake disc vibration are more obvious, and increasing vehicle speed and wear depth will steadily deteriorate the vibration of the disc. Besides, the effect of WPW is particularly pronounced on the dynamic behavior of the brake units closer to the wheels. Overall, the influence of wheel polygon cannot be neglected in the study of dynamic characteristics of brake system. At the same time, the proposed model can also be applied in the strength evaluation of brake components and the study of the tribological behaviors within the brake interface.