Experimental and numerical investigation on the brake interfacial tribology behavior of high-speed train under long-ramp braking conditions

Abstract

A dragging friction experiment is conducted on a scaled brake dynamometer to simulate long-ramp braking conditions of high-speed train. Heavy thermal load is generated due to the long-time friction process, resulting in a high interfacial temperature of more than 480 ℃. The friction heat will be concentrated in the sliding region of the disc surface, where significant temperature gradient is formed. Eccentric wear phenomenon is identified in the radial direction of the block surface. This is different from the cases of ordinary braking conditions which produce relative low temperature, ordinary parking braking, for example, eccentric wear is found in the friction direction. Meanwhile, the friction-induced vibration (FIV) is found to closely correlate with the interfacial temperature, the vibration amplitude increases with the increase of the temperature, while the main frequency of FIV decreases as the temperature gets large. For a further exploration, a novel fully coupled thermomechanical-wear-FIV numerical method is proposed to simulate the temperature, wear and FIV evolution of the brake process. It indicates the numerical model can well reproduce the tribology behavior of the brake system, and the underlying mechanism of the eccentric wear phenomenon is explained. This numerical method can be used as an auxiliary tool to design or optimize the brake system in engineering.