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

A dragging friction experiment is conducted on a scaled brake dynamometer to simulate the long-ramp braking conditions of a high-speed train. A heavy thermal load is generated due to the long-term friction process, resulting in a high interfacial temperature of more than 480 °C. Friction heat is concentrated in the sliding region of the disc surface, where a significant temperature gradient is formed. The eccentric wear phenomenon is identified in the radial direction of the block surface. This differs from that under ordinary braking conditions, which produce relatively low temperatures; under ordinary parking braking conditions, for example, eccentric wear is found in the friction direction. Moreover, friction-induced vibration (FIV) is closely correlated with the interfacial temperature, and the vibration amplitude increases with increasing temperature, whereas the main frequency of FIV decreases as the temperature increases. For further exploration, a novel fully coupled thermo-mechanical–wear–FIV numerical method is proposed to simulate the temperature, wear, and FIV evolution of the brake process. This indicates that the numerical model can reproduce the tribological behavior of the brake system well, 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 brake systems in engineering.