Effect of the Friction Block Shape of Railway Brakes on the Vibration and Noise under Dry and Wet Conditions

In this study, vibration and noise experiments are conducted under dry and wet conditions using a customized small-scale brake dynamometer and testing three friction blocks with different geometrical shapes. The effect of the block shapes on the generation and characteristics of the vibration and noise is evaluated and analyzed. The results show that the friction blocks with different geometrical shapes exhibit differences under dry and wet conditions. In the dry state, all three block samples exhibit successive vibration. The triangular block exhibits the strongest vibration acceleration and the highest sound pressure level, which resulted from the higher contact stress at the leading edge of the triangular block. In the wet state, no vibration noise occurs for the circular block and intermittent oscillations of the vibration signals are observed for the triangular and hexagonal blocks, and a low-frequency groaning noise is much more likely to occur when the brake interface is wet.