Experimental investigation of the squeal characteristics in railway disc brakes

In this study, a bespoke small-scale brake dynamometer was developed to simulate the braking conditions of a railway disc brake system. Braking squeal experiments were performed with this brake dynamometer at different braking pressures and disc rotation speeds, and the influence of these braking parameters on the generation and characterization of the squeal noise was evaluated and discussed. The obtained results show that both the braking pressure and the disc rotation speed have a significant influence on the generation and evolution of the squeal noise. Higher rotation speeds are found to result in higher sound pressures and more complicated squeal noise spectra, except at a particular braking pressure, for which the highest sound pressure level is found at various disc rotation speeds. This phenomenon indicates that a combination of specific braking parameters may lead to a strong instability of the brake system and consequently to squeal noise. Additionally, a possible correlation of the squeal noise characteristics with the pressure distribution at the braking interface was found and discussed.