Effect of the braking parameter on disc brake squeal of a railway vehicle

In order to study the generation mechanism of railway disc brake squeal and its influencing factors, a field test and a finite element analysis of disc brake squeal are carried out in the present paper. In the field test, the disc brake squeal of a railway brake unit for several different brake conditions is measured, the occurrence law of railway disc brake squeal is obtained. Test results show that the disc brake squeal has a coherent relationship with the brake pressure and the initial braking speed. The occurrence propensity of brake squeal depends on the variation of braking air pressure against time, especially the stepwise increase of brake pressure is the main cause of brake squeal. At the same time, the initial braking speed also has an effect on the occurrence of brake squeal. A full-size prediction model of brake squeal is established, which included disc, pad, bracket and two levers. The transient dynamic analysis method is used to study friction self-excited vibration characteristics of disc brake systems. The field test and finite element analysis show the disc brake finite element prediction model can correctly predict the frequency of brake noise. Finite element results show that brake pressure is the most critical factor causing brake noise. The increase of braking pressure will directly lead to the disc brake system to become more unstable. At the same time, the step growth of brake pressure also greatly increases the possibility of brake squeal. A large initial braking speed will intensify the friction vibration, and increase the frictional contact pressure.