The stability and transient response analysis in time-frequency domain of disc brake

Brake squeal has been one of key issues in brake industry, since this annoying high-pitched noise disturbs both vehicle passengers and environment, and leads to high warranty costs to brake and automotive manufacturers. In this paper, the finite element model of disc-pad system containing a ventilated brake disc and two brake pads is established. Through complex modal analysis, the complex modes and modal damping ratios of the disc-pad system in different cases are obtained. The negative damping ratio shows that the disc-pad system is unstable. Then, the transient dynamic analysis of the disc-pad system is carried out. The displacement of normal vibration of brake disc is studied in the time-frequency domain with STFT. It can be found that the vibration is violent when there is feed-in energy in the friction system, which means the feed-in energy can increase the tendency of brake squeal.