Dither effect on drum brake squeal

This paper describes the dither control system used for suppressing drum brake squeal. The dither force is generated by a piezoceramic actuator installed on the back plate of a drum brake system and successfully quenches the drum brake squeal to background noise level above the critical dither actuation level. The dither is represented as a forcing function in sine waveform in a bi-axial two degrees of freedom mathematical model of drum brake squeal. The model parameters are based on the complex eigenvalue obtained from the mobility measurement and verified with the measured frequency response function. The numerical results show that dither control is more efficient at low sliding speed where lower dither force is needed to quench the brake squeal. Both measured and simulated results show that dither tends to excite the sidebands of the squeal peak with equal frequency spacing at both sides, and these sidebands shift closer to the squeal peak with increase in the dither actuation force.