Analysis and prediction of the disc brake squeal considering pad damping and attached parts

Brake squeal is commonly defined as the high-frequency noise above 1 kHz during brake engagement. The objective of this study was to develop an efficient analytic method of the brake squeal and to investigate the major contributing factors on the occurrence of the disc brake squeal in passenger cars. After assessing important squeal factors based on the new approach, the improved design changes of a disc brake system have been suggested in order to suppress the occurrence of squeal. The new analytical method utilized the detailed contact kinematics to capture the contact between a rotating disc and two brake pads. Because friction is known to play an important role in causing dynamic instability like squeal, the pad liner of a brake shoe is newly considered in the analytic model with contact stiffness and viscous damping. In this way, the variations in frictional forces can be reflected in the contact model which is more realistic. The equations of motion were derived on the basis of the Lagrange’s equation and an assumed mode method. Consequently, the modal information of system components are combined with equations of motion derived from the analytical model. The method is able to examine the dynamic instability of a brake system, that may be the onset of squeal, in the finite element disc brake model subjected to a rotation effect.