Disk Brake Squeal: Modeling and Active Control

Considerable effort is spent in the design and testing of disk brakes of modern passenger cars. This effort can be reduced if refined mathematical-mechanical models are used for studying the dynamics of these brakes before prototypes are available. The present paper is devoted to the modeling of a floating caliper disk brake, special regard being given to the suppression of squeal. A simplified model for the dynamics of a floating caliper disk brake is presented. The model includes the brake disk, modeled as a flexible rotating plate, caliper and brake pads. In the model all the prominent features of squeal are reproduced, such as e.g. independence of the frequency on the speed, etc. For a moderately wide frequency range (1-5 kHz) the transverse vibration of the disk plays a significant role in squeal. The pad stiffness and damping coefficient are modeled by distributed nonlinear springs and linear dampers, respectively. In a test rig built in Darmstadt, the model is validated. In addition, the set-up also permits active control of some of the brake´s parameters. So far all the experimental results seem to agree very well with our model