Active Control of Brake Squeal Via “Smart Pads”

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 and new experimental techniques are used for studying the dynamics of these brakes. The present paper is devoted to the modeling and experimental investigation of a floating caliper disk brake, special regard being given to the suppression of squeal using active elements. To actively suppress brake squeal, smart pads were designed and manufactured. These pads contain piezoceramic staple actuators, which can be independently driven at both pads and within the pads. In experiments they were successfully used for the active suppression of squeal via optimal control. As the piezoceramic elements can be used both as actuators as well as sensors, the smart pads are also useful in experimental investigations such as measuring transfer functions. In this manner, design modifications proposed for conventional disk brakes can easily be tested using this method. Active control of squeal using smart pads is presently not envisaged as a technique to suppress squeal in mass produced disk brakes, but rather as a possible tool to be used in industrial laboratories to shorten the time for optimizing new brake designs, with high potential saving benefits. The development and laboratory implementation of the active squeal control goes along with a more profound understanding of brake squeal and a better modeling of the phenomena, ultimately leading to improvements in the design of disk brakes.