ANALYSIS OF DISC BRAKE SQUEAL: PROGRESS AND CHALLENGES

Brake squeal noise has been the subject of intense research efforts owing to concerns of car manufacturers caused by complaints lodged and warranty claim related costs arising from dissatisfied customers. Brake squeal is known to be fugitive, and often not repeatable, even under apparently similar operating conditions. The production of brake squeal is dependent on a large number of interacting parameters, such as the mechanical properties of the brake lining materials, contact conditions, wear, operating pressure and temperature which contribute to its often observed nonrepeatability. In this paper, an overview of the state-of-the-art understanding of brake squeal mechanisms and numerical analysis methods (primarily based on finite element analysis) for the prediction of brake squeal propensity is presented. The question of nonlinearity of brake squeal is raised in terms of analysing the mechanisms and how present solution methods reflect this degree of nonlinearity. This is complemented by a description of current industrial practice in the treatment of brake squeal which is, generally, managed on a case-by-case, trial-and-error basis using expensive equipment and timeconsuming noise dynamometer and/or on-vehicle tests. The gaps between theory and industrial practice and, hence, challenges for brake squeal research are identified. Recommendations for bridging these gaps and improving the usefulness of current numerical methods for practical industrial use are proposed.