ICSV 14 Cairns • Australia 9-12 July , 2007 1 DISC BRAKE SQUEAL : PROGRESS AND CHALLENGES
Brake squeal noise has been an ongoing concern with automotive brake systems since their inception. It is generated by the vibration of an unstable vibration mode of the brake system, usually with the brake rotor acting as a loudspeaker. The squeal noise that is of concern usually falls into a frequency range from 1 to 16 kHz. Although there is often not any degradation in the braking performance, most customers tend to interpret brake squeal noise as indicative of a defective brake. Furthermore, with improvements made in interior noise and comfort levels in vehicles, brake squeal noise has become an increasing source of customer dissatisfaction and is a major contributor to warranty cost. Research into predicting and controlling brake squeal has been conducted since the 1930s and despite significant research efforts in the past 2 decades, brake squeal still remains a challenging problem that is begging for a better understanding of its generation mechanisms and better methodologies for countermeasures other than empirical approaches. Brake squeal is a transient phenomenon and is highly dependent on geometries of brake components, complex interface conditions between components and material properties that are functions of both temperature and pressure. In this paper, recent developments in understanding and controlling brake squeal noise will be reviewed and challenges that remain to be met are discussed.
FRICTION-INDUCED NOISE AND VIBRATION OF DISC BRAKES
Abstract Several noise excitation theories have been proposed in the literature. These theories are found to be unsatisfactory for explaining the noise excitation phenomenon. In this paper, we propose a simple mechanical impact (hammering) model for brake noise generation. This model is independent of friction variation during the period of decreasing sliding speed.
Asbestos Free Brakes and Dry Clutches Reinforced with Kevlar ® Aramid Fiber
Kevlar aramid fiber contributes strength and wear resistance to asbestos free friction materials. The efficient strengthening provided by this fiber makes it possible to select inert fillers on the basis of thermal and wear characteristics with less concern about other physical characteristics of the filler. The resulting asbestos free friction materials can thus outperform the incumbent asbestos materials in critical applications.