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The purpose of this paper is to investigate the squealing mechanism of band brakes in order to develop effective treatments for the reduction or elimination of squeal noise. With increasing rotational drum speed, squeal frequency increases up to a constant frequency. This constant squeal frequency coincides precisely with the frequency of instability obtained by a linear analysis of the motion of a band on an elastic foundation when the frictional force between the lining of the band and the drum is taken into account. Through experiments and analyses, it will be demonstrated that squeals are induced by the coupling between two modes of the band.

The purpose of this paper is to investigate the mechanism of impact noise generation, in order to reduce noise at its source. A fundamental model, the case of a ball striking a clamped circular plate, was studied. In the experiments, the effects of plate thickness and observation distance on sound pressure were observed. In the theoretical analysis, the rotary inertia of the plate, shear deformation, and the air reaction of the radiated sound were considered. The impact force history was assumed to be a triangular pulse, since it was determined by three parameters: the maximum impact force, the impact duration, and the rise time. The time when the maximum sound pressure occurred, the influence of the rise time on the sound pressure level, and the vibrational modes which contributed to the sound were obtained using this approximation.