Modelling in-plane and out-of-plane vibrations in disc brake squeal

摘要

The analysis of a series of holograms recorded from a noisy (squealing) disc brake is developed. Consideration of the theory of holographic interferometry shows how detailed information including amplitude and phase of in-plane displacement field on the disc rotor can be obtained. This is in addition to the out-of-plane displacement that is usually obtained in holographic studies of the mode of vibration of brake noise. Animations are produced to show the complexities of the wave motion on the disc surface that produce squeal for a given brake system. It is shown that both radial and angular components of the in-plane displacement are significantly larger than the out-of-plane displacement. The implications of these results are considered for the notoriously difficult task of constructing meaningful mathematical models of brake noise. The analysis suggests that coupled in-plane and out-of-plane motion have to be considered in the development of reliable models.