Thermal and holographic investigations of a noisy commercial disc brake

Fieldhouse, John D., Beveridge, Carl and Talbot, Chris J. (2002) Thermal and holographic investigations of a noisy commercial disc brake. In: FISITA 2002 World Automotive Congress, 2nd-7th June 2002, Helsinki.

Abstract

The paper discusses a fundamental investigation of a noisy commercial spline driven disc brake using thermal and holographic techniques. A thermal camera is used to observe heat distribution within the sliding fist type brake system during a heavy braking situation. It is seen that the disc appears to exhibit localised hot areas and the pad is seen to vary in temperature along its length, it being hotter at the leading edge. Observations of the pad face after heavy braking gives some indication of the pressure distribution across its face during this operation. Interrogation of one image is able to indicate temperature variation across the hub region, even the splines being identified within the temperature profile.

A friction material with an artificially high coefficient of friction was used to promote noise. The whole body visual technique of holographic interferometry is used to investigate the modes of vibration of the principal component parts, mirrors being used to allow visual access to otherwise hidden areas. Holograms of the main vibrating components are presented and discussed. The images indicate the vibrational characteristics of the commercial brake are similar to those of a car brake and that positive cross-correlation of information may be a possibility. A fundamental analysis of the pad/disc interface geometry, as used on car brakes, is used to predict the probable instability frequency, this being the frequency generated during the tests

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