Investigation of Disc Brake Squeal via Sound Intensity and Laser Vibrometry 2001-01-1604
This paper presents an experimental investigation of methods for disc brake squeal source localization. The underlying data for the localization methods considered here was obtained through the use of a sound intensity probe and a scanning laser vibrometer. The ability to correctly identify the squeal sources is an essential first step in diagnosing brake squeal. Localization methods based upon the use of sound intensity and laser vibrometry, when used together, are shown to converge successfully upon squeal sources. The sound intensity probe is used to spatially locate regions of airborne squeal noise in the near field of the brake rotor and caliper system mounted on a brake squeal dynamometer. The scanning laser vibrometer is then used to further investigate the vibration behavior of the brake assembly within these suspect regions. In addition to mapping near field acoustic “hot spots” to local regions of high surface normal velocity, additional source identification methods explored in this paper include the use of the coherence between the airborne squeal noise and local surface vibration, the use of a partial-area sound power calculation, and the Null-Search Method.