Bench Test and Statistical Analysis of Uncertainty of Disc Brake Squeal

Abstract:

The frictional squeal of brake shows significant uncertainty characteristics. A bench test was carried out on a vibro acoustics test rig of brake to study the uncertainty of the brake squeal. So, a novel squeal confirmation and determination method based on time frequency analysis results, which could show the squeal variations in the domains of time, frequency and amplitude together, was presented. An uncertainty analysis flow chart was also established, in which statistical indexes of squeal frequency and sound pressure level, and probability density evaluation of frequency based on Quantile Quantile Plot（QQ plot）, were given. And a judgment method of frequency doubling was devised based on numerical multiple and occurrence concurrence, as well as the uncertainty statistical analysis method with a consideration of the frequency doubling. All the methods established were applied to the uncertainty analysis of brake squeal. It is found that, both squeal frequency and sound pressure level are dispersed, and each squeal has its own statistical results. The probability density of either squeal frequency approximates to normal distribution, while the frequency decreases as the corresponding sound pressure level increases. There are both the same and different squeal frequencies under drag module and in stop module, whose frequency and sound pressure level statistics are also different.

Key words:brake squeal; bench test; uncertainty; statistical analysis; frequency doubling