制动器摩擦尖叫台架试验与不确定性统计分析

Bench Test and Statistical Analysis of Uncertainty of Disc Brake Squeal

摘要:

制动器的摩擦尖叫具有显著的不确定特征.基于制动声振试验台，开展盘式制动器的多工况制动尖叫试验，考察了尖叫的不确定性.为了进行不确定性分析，提出了基于噪声信号时频分析结果，能够全面反映尖叫的时间、频率和幅值特征的摩擦尖叫提取方法；建立了尖叫不确定性的统计分析流程、尖叫频率和声压级的统计性指标和基于QQ图的概率密度分布检验方法；提出了“频率数值倍数性和发生时刻一致性”的尖叫倍频关系充分必要条件，并建立了考虑倍频关系的尖叫不确定性统计分析方法.利用这些流程和方法分析了制动尖叫的不确定性.研究发现：不同的尖叫频率及其声压级具有不同的均值和标准差统计特性；尖叫频率近似服从正态分布，尖叫声压级越高，发生频次越低；拖滞工况和减速工况下的尖叫频率既有相同频率，也存在不同频率，而且频率和声压级的统计特性也存在一定的差别.

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.