Abstract
Time-variability and uncertainty are inherent characterizations of automotive brake squeal induced by friction. In this paper, a drum brake squeal experiment was carried out on a test bench to analyze the time-varying and uncertain characteristics of the squeal. A data processing flow chart, as well as a set of evaluation index of squeal uncertainty based on statistical analysis was established. At the same time, the impact of test conditions on the squeal uncertainty was also investigated. It was found that, the frequency and the sound pressure level of squeal shows great time-variability and uncertainty, and strong dependency upon working conditions. The time-variability has mainly been seen in the changes of the squealing frequencies, their time-lasting characters and in the sound pressure level over the time. And, the uncertainty manifests itself in the randomness of squeal frequency and sound pressure level. The probability density distribution of squeal frequencies are approximately normal distribution, and the probability density distribution of the sound pressure levels at each squeal frequency are also close to the normal distributions with a mean of 60dB. The statistical characteristics of squeal at different frequency levels are distinct from each other.
KEYWORDS – Automotive brakes, Frictional squeal, Time-variability, Uncertainty, Statistical analysis