Identification of In-Plane and Out-of-Plane Modal Coupling Mechanism in Brake Squeal by the Empirical Mode Decomposition Method

Experimental verification is an important approach for understanding the mechanisms of disc brake squeal. One mechanism of disc brake squeal, i.e., coupling of in-plane and out-of-plane vibration modes of disc brake rotor, was found by experiments. Despite the vast amount of experimental data available, little effort has been dedicated to exploring what the time series information can reveal in relevance to squeal. In this paper, a new signal processing tool employing the Empirical Mode Decomposition Method (EMD) and its application to the identification of the characteristics of disc brake squeal will be discussed. The EMD was originally developed for ocean wave mechanics [1] and is particularly useful for the type of non-stationary data found in disc brake squeal. EMD is a time series analysis method that extracts a set of basis functions describing the fundamental characteristics of the response of a system. These basis functions are then processed through some transform technique (e.g., Hilbert, Fourier) to give useful frequency and amplitude information. The EMD is applied to process sets of disc brake squeal test data to support the mechanism of disc brake squeal: coupling of in-plane and out-of-plane vibration modes of disc brake rotor. The analysis results illustrate that this is a powerful tool that can be adopted to identify squeal characteristics.