Novel approaches to assessing brake squeal propensity: Comparative evaluation of two index formulations

The persistence of brake squeal as a significant NVH issue within automotive brake systems necessitates the development of robust methods for assessing squeal propensity. This study introduces two novel squeal index formulations for assessment purposes and evaluates their performance against the formulation defined by the SAE J2521 standard. Experimental data essential for formulating the squeal index are collected on a controlled mass-sliding belt experiment. Experiments are performed at three different spring stiffness levels, and squeal index formulations are derived based on time and frequency domain data. The first formulation places particular emphasis on the time domain, explicitly considering the duration of individual squeal events. Conversely, the second formulation is based on the frequency response characteristics of the system, which considers the number of super-harmonic peaks in frequency spectra. To evaluate the performance and discriminatory capabilities of the newly developed squeal index formulations, extensive comparisons are made against the Squeal Index based on the test procedure described in SAE J2521. In conclusion, through meticulous analysis and interpretation of the experimental results, it is discerned that the squeal index formulation defined by time domain exhibits superior efficacy in discerning the nuanced effects of varying design parameters on the occurrence of squeal-like behavior.