Experimental and computational investigation of disc brake squeal

In this paper, the high frequency noise problem brake squeal observed in automotive disc brake systems is experimentally and computationally investigated. First, modal testing on the components of the brake system (brake disc, brake pad, carrier, caliper) is performed and the corresponding natural frequencies and mode shapes are obtained. Second, computational models of the given components are built and normal mode analyses are executed. A good match between the experimental and computational results is obtained in terms of both frequencies and mode shapes. Third, a computational model of the brake corner assembly is built with the validated component models. Squeal analysis is then performed for different speed and brake pressure levels by using complex eigenvalue analysis. Based on the results, speed and brake pressure values that have high squeal propensity are identified. Finally, a controlled laboratory experiment is designed and built for the squeal investigation. In the setup, only a single brake corner assembly excluding the suspension system is used. During the experiments, acceleration and sound pressure data are recorded. Experiments at different speed and hydraulic brake pressure levels are performed, and several squeals are successfully measured at the same levels as calculated with the computational model. In conclusion, a finite element method for brake squeal is developed and experimentally validated.