Optimization of Insulating Material Selection for Effective Squeal Noise Damping

Squeal noise phenomenon in disc brakes is a complicated dynamic challenge which brake manufacturers have confronted for decades. The most prevalent technique apprehended by the brake manufactures is to simulate the braking conditions using a noise dynamometer. This is a well-established, expensive technique which is time-consuming. The objective of this paper is to understand the phenomenon of brake squeal, modal coupling and publish an analytical approach to predict a suitable damping material and thereby to optimize the dynamometer tests and time. As the temperature increases the stiffness of the component decreases thereby the resonance frequency tends to decrease. Compressing the pad increases its stiffness and thereby its resonance frequency. Compressibility being inversely proportional to stiffness has direct influence over the frequency response function of the brake components. Shim suppliers use generic structure to obtain the damping ratio at its resonance at every other degree. The damping ratio is measured only at the resonance of the generic structure which misses out most of the resonance frequency of the brake pad. Three shims were taken for study. The damping ratio measured reflects the system’s damping and not merely of the shim. So, pad shim assembly is ran over critical temperature obtained from the dynamometer results and the damping ratio is captured at critical frequency and plotted for various shims. Pad shim assembly is assembled in the brake dynamometer and the damping ratio is captured at the various pressures and plotted for various shims. From the plotted graphs, optimal shim can be selected. Following this analytical approach will optimize the dynamometer test.