An Investigation of In-Plane Vibration Modes in Disc Brake Squeal Noise

Abstract

Brake squeal noise has been an ongoing concern with automotive brake systems since their inception. Although they does not usually directly affect the mechanical performance of the brake, brake noise concerns can impact significantly on customer satisfaction levels and warranty costs. Complexity of brake squeal is attributed to the fact of that the squeal is a system phenomena and is very sensitive to factors including corner component design, component interaction, operating condition, environmental condition, and usage history. Of the various countermeasures used to address squeal noise, noise shims have proven to be very effective in addressing medium to high frequency squeal related to rotor bending vibration. However, for squeal noise at low frequency and squeal related to rotor in-plane vibration, noise shims are less effective. Recently, there is more and more evidence showing that many field claims of brake squeal noises are related to the brake rotor's in-plane vibration modes. Some published results addressed these concerns by designing a rotor with a good modal separation between in-plane and out of plane modes. However, our recent experience shows that this is not necessarily the case. In this paper, a study identifying the basic mechanism of squeal noise related to rotor in-plane vibration and controlling this type of squeal noise by optimizing rotor design is presented. A brake system with a squeal concern at high frequency was investigated by using large scale finite element models to predict the stability of the brake rotor modes. The results of the stability analysis showed that this squeal noise was attributed to rotor in-plane vibration. A design study was then carried out to investigate the effect of various aspects of the rotor designs on the in-plane squeal noise. Alternative designs were then proposed and investigated analytically before prototypes were manufactured and tested. The noise testing results of the proposed designs were found to be in excellent agreement with the analytical predictions.