Estimation and study of drum brake noise using a comprehensive nonlinear vibroacoustic model

Drum brakes produce significant noise in automobiles during a typical braking event, which affects its passengers. The noise is generated in the drum brakes as a result of non-linear vibrations due to the presence of friction, contact and kinematic nonlinearities. The work aims to quantify this drum brake vibroacoustic noise over the audible frequency range using an integrated framework of non-linear vibration analytical model and a numerical acoustic model. A 4-degree-of-freedom non-linear contact-mechanics-based model is developed to estimate the contact and reaction forces during braking, which in turn are the excitation forces for the acoustic model. Also, a finite element based acoustics model is designed to predict the sound pressure transfer function [p/f(!)] at various significant locations around the drum brake. The overall sound pressure level is calculated by multiplying the predicted forces with the corresponding transfer functions in the frequency domain. The sound pressure level for different source of noise (forces), braking conditions and contact parameters are evaluated. It is observed that the sound pressure level is a strong function of the contact parameters and braking conditions. It is proposed that the current work will lead to better drum brake design and development of effective health monitoring systems.