ANALYSIS OF THE VEHICLE BRAKE JUDDER PROBLEM BY EMPLOYING A SIMPLIFIED SOURCE-PATH-RECEIVER MODEL

摘要

An analytical formulation of the brake judder problem caused by disc thickness variation is described by using a simplified source-path-receiver model. Eigenvalue analysis is first conducted to determine the transfer mechanism from the brake source to the steering-wheel receiver. Calculations show that the peak vibration levels of the steering wheel are seen when the rotational frequency of the tyre coincides with the resonant frequency of the transfer path; in this case, only the first-order disc thickness variation is considered. The effects of two key parameters, associated with the source and the path respectively, are analytically and computationally studied. Analysis suggests that the lower pad stiffness and/or the higher bushing stiffness should effectively reduce the vibration levels. Finally, a new vibration control concept is proposed that modulates the actuation pressure; it is based on an approximate solution for the angular displacement of the disc in the model developed here. Preliminary work indicates that this concept could be very effective in reducing the receiver vibration level without sacrificing the brake performance.