Abstract
KEYWORDS – squeal, friction, correlation, noise
ABSTRACT
Various publications have found different correlations between brake noise and several parameters of the brake system. Of these parameters, friction is accepted to be a necessary contributor to brake noise. Standard NVH test stands calculate the friction coefficient by using several parameters, including the drive’s torque and the brake line pressure. Both of these parameters are measured at a relatively great distance from the friction contact. This measurement technique yields a friction coefficient of the complete brake system. This is an established method for acquiring brake performance information, but the influences of the brake system outside of the boundary layer, for example the brake callipers, significantly hinder investigations of the break squeal phenomena. The calculation of the coefficient of friction on the reduced scale brake dynamometer is independent from such influences, and therefore allows for analyses of these correlations that are more detailed than those achieved using a standard NVH testing device. [1][2]
This paper investigates the direct analysis of raw data from a professional full scale brake dynamometer and high frequency measurements of friction and noise from a reduced scale brake dynamometer. It focuses on the testing of classical hypotheses using both of these devices. The results are compared, considering both the averages of various parameters and their time dependent behaviours.