Brake Judder Analysis Using Transfer Functions

This paper presents results of experimental judder investigations on different vehicles. Judder excitation via machined discs or distorted drums will be explained with emphasize on controlling both the total variation value as well as order components. Transfer functions that characterize both the brake excitation (e.g. brake torque variation as an output and crum cylindricity variation as input) as well as transfer functions that characterize vehicle sensitivity will be presented. Transfer functions such as shake sensitivity and nibble sensitivity will be explained and case studies will be presented. The case will be made that using transfer functions for judder analysis can be a valuable tool for NVH engineers in the automotive industry.