Brake Squeal Rig and LACT Vehicle Test Correlation Improvements - Focus on Thermal Conditionings

Today's newer friction materials and brake systems are able to operate under extreme conditions that are not normally evaluated with the standard squeal rig procedures. This could cause some discrepancy between the squeal rig test results and the vehicle test results like Los Angeles City Traffic Test (LACT). In some cases the noise behavior of brake systems could change dramatically and take us by surprise with new squeal frequencies being uncovered or get flagged due to high occurrences. This discrepancy could also be a major handicap with respect to developing a noise fix in the lab if the squeal cannot be reproduced. In this paper, we evaluated some case studies where some extreme conditionings especially related to thermal inputs drastically changed the squeal behavior of the brake system. Comparison between the squeal rig tests and vehicle tests will be done to analyze the root cause of the discrepancies observed and help improve brake noise rig test procedures in future to better correlate with the vehicle tests. Finally, the future improvements on noise rig testing procedure will be discussed.