Experimental And Computational Research On Disc Brake Squeal

Disc brake squeal remains a difficult problem in vehicle industry. Many scientists have done much research on this problem with experimental, analytical and computational techniques. However, universal theory has not been found yet to explain brake squeal. There are still no systematic and effective measures to predict and eliminate brake squeal.In this paper, disc brake squeal phenomenon is investigated using the combination of experimental and computational techniques. Braking pads of powder metallurgy material are tested on a special brake test rig under different operation conditions independently and repeatedly. Experiment results are analyzed to get the three main system parameters named squeal frequencies, squeal occurrence and friction characteristics at squeaking frequencies. Results suggest that the friction characteristics plays a very important role on brake squeal.A finite element model is built based on the structural model of brake system from the used test rig TM-1. Finite element method of complex eigenvalue analysis in frequency domain and transient dynamic analysis in time domain is used for this study. The results of complex eigenvalue analysis meet well with those of experiments, which indicates that the finite element model used in this study is accurate and the complex eigenvalue analysis is feasible. Comparison between the results of the two methods suggests that, despite its over-predicting and missing frequencies, complex eigenvalue analysis remains an effective approach to be used on the research of disc brake squeal. Transient dynamic analysis, however, is not an effective tool so far.The influence factors of brake squeal are analyzed by complex eigenvalue method using ABAQUS. Friction-induced damping, especially negative damping, greatly affect system squeal performance, which is consistent with experimental results. Combined with results from modal analysis, this paper consider brake squeal as a system dynamic instability phenomenon, which is dominated by disc modal and induced by specific friction characteristics.