Improvement of Brake Squeal Simulation Reliability by Measurement and Identification of Friction Material Properties

Friction material properties influence brake squeal simulation results decisively. It is well known that friction materials exhibit nonlinear and transversely isotropic characteristics dependent on the type and direction of loading. In order to improve brake squeal prediction reliability, friction material properties identified under squeal loading conditions have to be introduced to the simulation models. Because of this fact, the development of a measurement and identification method for friction material properties in context of brake squeal simulation is in progress. The present paper presents the further developed Dynamic Compression Test Rig (DCTR) and the enhanced evaluation method for the estimation of the normal dynamic component stiffness of friction material specimens under typical squeal conditions. In general, the development of testing procedures implies a set of influence and uncertainty factors, which may influence measurement results decisively. For this reason it is strongly recommended to comprehend and evaluate these influence factors when identifying material parameters for brake squeal simulation by the DCTR measurement technique. In this context the evaluation of several influence factors are introduced. Furthermore a direct comparison of the results obtained with the DCTR and results from other state of the art measurement methods is made, pointing out significant quantitative and qualitative differences of the measurement results and their impact on complex eigenvalue analysis (CEA) results. Finally the new developed design concept for the estimation of normal and shear component stiffness, applying squeal typical combined normal and in-plane loading, is introduced.