Elastic Properties of Friction Materials

Thermo-mechanical properties of friction materials are influencing the comfort and performance behavior of brake systems on a broad base. Therefore, a great effort is being made to identify the influence of specific material properties and their respective effects within the brake system, e.g. influence of YOUNG's modulus on the natural frequency of brake pads.

Since numerical models are becoming more and more powerful and able to explain brake system phenomena, then specific laws describing friction material behavior (and not the behavior of the pad as a component) are required. Up to now no explicit laws of friction material behavior have been developed. Instead, special test procedures are used to measure the characteristic values of brake pads.

Presented within the scope of this report is a review of the published knowledge about friction material properties and associated test procedures. The different results obtained from various test procedures are explained. Also the importance of the usage of transversal isotropic and viscoelastic material parameters for simulation is highlighted. Verification of simulation results has been performed by the evaluation of test data from static and dynamic tests as well as data from natural frequency measurements.