13. Original Methodology Using DIC to Characterize Friction Materials Compression Behavior

Friction materials are expected to fulfill several requirements such as adequate friction coefficient, low noise, long life and low wear rate. In order to achieve these properties, friction materials are generally heterogeneous mixtures of fillers incorporated in a more or less continuous matrix. Therefore, a good understanding of the influence of row constituents (i.e., formulation, shape and size) and fabrication process on the mechanical behavior of as-produced heterogeneous materials is necessary to better customize the final products. Nowadays, the customizing process is purely empiric involving costly efforts to characterize the resulting performances. Moreover, the determination of the effect of each component is usually hampered because the behavior of row constituents can evolve during the fabrication process. An in situ compression test using X-ray laboratory tomography is performed in order to study the micro-mechanical behavior of a heterogeneous material. A DIC technique using the reconstructed images provides the displacement fields that are subsequently introduced into a FE simulation which will reproduce the material behavior. This novel methodology allows to identify the micro-constituents mechanical properties of the as-produced material as well as to optimize the numeric material constitutive law.