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During friction it is well known that the real contact area is much lower to the theoretical one and that it evolves constantly during braking. It influences drastically the system’s performance. Conversely the system behavior modifies the loading conditions and consequently the contact surface area. This interaction between scales is well-known for the problematic of vibrations induced by friction but also for the thermomechanical behavior. Indeed, it is necessary to develop models combining a fine description of the contact interface and a model of the whole brake system. This is the aim of the present work. A multiscale strategy is propose to integrate the microscopic behavior of the interface in a macroscopic numerical model. Semi-analytical resolution is done on patches at the contact scale while FEM solution with contact parameters embedded the solution at the microscale is used. Asperities and plateaus are considered at the contact interface.

An original methodology is described to characterize mechanical properties of braking sintered material from the microstructure. Firstly, a compressive test on cube extracted from the friction pad is performed. This compressive test is instrumented with a camera leading to use the digital image correlation method giving local information. Indeed, it is possible to identify the elastic and residual strains mechanisms and to make connection with the microstructure. All these information are introduced in a finite element analysis to identify the mechanical properties of the components using an optimization algorithm. As regards of the 2D measurements, it is relevant to confirm the tendency with a 3D information. Secondly, an ex-situ compression test in a micro tomography is performed. This test is coupled to digital image correlation and a 3D simulation is performed exhibiting elastic-plastic behavior and confirming results found in the 2D study.

Brake squeal noise has been under investigation by automotive manufacturers for decades due to consistent customer complaints and high warranty costs. Sound in a squealing brake is excited by the contact between pads and the disc. It is well known that the material friction pad consists of several components making it a heterogeneous material. It is also well known that a part of the wear particles agglomerate at the surface leading to non uniform contact properties. The aim of this paper is to investigate the effect of heterogeneities of the friction material on the dynamic behavior of the brake. For this, an analytical model with three degrees of freedom (a translation and a rotation for the pad and a translation for the disc) has been developed including friction at the disc-pad surface contact surface.