Many studies on disc brake squeal show the importance of considering thermo-mechanical macroscopic scale with realistic geometry and material properties, which can influence dynamical response. But in real case, many heterogeneities at different scale co-exists. Friction materials are multi-component materials with various particle sizes occurring. Furthermore, composite material implies surface heterogeneities and tribological considerations. This can be stacked up on non-plane geometry. Indeed, due to manufacturing and mounting conditions, discs surfaces always introduce a bump or a thickness variation. We propose to consider these difficulties on a simplified numerical pad-disc model regarding material heterogeneities (Young modulus and contact stiffness on the pad) and surfaces heterogeneities (pad contact plateaus and disc surface height variation) at different scales. This paper shows a multi-scale approach in which heterogeneities are introduced at the contact scale. Looking for the influence of heterogeneities on mode-coupling linked to squeal-noise, an impact classification on the macroscopic scale is done depending on the kind, the size and the distribution of heterogeneities. This classification shows that the disc bumping has the strongest impact on vibratory behaviour of the system, followed by surface state of the pad. Other heterogeneities influence the system too but to a lesser extent compare to disc dumping and it depends on the distribution.
Bonnay, Kevin; Magnier, Vincent; Brunel, Jean-Francois; Dufrénoy, Philippe; DeSaxcé, Géry; - Laboratoire de Mécanique de Lille (L.M.L.)