Investigation and modelling of rubber stationary friction on rough surfaces

This paper presents novel aspects regarding the physically motivated modelling of rubber stationary sliding friction on rough surfaces.The description of dynamic contact is treated within the framework of a generalized Greenwood-Williamson theory for rigid/soft frictional pairings.Due to the self-affinity of rough surfaces, both hysteresis and adhesion friction components arise from a multi-scale excitation of surface roughness.Beside a complete analytical formulation of contact parameters, the morphology of macrotexture is considered via the introduction of a second scaling range at large length scales which mostly contribute to hysteresis friction.Moreover, adhesion friction is related to the real area of contact combined with the kinetics of interfacial peeling effects.Friction experiments carried out with different rubbers on rough granite and asphalt point out the relevance of hysteresis and adhesion friction concepts on rough surfaces.The two scaling ranges approach significantly improves the description of wet and dry friction behaviour within the range of low sliding velocity.In addition, material and surface effects are predicted and understood on a physical basis.The applicability of such modelling is of high interest for materials developers and road constructors regarding the prediction of wet grip performance of tyres on road tracks.