Stick–slip oscillations: Dynamics of friction and surface roughness

While its classical model is relatively simple, friction actually depends on both the interface properties of interacting surfaces and on the dynamics of the system containing them. At a microscopic level, the true contact area changes as the surfaces move relative to each other. Thus at a macroscopic level, total friction and normal forces are time-dependent phenomena. This paper introduces a more detailed friction model, one that explicitly considers deformation of and adhesion between surface asperities. Using probabilistic surface models for two nominally flat surfaces, the stick–slip model sums adhesive and deformative forces over all asperities. Two features distinguish this approach from more traditional analyses: (i) Roughness distributions of the two interacting surfaces are considered to be independent, (ii) Intersurface contacts occur at both asperity peaks, as in previous models, and on their slopes. Slope contacts, in particular, are important because these oblique interactions produce motion...