Improvements to a scale-dependent model for contact and friction

In this investigation three effects are included in a recently developed scale-dependent multi-asperity model of elastic contact and friction. First, a Weibull distribution of asperity heights is used, which allows the skew and kurtosis to be varied, but not independently of each other. Second, the effect of non-constant radii of curvature of the asperity summits, with the curvature varying with asperity height, is examined. Finally, the influence of noncontacting asperities on the normal force and hence on contact and friction is included. It is noted that the contact and friction model used (Adams et al 2003 ASME J. Tribol. 125 700–8) includes the effects of adhesion and scale-dependent friction. It is demonstrated that positive/negative skew decreases/increases both the friction coefficient and its dependence on the normal load. The results also indicate that for radii of curvature that increase/decrease with height, the friction coefficient increases/decreases as does its dependence on load.