Modelling size, load and velocity effect on friction at micro/nanoscale

A model for size-, load-, and velocity-dependence of friction at micro/nanoscale is proposed. The friction force is equal to the real area of contact, depending upon the normal load, apparent size of contact (due to the surface self-affinity), and the sliding velocity (state-and-rate friction law), multiplied by the interfacial shear strength, depending upon the average size of individual asperity contacts a, while a, in turn, depends on the real area of contact (due to surface topography). The model accounts for effects of size, load and sliding velocity on friction and considers them in combination.