Abstract
Stick-slip behavior observed from nanoscale asperity frictional experiments are often modeled by the one-degree-of-freedom Tomlinson model, which is however unable to explain the effects of lattice structure and interface defects, or by molecular simulations which suffer temporal limitations in modeling the velocity- and temperature-dependent frictional behavior. A Peierls-type model developed in this work views the atomic frictional process as the initiation and gliding passage of dislocations with diffused cores on the interface. As a consequence of loss-of-ellipticity instability, the occurrence of stick-slip behavior relies on the interaction among interface slip field, contact stress fields, and existing defects. This model determines the spatially inhomogeneous nature of rate-limiting processes in the calculation of activation energy, and explains the coupling effects of contact size and interface incommensurability.
