Scale dependence of interface dislocation storage governing the frictional sliding of single asperities

Single-asperity friction tests have found a critical dependence of friction stress on the nanoscale contact size, as successfully explained by the nucleation of interface dislocations as opposed to concurrent sliding of all the interfacial atoms in contact. Modeling and simulation results, however, vary when the motion and interactions of multiple dislocations dominate at a larger scale regime. A Rice-Peierls framework is employed to investigate the multiplication and storage of interface dislocations, and the critical conditions for dislocation initiation and steady-state gliding are determined numerically. Our findings identify the key parameters that govern various friction mechanisms in the Hurtado-Kim and Deshpande-Needleman-van der Giessen models.