A Micromechanical Dislocation Model of Rough Surface Contact Plasticity

Rough surface contact plasticity, especially at mesoscale and nanoscale, has been playing a central role in a broad spectrum of novel applications, e.g. nanostructure fabrication and reliability. The multiscale nature of surface roughness, the structure- and size-sensitive material deformation behavior, and the importance of surface forces and other physical interactions give rise to very complex surface phenomena at mesoscale and nanoscale. We present a micromechanical model to study rough surface contact plasticity, based on dislocation nucleation and multiplication. Surface roughness can be sources of dislocation nucleation; though roughness is confined to a thin layer, the resulted dislocation plasticity can extend to a far depth. Depending on interface adhesion, roughness features and slip planes, we get a variety of surface micro-plasticity behaviors that are radically different from classic plasticity behaviors.