Size dependence of energy storage and dissipation in a discrete dislocation plasticity analysis of static friction

The initiation of frictional sliding between a flat-bottomed indenter and a planar single crystal substrate is analyzed using discrete dislocation plasticity. Plastic deformation is modeled through the motion of edge dislocations in an elastic solid with the lattice resistance to dislocation motion, dislocation nucleation, dislocation interaction with obstacles and dislocation annihilation incorporated through a set of constitutive rules. The adhesion between the indenter and the substrate is modeled using a shear traction versus sliding displacement cohesive relation. The evolution of the energy storage and dissipation are calculated as a function of contact size.