Dislocation Glides in Granular Media

Atomic crystals with dislocations deform plastically at low stresses via dislocation glide. Whether dislocation glide occurs in macroscopic frictional granular media remains unknown. We simulate structural and rheological responses of a granular crystal with an edge dislocation. We discover that dislocation glide occurs at low interparticle friction coefficients, whereas at high friction, the crystal order breaks down. When the dislocation glide occurs, the yield stress is markedly lower than in dislocation-free crystals and varies linearly with the interparticle friction coefficient. The linear dependence arises from both the elastic barrier associated with the Peierls stress and the interparticle friction slip criteria.