View article

Microscale deformations are investigated in numerical DEM experiments of a large two dimensional assembly of disks. The assembly was subjected to quasi-static biaxial loading at small to moderate strains. Deformations within individual voids were computed from the relative motions of surrounding particles. Evolution of the local fabric was measured in terms of void-based parameters, including effective void ratio, void cell valence, and shape-elongation of the voids, all of which increased monotonically during loading. A direct correlation was measured between local void shape and dilation, which accounts for the transition from compressive to dilatant behavior. Deformation was very nonuniform at the microscale of individual voids. The predominant deformation structures were thin obliquely trending bands of void cells within which slip deformation was most intense. These “microbands” appeared …