A simulation based on the cosserat continuum model of the vortex structure in granular materials

Displacement fluctuation is the difference between the real displacement and the affine displacement in deforming granular materials. The discrete element method (DEM) is widely used along with experimental approaches to investigate whether the displacement fluctuation represents the vortex structure. Current research suggests that the vortex structure is caused by the cooperative motion of particle groups on meso-scales, which results in strain localization in granular materials. In this brief article, we investigate the vortex structure using the finite element method (FEM) based on the Cosserat continuum model. The numerical example focuses on the relationship between the vortex structure and the shear bands under two conditions: (a) uniform granular materials; (b) granular materials with inclusions. When compared with distributions of the effective strain and the vortex structure, we find that the vortex structure coexists with the strain localization and originates from the stiffness cooperation of different locations in granular materials at the macro level.