Abstract
We model in this work granular materials composed of nonconvex and cohesive aggregates, in view of application to the rheology of UO2 powders. The effect of nonconvexity is analyzed in terms of bulk quantities (Coulomb internal friction and cohesion) and micro-mechanical parameters such as texture anisotropy and force transmission. In particular, we find that the packing fraction evolves in a complex manner with the shape nonconvexity and the shear strength increases but saturates due to interlocking between the aggregates. We introduce simple models to describe these features in terms of micro-mechanical parameters. Furthermore, a systematic investigation of shearing, uniaxial compaction and simple compression of cohesive packings show that bulk cohesion increases with non-convexity but is strongly influenced by the boundary conditions and shear bands or stress concentration.