Effect of local non-convexity on the critical shear strength of granular materials determined via the discrete element method
Multi-sphere clumps are commonly used to simulate non-spherical particles in discrete element method simulations. It is of interest whether the degree of local non-convexity λ affects the mechanical behaviour of granular materials with the same non-convexity η. A series of discrete-element-method biaxial shear tests are conducted on rough particle packings with η = 0.075 and different λ values (ranging from 0.134 to 0.770). The microscale results show that the contact type changes with an increase in λ. However, the critical strength is independent of λ. The evaluation of the contributions of different contact types to the critical shear strength and a detailed analysis of the anisotropies help clarify the microscopic mechanisms that result in the independence of the critical shear strength from λ.
Keywords: Multi-sphere clump, Local non-convexity, Discrete element method, Biaxial shear test, Contact type, Critical shear strength