Multi-Scale Analysis of Deformation Modes in Granular Material Using a Dynamic Hybrid Polygonal Finite Element-Discrete Element Formulation

We are interested in capturing the multi-scale behaviour of granular materials; that is, how micro-scale particle interactions influence the macroscopic behaviour of granular materials. We present a novel plane strain dynamic formulation for a multi-scale hybrid finite element-discrete element analysis. The formulation consists of two basis elements: hybrid polygonal body elements representing grains with linear elastic behaviour and interface elements representing the nonlinear interactions between grains. Combining the two elements provides a convenient technique for obtaining results akin to a discrete element simulation, but within a continuum-based finite element framework. We apply the model to simulate biaxial compression tests with an initial consolidation phase under uniform pressure followed by strain-controlled deviatoric loading. The model captures the stress-strain relationship of a typical compression test on granular material, including the post-peak softening regime. Eigen-analysis of the granular structure reveals that this modelling approach captures the rich bifurcation space associated with the failure of granular materials.