DEM Study on Particle Shape Evolution during Crushing of Granular Materials

Discrete element method (DEM) is widely used to simulate particle crushing, and the simulation results are further utilized for devising constitutive models for soils and rocks. However, particle shape evolution during the process of crushing is often neglected for brevity. In this study, one-dimensional (1D) compression on crushable granular materials is simulated using two-dimensional (2D) DEM to identify the specific role of evolving fragment shape during particle crushing on the macroscopic response. Two different particle crushing approaches are adopted here. In the first approach, grain crushing is mimicked by substituting parent particles with smaller particles once a breakage criterion is attained. In the second approach, a bonded agglomerate consisting of smaller particles is used instead of an intact particle, which breaks once the bond strength exceeds. The simulation results show that despite an equal amount of particle crushing at any given strain level, the axial stress-strain responses are different in the two approaches. On the other hand, the evolution of contact fabric anisotropy reduces, which increases the lateral stress. Further, the effect of particle shape on the limit compression response is also studied. The study finally proposes an exponential relationship between particle breakage and particle shape indicator during the comminution process.