DEM investigation of angle of repose for super-ellipsoidal particles

Abstract

We explore the effect of particle shape on the angle of repose (AoR) in granular packing using a three-dimensional discrete element method. Non-spherical particles were modeled using super-ellipsoids characterized by aspect ratio and blockiness. The relationship between AoR and particle shape was examined, followed by a series of analyses on the origin of AoR from a microscopic perspective. Results show that, with blockiness deviating from unity, AoR has an approximate “M” shape that exhibits a strong to weak trend with aspect ratio, matching results of previous reports. Another finding suggests a parabolic relationship between normalized AoR and normalized coordination number. AoR increases with anisotropy related more with the anisotropy of particle orientation than with the anisotropy of contact normal. Particle shape is more likely to affect AoR by affecting the tangential force than the normal contact force. An analysis based on traction indicates that dips in stress associated with the tangential force (compared with the normal force) and non-spherical particles (compared with spheres) are more significant. For various particle shapes, AoR is positively correlated with friction mobilization but is negatively correlated with friction mobilization for various coefficient of friction.