Asymmetric Granular materials

Abstract

My focus at RIT has been on radically non-spherical (asymmetric or anisometric) granular materials including long, thin cylinders, U-shaped staples and C-shaped annular-sector particles (ASPs). In this talk I’ll discuss three different experiments and simulations: 1) extensional rheology of 3d piles, 2) the influence container boundaries have on rod packings and 3) dimerization of ASPs under 2d shear. Extensional rheology is made possible by shape-dependent particle entanglement and can be explained using Weibullian weakest-link statistics.

These behaviors and models have subsequently been used to understand the rheology of ant-rafts and how elephants pick up granular foods. Granular experiments can be sensitive to pile preparation and container size. Experiments and simulations reveal the presence of both horizontal and vertical boundary layers that influence the bulk packing fraction. Finally, I’ll present preliminary experiments on annular-sector particles (ASPs) that can entangle under shear and form dimers (and trimers).