Identification of rolling resistance as a shape parameter in sheared granular media

TL;DR

This study demonstrates that rolling resistance in granular media can be used as a shape parameter to account for particle angularity, affecting shear strength, density, and force distribution.

Contribution

It establishes a direct link between rolling resistance and particle angularity, providing a new way to model noncircular granular particles.

Findings

Rolling resistance correlates with the number of sides in polygonal particles.

Hindered particle rotation influences shear strength and fabric anisotropy.

Energy dissipation due to rotation is key to understanding particle shape effects.

Abstract

Using contact dynamics simulations, we compare the effect of rolling resistance at the contacts in granular systems composed of disks with the effect of angularity in granular systems composed of regular polygonal particles. In simple shear conditions, we consider four aspects of the mechanical behavior of these systems in the steady state: shear strength, solid fraction, force and fabric anisotropies, and probability distribution of contact forces. Our main finding is that, based on the energy dissipation associated with relative rotation between two particles in contact, the effect of rolling resistance can explicitly be identified with that of the number of sides in a regular polygonal particle. This finding supports the use of rolling resistance as a shape parameter accounting for particle angularity and shows unambiguously that one of the main influencing factors behind the mechanical behavior of granular systems composed of noncircular particles is the partial hindrance of rotations as a result of angular particle shape.