Effects of particle angularity on granular self-organization

TL;DR

This study investigates how particle angularity influences self-organization in granular materials, revealing that certain stress and shape distributions are robust to angularity but sensitive to friction changes.

Contribution

It introduces a systematic simulation approach to analyze the effects of grain angularity on self-organization indicators in granular systems.

Findings

Stress-orientation correlations are unaffected by angularity.

Distribution collapses of scaled stress ratios are independent of angularity.

Angularity increases sensitivity of distribution collapses to friction coefficient.

Abstract

Recent studies of two-dimensional poly-disperse disc systems revealed a coordinated self-organisation of cell stresses and shapes, with certain distributions collapsing onto a master form for many processes, size distributions, friction coefficients, and cell orders. Here we examine the effects of grain angularity on the indicators of self-organisation, using simulations of bi-disperse regular $N$-polygons and varying $N$ systematically. We find that: the strong correlation between local cell stresses and orientations, as well as the collapses of the conditional distributions of scaled cell stress ratios to a master Weibull form for all cell orders $k$, are independent of angularity and friction coefficient. In contrast, increasing angularity makes the collapses of the conditional distributions sensitive to changes in the friction coefficient.