Packing geometry and statistics of force networks in granular media

TL;DR

This paper explores how packing geometry influences force network statistics in granular media, using simulations and experiments to relate force and weight distributions and examine the effects of packing disorder.

Contribution

It introduces a geometrical framework linking force and weight distributions in granular packings and analyzes the impact of packing disorder on force fluctuations.

Findings

Force distribution P(f) remains stable despite changes in contact network.

Changes in weight distribution P(w) are mainly due to contact network alterations.

Force fluctuations increase with depth beneath the surface.

Abstract

The relation between packing geometry and force network statistics is studied for granular media. Based on simulations of two-dimensional packings of Hertzian spheres, we develop a geometrical framework relating the distribution of interparticle forces P(f) to the weight distribution P}(w), which is measured in experiments. We apply this framework to reinterpret recent experimental data on strongly deformed packings, and suggest that the observed changes of P(w) are dominated by changes in contact network while P(f) remains relatively unaltered. We furthermore investigate the role of packing disorder in the context of the q-model, and address the question of how force fluctuations build up as a function of the distance beneath the top surface.