Granular packings of cohesive elongated particles

TL;DR

This paper investigates how cohesive forces influence the packing structure, stress distribution, and orientation of elongated particles in 2D, revealing significant differences from non-cohesive packings and highlighting the role of cohesion in granular materials.

Contribution

It provides a detailed numerical analysis of the effects of cohesion on the packing and stress properties of elongated particles, a topic less explored in prior research.

Findings

Cohesion disrupts horizontal alignment of elongated particles.

Cohesive particles form looser, more disordered structures as Bond number increases.

Pressure distribution becomes more isotropic and saturates faster with depth.

Abstract

We report numerical results of effective attractive forces on the packing properties of two-dimensional elongated grains. In deposits of non-cohesive rods in 2D, the topology of the packing is mainly dominated by the formation of ordered structures of aligned rods. Elongated particles tend to align horizontally and the stress is mainly transmitted from top to bottom, revealing an asymmetric distribution of local stress. However, for deposits of cohesive particles, the preferred horizontal orientation disappears. Very elongated particles with strong attractive forces form extremely loose structures, characterized by an orientation distribution, which tends to a uniform behavior when increasing the Bond number. As a result of these changes, the pressure distribution in the deposits changes qualitatively. The isotropic part of the local stress is notably enhanced with respect to the deviatoric part, which is related to the gravity direction. Consequently, the lateral stress transmission is dominated by the enhanced disorder and leads to a faster pressure saturation with depth.