Pore Stabilization in Cohesive Granular Systems

TL;DR

This paper models how cohesion and friction influence pore stabilization in cohesive granular materials, revealing that both forces can stabilize pores, with particle shape significantly affecting the outcome.

Contribution

It introduces a simulation approach combining cohesion law and rolling friction to analyze pore stabilization mechanisms in granular systems.

Findings

Porosity depends on cohesion strength scaled by external pressure.

Pores can be stabilized by Coulomb friction even without cohesion.

Nonspherical particles exhibit stronger pore stabilization effects.

Abstract

Cohesive powders tend to form porous aggregates which can be compacted by applying an external pressure. This process is modelled using the Contact Dynamics method supplemented with a cohesion law and rolling friction. Starting with ballistic deposits of varying density, we investigate how the porosity of the compacted sample depends on the cohesion strength and the friction coefficients. This allows to explain different pore stabilization mechanisms. The final porosity depends on the cohesion force scaled by the external pressure and on the lateral distance between branches of the ballistic deposit r_capt. Even if cohesion is switched off, pores can be stabilized by Coulomb friction alone. This effect is weak for round particles, as long as the friction coefficient is smaller than 1. However, for nonspherical particles the effect is much stronger.