Irreversible Incremental Behavior in a Granular Material

TL;DR

This study investigates the elastic and irreversible behaviors of granular materials under shear and volume strains using numerical simulations, revealing that volume strain is nearly reversible while shear strain exhibits increasing irreversibility with decreasing coordination number.

Contribution

It introduces a model that accurately predicts the elastic response of granular materials and characterizes the irreversibility in shear deformation based on coordination number.

Findings

Volume strain increments are nearly reversible.

Shear strain increments show increasing irreversibility with lower coordination number.

The elastic model matches simulation results across various coordination numbers.

Abstract

We test the elasticity of granular aggregates using increments of shear and volume strain in a numerical simulation. We find that the increment in volume strain is almost reversible, but the increment in shear strain is not. The strength of this irreversibility increases as the average number of contacts per particle (the coordination number) decreases. For increments of volume strain, an elastic model that includes both average and fluctuating motions between contacting particles reproduces well the numerical results over the entire range of coordination numbers. For increments of shear strain, the theory and simulations agree quite well for high values of the coordination number.