Dislocation Glides in Monolayered Granular Media: Effect of Lattice Constant

TL;DR

This study uses simulations to explore how lattice constant and friction influence dislocation glide and yielding in monolayered granular crystals, revealing that smaller lattice constants increase the critical friction for glide and yield stress scales linearly with normal stress.

Contribution

It systematically investigates the impact of lattice constant and friction on dislocation behavior in granular crystals, highlighting the role of microscopic parameters in macroscopic yielding.

Findings

Decreasing lattice constant raises the critical friction coefficient for glide.

Dislocation glide occurs below a critical friction coefficient $$.

Yield stress scales linearly with normal stress, except at very low friction.

Abstract

A recent study demonstrated that granular crystals containing a single dislocation exhibit dislocation glide analogous to that observed in atomic-scale crystals, resulting in plastic deformation at yield stresses several orders of magnitude lower than those of dislocation-free crystals. The yielding behavior strongly depends on the interparticle friction coefficient $\mu$: dislocation glide occurs for friction coefficients below a critical value $\mu_c$, while crystalline order deteriorates above $\mu_c$. In this work, we use discrete element method simulations to systematically investigate how the lattice constant, which determines the interparticle spacing and is a fundamental parameter in microscopic crystalline solids, and the friction coefficient $\mu$ influence the yielding behavior in monolayered granular crystals with dislocation. By decreasing the lattice constant, we find an increase in the critical friction coefficient $\mu_c$, allowing dislocation glide to persist at higher friction values. Furthermore, we observe a linear scaling of yield stress with normal stress, except at extremely low friction coefficients.