Size effects and idealized dislocation microstructure at small scales: predictions of a phenomenological model of Mesoscopic Field Dislocation Mechanics: Part I

TL;DR

This paper introduces a phenomenological mesoscopic model extending continuum plasticity to predict size effects and dislocation microstructures at small scales, focusing on the role of geometrically-necessary dislocations in work-hardening.

Contribution

It develops a new PMFDM model by averaging FDM equations and incorporating strain-gradient plasticity, advancing understanding of small-scale plasticity phenomena.

Findings

Predicts size-dependent plastic behavior

Models dislocation microstructure evolution

Highlights effects of GND in work-hardening

Abstract

A Phenomenological Mesoscopic Field Dislocation Mechanics (PMFDM) model is developed, extending continuum plasticity theory for studying initial-boundary value problems of small-scale plasticity. PMFDM results from an elementary space-time averaging of the equations of Field Dislocation Mechanics (FDM), followed by a closure assumption from any strain-gradient plasticity model that attempts to model effects of geometrically-necessary dislocations (GND) only in work-hardening.