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

TL;DR

This paper uses finite element simulations to explore size effects, inhomogeneity, and nonlocal elastic behavior in small-scale plasticity modeled by Mesoscopic Field Dislocation Mechanics, revealing key phenomena like the Bauschinger effect.

Contribution

It provides qualitative computational predictions of a mesoscopic plasticity model, demonstrating size-dependent effects and stability analysis in small-scale deformation.

Findings

Size effects in shear deformation of constrained grains

Development of inhomogeneity and dislocation density boundary layers

Nonlocal elastic effects causing Bauschinger phenomenon

Abstract

In Part I of this set of two papers, a model of mesoscopic plasticity is developed for studying initial-boundary value problems of small scale plasticity. Here we make qualitative, finite element method-based computational predictions of the theory. We demonstrate size effects and the development of strong inhomogeneity in simple shearing of plastically-constrained grains. Nonlocality in elastic straining leading to a strong Bauschinger effect is analyzed. Stability of the time dependent, spatially homogeneous, simple shearing solution of PMFDM is studied. Results from thermal cycling of small scale beams/films with different degrees of constraint to plastic flow are presented showing size effects and reciprocal-film-thickness scaling of dislocation density boundary layer width.