Discrete dislocation and continuum descriptions of plastic flow

Conventional continuum mechanics models of inelastic deformation processes are size scale independent. In contrast, there is considerable experimental evidence that plastic flow in crystalline materials is size-dependent over length scales of the order of tens of microns and smaller Geometrically ne cessary dislocations play a key role in this regard. At present there is no generally accepted framework for analyzing the size-dependent response of a plastically deforming crystal. Dislocation-based plasticity can provide i nformation on the form of the governing equations and the boundary conditio ns, as well as material properties. Two model problems that highlight the l imitations of conventional continuum plasticity are considered. For each pr oblem, solutions using discrete dislocation plasticity and a recently propo sed nonlocal continuum formulation are compared. The capabilities and Limit ations of the currently available nonlocal continuum theories are discussed . (C) 2001 Elsevier Science B.V. All rights reserved.