Discrete dislocation modeling in three-dimensional confined volumes

Plastic deformation of micron-sized specimens or smaller cannot be describe d by continuum plasticity, as the discrete nature of the dislocations can n o longer be ignored. This paper presents a three-dimensional dislocation dy namics plasticity method developed for the study of plasticity of such smal l specimens. The approach includes two components: (i) plasticity is descri bed by the dynamics of individual, discretized three-dimensional dislocatio n loops; (ii) a finite element model supplies 'image fields' that incorpora te traction or displacement boundary conditions on the specimen. A circular dislocation loop is used to validate the chosen discretization o f the dislocation. The critical stress for activating a Frank-Read source c onfirms the used line-tension description. A tensile test of a free-standin g thin film illustrates the incorporation of the boundary conditions into t he model. Particular attention is given to the treatment of dislocation loo ps that have glided partly out of the body, leaving a step at the surface. (C) 2001 Elsevier Science B.V. All rights reserved.