It was recalled that the plastic deformation of micron-sized specimens, or smaller, could not be described in terms of continuum plasticity because the discrete nature of the dislocations could no longer be ignored. The present work described a 3-dimensional dislocation dynamics plasticity method for the study of the plasticity of small specimens. The method comprised 2 features. Firstly, the plasticity was described by the dynamics of individual discretized 3-dimensional dislocation loops. Secondly, a finite element model supplied image fields which imposed traction or displacement boundary conditions on the specimen. A circular dislocation loop was used to check the chosen discretization of the dislocation. The critical stress for the activation of a Frank-Read source confirmed the line-tension description which was used. A tensile test of a free-standing thin film illustrated the incorporation of boundary conditions into the model. Particular attention was paid to the treatment of dislocation loops which had partly glided out of the body; thus leaving a step at the surface.

Discrete Dislocation Modelling in Three-Dimensional Confined Volumes. D.Weygand, L.H.Friedman, E.Van der Giessen, A.Needleman: Materials Science and Engineering A, 2001, 309-310, 420-4