Discrete dislocation dynamics simulations in three dimensions were performed on micro-sized bending beams, and the results were compared with experiment. A strong size-dependence of the flow stress, σf, (or bending moment) was found. The flow stress scaled approximately inversely with the beam thickness, t. The simulations showed that the dislocation structure contained pronounced pile-ups around the neutral plane of the beam. The back-stress from these pile-ups, acting on the dislocation sources, was analyzed by means of an analytical pile-up model. It was shown that the scaling behaviour, σf ∝ t-1, could be explained by a combination of pile-up and source-size limitation. The applicability of strain gradient plasticity models to micro-bending was considered.

Micro-Bending Tests - a Comparison between Three-Dimensional Discrete Dislocation Dynamics Simulations and Experiments. C.Motz, D.Weygand, J.Senger, P.Gumbsch: Acta Materialia, 2008, 56[9], 1942-55