Direct numerical simulation of deformation twinning in polycrystals

The ability to directly simulate the formation of twin domains in crystalline materials is of interest to the mechanics of materials community. While extensive work has been published on homogenized crystal mechanics treatments of twinning, publications that directly capture twin domain formation are relatively rare. This is due both to the complexities of model development and to the computational costs involved. We present results from simulations of twinning in polycrystals with finite elements that spatially resolve twin formation. Effects of interest include the role of stress concentrations in twin initiation, the interactions among twin systems, and competition between deformation twinning and dislocation glide plasticity. We anticipate that results from models that spatially resolve twin formation will help to inform more homogenized multiscale schemes. We show basic features of the model via numerical simulations on a model polycrystal system in simple shear, and also examine the complete model through large scale simulation of a dynamically compressed polycrystal. Comparisons are made between experimental data from far-field high energy diffraction microscopy (HEDM) and numerical simulations for a magnesium alloy polycrystal in compression. We finish with some final remarks and directions for future work. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.