Direct two-level crystal plasticity model: Application to analyze the influence of free specimen boundaries

In this work, using of direct modeling, the dependence of the inelastic deformation processes in a polycrystalline sample on their scale is shown. For this, a direct crystal plasticity model was used, in which the presence of a free surface and its effect on the mechanical properties of the material were explicitly taken into account. The presence of a free surface is taken into account through a decrease in the initial critical stresses in slip systems of near-surface elements. In this regard, plastic shears are initiated primarily at the free surface. Numerical experiments have shown that the growth of plastic deformations in grains, as well as fragmentation processes, proceed differently when the free surface is taken into account.