Linking continuum mechanics and 3D discrete dislocation simulations

A technique is developed for linking the methods of discrete dislocation dy namics simulation and finite element to treat elasto-plasticity problems. T he overall formulation views the plastically deforming crystal as an elasti c crystal with continuously changing dislocation microstructure which is tr acked by the numerical dynamics simulation. The FEM code needed in this reg ard is based an linear elasticity only. This formulation presented here is focused on a continuous updating of the outer shape of the crystal, for pos sible regeneration of the FEM mesh, and adjustment of the surface geometry, in particular the surface normal. The method is expected to be potentially applicable to the nano-indentation experiments, where the zone around the indenter-crystal contact undergoes significant permanent deformation, the r igorous determination of which is very important to the calculation of the indentation print area and in turn, the surface hardness. Furthermore, the technique is expected to account for the plastic history of the surface dis placement under the indenter. Other potential applications are mentioned in the text.