Three-dimensional modeling of indent-induced plastic zone at a mesoscale

In order to better understand how an indent-induced plastic zone forms, the experimental conditions associated with nanoindentation testing on f.c.c. crystals are modeled, using a combination of three- dimensional discrete di slocation simulation and the finite element method (FEM). At each stage of the loading, the FEM elastic solution enforcing the boundary conditions is superimposed to the infinite medium elastic solution of the discrete disloc ations. The plastic character of the indented material is accounted for by relaxing the elastic loading stresses through both the introduction of new nucleated discrete dislocations (loops) and their motion within the sample. Transmission Electron Microscopy observations of the indent-induced plasti c volume and analysis of the experimental loading curve help in defining a complete set of nucleation rules. A validation of the model is performed th rough direct comparisons between a simulation of a nanoindentation test on a [001] copper single crystal and the same experimental indentation. (C) 19 98 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights res erved.