ABSTRACT

The quasi-continuum multiscale method (QC) is applied to investigate position effect of cylindrical indenter on nanoindentation into Cu thin film. Load-displacement responses reflect that indenter position influences the critical load and critical displacement distinctly. The microscopic deformation mechanism shows that it is the retarding of dislocation nucleation beneath the indenter that actually leads to a relative lower critical load. Once the plastic deformation is retarded, the load-displacement curve will undulate several times until dislocations nucleate at the retarded region. It is found that the critical loads periodically change with indenter positions. The period equals to the distance between two adjacent atomic planes in [1 1 1] direction. An improved elastic model is proposed to predict the critical load in consideration of the effect of indenter position. The agreement between QC simulation and the present model has shown the effectiveness of the improved model.