Effects of small indenter size and its position on incipient yield loading during nanoindentation

The object of this paper is to study the effects of small indenter sizes and its positions on yield loading corresponding to onset plasticity during nanoindentation into a Cu(1 1 1) film surface with a small frictionless hard-cylindrical indenter by using the quasicontinuum method (QCM). The critical incipient yield loadings for some specified values of film thickness with different small indenter sizes and positions of indenter are compared. It is found that, both the indenter sizes and the tiny shift of contact positions between the two neighboring surface atoms along the [ 1 ¯   1 ¯   2 ] direction have significant effects on the critical yield loadings and the response of force on the indenter. In the meantime, results reveal that both the yield loadings and displacement of indenter corresponding to the incipient plasticity during nanoindentation are not constants but vary in the wave-like form with gradually shifting the initial positions of indenter along the [ 1 ¯   1 ¯   2 ] direction, and so does the variation of forces on the indenter in the horizontal direction.