Computation of the Stress Intensity Factor and COD for Submicron Sized Indentation Cracks

Abstract

The first part of the paper deals with the computation of stress intensity factors for pyramidal indentation cracks with a ratio of crack length c to indentation half-diagonal a between 1 and 2. The residual stress field due to quasi-plastic deformation below the indenter is described by using the Hill model of an expanding sphere. It is found that the proportionality factor in the relation for K_Ic decreases with c/a→1 and confirms experimental results with nanoindents on sapphire and fused quartz. In the second part, the crack opening displacement of such cracks is determined.