2006 Volume 114 Issue 1335 Pages 1044-1048
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 KIc 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.