Micromechanics of crack nucleation during indentations

An analysis for the nucleation of microcracks from the inhomogeneous flow lines in soda-lime glass under Vickers indentations is considered. The minimum loads for crack nucleation are shown to depend on the hardness,H, and the critical stress intensity factor,K_IC. Unlike the Lawn and Evans analysis, the present model does not require the presence of any fortuitous flaws of critical dimensions in the material, since the flaws are nucleated by the deformation in the deformed zone.