Prediction of ring crack initiation in ceramics and glasses using a stress–energy fracture criterion

Crack initiation in brittle materials upon spherical indentation is associated with the tensile radial stresses during loading. However, location of crack onset often differs (offset) from site maximal stress. In addition, experiments reveal a strong dependency forces on geometrical parameters as well surface condition sample. this work, coupled stress–energy fracture criterion introduced to describe ring cracks materials, which takes into account geometry contact and inherent strength toughness material. Several reported literature are evaluated compared. The can explain offset loading, observed various ceramics glasses. It also predicts force provided that compressive stresses, grinding or polishing processes, taken account. Furthermore, may be employed estimate residual stress ceramic parts, based simple damage experiments.