Quasibrittle fracture beneath a flat bearing surface

The problem of fracture of the quasibrittle and brittle material such as glass when subject to indentation by a relatively rigid, square-ended uniform punch is considered, using classical energy principles. The strain energy needed to form a crack adjacent to the punch edge is found, and from this the load needed to initiate fracture given. The calculation is of practical interest in the design rating of bearing blocks supporting structural glass. Additionally, it implies also the potential possibility to set up a very simple and practical technique for evaluating some strength-related properties of materials such as the fracture toughness using specimens without macro-pre-existing cracks.