Crack initiation: A non-local energy approach

A crack initiation criterion is proposed for brittle material where nucleation is treated as a sudden and discrete rupture event at the macroscopic level. At the heart of the criterion is the finite difference form of the energy release rate; an expression for the characteristic length is derived and the change in total potential energy is obtained from an asymptotic argument. The criterion can predict crack onset at a sharp or blunt notch. Fracture toughness and material strength are the only input requirements. The effectiveness of the criterion is demonstrated through predictions that are compared to experimental data.