Finite Fracture Mechanics — Application to the Onset of a Crack at a Bimaterial Corner

As emphasized by one of the authors in a recent paper (Leguillon 2001), energy and strength criteria are necessary conditions for fracture but neither one nor the other are sufficient. The incremental form of the energy criterion (the foundation of Finite Fracture Mechanics) gives a lower bound of admissible crack lengths. On the contrary, the strength criterion leads to an upper bound. The consistency between these two conditions provides a general form of a criterion for crack nucleation. There is a fair agreement with experiments on notched homogeneous materials (Dunn et al. 1997). This paper is dedicated to the extension of the previous results to bimaterial corners. Multiple singular modes must now be accounted for and a generalized concept of mode mixity is necessary. Comparisons with experiments remain quite good.