Nonlocal criterion of bridged cracks growth: Weak interface

A nonlocal fracture criterion with accounting of the work during bonds deformation at a fracture process zone has been implemented analytically for analysis of quasistatic cracks growth along a weak interface. The criterion consists of two clauses: (1) the necessary energy condition of the crack tip limit equilibrium which takes into account the energy release rate to the crack tip and the rate of the deformation energy consumed by bonds in the crack process zone; (2) the sufficient condition is the equality of the crack opening at the process zone trailing edge to the bond limit stretching. Subcritical and quasi-statical regimes of cracks growth are analyzed for the case of a homogeneous plate with internal straight bridged crack and bonds traction which is constant and independent of the external loading. The critical fracture stress and the crack bridged zone size in the limit equilibrium state have been determined and analyzed. The limit case of a crack which is filled with bonds is considered as a weak interface model.