Application the nonlocal criterion of bridged cracks growth with necessary and sufficient conditions

The nonlocal two-parameter fracture criterion of interface cracks with bridged zones is used to solve problems of cracks initiation and growth. This fracture criterion consists of the following conditions: 1) a necessary energy condition of the crack tip limit equilibrium based on the equality of the energy release rate and the rate of the energy dissipation by bonds; 2) a sufficient condition of the bond limit stretching at the trailing edge of the bridge zone. From these two conditions, the equilibrium size of the bridged zone and the critical external stress are determined. The regimes of the bridged zone and the crack tip equilibrium and growth are considered: a) the crack tip propagation and the bridged zone size increasing without bonds rupture; b) the bridged zone size decreasing without the crack tip propagation; c) the crack tip propagation with simultaneous bonds rupture.