On materials destruction criteria

In terms of nonlinear material fracture mechanics, the real (discrete)-structure material fracture model has been developed. The model rests on the demonstration of the fact that crack resistance $K_{1c}=2\sigma \sqrt l$ and fracture toughness are $G_{1c}=J_{1c}=2\sigma l$ obtained on the basis of energy conservation law and derived without linear material fracture mechanics assumptions can be respectively taken as force and energy criteria for non-linear fracture mechanics. It is shown that $G_{1c}=K_{1c}^2/E$ is the energy criterion of linear fracture mechanics of material and it is sufficiently less than $G_{1c} = J_{1c}=2\sigma l$.