Interrelation between toughness and both strength and structural parameters of material

摘要

The Neuber-Novozhilov fracture criterion is proposed for a description of tensile and shear fracture in the vicinity of the tip of a V-shaped cut. In the criterion proposed, the averaged limits of stresses on the cut axis depend on the presence, size and location of defects in the initial material. The parameter of the crystal lattice of material is chosen for the specific linear size. For V-shaped cuts, simple relations for tension and shear have been obtained that relate stress intensity factors at modified singularity coefficients; also obtained are these singularity coefficients and theoretical tensile and shear strengths of single crystal material with consideration of damage of the material in the vicinity of the cut tip. In the relations obtained, the passage to the limit by the angle from the V-shaped cut to a crack is possible. It has been shown that the critical stress intensity factor that is used when evaluating the strength of cracked solids is not a material constant.