The Two-parameter Fracture Criterion with Two-dimensional Crack Tip Front Constraint

The present paper deals with crack-tip constraint parameters based on the nonsingular stresses which are included in the asymptotic stress field ahead of the crack tip front in the case of elastic behavior of the material. In the case of the asymptotic elastic stress field according to Williams, the nonsingular T xx and T zz stresses characterize two-dimensional constraint in the transverse ( Т xx ) and longitudinal ( Т zz ) directions along the crack front in three-dimensional solids. The fracture criterion is based on the maximum tangential stress which should be equal to the local strength in the fracture process zone ahead of the crack tip front.