Normal/shear cracking model: Application to discrete crack analysis

A Simple but general model for normal/shear cracking in quasi-brittle materials is presented. It is defined in terms of the normal and shear stresses on the average plane of the crack and the corresponding normal and shear relative displacements. A crack surface in stress space determines crack initiation under pure tension, shear-tension, or shear-compression loading. Two independent fracture energy parameters are used: the classical Mode I fracture energy G(f)(I), and the asymptotic Mode II fracture energy G(f)(IIa) under very high shear-compression and no dilatancy. The cracking model proposed can be implemented in two ways: directly as the constitutive law of an interface element in the context of discrete crack analysis, or as the law of a generic cracking plane in a multicrack formulation in the context of smeared crack analysis. In this paper, the first approach is presented and examples are given of numerical constitutive testing and verification with experimental data.