Anisotropic Hosford-Coulomb fracture initiation model: Theory and application

An anisotropic extension of the Hosford-Coulomb localization criterion is obtained through the linear transformation of the stress tensor argument. Unlike for isotropic materials where the stress state is characterized through the stress triaxiality and Lode parameter, the normalized Cauchy stress tensor is used to describe the stress state in an anisotropic solid. Based on experiments on extruded aluminum 6260-T6 covering stress states from pure shear to equi-biaxial tension for different material orientations, it is shown that this phenomenological and uncoupled model is capable to provide reasonable engineering approximations of the strains and displacements to fracture for thirteen different loading conditions.