An Uncoupled Anisotropic Failure Model Based on the Hill48 Function

To accurately describe the failure behavior of ductile metal materials under a wide stress state range under different loading directions, this study creatively proposes the characteristic stress and loading direction parameters by reviewing and analyzing DF series models and anisotropic correction methods based on yield stress. Combining these parameters with Hill48’s plastic framework established an uncoupled fracture model that uniquely decoupled fracture initiation from plastic anisotropy while maintaining physical interpretability. The model has high accuracy in predicting the fracture strain of AA 6082-T6, AZ31, DP980 and AA 6k21 under multi-directional load and is inherently robust due to the intrinsic relationship between the stress state and the material orientation. In addition, based on an assumption of the relationship between the stress state and the principal stress coordinate system, the above model is extended to the three-dimensional stress state and parameter analysis, application and discussion are carried out.