Anisotropic-Asymmetric Hardening Characterization of BCC/FCC/HCP Metals: Experiments and Modeling

This research investigates the anisotropic-asymmetric hardening behaviors of different types of metals by experiments and analytical modeling. Experiments are conducted at shear, uniaxial tension, plane strain tension and equibiaxial tension states to characterize the anisotropic hardening behaviors of aluminum alloy 7075-T6 and magnesium alloy AZ31. The strain hardening behaviors are compared between different loading directions and stress states. An obvious anisotropic-differential hardening evolution is observed for AZ31. The anisotropic-asymmetric hardening behaviors are characterized by a newly proposed stress invariants-based function with isotropic and anisotropic forms. A newly linear transformation tensor is introduced based on that of Barlat et al. (1991) to extend the isotropic stress invariants-based function to an anisotropic form. The comparison shows that the anisotropic-asymmetric hardening behaviors are precisely modeled by the proposed yield function under different stress states of shear, uniaxial tension, plane strain tension and equibiaxial tension, and different loading directions. The extended anisotropic form is recommended for strongly anisotropic materials such as AZ31 due to its less computationally cost while maintaining high accuracy.