Determination of BBC2003 yield criterion constants for anisotropic aluminum alloy sheets based on plane strain tensile test

This paper puts forward a novel numerical-experimental method for calculation of constants of advanced anisotropic yield criterion BBC2003. Calculation of the eight constants of this yield criterion, demands experimental determination of eight mechanical properties of the material. These properties include; axial-yield stresses in 0, 45 and 90 degree with respect to the rolling direction, anisotropic parameters in the directions mentioned and plane strain yield stresses for 0 and 90 degree orientations. However, determination of the equi-biaxial yield stresses and anisotropic coefficients is relatively expensive. In the method presented in this paper, using a simple technique, the constants of the yield criterion are calculated based on plane strain yield stresses in 0 and 90 degree to the rolling direction. The system of equations involving the contestants of the yield function, is solved numerically through defining an error function and minimizing it using steepest descent method. In two case studies, the constants of BBC2003 yield criterion for anisotropic sheets of aluminum alloys AA3105 and AA6061-O, were calculated using this method. Subsequently, the accuracy of predicting of axial-yield stress and anisotropic coefficient in different directions as well as the coincidence of yield surface with experimental results for BBC2003 and Hill48 yield criteria have been investigated. The results show that the proposed method has good accuracy and stability in calculating of advanced yield criterion constants and consequently the mechanical properties of anisotropic sheets in different directions.