Numerical Verification of Biaxial Tensile Test Using Cruciform Specimen with Angle between Axes of Anisotropy and Principal Stress

To improve the accuracy of sheet forming analysis, it is necessary to model an anisotropic yield surface on the basis of the measurement of biaxial stress status. To measure the plastic anisotropy, uniaxial tensile tests with an angle inclined to the rolling direction are carried out. Biaxial tensile tests with cruciform specimens are also preferred to be carried out with an angle between the axes of principal stress and the anisotropy. However, the accuracy of measured stress and the direction of plastic strain increment in the inclined biaxial tensile tests has not been verified. In this study, cruciform biaxial tensile tests with an inclined angle were analyzed using the finite element method. Using the finite element analysis as a virtual experiment, the stress points on equal plastic work contours and the directions of plastic strain increment were obtained from the tensile load and local strain. The results of virtual experiments were compared with the yield surface and normal direction derived from the yield function used in the finite element analysis. It was verified that the yield surface can be measured properly in biaxial tensile tests using cruciform specimens with an inclined angle.