抄録
The final purpose of this study is to verify that the Natural Strain theory is effective strain expression for representing the large deformation behavior. In this paper, the method for estimation of yield stress, which is determined from the tangent modulus of the principal deviatoric stress- deviatoric strain curve, is examined on the basis of the Natural Strain theory. As the most fundamental case, the pre-deformations, i.e., the large uni-axial tension, the large simple shear and the proportional deformation of them, are investigated under different strain hardening conditions. The yield stress at the opposite side of these pre-deformations is estimated on the basis of the magnitude of tangent modulus at re-yielding. Then, the estimated yield stress based on this method is compared with the results of the commonly-used proof stress.
