Abstract
The Natural Strain is obtained by integrating an infmitesimal strain increment on an identical line element. Hence, this theory has merits that can remove the rigid body rotation from the rotating angle of a line element and can satisfy the additive law of strain on an identical line element. In our previous report, the different defomiation histories, i.e. the large simple shear in a certain direction and in the opposite direction, are chosen as the pre-deformation, and the relation between the progress of anisotropy for elastic modulus G and the magnitude of strain hardening induced by these pre-deformation has been revealed. In this paper, using the Natural Strain theory, the configuration of the yield surface and the distribution of elastic modulus G in the yield surface are estimated by performing the proportional loading tests for tension and torsion after giving the pre-deformation of uni-axial tension to the test pieces.
