Yield Surfaces of SUS304 Under Cyclic Loading

To formulate the constitutive equations for cyclic plasticity, the subsequent yield surfaces should be examined carefully. In this paper, the subsequent yield surfaces have been examined from the experiment for the initially isotropic material of SUS304 subject to cyclic loading, using a 50µm/m offset strain criterion for yielding probed at the current center of the yield surface. The experiment shows a translation, distorsion, and rotation of the subsequent yield surfaces because of the deformation-induced-anisotropy due to proportional or nonproportional cyclic loading in tension-torsion space. These yield surfaces could be represented by the quadratic function of stresses with fourth rank anisotropic coefficient tensor components. These anisotropic coefficient tensor components are found to be represented by the strain amplitude of cyclic loading. As a result, the loading function obtained shows availability to derive the constitutive equations of cyclic plasticity.