Elastoplastic constitutive equation of metals under cyclic loading

The subloading surface model is based on the natural concept that the plastic strain rate develops continuously as the stress approaches the yield surface, in which an elastic domain is not assumed in this model. It therefore always describes the continuous variation of the tangent modulus. It does not require the determination of the offset value for yielding and the incorporation of an algorithm for the judgment of yielding, i.e. judgment of whether or not the stress reaches the yield surface. In addition, the stress is always attracted to the yield surface in the plastic loading process and thus it is automatically pulled-back to the yield surface when it goes out from the yield surface. In this article, complete elastoplastic constitutive equation of metals is formulated within the framework of the subloading surface model. The applicability of the present model to the description of actual metal deformation behavior is verified by comparison with various cyclic loading test data.