Anisotropic Distortional Yield Model

A yield surface model is proposed in this work which may be adapted to both small strain and large strain offset definitions of yielding. The proposed anisotropic distortional yield model is capable of translation, uniform expansion or contraction, as well as distortion of the subsequent yield surface. Two versions of the proposed model are introduced through variations in fourth-order anisotropy tensor M of the yield surface. Experimental observations by Phillips and co-workers (1973, 1974, 1977, 1979, 1985), Helling et al. (1986), and Stout et al. (1985) are taken into consideration in the development of the proposed model. The corresponding fourth-order elastoplastic stiffness matrix is formulated and specific examples are given.