Abstract: A generalized yield criterion is proposed based on the metal plastic deformation mechanics and the fundamental formula in theory of plasticity. Using the generalized yield criterion, the reason is explained that Mises yield criterion and Tresca yield criterion do not completely match with experimental data. It has been shown that the yield criteria of ductile metals depend not only on the quadratic invariant of the deviatoric stress tensor J¬2, but also on the cubic invariant of the deviatoric stress tensor J3 and the ratio of the yield stress in pure shear to the yield stress in uniaxial tension k/σ¬s. The reason that Mises yield criterion and Tresca yield criterion are not in good agreement with the experimental data is that the effect of J¬3 and k/σ¬s is neglected.

Key words: Metal, Plastic deformation, Yield criterion