 The T-criteria use the volumetric stress in addition to the deviatoric stress used by the von Mises criterion and are similar to the Drucker Prager yield criterion.T-criteria have been designed on the basis of energy considerations and the observation that the reversible elastic energy density storage process has a limit which can be used to determine when a material has failed.The strain energy density stored in the material and calculated by the area under the formula_1-formula_2 curve represents the total amount of energy stored in the material only in the case of pure shear.