Before revision: Practical engineering usage of the von Mises yield criterion As shown in the equations above, the use of the von Mises criterion as a yield criterion is only exactly applicable when the following material properties are homogeneous and have a ratio of : Since no material will have this ratio precisely, in practice it is necessary to use engineering judgement to decide what failure theory is appropriate for a given material.
After revision: Practical engineering usage of the von Mises yield criterion As shown in the equations above, the use of the von Mises criterion as a yield criterion is only exactly applicable when the following material properties are isotropic, and the ratio of the shear yield strength to the tensile yield strength has the following value : Since no material will have this ratio precisely, in practice it is necessary to use engineering judgement to decide what failure theory is appropriate for a given material.