Comments on anisotropic yield criteria

Abstract Limitations of several anisotropic yield criteria are discussed. Hill's 1948 criterion overestimates the variation of yield strength with direction, while the specializations of Hill's 1979 theory assume planar isotropy. Shear stress terms cannot simply be included in either the author's 1979 criterion or in Hill's 1979 general criteria. It is suggested that the author's criterion be modified so that it is expressed in terms of principal stresses rather than referring stresses to the symmetry axes.