ON ISOTROPY AND ANISOTROPY IN THE THEORY OF PLASTICITY.

TEST RESULTS ON THE PLASTIC BEHAVIOR OF A RANGE OF ENGINEERING METALS AND ALLOYS UNDER PROPORTIONATE LOADING ARE EXAMINED IN TERMS OF THE ISOTROPIC HARDENING RULE WITH HOMOGENEOUSYIELD FUNCTIONS. ALTERNATIVE YIELD FUNCTIONS ARE PRESENTED WHERE DEFORMATION BEHAVIOR HAS BEEN IDENTIFIED WITH INITIALLY ANISOTROPY MATERIAL. THE DISTINCTION BETWEEN ISOTROPIC ANDANISOTROPIC YIELD FUNCTIONS IS CLARIFIED BY AN EXAMINATION OF COMPONENT PLASTIC STRAIN PATHS IN A TENSION TEST.