A CONSTITUTIVE FORMULATION FOR ANISOTROPIC MATERIALS SUITABLE FOR WAVE-PROPAGATION COMPUTER-PROGRAMS .2.

The constitutive relationships for an anisotropic material are established for shock wave propagation and nonlinear, large deformation computer programs, commonly referred to as hydrocodes. Stresses are formulated in terms of strains; the procedure for separating material compressibility effects (equation of state) from strength effects is formulated which permits the consistent calculation of stresses in the elastic regime, and allows the mean pressure to be defined in accordance with their scalar interpretations. Further, this procedure permits the computation of inelastic response by scaling of deviatoric stresses, so the equivalent stress resides on a yield or failure surface, without changing the pressure. The procedure for computing the equivalent plastic strain and non-radial return to the yield surface, which results from a calculated overstress, is developed. Also, the transformation matrices for large deformation (rotation), necessary for transformation between material and geometric coordinates, are presented.