A complete potential based framework utilizing internal state variables is put forth for the derivation of reversible and irreversible constitutive equations. In this framework, the existence of the total (integrated) form of either the (Helmholtz) free energy or the (Gibbs) com- plementary free energy are assumed a priori. Two options for describing the flow and evolu- tionary equations are described, wherein option one (the fully coupled form) is shown to be over restrictive and the second option (the decoupledform) provides significant flexibility. As a con- sequence of the decoupled form, a new operator, that is, the compliance operator, is defined, which provides a link between the assumed Gibb's and complementary dissipation potential and ensures a number of desirable numerical features, for example, the symmetry of the resulting consistent tangent stiffness matrix. An important conclusion reached is that although many theo- ries in the literature do not conform to the general potential framework outlined, it is still pos- sible in some cases, by slight modifications of the employed forms, to restore the complete potential structure.

Jean-Louis Chaboche

Papers

Coupled thermoelastic-vi scoplastic- damage modeling