A THERMODYNAMICALLY CONSISTENT FRAMEWORK FOR THEORIES OF ELASTOPLASTICITY COUPLED WITH DAMAGE

A unified framework for coupled elastoplastic and damage theories is d eveloped. A rigorous thermodynamic procedure is followed that is suffi ciently general to include anisotropic plasticity and anisotropic dama ge formulations. The concept of effective stress is the critical mecha nism for coupling these theories, Yield and damage functions, construc ted of homogeneous functions of degree one, are shown to satisfy therm odynamic restrictions. The principle of maximum entropy provides the e volutionary relations, the loading and unloading conditions, and the c onvexity of the undamaging elastic domain. The plastic and damage vari ables evolve normal to their respective surfaces which for plasticity corresponds to an associative flow for plastic strain. This general fr amework is shown to be sufficiently general lo encompass several popul ar theories for plasticity and damage. Limitations of some existing da mage theories are discussed. The performance of two specific coupled f ormulations are illustrated by replicating the experimental behavior o f an aluminum alloy.