Summary and Critique

Abstract

Unified creep-plasticity (UCP) models have many facets. Because there is no clear demarcation between plastic and creeping behavior, a good model should mimic both behaviors and should pass from one behavior to the other in a continuous manner. Furthermore, since plasticity and creep are both caused by similar physical processes, there should be no specific separation of the processes in the constitutive model. It appears that all of the models examined here have accomplished these basic objectives and in that sense qualify as unified creep-plasticity models. But constitutive modeling is multifaceted as stated above. Some authors have made a great effort to model time-dependent monotonic mechanical loading, others cyclic mechanical loading, and others multiaxial or temperature effects. Each author has also identified microstructural processes which he is modeling, and these are not the same in every case.