A Model-based Simulation Procedure for the Evolution of Tertiary Creep with Combined Damage Diffusion and Viscoplasticity

Abstract

It appears from macro- and micro-experiments that the essential feature of the tertiary creep of certain materials is characterized by the evolution of localized damage that results in the formation and evolution of macrocracks. Higher-order continuum models, such as nonlocal integral or strain gradient models, have been developed by the research community over the last twenty years to predict the evolution of localized failure. However, the use of higher-order models yields higher-order governing differential equations with the ambiguity in the physics behind additional boundary conditions, and with the difficulty in large-scale model-based simulations. To simulate the evolution of localized failure in tertiary creep with the least computational cost, therefore, the relationship among the existing regularizing approaches of localization is investigated first. Based on the analysis, it is then proposed that a coupled viscoplasticity-damage model be combined with a damage diffusion law to simulate a complete creep process. As a result, the mesh-objective solutions could be obtained without invoking higher-order spatial terms in the strain-stress space. Example problems are considered to illustrate the potential of the proposed model-based numerical procedure in a large-scale simulation.