History-dependent coupled growth of creep damage under variable stress conditions

Abstract

A multiaxial constitutive model is presented for the description of the history-dependent inelastic and damage behavior of polycrystalline metallic materials in the high-temperature range under variable loading conditions. A particular emphasis is placed on a new formulation for the history-dependent material degradation which is based on a coupling between hardening and damage. The total damage is given by the sum of damage components which have different history dependence. The associated continuum damage variables are defined through their ew)lution equations coupled with hardening parameters involved with a kinematic hardening model. The non-classical coupling belwecn hardening and damage is incorporated into the modified kinematic hardening model which has been developed for describing the complicated hardening and softening behavior under repeated stress changes. Numerical simulations for differen! material parameters show that the proposed damage-coupled constitutive model can predict an acceleration as well as ' ,~ deceleration of creep damage growth due lo stress w~rialions.

Off-Axis Creep Recovery of Unidirectional Carbon/Epoxy Composites at High Temperature

“…The viscoplatic behavior of PMCs in the high stress regime, however, has not sufficiently been elucidated [3]. Moreover, since most PMC structures are subjected to unsteady loading during service, it is also important to develop techniques for coping with the time-dependent behavior of PMCs under variable loading conditions [4].…”

Constitutive Modeling of Creep and Damage Behaviors of the Non-Mises Type for a Class of Polycrystalline Metals

“…Moreover, in view of the significant history dependence of the macroscopic creep behavior of polycrystalline metals (Kawai, 1989), we believe that strain-induced damage under creep condition also depends on history. For an accurate modeling of creep damage, it is thus very important to consider appropriately an interaction between creep deformation and creep damage (Kawai, 1996(Kawai, , 1998. For precise and reliable designs of high-temperature structural components, it is crucial to enhance the accuracy of predictions of the local development of creep deformation and creep damage and of the creep life under service conditions.…”