UNIFIED MODELING OF TIME-DEPENDENT DAMAGE TAKING INTO ACCOUNT AN EXPLICIT DEPENDENCY ON BACKSTRESS

A new continuum damage model is presented. It describes the time depen dent damage of metallic materials at high temperatures in a unified ma nner, without a subdivision into creep and fatigue damage parts. Takin g into account the dependence of damage evolution on the deformation h istory, a dependency of the damage rate on an internal variable, the b ackstress, is incorporated. The model is formulated first with a scala r damage variable for uniaxial load cases. Some ideas on a multiaxial extension are discussed. For application, the new model is coupled wit h the viscoplastic deformation model proposed by Chaboche. Low-cycle f atigue tests with the Ni-base alloy Nicrofer 5520 Co are considered, a nd the results are presented. The influence of the deformation model o n the results of prediction of the new damage model is discussed. Copy right (C) 1997 Elsevier Science Limited.