Normalized life prediction in terms of stress relaxation behavior under creep-fatigue interaction

A new normalized life prediction function based on a model in terms of stress relaxation during hold time under creep-fatigue condition is proposed. From the concept that the reduction of fatigue life with hold is due to the creep effect of stress relaxation, the relaxed stress range is suggested to be a creep-fatigue damage function. The creep-fatigue data from the present and other investigators are used to check the validity of the: proposed life prediction. It is shown that the data satisfy the applicability of the normalized life relation model. Accordingly, using this life prediction model, one may realize that all the Coffin-Manson plots at the various levels of hold time under strain-controlled creep-fatigue tests can be normalized to make one master curve. (C) 2001 Elsevier Science B.V. All rights reserved.