A CDM-based study of fatigue-creep interaction behavior

Under stress control mode, the damage evolution during fatigue, creep and their interaction behaviour actually is a ductility exhaustion process in response to cyclic and static creep. Based on the ductility dissipation theory and effective stress concept of continuum damage mechanism (CDM), a new fatigue creep interaction damage model has been developed in this paper, where the change of the inelastic strain energy density is used to define the damage variable. To assess this damage model, high temperature fatigue-creep interaction experiments have been carried out for 1.25Cr0.5Mo steel under stress control mode employing a trapezium waveform. The damage evolution laws of 1.25Cr0.5Mo steel under various combinatorial conditions with different maximum stresses and stress amplitudes are derived. Results indicate that the damage parameter and damage model presented in this paper are applicable to describe the damage evolution for fatigue-creep interaction. (C) 2009 Elsevier Ltd. All rights reserved