An efficient life prediction methodology for low cycle fatigue–creep based on ductility exhaustion theory

Low cycle fatigue–creep is the main reason for the failures of many engineering components under high temperature and cyclic loading. Based on the exhaustion of the static toughness and dissipation of the plastic strain energy during fatigue failure, a new low cycle fatigue–creep life prediction model that is consistent with the fatigue–creep damage mechanism and sensitive to the fatigue damage process is presented in an attempt to develop viscosity-based approaches for general use in isothermal and thermo-mechanical loading. In this model, the theory of ductility exhaustion is used to describe the process of fatigue–creep interaction. It was assumed that the ductility exhaustion related only to the plastic strain and creep strain caused by tensile stress under stress-controlled conditions. In addition, the mechanisms of loading waveform, creep and mean stress effects were taken into account in a low cycle fatigue– creep regime. The predicted lives by the proposed model agree well with the reported experimental data from literature under different temperature loading conditions.