An efficient fatigue-creep interaction life prediction model based on frequency separation and strain energy damage theory

The high temperature equipment is used more and more widely with the development of aviation, aerospace, petrochemical and other industries. Such components and structures of these equipments are subjected to creep damage during steady-state operation and thermal fatigue damage in the frequent on-off operation, its potential danger is great, once an accident happens, it is always catastrophic. In this paper, we proposed a new model for the fatigue-creep interaction life prediction under the high temperature low cycle loading, which is based on the frequency-modified Manson-Coffin equation and Ostergren´s theory. The proposed model can consider the effects of the stress ratio, hold time, loading waveforms, frequency, and it is applicable to not only stress controlling mode, but also strain controlling mode. In additional, the predicting precisions of the models are greatly improved comparing with the model which was proposed by Smith, Watson and Topper (SWT) and the plastic strain energy and fatigue model (PSED). Experimental data from literature are used to verify the proposed model. The results show that the proposed model has a better predictability for the fatigue-creep interaction.