Application of a combined high and low cycle fatigue life model on life prediction of SC blade

A combined high and low cycle fatigue life prediction model for nickel-base single crystal (SC) has been presented to analyze the low cycle fatigue (LCF) and high cycle fatigue (HCF) life of SC blade. In the paper, a power law function of life model based on crystallographic theory is adopted to predict the LCF life. A power law function based on elastic analysis is adopted to predict the HCF life. Furthermore, the LCF and HCF experiments at different temperature are carried out to obtain the model parameters. The predicted results show that the model is reasonable for LCF and HCF. The linear life model introduced in the paper satisfies the combined high and low cycle fatigue life prediction of nickel-base single crystal superalloy. Special attention is put on the combined high and low cycle fatigue life of SC turbine blade. The resolved shear stress and first-order vibration stress are analyzed by the crystallographic rate dependent finite element analysis (FEA) and orthotropic elastic FEA, respectively. It is shown that the prediction model can be well used in the fatigue life prediction of SC blade.