For a machine that operates periodically, fluctuations within its operational cycles can significantly affect its stability and service life. In aircraft engines, blades suffer from low cycle fatigue (LCF) caused by prolonged centrifugal loads and high cycle fatigue (HCF) induced by vibration loads. The severity of high-frequency load fluctuations reflects the important characteristics of combined high and low cycle fatigue (CCF) load spectra and has a significant impact on fatigue life. In this paper, a fluctuation coefficient is introduced to represent the severity of HCF load variations, which is used to characterize the additional coupled damage that occurs under CCF loading. A CCF life prediction model is established incorporating the fluctuation coefficient without additional fitting parameters. Validation using materials such as GH4169, 2024-T3 aluminum alloy, TC6, and TC11 demonstrates that the model exhibits high predictive accuracy, and outperforms the Miner’s rule and the T-K model.
Jing et al. (Wed,) studied this question.