A hybrid frequency‐time domain life prediction method based on the critical plane theory

This study proposes a multiaxial rainflow counting method to realize simultaneous counting of four‐channel data. The power spectral density (PSD) expressions of stresses and strains in different planes are derived according to multiaxial theories to address the fatigue problems under random vibration loading. This study takes the plane with maximum variance of shear strain PSD as the critical plane and proposes a hybrid frequency‐time domain life prediction method for calculating the life under random vibration loading in combination with the proposed new multiaxial rainflow counting method. Both the feasibilities of the proposed multiaxial rainflow counting method and hybrid frequency‐time domain life prediction method are verified by using the multiaxial fatigue experimental results of 6061‐T6 and 7075‐T6 aluminum alloys under random loading. Meanwhile, the calculation results and efficiencies of the proposed life prediction method are summarized, and the prediction effects of the different multiaxial fatigue models are evaluated, and different rainflow counting methods are compared. Highlights A novel four‐channel multiaxial rainflow counting method is proposed. A novel hybrid frequency‐time domain life prediction method is proposed. Validities of the proposed methods are confirmed by the fatigue life prediction cases. Different life prediction methods and multiaxial fatigue models are evaluated.