Influences of correlations between biaxial random vibrations on the fatigue lives of notched metallic specimens

摘要

In the study, a hybrid frequency-time method is proposed to estimate the fatigue lives of notched metallic specimens under multiaxial random vibrations with different correlations. Firstly, a testing structure is designed and the biaxial random vibration fatigue tests are conducted to study the influences of correlations between two vibration axes on the fatigue lives of the notched specimens. Then, the crack initiation point of the notched specimen is determined by the random vibration analysis with the finite element method (FEM). And the fatigue critical point is determined through the crack initiation point and the point method of the theory of critical distance (TCD). The stress time histories at the fatigue critical point are generated from the stress power spectral density (PSD) matrix by the time domain randomization approach. Finally, the fatigue life estimation is performed by the modified Woehler curve method (MWCM) at the fatigue critical point. The results show that all the estimated fatigue lives are within the three-time scatter band of the experimental fatigue lives.