Novel Integrated Model Approach for High Cycle Fatigue Life and Reliability Assessment of Helicopter Flange Structures

As one of the critical components in helicopter transmission systems, the flange is prone to fatigue damage and failure under complex operational conditions, which seriously influence operational safety and service life. To improve the structural integrity of flanges, an exponential distribution optimizer (EDO)-based integrated surrogate model (ISM) method is proposed for the fatigue life prediction and reliability evaluation of the flange structure. In this method, the Bayesian model averaging method is adopted to build a high-efficient surrogate model and the EDO is used to find the optimal parameters of the model. The high cycle fatigue (HCF) life prediction and reliability evaluation of the helicopter flange structure are performed by the proposed EDO-ISM method and other methods. Results demonstrated that the EDO-ISM method improves modeling precision by 63.17% and computational efficiency by 8.743%, relative to other methods. The reliability analysis shows a high reliability degree of 0.9981 for the flange structure, while sensitivity analysis reveals that rotational torque (S = 0.386, I = 0.312) and the fatigue ductility index (S = 0.312, I = 0.278) are the most significant parameters affecting the flange HCF life. These results reveal the strengths of the EDO-ISM method in the HCF life prediction and reliability evaluation of the helicopter flange structure. The efforts of this study provide a promising method for the HCF life prediction and reliability evaluation of complex structures besides helicopter flanges under complex working conditions.