Observational analysis predicts fatigue life of wind turbine gears under random wind loads, suggesting factors impacting crack growth.
This paper aims to put forward a forecasting approach for the residual fatigue life of cracks in wind turbine gears under random wind loads. Taking the NREL 5MW offshore fixed-type wind turbine as the research subject, a profound exploration of the influence of diverse factors on the fatigue crack growth at the gear roots is carried out by integrating the overall analysis of the wind turbine, the dynamic analysis of the gearbox, and the fatigue crack growth analysis of the gear roots. Through the overall analysis of the wind turbine, the input torque and output speed of the gearbox under random wind loads are derived, based on which the dynamic meshing forces and rotational speeds among each gear are computed using the dynamic analysis of the gearbox. The dynamic meshing forces are then compiled into a load spectrum and applied to a single-tooth model with cracks through gear fatigue crack analysis to obtain the remaining number of cycles of the gear. Based on the fracture mechanics method, the residual fatigue life of the sun gear in the first-stage planetary gear train is calculated under different conditions of average wind speeds (7 m/s, 9 m/s, 12 m/s, 18 m/s) and turbulence intensities (14%, 28%, 42%), and the impact of initial double-cracks on the residual fatigue life of gears is also deliberated. The research findings can offer a certain reference for predicting the residual fatigue life of cracked gears in wind power gearboxes.
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Zhang et al. (2025) studied this question.