Fatigue prediction of wind turbine main bearing based on field measurement and three-dimensional elastic drivetrain model

• A three-dimensional elastic drivetrain model is proposed to predict the shaft moments and torque arm movements. • The load factor caused by the pounding is evaluated by the proposed pounding model of main bearing. • The new parameters of life ratio and load factor play an important role in accurately predicting the rating life of main bearing. Fatigue of main bearing significantly affects the reliability of drivetrain system (DTS) and strongly depends on the DTS configuration. Main bearing failure rate is high for Three-Point Mount wind turbine within the designed life. In this study, a three-dimensional elastic DTS model is established and validated with field measurements. The predicted shaft moments and torque arm motions show good agreements with observations. A numerical pounding model of main bearing is then proposed to evaluate the load factor due to pounding. Finally, the formulas in ISO 281 for predicting main bearing rating life L 10 are modified by introducing two new parameters: life ratio and load factor. The predicted rating life L 10 matches well with the onsite records.