HIGH SPEED BEARING FATIGUE LIFE AND RELIABILITY ANALYSIS OF WIND TURBINE GEARBOX UNDER RANDOM LOAD

In order to explore the fatigue life and reliability of the high-speed shaft cylindrical roller bearing of the wind turbine gearbox during service，with the annual wind load of the Dabancheng wind farm in Xinjiang as the external excitation，a stochastic wind speed model based on Weibull distribution，and a gear- bearing coupling dynamics model of the wind power gear transmission system considering incentive factors such as the time-varying mesh stiffness of the internal gear and the time-varying stiffness of the bearing，were established. And dynamic load of the high-speed shaft bearings was solving by Newmark integral method. The symmetrical cyclic stress was obtained by using the rain-flow counting method and the Goodman mean stress correction method. The contact fatigue life and dynamic reliability of the bearing were obtained by comparing the linear damage theory and the nonlinear damage theory. The results show that at a rated power，under the combined action of external random wind load excitation and internal gear-bearing coupling，the internal excitation still plays a major role in the dynamic load of the high-speed shaft bearing system. Compared with the linear damage accumulation theory，the nonlinear theory considers the sequential effect of load loading，thus could be better to describe the fatigue damage of the bearing at each stage throughout the fatigue life. During the service process of the bearing，the damage in the first 15 years is relatively small，and the reliability decays slowly，but the reliability shows a nonlinear rapid decline trend in the later period，thus the maintenance strategy should be adjusted in time. © 2023 Science Press. All rights reserved.