Wind turbine gearboxes are subjected to contact loads during operation, resulting in contact fatigue damage in the gears, which significantly affects their service life. To accurately predict the contact fatigue life of gears, this study takes a 6 MW wind turbine gearbox operating at Dabancheng Wind Farm, Xinjiang, as the research object. A gearbox dynamic model considering both internal and external excitations is established to calculate the dynamic meshing forces of each helical gear pair. The analysis incorporates local material properties and residual stresses in the gears. By applying the Dang Van multiaxial fatigue criterion combined with S-N curves, the fatigue damage distribution in the helical gears under contact loading is analyzed. Fatigue hotspots are identified, and critical operating conditions are extracted to develop a surrogate model, which quantifies the contact fatigue damage and estimates the contact fatigue life of each gear over a 20-year design period. The results indicate that the engage-in and recess points of external meshing pairs in helical gears are the primary fatigue hotspots, making them more susceptible to fatigue failure. Among all gears, the sun gears exhibit the most severe contact fatigue damage, with estimated contact fatigue life of 8 years for the high-speed sun gear and 21 years for the low-speed sun gear. Conversely, the planetary gears in both stages show relatively lower fatigue damage, with their contact fatigue life exceeding 30 years. The ring gear experiences the least fatigue damage, resulting in an exceptionally long service life.

gears  /  wind turbines  /  fatigue damage  /  multiaxial fatigue criterion  /  contact loads  /  key operating conditions