Time-Varying Meshing Stiffness Investigation of Faulty Wind Turbine Sun Gear Under Dynamic Conditions

The increasing financial implications of gearbox failures for wind turbines have necessitated a need for proactive measures to abate downtimes of the system. The sun gear of this gearbox is most vulnerable to failure due to the increased number of planet gears meshing in this stage and its higher load transmission capabilities. The study of the stiffness of the teeth during meshing is vital in investigating different failure occurrences in the gears. Estimating the time-varying meshing stiffness (TVMS) accurately under dynamic conditions requires the finite element method (FEM). Hence, this study utilizes FEM to investigate the impact of the most recurring faults (cracks and pits) on TVMS under dynamic conditions. The TVMS of a healthy sun-planet gear model is computed using FEM considering loading from a critical season in the Western Cape, South Africa. To accommodate dynamic load variation, thirteen defects of cracks and pits are induced on the teeth of the sun gear model, and their TVMS are simulated. Furthermore, the impact of both faults occurring at the same time is examined. The full TVMS results of the healthy and faulty models are compared, and their mean deviations were estimated. The mean deviations from the healthy response of the cracked, pitted, and simultaneous fault responses are 2.75%, 4.58%, and 6.11%, respectively. The TVMS of the simultaneous occurrence was found to be influenced by the combined effect of both faults.