An improved fault model of wind turbine gear drive under multi-stage cracks

Considering the real crack propagation paths using the fracture mechanics theory, a novel simulation dynamic model for the two-stage cracked gear drive of the wind turbine is established. The mesh characteristics (time-varying mesh stiffness, contact stress) are obtained with the finite element method. The mesh stiffness under the single-stage and multi-stage cracks is imported into the two-stage cracked gear drive dynamic model to solve the dynamics. The results of the simulation and experiment are performed to verify the proposed dynamic model. The dynamic characteristics and statistical indicators under different cracks are discussed. The results reveal that the crack has a significant influence on the mesh stiffness of the single-tooth contact zone. A rotating periodic impact is found on the time-domain response for the cracked gear drive. Under the single-stage crack, the components of rotating sideband frequencies also appear in the other -stage healthy gear drive. The gear acceleration amplitudes under the multi-cracks are larger than that under the single-stage crack. Therefore, the single-stage crack has an influence on the other -stage gear in the coupling system. This developed result can be applied well to vibration mea-surement and fault diagnosis.