Investigating the vibration response and modulation mechanism for health monitoring of wind turbine planetary gearboxes using a tribodynamics-based analytical model

In a wind turbine (WT) planetary gearbox system, the characteristics of incipient faults are difficult to recognize with increasing friction under a lack of lubrication condition. To this end, a translational–torsional coupled nonlinear tribodynamic model considering local faults is developed. A fitted time-varying transfer function is obtained using an impact experiment excited by a planet gear with a missing tooth and is further used to represent the modulation effect caused by the carrier. Using the proposed analytical model, the vibration response and modulation mechanism of the resultant signal under the coupling effect of tooth root crack and sliding friction are investigated. It is demonstrated that specific sidebands are greatly excited and the spectrum structure becomes extremely complex after the introduction of friction. Based on these results, sideband indicators are obtained to monitor the lubrication state and detect incipient faults. The experimental results based on an in-house WT drivetrain testbench are in good agreement with the simulation results.