Rated Life Calculation Potential of Gearbox Model Based Force Estimates

One main contributor for gearbox rated lifetime estimation is the assessment of bearing loading during predicted operating conditions. This paper investigates an approach to determine input bearing loading by means of a TPA (Transfer Path Analysis) approach. TPA is suggested to retrieve internal bearing forces from acceleration measurements acquired at the outside of the gearbox housing. However, classical TPA methods would require the gearbox to be dismantled during the transfer path determination process. This poses significant practical challenges. To overcome this issue, this paper investigates the possibility of using a flexible multibody simulation model to calculate the different frequency response functions between bearings forces and acceleration sensors. All simulations use a flexible multibody modeling approach, which has been extensively validated. Main results of this validation process have been published by the authors in the past. The paper discusses the results of such analysis on a multi-megawatt wind turbine gearbox. Here, simulated acceleration measurements on the gearbox housing are processed into bearing forces. The feasibility of using these forces for a rating life calculation is investigated.