Framework for the Dynamic Modeling of a Helicopter Planetary Gear Train with Gear or Bearing Defect

Gear and bearing dynamics have been independently and widely studied over the past decades in the scope of different applications like the automotive, the energy or the aeronautical industries. Research about dynamic behavior of gear systems under many failure cases has also been conducted: spalling, eccentricity, or teeth breakage are often depicted and their influence over the dynamic behavior and vibrations are of great interest for both researchers and industrials, especially in a goal of predictive maintenance. This research is looking for enhancing the vibration detectability of a particular defect which has not been much considered in literature models, namely a gear rim crack. This particular defect can be initiated on integrated bearing races which are encountered on complex transmission systems: planetary gear trains of helicopter gearboxes. The added value of this paper is based on proposing a framework gathering models from literature, analytical approaches or FE models which deal with the different sub-systems composing the gear train (planet gear, spherical bearing and housing components…) with or without defect. The framework offers the possibility to assemble different models in order to assess the global behavior. The assembly is selected based on tradeoffs between the computation efficiency and the behavior fidelity. Coupling and interoperation methods between sub-models are studied to guaranty the modularity and upgradability of the model, allowing the method to be transposed to future architectures.