New methodology to define roller geometry on power bearings

This article presents new tools developed to improve the geometrical corrections required on roller bearings of Helicopter gearboxes suffering from heavy deflection. A complex non-linear finite element model of the whole gearbox is firstly implemented to identify the deflection of inner and outer raceways under operational loads. The computed misalignment is then used as an input to predict and check the contact pressure edge effects occurring in the contact area and iteratively optimize the roller shape. Several approaches are tested based either on Boussinesq's potential theory or on specific FEM calculations. They permit increasing the service life of the bearings while reducing the overall gearbox development lead-time.