Fatigue Analysis of Bearings in Planetary Gearboxes of Turbofan Engines Taking into Account Dynamic Loading

This paper presents a calculation method for assessing dynamic loading of bearings in satellites of planetary gearboxes of turbofan engines. The method is based on the analysis of a dynamic model of a planetary gearbox with lumped parameters for a planetary gear set with a fixed carrier. Simulation of the variable stiffness function of gear tooth meshing using the finite element method in a quasistatic formulation is employed for a more accurate assessment of the main source of excitation in the tooth meshing, that is the kinematic error, which includes both tooth deformations under load and technological deviations. Based on the comparison of the frequency response of the dynamic coefficient with and without tooth modification, it is established that the introduction of a modification reduces the dynamic coefficient in some modes by 2 times. The calculation results demonstrate that without taking into account the dynamic loading of the bearings, the bearing life is overestimated by about 11%. The design of a gearbox with satellite bearings on rolling bearings is considered.

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