Microvibration simulation of reaction wheel ball bearings

Microvibrations on board satellites are a well-known problem affecting their pointing accuracy by inducing oscillations to the line-of-sight. Fast rotating devices, such as reaction wheel assemblies (RWAs) are a major cause of these onboard mechanical disturbances. Imbalances in the flywheel, as well as imperfections in the ball-bearing components yield low-amplitude vibrations that are transmitted to the satellite structure, adversely affecting the performance of sensitive onboard instruments. This research focuses on the RWA's ball bearing microvibration frequency and amplitude characterization. This is achieved by introducing specific geometry im-perfections on the ball bearing rotating elements. In addition, variables such as the ball bearing preload, the number of balls and their dimensions are altered to understand how the bearing microvibration changes in order to minimize it. Finally, available physical microvibration test data is used to compare and cross-correlate the microvibration waterfall plots obtained from the transient FEA of the parametrized bearing models introduced herein. This work provides a better understanding of the relation between the main structural ball bearing parameters and the microvibration disturbances emitted by the RWA to minimize its mechanical noise.