Numerical and analytic characterization of satellite microvibration produced by ball bearings

Microvibrations onboard satellites are a well-known problem which degrades the pointing accuracy of satellites by inducing oscillations to their line-of-sight. Rotating devices, such as reaction wheel assemblies (RWAs) are the major cause of these 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, affecting sensitive instruments' performance. This research focuses on the characterization of RWA microvibration frequency and amplitude by implementing an articulated series of high-fidelity finite element analyses (FEA), complemented by analytical modeling. This is achieved by introducing bearing geometry imperfections and varying some structural parameters such as the preload, as well as the number of rolling balls and their dimensions. Finally, the data collected is used to construct the microvibration waterfall plots of the different defects. Their noise signatures are post-processed and compared so as to find the most beneficial top-level RWA design parameters.