A rotating machine with active magnetic bearings (AMBs) requires conventional bearings as a backup support system in the case of AMB failure. This paper presents an estimated auxiliary/catcher bearing (CB) L10 fatigue life based on the Hertzian contact dynamic loads between bearing ball and races during the touchdown. The thermal growths of bearing components are predicted using a one-dimensional thermal model, and the resulting expansions contribute to the calculation for the Hertzian contact loads. Numerical simulations for an energy-storage flywheel module reveal that a high-speed backward whirl significantly reduces the CB life and that an optimal damping lowers the CB temperature and increases the CB life.

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