Abstract: When an active magnetic bearing （AMB） is used in advanced jet aero-engines, the base of the AMB system in flight will vibrate at the same frequency as the wing of the airplane and endure an impact load in landing. In these cases, the base vibration and the impact load not only have a great effect on the dynamic behaviour of a rotor system supported on AMBs, but also possibly make the rotating shaft contact with the back-up bearing of the AMB system or make the AMB system fail. The effect of the sinusoidal base vibration at different exciting frequencies and amplitudes on the dynamic behaviour of a rotor system supported on the AMB is experimentally studied in this paper. It is shown that the capability of the AMB's controller for suppressing the base vibration is very limited and that the effect of the base vibration on the dynamic behaviour of the AMB-rotor system must be considered in designing the AMB's controller, otherwise, the AMB will lose its support capability. The higher the amplitude of the base vibration, the greater the effect of the base vibration on the AMB and the higher the possibility of the AMB system failure.

Key words: active magnetic bearing, base vibration, rotor-dynamics, vibration, rotor, controller