Vibration reduction in a hollow-shaft rotor using flexibly-mounted internal-stator magnetic bearings

A topology composed of a hollow-shaft rotor on rolling element bearings coupled with internal-stator magnetic bearings mounted on independently supported flexible shafts is considered for the purposes of vibration reduc- tion. Details of a bespoke test rig constructed to assess this topology are presented. The rig makes use of custom-designed internal-stator magnetic bearings fabricated from Soft Magnetic Composite material. Results from standard numerical analysis of the rig are given to demonstrate the expected behaviour of the system, with a particular focus on its potential to reduce synchronous vibration seen while passing critical speeds. These be- haviours are then confirmed via both impulse frequency response tests and rotating run-down tests. These results show that the proposed topology can be used effectively to alter the system vibration behaviour.