Auxiliary bearings are present in active magnetic bearing systems to prevent rotor/stator contact. If rotor/bearing contact occurs, significant impact forces may arise. Furthermore, linear control strategies may become ineffective due to the non-linear dynamics introduced by the auxiliary bearing. Rotor/auxiliary bearing contact is therefore an important consideration for the continued safe operation of an active magnetic bearing system. This work utilizes the localized nature of wavelets coefficients in characterising rotor/bearing contact responses. An experimental approach is adopted using a flexible rotor/active magnetic bearing test rig. Different disturbances resulting in periodic rotor contact and rotor/bearing rub were applied using a single active magnetic bearing. Rotor displacements were measured and the radial component and associated wavelet coefficients identified from off-line data processing. Variations of the wavelet coefficients characteristics corresponding to the periodic contact and rotor/bearing rub are assessed. The choice of mother wavelet is seen to have only a small effect on wavelet coefficient values. Wavelet analysis is shown as a feasible method for identifying time-frequency characteristics of rotor/bearing contact.

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