Influence of electromagnetic bearings on lateral vibrations and sound radiation of a shaft-hull system

The fluctuating load of a propeller in the non-uniform wake field can excite the propulsion shafting system and further induce vibrations in the hull structure. In order to reduce transmission of lateral vibration from the shafting system to the hull, a new method using electromagnetic bearings is proposed. The feasibility of using active bearings in vibration and sound control is evaluated. A dynamic model of the shaft-hull system is established with the frequency response synthesis method at first and subsequently, the influence of the dynamic magnetic forces provided by the electromagnetic bearings on the suppression of vibration transmission is analyzed. Numerical results indicate that the equivalent stiffness and damping of the shafting support and the associated vibration transmission are changed by the electromagnetic bearings, which results in decreased vibration and sound radiation of the hull.