Suppression of lateral vibration in a shafting system via an auxiliary active magnetic bearing with position control

The bearings in a shafting system are important paths for the lateral vibration of the shaft to transmit to the hull structure and induce underwater sound. An auxiliary active magnetic bearing for suppressing the lateral vibration at the stern support of a shafting system is investigated. The active magnetic bearing situated close to the stern bearing generates electromagnetic forces to support the shaft, which decreases the contact stiffness as well as the friction between the shaft and the stern bearing and accordingly reduces the stern support acceleration. A dynamic model is established using the Timoshenko beam theory and Hamilton's principle and the performance of the active magnetic bearing in vibration suppression of the shafting system is evaluated with position control. An experimental system is also built to verify the effectiveness of the active magnetic bearing. Numerical and experimental results have shown that the active magnetic bearing is able to suppress the stern support acceleration responses after the shaft is suspended by the active magnetic bearing. Moreover, the orbit of the shaft center is controlled as well.