Improvement of the Static and Dynamic Characteristics of Water-Lubricated Bearings With Integrated Halbach Magnet Arrays

Abstract

The generation of frictional vibration and noise by water-lubricated bearings is one of the most severe problems putting at risk the safety and concealment of ships. Here, Halbach magnet arrays were integrated as the upper bush of the water-lubricated bearing with the aim of suppressing frictional vibration. Simulations and experiments were conducted and compared between the magnetic bearing and a normal rubber bearing. Effects of magnetic strength, Halbach array length, rotational speed, and external load on bearing characteristics were analyzed. The results show superior static and dynamic performances on the magnetic bearing. More specifically, attractive forces generated by Halbach magnets can reduce static pressure by nearly 37% on the bottom bush. Stiffness of magnetic bearings was calculated as smaller than for normal bearings, indicating a lower natural frequency. Shaft trajectories were observed close to the geometric center of bearing yielding less stress concentration on the bottom bush of the magnetic bearing. Finally, test rig experiments demonstrated suppressed vibrational peaks and reduced frictional vibration (more than 10 dB) on the magnetic bearing. It is also interesting to note that the magnetic bearing even shows exceptional robustness regarding fluctuations of rotating speed or external load. This study presents a new routine for overcoming the frictional vibration and noise of water-lubricated bearings.