Design and optimization of permanent magnetic thrust bearing used in vessels

To isolate the vibration transmitted from the propeller to the vessel's hull, the main engine, the shaft together with the bearings are proposed to be installed on a large-scale isolation system. Permanent magnetic thrust bearing (PMTB) is applied to further reduce the vibration transmission. The Coulombian model is adopted to calculate the force and stiffness, which determine the application feasibility of the PMTB in vessels. Explicit computations are presented for stacked PMTB. The calculation result is compared with that obtained by finite element method (FEM) and experimentally tested. It is revealed that the Coulombian model is accurate enough and more economic than the FEM, which make it advantageous to the structure design and parameter optimization of PMTB. In the influence study by Coulombian model, it is found that the airgap width can exponentially change the maximum axial magnetic force and stiffness; the radial width is not a sensitive factor for both force and stiffness; the axial length should be 4/5 of the radial thickness to obtain the largest force and decent stiffness.