Abstract
To meet the demands of high speed and excellent stability in modern oil free turbomachinery, a hybrid foil-magnetic bearing (HFMB) was first designed by Heshmat in 2000 [1]. However, in the HFMB, the journal should be carried out in certain eccentricity and attitude angle to the center of the bearing house due to hydrodynamic force which provided by the GFB. While the magnetic force caused by the AMB would try to force the journal of the reference position which is usually the center of the bearing at all times when using a conventional PD controller. While magnetic forces were commonly linearize at the center position of the bearing with respect to journal displacement and coil current. Therefore, the fully nonlinear force to displacement and the force to current characteristics concerning the journal eccentricity effect should be applied. The main objective of this paper is to represent a kind of theoretical method to calculate the load capacity, dynamic stiffness and damping coefficients of the HFMB under a specified load sharing factor λ with the predetermined operational state.