Abstract: In the bearing-rotor system, rotor misalignment occurs from time to time, which has a great impact on the bearing performance. At present, most of the studies on gas foil bearings are two-dimensional models, which cannot consider the difference in axial deformation of bearings, so it is impossible to analyze rotor misalignment.. In this research, the shell theory is used to simulate the gas foil bearing, and the three-dimensional model is established. The shell element is used to model the top and bump foils, and the membrane, bending and shear effect are considered. The friction contact between bump and top foil is based on point-line contact, and the contact force is calculated by penalty function method. Due to the high nonlinearity of Coulomb friction model, in order to avoid the difficulty of numerical solution, it is regularized and solved by incremental iterative method. The results show that the model can simulate the structure of foil bearing effectively. When the rotor is not correct, the gas film thickness in the foil bearing will be distributed unevenly along the axis. The minimum film thickness decreases with the increase of the inclination Angle, and the inclination Angle almost does not affect the rotor eccentricity. The deformation of one end of the fop foil is much larger than that of the other end, which will reduce the bearing capacity of the foil, even cause damage.

Key words: gas foil bearing, misalignment, shell theory, the incremental iterative method, contact mechanics