Static Performance of Multi-leaf Compliant Gas Foil Journal Bearings with Assembly Preload

Gas Foil Bearings (GFBs) are self-acting hydrodynamic bearings and potential alternatives to rolling element bearings for high speed applications. In order to increase load capacity, the assembly preload is often added to GFBs now. Firstly, for multi-leaf GFBs with assembly preload, this paper presents a method to fabricate the bearings with assembly preload, and the precision of the shape of the top foils is discussed. Then, the bearing deflection with static load of the foil bearing was measured. A static load, which is up to 340N, could be applied to the tested GFBs with assembly preload by a mechanical loading device, and a strain gauge type load cell was used to measure the applied static load. Finally, the stiffness coefficient of the tested bearing was estimated and a cubic polynomial of stiffness coefficient for test bearings is estimated using the measured static load versus deflection test data. The results show the radius of top foils which were fabricated by this method can be changed by different pressures and the accuracy of foil shape is improved. The load capacity and stiffness are both two times larger than bump-type GFBs.