2021 Volume 66 Issue 5 Pages 372-383
Bump foil journal bearings are prospective applicants that can support a small-sized rotor of high-speed rotating machinery. The performance characteristics of the bearings are predicted by using a model bearing. When the air film thickness can be assumed to be uniform in the axial direction, a finite element (FE) model using curved beam element is appropriate to be applied in analyzing the displacement of bearing surface which is referred to as top foil. On the other hand, the top foil need be replaced with a thin shell in order to predict the performances of the bearing that has non-uniform air film thickness in the direction. In this study, an isoparametric shell element, which can couple the membrane and the bending effects of top foil, is introduced into the deformation analysis instead of a plate shell element adopted in the previous paper. The replacement of FE model is found to have a large influence on the bearing performance because of the change in the air film characteristics. It is concluded that the isoparametric shell element is appropriate in predicting the performance of the bearing that has non-uniform air film thickness in the axial direction.
