포일 구조의 3차원 형상을 고려한 포일 저널 베어링의 정특성 해석

Foil bearings comprise a foil structure made of a corrugated bump foil layer covered by a top foil surface. To obtain the foil bearing characteristics, the fluid film pressure needs to be coupled with the elastic deformation of the foil structure. A number of successful analytical models to predict its deformation have been developed by many investigators, and some models show very good agreement with experimental data. However, all the structural models so far treat a bump foil layer as a simple elastic foundation without consideration of its three dimensional shape. In this study, a finite element foil structural model is proposed. In this model, the bending and membrane stiffness effects of the top foil and bump foil are included and the three-dimensional shape of the foil structure is considered. Using developed model, the deflections of inter-connected bumps are compared with those of separated bumps to investigate stiffness effects of segment between bumps. The minimum film thickness determined from the proposed structural models compared to those of previous models. In addition, the effects of top foil and bump foil thickness on the foil bearing static performances are evaluated.