A Simple FEM Model for Foil Bearings Under Differential Pressure

A bump-type foil bearing consists of a compliant corrugated sheet metal supporting structure that is covered by a thin top foil surface. Bumps serve as stiffener and damping elements to increase the stability of the system while top foil creates necessary wedge surface for aerodynamic film formation. Foil bearings are hard to analyze as flexible foil surface deforms and changes shape while aerodynamic film pressure forms. Iterative solutions required typical of EHL analysis. This work utilizes Reynolds Equation to solve aerodynamic film pressure by coupling structural deformation and the fluid film pressure formation. Bearing performance under various operating conditions and the effect of differential pressure boundary condition on sealing capacity is discussed.