Revisit to Stiffness of Bump Foils in Air Foil Bearings

Air foil bearings have compliant elastic foundation to provide compliance to bearing surface and damping. The most widely used elastic structure is the corrugated bump foil. All the currently available formulas for the bump stiffness [1–3] do not consider bending moments at the bump supports and within the straight contact patch which connects the bumps. However, for continuous bump foils, bending moments at the support points where contact is made with the bearing sleeve cannot be neglected. This paper introduces a set of new formulations for stiffness of bump foils considering the bending moments at the support points. All the formulas were derived using computer algebra software. The results are compared with the result from other formula [3].