Active bump-type foil bearing with controllable mechanical preloads

This paper presents an active bump-type foil bearing (ABFB), in which mechanical preloads can be actively adjusted by controlling the driving voltages of piezoelectric actuators (PZTs) to create a variable multiple-lobe clearance and enhance bearing performance. A theoretical model that couples active and compliant foil structures is proposed, and static load-deformation tests and measurements of airborne drag torque on the basis of a prototype bearing are conducted at different driving voltages. Tests results show that the proposed active structure is feasible and effective in controlling mechanical preload. Moreover, the static and dynamic performances of ABFB are discussed. This work lays foundation for the further study of active control methods in gas foil bearings.