Nonlinear dynamic responses of a rigid rotor supported by active bump-type foil bearings

Abstract

Active bump-type foil bearings (ABFBs) enhance the rotordynamic characteristics of rotor–bearing systems with the advantage of controllable mechanical preloads. However, the coupling of controllable mechanical preloads, compressible gas film, and foil structures induce strong nonlinear characteristics and affect the dynamic responses of rotor. In this study, a nonlinear theoretical model that considers the gyroscopic effect of rotor, nonlinear Reynolds equation, complicated foil structures, and dynamic motions of active substructures is presented. This model is verified by a corresponding rotordynamic test. The nonlinear dynamic responses of a rotor–ABFB system are discussed on the basis of waterfall plots, orbit simulations, and Poincare maps of rotor center, fast Fourier transform, minimum film thickness, and power loss during one cycle of journal orbit. The effects of voltage on piezoelectric actuators, nominal clearance, width of flexure hinge, and static load on the nonlinear rotordynamic responses of rotor are analyzed to provide guidelines on selecting the design and control parameters of rotor–ABFB systems.