Effects of Frequency on Structural Stiffness and Damping in a Self-Acting Compliant Foil Journal Bearing

Abstract

This paper presents the results of an investigation into the dynamic structural properties of self-acting compliant foil journal bearings. A test facility with a journal supported by a compliant foil journal bearing was built. The nonrotating journal was driven by two shakers which were used to simulate the dynamic forces acting on the bump foil strips. The structural stiffness and equivalent viscous damping coefficients are calculated based on the experimental measurements for a wide range of operating conditions. The results are compared to the analytical predictions obtained by a theoretical model developed earlier, and the effects of frequency are investigated. Both theoretical and experimental results show that an increase in the excitation frequency decreases the direct damping term. The effect of frequency on the cross-coupling terms is much less than on the direct terms.