Effects of Static Load on Dynamic Structural Properties in a Flexible Supported Foil Journal Bearing

This paper describes an experimental investigation into the structural dynamic characteristics of corrugated foil (bump foil) strips used in one type of compliant surface foil journal bearings and dampers. The nonrotating journal was supported by a compliant foil journal bearing and driven by two shakers which were used to simulate dynamic forces acting on the bump foil strips. The dynamic structural stiffness and equivalent viscous damping coefficients were calculated based on the experimental measurements for a wide range of operating conditions. The results were compared to the analytical predictions obtained by a theoretical model developed earlier, and the agreement is considered reasonably well. Both experimental and theoretical results show that the direct structural stiffness and damping coefficients increase with increasing bearing static load.