Dynamics Analysis of Elastic Ring-Type Extruded Oil Film Damper Considering Time-Varying Characteristics

The elastic ring squeeze film damper (ERSFD), due to its compact structure and excellent mechanical properties, has been increasingly applied in various types of combination bearings for aero-engines. During operation, the force state of the elastic ring varies with different precession angles of the journal, leading to changes in the stiffness of the elastic ring. This study, based on a bidirectional fluid-structure interaction (FSI) theory, analyzes the deformation and stiffness of the elastic ring under different contact conditions. The time-varying stiffness curve of the elastic ring is obtained, and the influence of various parameters on its time-varying stiffness characteristics is further investigated. An equivalent stiffness method for the elastic ring is proposed, which improves accuracy by more than 3% at low speeds compared to traditional methods. Using this equivalent method, the effects of parameters such as the number of ring protrusions, protrusion width, protrusion angle, elastic ring thickness, and oil film eccentricity on the pressure distribution of the inner and outer oil films are analyzed. The results indicate that an increase in the number of elastic rings, protrusion width, axial length, and ring thickness leads to a rise in stiffness, with the number of protrusions having the strongest effect and the axial length having the weakest effect. Additionally, as the number of protrusions, protrusion width, and protrusion angle increase, both the damping and stiffness of the inner and outer oil films decrease by approximately 10%, with a more significant impact on the outer oil film than on the inner oil film. When the axial length and oil film eccentricity increase, both the damping and stiffness of the inner and outer oil films also increase, with the inner oil film being highly sensitive to eccentricity. However, excessive eccentricity enhances the nonlinearity of the oil film. The findings of this study provide a theoretical foundation for the design, application, and maintenance of combination bearings incorporating elastic ring squeeze film dampers.