The damping capacity of the squeeze film damper in suppressing vibration of a rotating assembly

A flexible shaft with an overhung disc supported by the squeeze-film damper is investigated theoretically and experimentally. The system is simplified as a three-mass system based on a transfer matrix calculation. Governing equations for both models with and without retainer spring are derived. A fast integration method is used to obtain vibration responses. Both concentric and eccentric responses at the damper are examined. Different imbalances and different supply pressures are supplied to see their influence on the vibration of the system. It is found that for the system with retainer spring, positions of the resonance move between two extremes, one of which is the case with no damping in the system and the other with “full damping” where the SFD is locked-out and the system behaves exactly like one without a retainer spring. Therefore, improvements can be obtained by using a centralizing retainer spring and an accompanying SFD as resonance peaks can be moved to lower frequencies and/or such peaks can be kept down to reasonable limits. Nonlinear subharmonic and superharmonic responses are also found.