ON THE DYNAMICS OF UNSUPPORTED SQUEEZE FILM DAMPER BEARINGS

摘要

Stability and bifurcation analysis of squeeze film damped rigid rotors has largely been conducted on configurations where the squeeze film is in parallel with a retainer spring within a rigid housing. A "π-film" cavitation model for the squeeze film has been used in such studies. This paper considers an unsupported squeeze film in series with the bearing housing flexibility. In such a case the squeeze film acts as a bearing, as well as a damper. Moreover, a model for the squeeze film in which cavitation occurs at absolute zero pressure is known to be more appropriate than the "π-film" model. Using this model for the squeeze film, a harmonic balance and stability analysis is performed on the series configuration. Where necessary, numerical integration is also used. The system dynamics are found to be particularly rich around resonance, exhibiting a jump, period doubling bifurcations and quasi-periodicity. A spring softening characteristic is obtained, in contrast to the hardening characteristic observed in parallel configurations. The predicted effects agree with experimental observations reported in the literature.