SUBHARMONIC, QUASI-PERIODIC AND CHAOTIC MOTIONS OF A RIGID ROTOR SUPPORTED BY AN ECCENTRIC SQUEEZE FILM DAMPER

This paper analyses the complexity of the unbalance response possible with a simple rigid rotor supported by an eccentric squeeze film dampe r. The damper forces are obtained from the 'pi' film short bearing app roximation to the Reynolds equation and a fourth-order Runge-Kutta int egration is used to evaluate the rotor response. Poincare maps, rotor trajectories, bifurcation diagrams and power spectra are used to eluci date and to illustrate the diversity of the system behaviour. It is sh own that for a large unbalance and static eccentricity ratio, the syst em can exhibit undesirable jump phenomenon and subharmonic, quasi-peri odic and even chaotic motions, which limit the operating conditions at which dampers should be used.