The rotor investigated is supported on two major ball bearings with squeeze-film dampers in the absence of the centralizing retaining springs. The coefficients of the film forces are linearized by using dynamical performances of the damper in the fixed coordinate system (four oil-film stiffness and four oil-film damping coefficients). The steady-state unbalance responses of an asymmtrical flexile rotor system has been easily determined by means of transfer matrix and linear iterative methods. Generally speaking

for the rotor system with nonlinear squeeze-film dampers

the optimum damper design with suitable unbalance level of the rotor

i.e. the mass eccentricity e = 0.01cm

will achieve the effect of vibration depression. The calculations show that the effect of vibration depression with two squeeze-film dampers is better than that with one. This conclusion has also been proved by the measured vibration data of a jet engine.