Experimental investigation for effects of static eccentricity on vibration attenuating characteristics of squeeze film damper

A flexible rotor system with squeeze film damper (SFD) was constructed and the static eccentricity of the SFD can be altered independently. Performance of the damper, resistance capability for the vibration and the character of the nonlinear vibration of the rotor are experimentally investigated under different static eccentricity level. The results reveal that the static eccentricity results in the increase of the critical speed. Critical amplitude decreases with the increase of the static eccentricity ratio ε_s when ε_s< 0.6, while the critical amplitude increases sharply with the increase of the static eccentricity ratio when 0.6 < ε_s < 1. When the static eccentricity rises, the unbalance of failure of attenuating vibration for the damper decreases significantly and the vibration resistance ability of the rotor is also influenced greatly. The static eccentricity ratio should be less than 0.2 to insure effective damping performances of SFD. The bistable jump phenomena are observed with a low level static eccentricity (ε_s <0.2), while the non-linear soften-spring effect and the nonsynchronous vibration can be observed with a high level static eccentricity (ε_s>0.3), when the failure of attenuating vibration happens. The vibration characteristics when damper fail to attenuate vibration can be used to identify the static eccentricity level of the damper.