Fig. 8 Relationship between Resonant Torsioal Amplitude and Natural Frequency by Dimensional Change of Clearance in Every Kinematics Viscosity, (4.5th Order Vibration, Inertia Rings: No.04, No.05, No.07)
The clearance dimension under 0.5 mm in the range of the low viscosity of the silicone oil is more effective on the reduction of the resonant torsional amplitude than the clearance dimension of 0.5 mm given by BICERA's empirical formula [27]*. But the resonant torsional amplitude in the clearance dimension under 0.5 mm become larger in the range of the high viscosity of the filling silicone oil than that of the clearance dimension of 0.5 mm. And, the optimum clearance dimension of the damper filling with the high viscosity of the silicone oil is nearly 0.5 mm. Fig. 10 (a), (b) shows the relationship between the absolute value of the complex coefficient of torsional viscous damping and natural frequency damper coefficient, respectively. The absolute values of the complex coefficient of torsional viscous damping have approximately the tendencies to decrease with the increase of natural frequency and to increase with the decrease of damper coefficient.
Fig. 10 (b) Relationship between Absolute Damping Coefficient and Damper Coefficient
8. CONCLUSIONS
The experiments, in which the clearance dimensions of the peripheral and lateral gaps filled with viscous fluid and also the kinematics viscosity of its silicone oil are diversely varied, have been carried out and the angular displacements of torsional vibration at the inertia ring and the casing are measured simultaneously. As the results of the experiment on the dynamic properties of the viscous-friction dampers, the following conclusions are obtained;
[1] The clearance value determined from BICERA's empirical formula is not always optimum on the every viscosity of the filled silicone oil of the viscous dampers.
[2] The optimum viscosity is different by the dimensions of the peripheral and lateral gaps filled with viscous fluid between the outside of the inertia ring and the inside of the casing.
