Theoretical modeling and experimental study of fluid-elastic isolator

Abstract

The fluid-elastic vibration isolator, mounted on the final reduction channel of a helicopter, could reduce the vibration acting on the airframe effectively. It is an efficient approach to vibration load isolation, therefore has been studied and employed vastly abroad. A fluid-elastic vibration isolator is designed based on the theory of dynamic anti-vibration isolation. The equation of motion is derived by applying the Lagrange principle. Parametric study is carried out to investigate the dynamic performance with varying parameters. Then the main design parameters are determined on the basis of the vibration characteristics of a civil helicopter. Experiments are conducted on the fluid-elastic vibration isolator; the performances are evaluated for different excitation displacements employing the frequency-sweeping technique. Theoretical analysis indicates that the performance of an isolator is the overall effect of various parameters, therefore all the factors should be considered for a specific isolation frequency. Experimental results reveal that the fluid-elastic vibration isolator demonstrates only a 30% of displacement transfer rate. The theoretical analysis is in good agreement with the experimental finding. Experiments with different excitation displacements show that the displacement transfer rate increases slightly with the increase of the displacement.

Keywords

• fluid elastic vibration isolator
• dynamic anti-resonance
• parametric influence analysis
• displacement transfer rate
• vibration isolation experiment