Theoretical modeling and experimental study of fluid-elastic isolator

组合式液弹隔振器传递特性分析及试验研究

China Helicopter Research and Development Institute, Jingdezhen 333001, China

Received: 10 May 2021

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.

摘要

液弹隔振器作用在直升机主传递通道上, 能大幅降低旋翼传递到机身的振动载荷, 是一种直接有效的隔振方式, 在国外已被广泛研究并实现工程应用。根据动力反共振原理建立了组合式液弹隔振器模型, 并基于广义Lagrange方程推导了其动力学方程。研究了液弹隔振器传递特性随参数的变化规律, 并据此针对某民用直升机振动特性完成液弹隔振器主要参数设计。制作隔振器原理样件并开展组合式液弹隔振器传递特性试验, 采用扫频方式考察液弹隔振器在不同激励频率及激振位移幅值下的位移传递率。结果表明, 理论分析与试验结果具有较好的一致性, 在3种激振幅值下, 所设计的隔振器在反共振点仅有30%的位移传递率, 表明组合式液弹隔振器具有较好隔振效率。理论分析显示液弹隔振器隔振效果受到多种设计参数的综合影响, 针对特定隔振频率, 需统筹完成隔振器参数设计。