隔振是一种航天器振动控制的重要方法,隔振器动力学特性的理论研究是隔振设计的重要基础。本文针对一种航天新型粘性流体微振动隔振器,基于非牛顿流体物理属性、隔振器宏观传热特性、运载火箭-卫星轴向振动特性,提出了发射段的隔振器及运载火箭-卫星-隔振器系统的非线性热-振耦合模型。通过自行设计基础激励试验测试平台,对不同环境温度下的流体阻尼系数和体积刚度系数进行测试,并将试验得到的阻尼、刚度数据输入隔振模型中进行仿真分析。研究结果表明,隔振系统具有时变性和非线性,流体粘性热导致共振频率漂移、共振幅值变化,隔振器性能与激励幅值、激励频率相关,需要采用新的“共振带”和“隔振带”的概念进行设计。本文理论模型和研究方法可为隔振器热振耦合特性评估、优化设计及工程应用提供理论依据和参考。
Vibration isolation is an important method of spacecraft vibration control, and the theoretical study of the isolators' dynamic characteristics is an important foundation to design a specified isolator. In this paper, a new type of micro-vibration isolator which contains viscous fluid is investigated. Based on the Non-Newtonian fluid property, macroscopic heat transfer characteristics of the isolator and the axial vibration behavior of a typical launch vehicle-satellite system, two nonlinear thermo-vibration coupling models of the isolator and the launch vehicle-satellite-isolator system during the launch stage are firstly proposed. Then the damping coefficients and volumetric stiffness coefficients under different temperature environments are measured with the self-designed base excitation test-setup, and these parameters are input into the above models to conduct a simulation. The results show that the behavior of the vibration isolation system is nonlinear and time-variant, and the fluid temperature increase which comes from the viscous heating can lead to a shift of resonant frequency and a fluctuation of resonant amplitude. Moreover, the performance of the isolator is also closely related to the excitation amplitude and excitation frequency, and two new conceptions, i.e., resonant band and isolated band, should be utilized to design the detailed interior structure. Thus the presented theory and method can provide a reference and a theoretical basis for the thermo-vibration coupling characteristics evaluation, optimal design and engineering application of this type of fluid micro-vibration isolators.