低温容器新型纤维支撑系统固有频率特性研究

Research on Natural Frequencies of the New Support Structure for Cryogenic System

为降低某航天用小型低温杜瓦的漏热,同时提升其力学性能,采用了超高强度、低热导率且密度小的凯夫拉纤维作为杜瓦的支撑材料,设计了支撑结构。通过对结构建立固有频率理论模型,采用Rayleigh法推导了前6阶固有频率的表达式,用有限元分析软件Ansys与理论计算结果进行了对比。对其中某工况设计了实际的实验支撑结构,对结构进行了三向扫频实验。理论计算结果与有限元仿真结果趋势符合良好,实验结果与理论模型误差在20%以内。结果表明,在此种支撑结构中,凯夫拉纤维的横截面积、纤维绳索布置的轴向角以及平面角对其固有频率具有较大影响,接触点距离以及纤维绳索预紧力对固有频率影响较小。

In order to decrease the heat leak of some space used Dewar and enhance the mechanical property at the same time, Kevlar fiber which has ultra-high strength,ultra-low thermal conductivity and low density is used as the support material, and the support structure is designed at the same time. A theoretical model of the natural frequency is established and the six natural frequencies are deduced from the model using Rayleigh method. Finite element method (ANSYS) is used to compare with the computation results. Finally, the support structure under certain condition is designed and the frequency experiment is done. The theoretical results are in agreement with the simulation and the deviation between theoretical model and experimental results is smaller than 20%. Results show that the cross area, axial angle and plane angle of the Kevlar support structure have a great influence on the natural frequency, but contact point distance Ls and the pre-tightening load have less influences.