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针对大型可展开环形桁架天线结构开展了模态实验和有限元仿真分析。首先设计加工了环形桁架实验模型,采用锤击法对自由边界条件下环形桁架结构进行了实验模态分析,得到环形桁架结构的前六阶固有频率及其对应模态振型,并通过模态置信准则对实验结果进行了可靠性分析。其次,建立了环形桁架实验模型的有限元模型并进行模态分析,仿真得到其前六阶固有频率和模态振型。最后详细对比分析了实验结果与有限元仿真结果。结果表明:二者固有频率误差小于5%,且实验模态振型与有限元仿真模态振型一致,证明了本文分析结果真实可靠;同时,分析得到了环形桁架结构第一、二阶振型为椭圆形,第三、四阶振型为三角形,第五、六阶振型为四边形。
The modal experiment and finite element simulation analysis are carried out for the large deployable annular truss antenna structure. Firstly, the experimental model of the annular truss was designed and processed. The experimental modal analysis of the annular truss structure under the free boundary condition was carried out by the hammering method. The first six natural frequencies and their corresponding mode shapes of the annular truss structure were obtained, Confidence criteria for the reliability of the experimental results were analyzed. Secondly, the finite element model of annular truss experimental model was established and modeled, the first six natural frequencies and mode shapes were obtained. Finally, a detailed comparative analysis of the experimental results and finite element simulation results. The results show that the natural frequency error of the two is less than 5%, and the experimental modes are consistent with the mode shapes of the finite element simulation. It proves that the analysis results in this paper are true and reliable. At the same time, Type is oval, the third and fourth modes are triangular, the fifth and sixth modes are quadrilateral.