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本文首先论述了目前解决液固耦合振动的几种主要的数值方法,分析了各种方法的优点与不足。其中建立液体单元,从而构造比较协调的液固组合单元的方法,是解决液固耦合效应十分有效可取的方法。文中详细推导了三维等参液体单元的特性矩阵公式及其有限元静、动力平衡方程。利用三维等参液体元和固体壳元的组合有限元模型对某箭第三级共底双贮箱进行了有限元分析计算,求得了真实液体燃料和试验取代液体对频率、振型及振型斜率的影响。最后得出结论:完全可以用取代液体代替真实液体燃料进行动特性试验,得到的振型和斜率是可信的。
This paper first discusses several main numerical methods to solve the liquid-solid coupling vibration and analyzes the advantages and disadvantages of various methods. The method of establishing the liquid unit and constructing a more coordinated liquid-solid combination unit is a very effective method to solve the liquid-solid coupling effect. In this paper, the characteristic matrix formula of three-dimensional isoparametric liquid element and its static and dynamic equilibrium equations are deduced in detail. The finite element analysis of the third-level common-bottom double-tank of an arrow was carried out by using the combined finite element model of the three-dimensional isoparametric liquid element and the solid shell element. The effects of the real liquid fuel and the test-replacement liquid on the frequency, mode shape and vibration mode The effect of slope. Finally, it is concluded that it is entirely possible to test the dynamic properties by replacing liquid with real liquid fuel, and the obtained modes and slopes are credible.