【作者】 张铁亮；

【导师】 丁运亮；

【作者基本信息】 南京航空航天大学 ， 飞行器设计， 2012， 博士

【摘要】 随着航天器功能的不断增加，工艺、材料与分析手段的不断改进和发展，总体上看，航天器结构逐步复杂化、轻量化、柔性化、大型化。本文针对卫星结构设计中的若干技术问题，主要进行了以下几方面的研究工作：蜂窝夹层结构在卫星结构中得到广泛的应用。在对蜂窝夹层结构进行有限元分析时，要对其进行等效处理，采取等效方法的合理性将直接影响计算结果的准确性。采用Reissner理论、Hoff理论和三明治夹芯板理论三种不同的等效方法建立有限元模型，分别进行静力分析和模态分析，并将每种等效方法的计算结果与实体单元建立模型的计算结果在不同载荷工况下，从位移大小、应力水平和频率大小三个方面进行了分析比较。结果表明采用三明治夹芯板理论对蜂窝夹层结构进行等效要优于其他两种等效理论。基于有限元法进一步研究蜂窝夹层结构的稳定性问题。蜂窝夹层结构随面板厚度的逐渐变化会出现不同的屈曲现象。针对连续芯层有限元模型，求出不同面板厚度时结构的屈曲因子，并与经验失稳公式预测值进行对比，两种方法的结果基本吻合。建立考虑芯层几何特征的有限元模型，进行屈曲分析并研究芯层几何参数对结构稳定性的影响。介绍了一种局部屈曲现象——蜂窝壁屈曲，提出了相应的失稳预测分析方法，并与三维有限元分析结果进行比较，以验证该方法的正确性。对承受多轴惯性载荷的蜂窝夹层承力筒结构进行稳定性分析，通过改变面板厚度和纵横惯性载荷比，得到一系列有限元解，给出了相关的多轴惯性载荷相关方程。该方程能够指导夹层承力筒结构设计，有一定的工程应用价值。各结构之间连接刚度的设计与关键连接部位的等效处理，决定着结构是否满足设计要求和有限元模型的精度。文中针对航天器推进剂贮箱并列放置于中心承力筒内的结构布局形式，采用在贮箱支架内是否预埋金属加强框的方法来改变贮箱支架的刚度和强度，通过比较四种不同贮箱支架结构设计方案的优劣，研究了贮箱支架刚度和强度的安装方式，提出了推进剂贮箱系统安装的“上弱下强”设计准则。并结合结构布局的特点，为了满足设计要求，对推进剂贮箱支架结构进行了改进设计。同时，归类总结卫星结构的主要连接方式，并对卫星关键连接部位的等效处理方法进行了研究。分别采用MPC（Multi Point Constraints）法、Beam元法、Bush元法和Fastener元法四种方法模拟关键部位的螺栓连接建立整星有限元模型，对其进行了模态分析和静力分析，分析了每种建模方法的优劣。针对有附加结构的卫星天线桁架结构，提出了一种实现结构多目标优化的综合设计方法。首先，探讨附加结构刚度对桁架结构动力学特性的影响，以便建立精确的有限元模型，为进行优化设计奠定基础。之后，交替采用代理模型方法和人机交互方式进行结构拓扑构型设计，其中代理模型是采用优化拉丁超立方法进行试验设计，结合径向基函数近似方法生成的。最后，应用NSGA-II全局优化方法实现以重量最小和频率最大的多目标优化分析，并根据分层图（不考虑设计偏好和考虑设计偏好两种）定量可视化地从Pareto前端和Pareto最优解集中筛选最优设计方案。方法有利于提高设计效率，降低全局优化的复杂度，同时能够得到满足设计要求的设计方案，适用于多目标结构优化设计。最后，为了有效地确定航天器结构设计和试验验证所需要的振动环境，需要通过星箭耦合分析给出星箭分离面的载荷响应。根据航天器结构的动力学特性，利用等效模型代替复杂的有限元模型进行星箭耦合设计分析。等效模型由一系列的单自由度质量块弹簧元构成，并根据模态有效质量的概念，给出了等效模型中各参数的计算方法。以某卫星为例，分别采用等效模型和复杂有限元模型两种方法进行星箭耦合动力学计算分析，并将得到的响应分析结果进行比较。结果表明等效模型可以代替复杂的有限元模型进行星箭耦合分析。更多还原

【Abstract】 With the increasing of spacecraft functions and the development of processing technology,material and analysis methods, spacecraft structures are being more complex, lighter, more flexibilityand larger scale. The research works for some technological problems of design for satellite structureare as follows:Honeycomb sandwich structures are widely applied to the satellite structures. During the finiteelement analysis (FEA) for honeycomb sandwich structures, the equivalent elastic constants directlyinfluence the accuracy of results. Three equivalent methods, including Reissner theory, Hoff theoryand sandwich theory, are used. Static analysis and mode analysis for honeycomb sandwich plates areperformed. The calculation results of each equivalent theory are compared with the results of3-Dsolid element model in different load cases, including the displacement, the stress and the normalfrequency. Results show that the sandwich theory is better than the other two equivalent theories.A research method of stability problem of honeycomb sandwich structures based on the FEA ispresented. The buckling factors of honeycomb sandwich structures with fixed size core are obtainedwith different faceplate thicknesses using homogenization core models. The solutions obtained withthe FEA approach are compared with the results from the conventional analytical formulas. Theresults obtained by two kinds of methods are basically consistent. The finite element modelsconsidering the geometry characteristics of the core are used. And the effect of the core’s geometrycharacteristics on the stability problem is discussed. A local instability phenomenon, called cell-wallbuckling, is introduced. A prediction analytical approach for the phenomenon is presented. And theresults are compared with that of the FEA to validate the proposed approach. The stability problem ofsatellite sandwich bearing cylinder under the multi-axis inertial loads is researched. The finite elementresults are obtained with different faceplate thicknesses and different ratios of vertical and horizontalinertial load. The related analysis equation for the multi-axis inertial loads is given. It can guide thebearing cylinder design.Design for structure connection stiffness and the equivalent method of the important connectionpart influence the design requirements satisfied or not, and the accuracy of results. The hydrazinetanks are apposed in the bearing cylinder. The stiffness and strength of hydrazine tank brackets arechanged through the strengthen frames. Compared with four different design schemes of thehydrazine tank bracket structure, the installation way is researched. The design principle of “the lowerstrong, the upper weak” for hydrazine tank system is proposed. To satisfy the design requirements, the hydrazine tank bracket structure is further improved.The connection modes of satellite structure are classified. The equivalent method of theimportant connection part is researched. Four equivalent methods, including MPC(Multi-PointConstraint) method, beam element method, bush element method and fastener element method，areused to simulate the bolt joints for normal mode analysis and linear static analysis. The advantagesand disadvantages of each equivalent method are listed.A multiobjective optimization method is presented for trusses of spacecraft antenna withappended structures. To set up an accurate finite element model for optimization design, the effect ofappended structure stiffness on the truss structure dynamic characters must be discussed. Thestructural topological configuration is decided iteratively using the surrogate model and theman-machine interactive method. For the surrogate model, optimal Latin hypercube sampling methodis used as the design of experiments strategy, and radial basis functions are selected as theapproximation method. The multiobjective evolutionary algorithm NSGA-II which produces a set ofPareto front points and Pareto solutions is employed as the optimization strategy to tradeoff theminimization of weight and the maximization of natural frequency. The optimum solution is visuallychosen with the level diagrams (considering the design preference and no considering the designpreference). This method not only can maintain good design efficiency, but also increase the globalsearch capability. And it is very useful for the multiobjective optimization design of spacecraftstructure.Finally, for defining the vibration environment which is needed for spacecraft structure designand experiment verified, the load responses of spacecraft and launch-vehicle interfaces need to begiven in the coupled analysis. According to the dynamic characters, the equivalent models instead ofthe finite element model are used. The equivalent models consist of some single-degree-of-freedommass-springs. Based on the concept of modal efficient mass, the calculation formulas of theparameters of equivalent models are derived. Taken a satellite as an example, the equivalent modelsand the finite element model are respectively used in the coupled analysis of spacecraft andlaunch-vehicle. Then the results of the above two models are compared. It is demonstrated that theequivalent models can be used to replace the complex finite element model.更多还原