【作者】 狄杰建；

【导师】 段宝岩；

【作者基本信息】 西安电子科技大学 ， 机械制造及其自动化， 2005， 博士

【摘要】 本文针对星载天线高精度、轻质量的要求,以索网式天线为研究对象,较系统而深入地研究了初始平衡模型、静、动力学分析、以及网面精度调整等问题,结果表明基于优化技术的网面精度调整方法是可行的。具体如下: 1.建立了索网结构非线性有限元模型,提出了基于优化的综合找形法,确定了索网式天线结构的初始平衡模型。提出了两种施加索网预张力的实现途径:一是通过改变纵向调整索的张力来改变调整索对索网网面的作用力;另一种是通过改变网面上、下弦索的水平张力来改变网面的受力状况。数值结果表明,两种方法都能获得表面精度较高的初始模型,为索网式天线结构预张力的施加奠定了基础。 2.提出了基于优化技术的网面精度调整法,以单片辐射网为例研究了网面精度调整的策略与方法。建立了以反射面表面精度为目标,强度和频率为约束的优化数学模型。通过大量的数值计算,得出了基于索长改变量为设计变量的优化调整方法效率高的结论,为天线整体结构的网面调整奠定了基础。 3.针对索网式大型星载天线整体结构尺寸大、刚性差、单元数量多、约束条件多的特点,分别采用变量归并和累计函数技术,减少了设计变量与约束函数的个数。通过两种途径数值模拟了网面调整过程:一是对每片的16个纵向调整索都进行相应调整;另一种是对调整量和调整数目同时进行优化。数值结果表明,两种途径都能实现所要求的表面精度,对天线的网面调整工作具有一定的指导意义。 4.建立了以片数、纵向索数和预张力为设计变量,表面精度和结构重量为目标,应力和频率为约束的混合变量双目标优化模型,采用权重系数法将双目标化为单目标。数值结果表明,周边支撑对天线结构重量的影响较大,为提高天线的表面精度,可在设计阶段适当增多辐射单元的片数。这对天线的实际工程设计具有一定的参考价值。 5.简要介绍了国内外天线反射面表面精度的测量方法,提出了基于空间坐标测量的索力测定方法,减少了工程中借助索力测定工具进行测量的繁杂劳动。更多还原

【Abstract】 Considering the requirement for high surface accuracy, low weight of space-borne antenna structures, the initial equilibrium model is investigated systemically and deeply. The static and dynamic analysis, and shape adjustment has been performed. The adjustment process is simulated, and the results show the feasibility of optimal shape adjustment method. The main research works can be described in details as follows:1. Nonlinear finite element model is built, synthesis method for shape finding based on optimization is presented, and the initial equilibrium model is also determined. Two methods for pretensioning the cable net structures are presented: one is that the force of tie cables on cable-net is changed by variation of the force of vertical cables;the other is that the loading distribution will be changed by the variation of up and down cable tensions. The simulation results have shown that the initial model with high accuracy can be obtained by both methods. It can provide the theoretic base for the pretensions of cable-net antenna structures.2. The optimal shape adjustment method is studied. The adjusting strategy and methodology are described through the single radial cable net unit. The optimal mathematic model is built, with the surface accuracy as objective, the strength and frequency as constrains, and solved accordingly. It is found that the efficiency of optimal adjustment method with the variation of cable length as design variables is high. It has based a way for the shape adjustment of whole cable net antenna structure.3. Aiming at the characteristics of large size, weak stiffness, large number of elements and constraints, the number of design variables and constraints is reduced by the technology of variable merger and aggregation function, respectively. The shape adjustment is simulated in two ways: one is that all the sixteen tie cables are adjusted simultaneously, the other is that the adjustment amount and the number of adjustable cables are optimized simultaneously, then shape adjustment is carried out accordingly. The simulation results have shown that the desired surface accuracy can be achieved by two ways, and it can be referred to in engineering shape adjustment.4. Mixed Variables biobjective optimal mathematical model is proposed, with the number of radial units and vertical cables, and the pretensions as design variables, surface accuracy and structural weight as objectives, stresses and frequency as constraints. Biobjective is transformed into single objective by weighted method. The simulation results show that the circular support has a larger effect on the weight of antenna structural. More radial units can be introduced properly in the design stage to improve the surface accuracy. It can provide some reference to the engineering design.5. The present measurement method for the reflector surface precision is summarized, and the method of measuring force on the three dimensional coordinate is presented. The laboring of measuring the force by special tools is also reduced.6. The problem whether or not there are gravity effects on ground and in space is preliminarily studied, the analytic and mathematic model are presented. Mathematic model reasonably approaches the real state by the strategy and method of iteratively comparing the physical reduced scaled model and mathematic model, in order to solve the problem how to guarantee the antenna made on ground can satisfy the requirement in space.更多还原