环形展开天线索网结构优化设计与分析

发布时间：2018-03-31 18:14

本文选题：索网天线　切入点：找形　出处：《哈尔滨工业大学》2015年硕士论文

【摘要】：本文选取周边桁架可展式索网天线作为研究目标,对其表面网格的设计,网面的预张力设计,精度调整的方法和系统的静态力学性能进行了详细的分析研究。基于AGRAWAL最小原理误差,天线索网结构采用在光学口径上投影为正三角形的索网网格形式。之后对索网进行预应力的优化配置问题研究,采用以网面精度均方根误差和力均匀性为双目标优化方法,分别对比研究了不考虑垂跨比和考虑垂跨比下的索网预应力配置问题,同时提出了基于理想抛物面的轴向误差精度和失焦误差作为网面精度判定的另外两个参考指标,并给出了考虑桁架变形的网面找形设计方法,获得最接近真实情况下的索网初始设计精度与应力配置,算例结果表明前述方法能够获得良好的网面精度和均匀性索力配置。考虑到索网在实际制造中存在的随机误差,建立了索网结构的有限元分析模型,针对不同纵向索对精度调整的敏感性研究,获得最佳的调整索,并建立了以最佳的调整索索长变化为设计变量,网面精度为设计目标的网面精度调整的数学模型,提出了基于多维进退法实现网面精度的快速优化的调整。通过算例验证分析,采用这个调整方法能够提高调整效率,并能够有效的改善反射面的形面精度。针对索网系统在实际太空环境下容易受到随机外力的影响,本文还提出了基于最小势能原理的索系统受外力后再平衡有限元静力分析方法,方法中考虑索的小变形大位移的几何非线性特性,并通过Newton-Raphson法迭代求解结构有限元模型,获得其数值解,计算具体算例分析说明了该方法的有效性,之后评估了不同初始条件对索结构刚度影响,发现增大索截面尺寸和预应力能够获得索系统更优的受力性能。为了研究柔索随着外部环形桁架展开的关键离散质点的运动学特性,建立了基于悬链线的柔索运动学模型。并用具体算例分析表明,在展开过程中要尽量使得后期牵引端的速度降低,则能使得整个索系统的运动趋于平稳,冲击性小。并给出了基于影响系数法的索网天线整体结构的刚度和模态分析,得到了索网天线结构固有频率达到了2Hz,符合实际天线最低频率要求。
[Abstract]:In this paper, the peripheral truss deployable cable mesh antenna is chosen as the research object. The design of the surface mesh, the design of the pre-tension of the mesh surface, the method of precision adjustment and the static mechanical properties of the system are analyzed and studied in detail.Based on the minimum principle error of AGRAWAL, the cable mesh structure of the antenna adopts the form of triangular cable mesh projected on the optical aperture.After that, the optimization problem of cable net prestress is studied, and the problem of cable net prestressing is studied by taking the root mean square error of mesh precision and force uniformity as the double objective optimization method, which does not consider the vertical span ratio and the vertical span ratio, respectively.At the same time, the axial error accuracy and out-of-focus error based on ideal paraboloid are proposed as the other two reference indexes to determine the accuracy of the mesh surface, and the design method for the shape finding of the mesh surface considering the deformation of the truss is given.The initial design accuracy and stress configuration of cable net are obtained in the closest real case. The numerical results show that the proposed method can obtain good mesh accuracy and uniform cable force configuration.Considering the random error of cable net in actual manufacture, the finite element analysis model of cable net structure is established, and the optimum adjusting cable is obtained according to the sensitivity of different longitudinal cables to precision adjustment.The mathematical model of adjusting the accuracy of the mesh surface with the optimal cable length as the design variable and the precision of the mesh as the design objective is established. The fast optimization adjustment of the precision of the network is proposed based on the multidimensional advance and backward method.The example shows that this method can improve the efficiency of the adjustment and improve the accuracy of the shape surface of the reflector.In this method, the geometric nonlinearity of cable with small deformation and large displacement is considered, and the numerical solution of the finite element model of the structure is obtained iteratively by the Newton-Raphson method. An example is given to illustrate the effectiveness of the method.Then the influence of different initial conditions on the stiffness of cable structure is evaluated. It is found that increasing the size of cable section and prestressing force can obtain better performance of cable system.In order to study the kinematics characteristics of the key discrete particles of flexible cables with the expansion of external ring truss, a catenary based kinematics model of flexible cables is established.The analysis of concrete examples shows that the motion of the whole cable system tends to be stable and the impact is small if the speed of the later traction end is reduced as far as possible in the process of development.The stiffness and modal analysis of the cable mesh antenna structure based on the influence coefficient method are given. The natural frequency of the cable mesh antenna structure is up to 2 Hz, which meets the minimum frequency requirement of the actual antenna.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN820

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