基于SiC材料的大长宽比长条型反射镜轻量化结构设计

Lightweight structure design of large strip mirror based on SiC material

介绍了一种大长宽比长条型反射镜的轻量化结构设计方法。讨论了反射镜的材料选择和轻量化结构形式,同时在轻量化设计过程中引入拓扑优化方法,以反射镜柔性变形为设计约束,以最小体积为设计目标,经过迭代计算得到最优结果。根据优化结果,建立反射镜的三维实体模型,并利用MSC.Patran软件建立反射镜的有限元模型,对影响反射镜自重变形的各项参数给出了详细的分析和讨论,包括径厚比的选择、支撑点位置、轻量化形式等,得到了各参数对反射镜面形精度的影响曲线。根据反射镜的加工工艺特点给出了一种合理的轻量化结构形式,轻量化率达到了70%,轻量化后反射镜的质量为12.5kg。面形误差的RMS值小于λ/50(λ=632.8nm),满足设计要求。

According to the demands of high quality reflection mirrors for space telescopes, a design method ot hght weight structure for large strip space using mirror is proposed, and the selection of materials, aspect ratio of diameter to thickness, light-weighting structure, as well as the position of support points are discussed. The topology method is in- troduced into the design, taking general flexibility as design constraint, minimum volume as design obiective, after itera- tions, a better structure is gotten. According to the result of topology optimization, a parameter structure model is estab- lished using the finite element method. As the results of the analysis, some curves are presented. A lightweight structure for the large strip SiC mirror is given, the mass of the mirror is 12.5kg and the lightweight ratio reaches 70%. The surface figure accuracy is superior to λ/50 RMS（λ=632.8nm）, which can fulfil the demand of the design.