针对轻小卫星相机质量更轻、性能更好的设计要求, 对空间某中等口径的长条形反射镜提出一种基于中心支撑形式的轻型优化设计方法。选用背部中心单点支撑形式, 不仅从整体上减小了反射镜及其组件的质量, 而且大大简化了支撑结构的设计。采用多目标集成优化的方法, 提高了反射镜在Z向重力工况下的面形精度。设计了适用于中心支撑的柔性支撑结构, 克服了中心支撑刚度低、动态可靠性差的缺点。仿真分析了反射镜及其组件的综合性能, 并与背部三点支撑形式进行了比较。结果表明, 中心支撑的反射镜质量更轻(3.36 kg), 与实体反射镜相比, 轻量化率达到了87%, 组件质量也较三点支撑减小了24%; 在X、Y、Z三轴方向1 g重力工况下的面形精度RMS值分别达到2.2、2.1、7.5 nm, 优于三点支撑形式; 4 ℃均匀温升载荷工况下的面形精度RMS值为2.8 nm, 远小于设计要求的RMS≤12 nm; 反射镜组件的一阶固有频率为135 Hz, 重力作用下镜面的最大刚体位移为3.96 ?滋m。该设计在极大地减小了反射镜及其组件质量的同时, 保证了反射镜的面形精度和组件的动、静态刚度, 满足设计要求, 为同类型空间反射镜的轻型优化设计提供了一种新思路。

A lightweight and optimization design method for a medium aperture rectangular mirror supported in centre was proposed to meet the requirement of designing lighter and better satellite cameras. By choosing the method of rear support in centre by single point, the mass of both mirror and subassembly was decreased and the design of the support structure was simplified. By using multi-objective optimization design, the surface figure accuracy under the load case of gravity in Z-direction was improved. A flexible support structure dedicated to the mirror supported in centre was designed to overcome its shortcomings of low stiffness and low dynamic reliability. The integrated performance of the mirror was simulated and compared with that of the mirror mounted via rear three points. It shows that the mirror supported in centre has a lighter mass of 3.36 kg and the lightweight ratio is 87% compared with the solid mirror, and that the mass of the mirror subassembly is decreased 24% of the one supported by three points. The surface figure accuracy RMS of the mirror reaches respectively 2.2, 2.1 and 7.5 nm when gravity load is applied in the directions of X, Y and Z axes, which is better than that of the one supported by three points. Furthermore, the RMS is 2.8 nm when the mirror subassembly is under the load condition of uniform temperature rise of 4 ℃, which is far less than the requirement of RMS≤12 nm. Otherwise, the first order natural frequency of the mirror subassembly is 135 Hz, and the maximum rigid body displacement is 3.96 ?滋m. The proposed design method not only reduces the mass of the mirror with its support structure extremely, but also ensures the surface figure accuracy of the mirror and the dynamic and static rigid of the mirror subassembly requirement, provides a new approach to lightweight and optimization design for the same type space mirrors.