中心支撑610mm圆形主镜的超轻量化设计

Ultra-lightweight Design of 610mm Circular Primary Mirror Supported in Centre

为满足轻小卫星相机质量更轻、性能更好的要求,对某离轴三反空间相机610mm口径圆形主镜进行了超轻量化设计.选用背部中心单点支撑方式,采用变筋厚和变筋高的设计形式,结合集成优化方法,设计的主镜质量仅为6.23kg,面密度约为21.3kg/m2.并设计了主镜的支撑结构,仿真分析了组件的静、动力学性能.结果表明:三个方向重力工况下主镜的面形准确度(RMS值)均优于6nm,4℃均匀温变载荷工况下主镜的面形准确度优于1nm;主镜组件的一阶自然频率为112 Hz,频响分析的最大应力发生在钛合金柔性连接件的螺栓孔处,最大应力值为104 MPa,远小于钛合金的屈服极限870 MPa.主镜轻量化效果显著,主镜组件的静、动力学性能均满足设计要求,本文所述单点支撑形式的最大适用口径为683mm,为同类型空间反射镜的超轻量化设计提供了思路和参考.

A circular primary mirror of an off-axis three mirror anastigmat space camera with an aperture ofφ610mm was ultra–lightweight designed to meet the requirement of designing lighter and better satellite cameras.By choosing the back-centre-single point supporting way,using the variable rib thickness and the variable rib height sturctural style and combining with the integrated optimization design method,the mirror was designed with a weight of only 6.23 kg and the surface density about21.3kg/m2.The support structure for the mirror was designed and the static and dynamic performances of the mirror subassembly were simulated.The simulation results show that the surface figure error（RMS value）is less than 6nm when the mirror subassembly is under the load condition of gravity in three different directions and is less than 1nm when the temperature variation is within±4℃.The first-order natural frequency of the mirror subassembly is 112 Hz.The results of frequency response analysis present that the maximum stress in the screw hole of the flexible structure is below the yield strength of its material.All performance indexes of the ultra-lightweight mirror designed in this paper meet the requirements of design and the maximum aperture of the mirror which can be supported by single point in centre isφ610mm.The design proposes a method and reference to ultra-lightweight design of same type mirrors.