大口径SiC轻量化反射镜组件的结构设计

Structural design of large aperture SiC mirror subassembly

针对某空间相机1.1 m口径反射镜的光机结构设计任务,为降低反射镜的重量,提高其环境适应性,设计了一种重力变形小、抗振性强、热尺寸稳定性高的空间反射镜结构系统。首先,详细分析了反射镜及支撑结构选材依据及应考虑的主要因素。然后,提出一种背部半封闭式扇形轻量化孔的反射镜轻量化结构方案,并利用参数化建模分析的方法对其结构参数进行了优化设计。采用背部三点柔性支撑方式对反射镜进行支撑,通过柔性铰链的柔性来调节由于装配中的过定位和热环境变化导致的反射镜面形精度降低问题。最后,对反射镜组件的力学和热特性分析结果表明,反射镜在X向1 g重力作用下反射镜面形精度PV为62.4 nm,RMS为5.7 nm,在20±4℃环境温度变化范围内面形精度达到PV为61.7 nm,RMS为6.3 nm,反射镜组件基频为150 Hz,能够满足静态刚度、动态刚度和热尺寸稳定性的设计指标要求。

For some 1.1 m diameter space mirror opto-mechanical design task, in order to decrease the weight of the mirror, improve its environmental adaptability, a small gravity deformation and strong vibration resistance, high thermal stability of space mirror structure system was designed. Firstly, mirror and support structure material selection principles and the matters needing attention were analyzed in detail. Then, a semi-closed back with a fan-shaped lightweight hole mirror lightweight structure schemes was proposed, and by using the method of parametric modeling, analysis of its structural parameters optimization design was carried out. The back three-point flexible support scheme was used to support the mirror. By adjusting the flexibility of flexure hinge can solve the problem of mirror surface figure accuracy degradation caused by assembly position and thermal environment change. Finally, on the mechanical and thermal properties of the mirror subassembly analysis results show that, the surface figure accuracy of the mirror was PV 62.4 nm and RMS 5.7 nm under load case of 1 g gravity in the direction of X axis, in the 20 ±4 ℃ environment temperature range the surface figure accuracy reached PV 61.7 nm,RMS 6.3 nm, and the fundamental frequency of the mirror subassembly was 150 Hz which can satisfy the static stiffness, dynamic stiffness and thermal dimensional stability index requirements.