Structural design of large aperture SiC mirror subassembly

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 204 ℃ 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.