Integrated Opto-mechanical-thermal Analysis and Optimization Design of a Low-Orbit Remote Sensing Camera
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摘要: 低轨道卫星热环境复杂恶劣,对遥感相机光机结构的热性能提出了严格要求。本文提出了一种基于在轨温度场的光、机、热一体化仿真分析方法,以某低轨道卫星相机为例,分别采用Thermal Desktop、MSC Patran/Nastran、Code V构建热分析模型、结构有限元分析模型、光学分析模型,分析得出了相机单次成像时间内最极端工况下各反射镜的平移、倾斜及镜间距变化量等结构变形特性,计算了光学系统MTF的变化,并剖析了系统传函的主要影响因素。然后从主承力结构的结构参数出发进行了优化设计,优化结果表明主承力结构线胀系数在(5~5.5)×10-6时系统热特性最优,系统传函满足指标要求。Abstract: The complex and harsh thermal environment of low-orbit satellites necessitates strict requirements for the performance of the optical-mechanical structure of remote sensing cameras. In this study, an integrated opto-mechanical-thermal simulation analysis method based on an on-orbit temperature field is proposed by using a low-orbit satellite camera as an example. Thermal desktop, MSC Patran/Nastran, and Code V are used to construct the thermal, structural finite element, and optical analysis models, respectively. The structural deformation characteristics, including the shift, tilt, and distance of each mirror in the most extreme conditions of single camera imaging time, are obtained. Changes in the MTF of the optical system are analyzed and the primary influencing factors of the system transfer function are determined. Subsequently, optimization design is performed based on the structural parameters of the primary force-taking structure. The optimization results show that the thermal characteristics of the system are optimal when the linear expansion coefficient of the primary force-taking structure ranges from 5.0e-6 to 5.5e-6, and the system transfer function meets the target requirements.
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表 1 相机反射镜及结构支撑材料属性
Table 1. Materials and properties of mirror structural supports
Material Density/(kg/m3) Young’s modulus/GPa Poisson’s ratio Linear expansion coefficient/(10-6/℃) Zerodur 2530 91 0.24 0.05 SiC 3120 350 0.17 2.2 4J32 8180 145 0.25 0.05 TC4 4450 110 0.34 9.1 C/SiC 2100 100 0.089 1.3 XM23 1000 0.002 0.49 236 表 2 主镜Zernike系数
Table 2. Zernike coefficient of primary mirror
Serial number Expression Value
(The lowest temperature condition)Value
(The highest temperature condition)1 1 −4.05E+01 1.59E+01 2 ρcosθ 6.08E−02 1.27E−01 3 ρsinθ −3.14E+00 2.27E−01 4 2ρ2−1 −6.66E−02 1.32E−01 5 ρ2cos2θ 5.32E−03 −6.68E−03 6 ρ2sin2θ 7.25E−04 9.03E−04 7 (3ρ2−2ρ) cosθ 6.33E−04 2.94E−03 8 (3ρ2−2ρ) sinθ −5.26E−02 7.71E−04 9 6ρ4−6ρ2+1 1.10E−04 −1.34E−03 -
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