超宽覆盖空间相机结构设计与优化

	超宽覆盖空间相机结构设计与优化
	李畅
学位类型	博士
导师	吴清文,何欣
	2014-07
学位授予单位	中国科学院大学
学位专业	机械制造及其自动化
摘要	随着科学技术的不断发展以及对地观测要求的不断提高，高分辨率、宽覆盖成像逐渐成为空间相机的一项重要发展趋势。本文对某超宽覆盖空间相机的结构进行了优化设计，其地面覆盖宽度超过500km，结构外形尺寸长宽比接近1:1.2。根据上述结构特点，为减轻重量，增强结构稳定性，相机的反射镜和框架结构在材料和结构形式上都必须做出相应调整。另外，空间相机从研制、装配、运输、发射到在轨运行等各个阶段，会经历各种外界载荷和环境因素的考验，而相机结构在上述情况下的稳定性对成像质量有较大影响，这都对相机结构设计提出了更严格的要求。基于此，本文根据某超宽覆盖空间相机的项目需求和结构特点，对相机内大口径反射镜和框架结构的设计及优化进行了深入研究。第一，介绍了空间相机在各个阶段所经历的力学环境，提出了载荷特征和结构响应的评价方法。从理论上推导了接触刚度的计算公式，分析了其主要影响因素，针对螺栓连接结构提出了一种新的有限元建模方法，综合考虑接触及螺栓预紧力对结构刚度矩阵的影响，提高了的动力学分析的精度及效率。第二，结合项目研制需求介绍了空间相机反射镜结构的设计依据。根据各材料性能及工艺性对比，完成了反射镜镜体和支撑结构材料的选择。综合考虑反射镜支撑理论及项目要求，设计出一种新的柔性支撑结构，并完成镜体轻量化优化，对反射镜组件进行了相应的有限元分析。结果表明，一阶频率较高，并具有较高的比刚度和温度适应性，满足成像质量要求。第三，提出整体式框架结构和桁架式框架结构两套设计方案。基于桁架式框架设计方案，根据能量守恒原理，采用基于Rayleigh算法的单位力法，研究了桁架杆间夹角对框架频率的影响，并以此为基础完成对桁架式框架结构的优化设计。基于整体式框架设计方案，选用了具有高比刚度和热稳定性的高体份SiC/Al复合材料，在框架具体结构形式未知的前提下，依据变密度法建立SIMP材料插值模型，通过设定相应的约束条件和目标函数，完成整体式框架结构的优化设计。根据有限元分析结果，对比桁架式框架及整体式框架各自的优缺点，并结合项目适应性的要求，最终选定了整体式框架的设计方案。第四，对空间相机整机结构进行了有限元分析，并采用光机综合分析法，研究了各种环境因素对相机成像质量的影响。对空间相机进行了环境试验，结果表明空间相机的力学特性和热稳定性较好，各部分的动力学响应均在合理的范围内。有限元分析结果与试验值误差较小，证明了通过有限元分析指导和验证结构设计这一方法的合理性。最终完成了空间相机高刚度、轻量化的结构设计目标。
其他摘要	As the continuous development of the science and technology and the continuous improvement of the observation requirement, the space camera with high resolution and extra-wide coverage is becoming the development tendency of the optical remote sensor. The coverage width of space extra-wide coverage camera researched in the paper is more than 500km, the length-width ratio of the structure is close to 1:1.2. Based on the structure characteristic, the mirror and frame of camera have to be adjusted in the material and structure form, in order to reducing camera weight, enhancing structure stiffness and stability. Besides, the camera has to undergo external loads and environmental factors, such as manufacturing, assembling, transporting, launching and working process, which influence the imaging quality. Thus, according to optical structure characteristics of camera and design requirements, the space camera with the large-aperture mirror and frame structure is researched deeply. First, the evaluation method for the environmental characteristics and mechanical response of space camera is presented, by introducing mechanical environments experienced. The principal factor affected by contact stiffness is analyzed theoretically, combining with finite element analysis principle; a novel finite element modelling method for bolt joint is presented. And the efficiency and precision of dynamics analysis are improved by considering synthetically the influences of the contact and bolt pre-tightening on structure stiffness matrixes. Second, the design basis of space camera mirror structure is described. The material of mirror and support structure is selected, in accordance with performance and manufacturability of materials. A novel design of flexible support structure and a light-weight design of the mirror are accomplished. The results of finite element analysis show that the design is reasonable, and the mirror has desirable properties, such as high specific stiffness, temperature suitability, which meets the imaging quality requirements. Third, the designing scheme of the integral frame and truss frame structure is presented. The influence of the angle between the girder poles on frame frequency is studied, and the design and optimization on truss frame structure are completed, based on the principle of conservation of energy and Rayleigh algorithm unit force method. Applying the high volume fraction SiC/Al composites with high specific stiffness and thermal stability, and constructing the interpolation model of SIMP material, the integral frame structure is designed and optimized through setting constraint condition and objective function. And finally the integral frame structure is designated by means of contrastive analysis. Fourth, the finite element analysis and mechanical testing are carried out and the influences of environmental factors on the imaging quality are analyzed. The results show that the space camera has good mechanics property and thermal stability, and the dynamic response is in a reasonable range. The error between the finite element analysis and tests is small, which proves the rationality of structure design by finite element analysis method. And the structure design target of space camera with high specific stiffness and light-weight is finally completed.
语种	中文
文献类型	学位论文
条目标识符	http://ir.ciomp.ac.cn/handle/181722/41423
专题	中科院长春光机所知识产出
推荐引用方式 GB/T 7714	李畅. 超宽覆盖空间相机结构设计与优化[D]. 中国科学院大学,2014.

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