大型空间相机桁架结构稳定性研究

发布时间：2018-06-28 14:46

本文选题：空间相机桁架结构 + 稳定性　；参考：《中国科学院长春光学精密机械与物理研究所》2017年博士论文

【摘要】：随着空间遥感器的发展,低分辨率的空间相机已经不能满足人类对空间观测和利用的需求,这些需求促使其向着大口径、长焦距的方向发展,以满足空间遥感器对高分辨率的要求。随着空间相机焦距的增加、口径的增大、光学性能要求的增强,由此产生的问题是空间遥感器不仅整体质量的增加,而且也使其支撑结构的制造加工难度增大。空间相机支撑结构必须满足较高的比刚度、较好的动态稳定性及对镜面较小的影响等要求,而这些要求又不是传统的筒式、箱式等结构形式所能满足的。因此自从Michell在1904年首次提出了桁架理论以来,桁架结构以其结构简单可靠、组装灵活、比刚度高、可设计性强等优点而得到广泛的应用。本论文以5m量级的大型空间相机桁架结构为研究对象,从理论分析、结构设计、优化设计、工程分析等方面对桁架结构的稳定性进行深入的研究,其研究内容主要包括基于“类泊松效应”的消热桁架结构研究、基于Rayleigh法的高刚度桁架结构研究及空间科学仪器对桁架结构稳定性的影响研究针对大型空间相机桁架结构的消热问题,提出了一种基于“类泊松效应”的消热桁架结构。通过引入“类泊松效应”,推导出了桁架结构热变形量与支撑杆夹角之间的关系式。根据消热设计的判别式,得到高热稳定的桁架结构支撑杆的布局角度:31.4°≤β1≤65.4°、19.5°≤β2≤69.4°。从桁架结构构型设计及支撑杆尺寸优化两个方面对大型空间相机高刚度桁架结构进行研究。通过引入Rayleigh法,得到了桁架结构的特征频率与支撑杆夹角之间的关系式。在综合考虑热稳定性及高刚度特性的情况下,完成桁架结构支撑杆的初始构型设计,其支撑杆的最佳设计角度:β1=35.6°,β2=25.5°。针对大型空间相机桁架结构支撑杆数目多、优化困难等问题,提出了一种将灵敏度分析与试验设计相结合的快速优化方法。该方法效率高、结果收敛速度快,并能够快速获得最优性能的结构。针对科学仪器对桁架结构稳定性的影响问题,提出了一种基于等效柔度和Rayleigh法的切向-双脚架运动学支撑结构。根据单边直圆柔性铰链的柔度矩阵,推导出了双脚架结构在X轴、Y轴、Z轴方向的等效柔度的解析式,进而通过引用Rayleigh法得到切向-双脚架运动学支撑结构的特征频率解析式。根据设计要求,设计出了能够降低科学仪器对桁架结构稳定性影响的运动学支撑结构。通过有限元分析对桁架结构稳定性进行验证,其结果表明:桁架结构具有良好的刚度特性,能够满足相机对整机结构特征频率的要求;在重力载荷作用下桁架结构的主次镜安装面位置的相对变化满足力学稳定性指标;在温度载荷作用下,桁架结构主次镜安装面位置的相对变化较小,具有良好的热稳定性;科学仪器的温度变化对桁架结构主次镜间安装面位置的相对变化影响很小,所设计的运动学支撑结构具有降低科学仪器对桁架结构稳定性影响的作用。
[Abstract]:With the development of space remote sensors, low resolution space cameras are unable to meet the needs of human space observation and utilization. These demands make them develop toward large aperture and long focal distance to meet the high resolution requirements of space remote sensors. With the increase of space camera focal length, the aperture is increased, optical performance is required. The problem is that the spatial remote sensor not only increases the overall quality, but also makes the manufacturing difficulty of the supporting structure more difficult. The support structure of the space camera must meet the high specific stiffness, better dynamic stability and the smaller influence on the mirror surface, and these requirements are not the traditional tube type, box type knot. Since the truss theory was first proposed by Michell in 1904, the truss structure has been widely used in its simple and reliable structure, flexible assembly, high stiffness and strong design. This paper takes the truss structure of large space camera at the order of 5m as the research object, from theoretical analysis and structure design. The stability of truss structure is deeply studied in the aspects of optimization design and engineering analysis. The main contents of the study include the study of the heat dissipation truss structure based on the "class Poisson effect", the study of the high stiffness truss structure based on the Rayleigh method and the influence of the space scientific instrument on the stability of the truss structure. A kind of heat dissipation truss structure based on "class Poisson effect" is proposed. By introducing "class Poisson effect", the relationship between the thermal deformation of truss structure and the angle of support rod is derived. According to the discriminant of heat dissipation design, the layout angle of the truss structure with high heat and stability is obtained: 31.4 degrees less than beta 1 The structure of a large space camera with high stiffness is studied in two aspects of the structure design of truss structure and the optimization of the size of support rod in two aspects. The relationship between the characteristic frequency of the truss structure and the angle of the support rod is obtained by introducing the Rayleigh method. The relationship between the thermal stability and the high stiffness characteristics is taken into consideration. In the case of the initial configuration design of the truss structure support rod, the optimum design angle of the supporting rod is: beta 1=35.6, beta 2=25.5. In view of the large number of support rods in the truss structure of the large space camera and the difficulty of optimization, a fast optimization method is put forward to combine the sensitivity analysis with the test design. The method is efficient and converges. In view of the influence of the scientific instruments on the stability of the truss structure, a kinematic support structure of the tangential double foot frame based on the equivalent flexibility and Rayleigh method is proposed. According to the flexibility matrix of the single side straight circular flexure hinges, the structure of the double foot frame in the direction of the X axis, Y axis and Z axis is derived. The analytical formula of the equivalent flexibility is obtained by using the Rayleigh method to obtain the characteristic frequency analysis of the kinematic support structure of the tangential double foot frame. According to the design requirements, a kinematic support structure is designed to reduce the influence of the scientific instrument on the stability of the truss structure. The results of the finite element analysis are used to verify the stability of the truss structure. It is shown that the truss structure has a good stiffness characteristic and can meet the requirement of the frequency of the structure of the whole machine. Under the action of gravity load, the relative change of the position of the mounting face of the main and secondary mirror of the truss structure satisfies the index of the mechanical stability. The temperature change of the scientific instrument has little influence on the relative change of the position of the mounting surface between the main and secondary mirrors of the truss structure, and the designed kinematic support structure has the effect of reducing the influence of the scientific instrument on the stability of the truss structure.
【学位授予单位】：中国科学院长春光学精密机械与物理研究所
【学位级别】：博士
【学位授予年份】：2017
【分类号】：V445.8

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