设计了一种18杆空间相机桁架式主支撑结构，解决了大型离轴三反空间相机主支撑结构要求同时具备轻质、高刚度、高强度和高热尺寸稳定性的难题。分析了采用整体框架结构及桁架支撑结构作为离轴三反空间相机主支撑结构的优缺点，根据光学系统及相机整体结构尺寸特点，确定了桁架支撑方案。分析对比了单层6杆桁架结构和双层18杆桁架结构的动静态刚度。合理选取了桁架式主支撑结构的材料，分析了对支杆基频的影响因素，优化设计了支杆的结构参数，分析了18杆桁架支撑结构的力、热特性，并对支杆与杆接头的胶粘结强度进行了试验测试。有限元分析结果表明，相机桁架主支撑结构一阶固有频率为78.4 Hz，次镜在X向重力作用下绕Y轴的最大倾角为4.6″，动静态刚度均满足设计指标要求。碳纤支杆拉伸试验结果表明，胶粘结支杆的抗拉强度为5.85 MPa，满足强度要求。%In order to keep a lightweight structure, high stiffness, strength and thermal dimensional stability, an 18-strut truss main support structure was designed for large-scale and off-axis Three-mirror Anastigmat (TMA) space camera. The merit and demerit of main support structure of off-axis TMA space camera with overall framework and truss support structure were analyzed. The truss support scheme was confirmed on the basis of optical system and the whole structure size characteristic of the camera. The dynamic and static stiffness single-layer 6-strut and double-layer 18-strut truss structure were analyzed and contrasted. The materials of truss main support structure were selected reasonably. The influence factor of the strut fundamental frequency was analyzed, and then the structure parameters of the strut were optimally designed. The mechanical and thermal characteristics of 18-strut truss support structure were analyzed. Finally, adhesive strength between strut and pipe joint was tested. As shown as the result of finite element analysis, the fundamental frequency of truss main support structure is 78.4 Hz, and the maximum tilt angle of the secondary mirror is 4.6″ around Y axis under the action of gravity in X axis direction. Dynamic and static stiffness index meet the design requirements. The tensile test results show that the strut tensile strength of the adhesive joint is 5.85 MPa, which is satisfied to strength requirements.
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