A Design Of CFRP Supported Structure For A New Space Camera And Research On Mechanical And Thermal Stability Of The Camera

With the improvement of space remote sensing technology and the level of space-to-Earth observation,high resolution and large image width have become an important development trend of space camera.In order to increase the imaging width while maintaining the resolution,a series of new imaging modes,such as side pendulum imaging and scan imaging,have been derived from the previous sweep imaging mode of space camera.In this paper,the support structure of a new imaging mode space camera is designed and optimized.In order to meet the requirements of space camera for low weight and high stability of the support structure,it is necessary to select and design the support structure reasonably and scientifically so that it has high rigidity and low weight,so as to obtain good dynamic characteristics of the structure and resist the interference of dynamic environmental factors.In addition,the structure should have good dimensional stability in order to achieve good imaging quality under complex and variable mechanical and thermal loads.Considering the structural characteristics and design requirements of the new space camera,the design and optimization of the camera support structure as well as the mechanical and thermal stability of the camera are deeply researched.Firstly,on the basis of fully studying the development trend of optical remote sensors at home and abroad,we analyzed and studied the material and structure form of main structure of space camera,and determined the material and structure form of new support structure of space camera.According to the weight requirement of the camera support structure and the characteristics of the camera optics structure,CFRP is selected as the material of support structure.The mechanical and thermal stability requirements of the camera are satisfied by the high specific rigidity and modulus of CFRP and the designable thermal expansion coefficient.Secondly,according to the optical system of the camera,by comparing the main structure forms,the split frame structure support mode for large space camera is selected.Based on the design scheme of split frame,in order to obtain the best distribution scheme of materials in support structure,SIMP topology optimization model is established according to variable density method,and the topology structure design of split frame structure is completed by setting reasonable objective function and constraints.Then,with the aid of the sensitivity analysis of frame structure size,the sensitivity of different structure size parameters to the overall stiffness of the support structure is determined.Based on this,the specific size parameters of the camera support structure are optimized,and the optimal configuration and design size of the camera support structure are finally determined.Thirdly,according to the thermal stability of asymmetric support structure of new space camera,a design scheme of thermal stability support structure for off-axis three-mirror space camera is proposed.Based on the classical laminate theory,the influence formula of thermal expansion coefficient in CFRP was deduced and two near-zero thermal expansion designs of CFRP were completed.Finally,the thermal stability design of space camera support structure is completed by adjusting the fiber ply angle according to the structure characteristics of off-axis space camera.Fourthly,the overall structure of the new space camera is analyzed in detail by finite element method.The dimensional stability of the camera under gravity,temperature,rotation and acceleration response under dynamic load are calculated.The results show that the mechanical characteristics and thermal stability of the space camera are good,and the position and surface accuracy of the reflector are still guaranteed under various complex conditions,and the dynamic response of each component is within a reasonable range.The scale prototype was developed and the dynamic and thermal stability tests were carried out.The results show that the mechanical properties and thermal stability of the scale prototype are good,and the errors are small compared with the results of finite element analysis.The rationality of structural performance was verified by finite element analysis.Finally,the high rigidity,high stability and lightweight design results of the support structure of the new space camera were determined.