Design Of Film Shield Based On Origami And Thermal Deformation Analysis Of Space Optical Camera

With the increasingly stringent requirements on the imaging performance of space optical cameras,the harsh space environment has become an important factor affecting the imaging quality.In order to meet the imaging requirements of the camera and ensure the image taken is clear,the film shield is used to cover the camera to achieve a stable temperature field and maintain the dimensional stability of the height.For high-precision space developable optical camera,its optical primary mirror is expanded by developable mechanism after it is put into orbit,and the film shield is expanded with it,and finally surrounds the outer surface of the camera.According to the research progress of the film shield at home and abroad,the research of the film shield mainly focuses on its development mode,and there are few researches on the repetitive developable film shield.The film shield currently used has problems such as complex structure,low folding ratio,high weight,etc.,and cannot meet the requirements of the space camera.Therefore,it is meaningful to study the folding method of repeatable developable film shield.Taking the lightweight and expandable space optical camera as the application object,the film shield folding method that can be unfolded many times is designed.Based on the folding principles of Miura origami and Kresling origami,the mathematical models of the crease pattern are established,and their folding movement process are analyzed.A series of folding methods for cylindrical origami structures are designed,which can be applied to space cameras with different geometric contours.The mathematical model is used to solve the dimensional parameters of the film shield,and multi-layer insulation material is used to verify the two folding schemes.A controlled buckling method with variable thickness is established to achieve orderly closure of the film shield.The elastic energy expressions of single crease and single vertex with four creases are derived based on space vector.Based on the assumption of rigid surface and the principle of virtual work,the dynamic characteristics of the folding process of the film shield are deduced,the maximum force required for complete folding is determined,and the influence of structural parameters such as crease stiffness,number of elements,elements width and initial folding angle on the mechanical characteristics of the folding process of the film shield is analyzed.Based on the thermal analysis of multi-layer insulation,the thermal insulation performance is equivalent simplified,and the thermal control design of optical camera system is completed.NX TMG software is used to analyze the in-orbit temperature field of the optical camera with or without a film shield,and the overall temperature range of the optical system during the entire period is obtained.The temperature curve with time is drawn to verify the inhomogeneity of the temperature field inside the camera.The deformation of the mounting surface of the optical camera caused by temperature field under extremely high and low temperature conditions is analyzed.By comparing the theoretical calculation and simulation analysis of thermal deformation of space camera,the accuracy of simulation is verified.The workbench simulation software is used to study the thermal deformation of the mounting surface of the main mirror of the optical camera under different temperature gradients.The least square method is used to optimize the surface deformation data of the mounting surface of the primary mirror,and the curves of deformation with temperature difference are drawn to obtain the sensitivity of the camera to various temperature loads,which provided a reference for the optimal design of the structure and thermal control of the camera.