The Optimization Of Thermal Deformation Of Space Ultrahigh Frequency Remote Sensing Reflector And Zero-expansion Composite Design

With the application of space remote sensing technology in fields such as military,meteorology,environment and urban regulations,the requirements for the operating frequency range of microwave remote sensors have been higher.Therefore,the study of ultrahigh frequency remote sensing reflectors with operating frequencies above hundreds of GHz is greatly essential.High surface accuracy is a key requirement for ultrahigh frequency reflectors of remote sensing.For ultrahigh frequency reflectors operating at 600GHz,the RMS value of thermal deformation in-orbit must be less than 10?m.First of all,in order to achieve the reflector with high precision and light weight,this paper innovatively proposes a reflector structure—single skin-grid rib structure.The structure can not only take into account the advantages of the traditional double skin-grid rib structure in high precision,but also can reduce the quality of half the skin,having achieved the purpose of lightweight design.Then,in order to reduce the thermal deformation of the reflector,a finite element model of a reflector with a diameter of 1.82m was established.The thermal deformation of the reflector was analyzed and the different structural parameters of the reflector were studied.The influence of the RMS value on the thermal deformation of the reflector is optimized,and the main structural parameters of the reflector are optimized on the principle of low thermal deformation and low mass,including the reflector's ply angle and number of layers,rib height,rib's ply angle and number of layers.The optimization results show that under the premise of ensuring the weight to meet the requirements,the reflector can not meet the accuracy requirements by structural optimization only.So,it is essential to reduce the thermal expansion coefficient of the material for reflectors.Therefore,a zero-expansion material of CFRP combined with Kevlar fabric was firstly suggested,designed and manufactured in the thesis.The material has a thermal expansion coefficient CTE?0.5×10-7/?.This paper describes in detail the design theory,design scheme,FEM verification methods and manufacturing technology of the zero-expansion material.The zero-expansion material is applied to the skin and grid of the reflector as verification by Finite Element Method,which can effectively reduce the thermal deformation and weight of the reflector.Finally,the reflector designed meets all the requirements for the working frequency up to 600GHz..