Study Of Bipod Flexure Mounting Technology For Space Reflector

With the continuous development of space remote sensing instrument, the instrument resolution have become increasingly demanding. According to the optical theory, the image resolution increases as the mirror diameter and improved. So the development of large-diameter mirror space is one of the future trends. Mirror caliber increases will lead to increased support structure size, weight increase; at the same time increasing the amount of thermal deformation, surface accuracy drops, temperature adaptability decline. In order to meet good space mirror assembly temperature adaptability, compact structure requirements, a ?335mm ULE space mirror was taken as the support object, bipod support techniques were studied, and a flexible support structure back bipod was designed.Firstly, the mechanical environment for the mirror during the processing of alignment, emission, and operation is analyzed, and the design specifications of the mirror assembly are given. Three design principles are described in accordance with the load characteristic, based on which the supporting plan is made. At first, bipod support structure and the traditional back three-point support structure are compared from the perspective of freedom; the results show that bipod support structure has more potential for optimization. Then back support structure is selected in order to meet the optical structure requirements, and finally the advantages and disadvantages of ball hinges and flexible hinge are compared, the relationship between the parameters of the flexible hinge and stiffness are analyzed, and flexible hinge has been chosen to realize bipod support structure.Secondly, the support structure is designed using parametric modeling method, the influence of flexible hinge structure parameters on surface figure error are analyzed and optimized, standpoint is proposed that the bipod apex position should be regarded as the key design parameters of backside bipod support, and the bonding position should be designed, respectively. The results show that the backside bipod flexible support structure after optimization has a good adaptability of temperature, as well as better support effects and dynamic stiffness. The surface figure error obtained by analysis is that RMS = 0.0056λ, the first order frequency component reaches 104 Hz, which meets the design requirements. The design efficiency is improved by integrated system of modeling, simulation, post-processing of the surface shape programed using MATLAB.Finally, mirror support system is assembled, optical surface shape testing, mechanical testing, and temperature experiments are performed. The results showed that the first order frequency of mirror assembly is 95 Hz with a finite element analysis error of 9%; surface figure error stable at RMS = 0.0278λ after vibration test, and no displacement nor tilt occurred considering measurement error; when the backplane is made of aluminum, components temperature range is better than ±18℃, which meet the design requirements.