Configuration Design And Mechanical Characteristics Analysis Of Plane Membrane Sunshield

In recent years,with the rapid development of large-scale deep-space exploration telescopes,the sunshade screen as the temperature control system of large-scale telescopes has gradually become larger and larger.Although the traditional truss-type deployment mechanism has the advantages of mature technology and high stability,as the size of the sunshield continues to increase,its mass,torque,etc.have increased exponentially,which is obviously not suitable for large-scale deployable structures.Moreover,due to the low folding rate and high quality of the truss structure,it also poses new challenges to the carrying volume and carrying capacity of the rocket.The membrane expandable mechanism has gradually become the preferred design of large sunshade screens due to its advantages of lightweight,simple structure and high storage ratio.For large-scale flat membrane sunshade screens,its reasonable configuration design and mechanical characteristics analysis are the main research hotspots.This article mainly focuses on configuration design and mechanical characteristics analysis.One is to complete the configuration design of the thin membrane sunshield,and the other is to analyze the mechanical properties of the thin membrane sunshield.According to the current development status of sunshields at home and abroad,the system scheme design of membrane sunshields is proposed.Taking the minimum mass corresponding to the unit effective area ratio as the optimization goal,combined with the dynamic analysis of the support rod to establish the best configuration of the membrane sunshield.The mechanical characteristics of the corner tensioned membrane and the pipe rope tensioned membrane are analyzed respectively.The theoretical formulas for the stress propagation of the membrane under different tensioning methods are deduced.The stress propagation laws and changing trends under different tensioning methods are analyzed.Through the verification of the examples,under the same tension,the corner tension membrane can better introduce the stress into the membrane.Through the finite element simulation method,the mechanical properties of the non-arcedged membrane and the curved-edged membrane at the corner points and the arc theoretical pipe tension are analyzed.Analyzing the surface,the design of the arc edge of the membrane can effectively improve the stress distribution at the edge of the membrane.The pipe tension can make the overall stress distribution of the membrane uniform,but its stress level and fundamental frequency are lower than the corner tension membrane.It can be seen that the mechanical properties of the corner tension membrane are better than the pipe rope tension membrane,and the corner tension is determined as the final tension plan of the membrane sunshield.Based on the configuration and tensioning method of the film sunshield,the response surface method is used to establish the mathematical proxy calculation formula that affects the fundamental frequency of the membrane sunshield.The formula mainly includes influencing factors such as effective area radius,corner tension and arc edge arch height.Then,through finite element simulation and theoretical calculation of the relative ratio,the reliability and versatility of the formula are verified.Finally,the influence of different parameters on the fundamental frequency of thin membrane sunshield is analyzed by the fundamental frequency fitting formula.According to the influence of the membrane radian parameter on the effective area of the sunshield,the optimization process of the fundamental frequency of the sun-shield and the multi-objective optimization function is established.The test of the prototype of the film sunshade screen verifies the reliability of the system design of the membrane sunshield.The modal test was carried out on the scaled-down prototype of the thin membrane sunshield,and the finite element simulation result was compared with the test result,and the consistency of the finite element simulation result and the modal test result was obtained.It can be seen that under the same boundary conditions,the use of finite element simulation software to analyze the dynamic characteristics of the thin-membrane sunshield has a certain degree of reliability.