Research On Thin-Walled Elastic Deployable Booms Facing Deployable Planar Membrane Structures

With the rapid development of China's aerospace industry in the areas of high-precision earth observation and high-power space station,it is urgent to innovate and research a new generation space deployable structures with large deploy-fold ratio and light weight,which can be used in large capacity communication antennas and high-power solar arrays.Comparing with the traditional truss deployable mechanisms,space membrane structures have many advantages in deploy-fold ratio and total weight,which provide a huge development prospect for the improvement of the space deployable mechanisms.As the most critical component in a deployable membrane structure,the thin-walled elastic deployable boom plays the role of driving and supporting respectively when the membrane structure is deploying and deployed.Thus,the boom's stability and reliability are quite critical in membrane structures.Thin-walled elastic deployable boom is a kind of non-hinge deployment mechanism,which has great advantages of high storage ratio,light weight and low power consumption.However,the development of the boom is seriously restricted by the issues of deployment failure and low deployed stiffness.In recent years,most of the research on deployable booms is mainly concentrated on the field of engineering application.However,the research concerning on boom theoretical model establishment and finding development and failure mechanism is less.In this paper,after establishing a boom theoretical model,the boom working performances are analyzed in depth.This research is to make the boom deploy smoothly and work stably in membrane systems.At first,based on the principle of energy,this paper establishes boom deployment strain energy model by analyzing the strain energy release modes of boom infinitesimals.From the model,the mechanism of boom normal deployment and blossoming can be revealed,and the boom tip force can be acquired.As it is impossible to solve the effect of the friction between boom coiled layers by relying on analytical algorithms alone,this paper establishes a boom finite element model to assist this research.According to the model,the formula to calculate the total pressure between boom coiled layers is acquired through dimensional analysis.After that,based on the deployment strain energy model,the variation of the boom tip force during the normal deployment and blossoming is studied,and then the boom's maximum driving force in its whole deployment process can be obtained.The maximum driving forces of the bistable booms and equivalent mono-stable booms are compared.And then,by elaborating the cause of the boom natural coiled radius,the reason why the bistable property can improve a boom's deployment performance is revealed.Based on parametric study for the boom deployment performance,the effective measures to improve a boom's deployed performance are acquired.Further more,the proper boom cross-section for using in a membrane structure is selected,and the parametric design is proceeded.Then,the static characteristics of deployed booms is analyzed.Further,the fundamental frequency of a membrane structure supported by deployable booms is also acquired,and the influence of boom parameters on the membrane structure is analyzed.Considering the design requirements of the membrane structure on boom deploying and deployed states comprehensively,the final parameters of the deployable booms are obtained.At last,the experimental samples of deployable booms,prototypes of a deployment mechanism and a membrane structure are manufactured respectively,and the corresponding testing systems are also established.The deploying and deployed experiments of the booms and the membrane structure are carried out respectively.The maximum driving force,bending stiffness of the booms and the fundamental frequency of the membrane system are measured.The theories in this thesis are verified by comparing the theoretical and experimental results.