Mechanical Characteristics Analysis Of Tensioned Membrane Structure And Design Of Triangular Prism Membrane Support Mast

With large spacecraft playing a more and more important role in space exploration,the development of large lightweight structure is paid more and more attention.Due to its light weight and high aspect ratio,the membrane structure has a huge potential to be used in future spacecraft,including antennas,solar sails,solar arrays,sunshields and optical imaging mirrors.As a kind of tensioned structure,membrane has different characteristics in terms of stiffness and stability compared with the traditional structures,which will produce more complex technical problems in the space application.Only by continuing to develop the membrane theory can the technical constraints be fundamentally broken through.The application of membrane in space depends on the support of deployable structures,but the sensitivity of membrane structure to boundary conditions puts forward higher design requirements for the large-scale support mast.Due to its low stiffness and weak bearing capacity,the collapsible tubular mast suitable for deploying membrane is limited in the application of large-scale space membrane structures,which can not give full play to its advantages of foldability and lightweight.When the membrane structure serves the space exploration task,it is necessary to solve the difficulties and shortcomings of membrane theory,develop the understanding of the mechanical characteristics of membrane structure,enrich the design of membrane support structure,and enhance the application ability of membrane structure in space.From these two angles,on the one hand,this paper conducts the theoretical modeling and mechanical characteristics analysis of the membrane structure.On the other hand,the triangular prism membrane support mast based on collapsible tubular masts is designed.In this paper,based on the tension symmetry of the pre-wrinkling membrane,the stress superposition method of tensioned membrane is proposed.Through the division of stress superposition group,the stress distribution of multi-point tensioned rectangular membrane is decoupled into the calculation of stress distributions under each vertex corner load,length corner load and width corner load,respectively.The division forms of stress regions and the stress calculation means under each tension are proposed,thus establishing the analytical solution method for the membrane stress distribution.Considering the geometric stiffness,mesh generation and air added mass of the membrane,the free vibration equation of the membrane is established.The method to determine the effective forces for any point in the membrane is given,and the calculation flow of free vibration based on stress superposition method is established.Based on the stress superposition method,the stress distributions of corner tensioned and multi-point tensioned membranes are calculated.By comparing with the results of finite element simulation,the theoretical results of stress distribution of tensioned membrane structure are verified.Based on the requirements of multi-point tensioned membrane ground experiment,the membrane dynamic experiment platform is designed,and the membrane vibration test system is established.The theoretical results are compared with the experimental data available in the literature.Analyzing different research objects of tensioned membrane structures through simulation,experiment and theoretical computation,the stress distribution and modal results of membrane structures are compared comprehensively to verify the stress superposition method and the membrane free vibration calculation based on this method.Based on the established stress superposition method and free vibration calculation theory,the effects of tension boundary parameters on membrane stress distribution and the first six modes are studied.The influence of edge arcs on the mechanical characteristics is analyzed for the corner tensioned rectangular membranes with different aspect ratios.The formula for each order's fundamental frequency ratio of atmospheric to spatial environment is proposed.The change of membrane stress distribution and modes with aspect ratio is analyzed.The effects of the value and density of the length and width tension on the stress distribution,longitudinal modes and transverse modes are compared and analyzed.According to the analysis of mechanical characteristics,the tension design of the strip membrane is proposed,and the basis of membrane structure parameters is obtained.Based on the space application background of large-scale membrane structure,a triangular prism membrane support mast based on the collapsible tubular mast is proposed,and the double-level guyed configuration is adopted to improve the support stiffness for the membrane.Based on the modeling of the collapsible tubular mast,according to the principle of energy equivalence,the equivalent beam model of the triangular prism mast is deduced.Combined with the theory of parallel mechanism,the equivalent 2(3-SPS-S)mechanism model of the guyed support mast is established.Taking the minimum mass per unit length of mast as the optimization objective,the bending performance index of the triangular prism mast is established,and the cross-section parameters of the collapsible tubular mast are designed.Taking the maximum support stiffness of the guyed mast as the optimization objective,the parameters of the guyed support mast are designed.The correctness of the equivalent model is verified by finite element simulation.The structural parameters of the membrane support mast with the optimal comprehensive characteristics of mass and stiffness are obtained.Based on the application background of membrane in triangular prism truss,the experimental prototype of triangular prism membrane support mast is designed.The dynamic coupling model between the triangular prism truss and the membrane is verified through experiments,which provides reference for the design and application of space membrane structures.