Study On Wrinkling Behavior And Characteristic Of Space Membrane Structures

Ultra-large and ultra-lightweight space membrane structures have received the widest attention due to their small packaging volume and low launching cost. Wrinkles are the common deformation status of the membrane structures, and they are the most important influencing factors on the structural performances. For the design of space membrane structures with high requirement of surface accuracy, the wrinkles are especially treated as the failure mode. The researches on the wrinkling synthetically apply several cross subjects, such as membrane structural mechanics, nonlinear mechanics, buckling theory and dynamics, therefore, the studies on the problems of wrinkles in membrane structures are considerably valuable on theoretical studies and engineering applications.The technique of"printed-dot target"is firstly presented in this paper, and the new technique and the photogrammetric measurement technique are combined to realize the accurate measurement of small amplitude wrinkles. The formation and evolution mechanisms are obtained by carrying out comprehensive experimental investigations on the wrinkling behaviors and the characteristics of wrinkle deformation. The procedures of wrinkle evolution are divided into several special phases, and the characteristics of wrinkle behaviors and evolution mechanisms are pertinently analyzed in every special phase.The stability of model is the key factor to influence numerical analysis of wrinkles. By introducing the Modified Displacement Component (MDC) method to perform the resolution of displacement, the singularity of the stiffness matrix is eliminated at the bifurcation point. The proper buckling mode is treated as the perturbation and applied to the analytical model, and the equilibrium path is successfully transferred from the initial elementary path to the bifurcation path. By making the post-buckling load path to develop with the bifurcation path, the wrinkling analysis is performed to the post-buckling phase. The numerical analysis and simulation technique are combined to analyze the static wrinkle deformation of different structures subjected to several load cases and boundary conditions, and the validity is confirmed by comparing the numerical prediction and the experimental results. The dynamics explicit finite element method is presented to analyze the wrinkles of space inflatable membrane structures by treating the wrinkles as the structural dynamic deformation responses, and the results show good agreement with the experimental observations.Based upon the bifurcation buckling theory, the wrinkle criterion is established and expressed as the form of in-plane tension. The nonlinear large deflection stability theoretical model of wrinkle analysis is presented in this paper to determine the quantified characterization relationship of the stress distribution and the wrinkle deformation in the post-wrinkling phase. The theoretical analysis is systematically carried out to understand the whole evolution procedure of the membrane wrinkles. And the rules of nonuniform and regional distribution of post-wrinkling stress are also obtained. The wrinkles will occur when the compressive stress in the membrane structure reaches the wrinkling critical value.The expression and the variable rules of the wrinkle wavelength and amplitude are obtained according to the wrinkle prediction model, which is presented in this paper. The correct and validity are confirmed by comparing the model prediction and the experimental and numerical results. Based on the prediction model, the prediction of wrinkles in the different membrane structures with several boundary conditions and load cases is performed to validate the universal extension and applicability, and the perfect results are obtained according to the wrinkling analysis.The studies on the subject of wrinkles are the theoretical basis in the design and analysis of space membrane structures, and the wrinkling studies are the key and basic references of wrinkle control and accuracy analysis of space inflatable membrane structures with high accuracy requirement, and it is the basic of the following study on the wrinkling behavior of large space membrane structures in space environment.