Estimation of Deformation and Improvement of Shape Accuracy of Gossamer Space Structure

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The gossamer structure is the structure that consists of extraordinary thin elastic bodies such as membranes, polymer meshes, and cables. In this project, the author showed by using his numerical analysis code that the inelastic behavior of the fold lines, (2)self-contact of the membrane, and (3)the wrinkles caused by small disturbances such as thermal strain gives serious effect on the deployment motion and the dynamic behavior of the structure after the deployment. The author and the colleagues proposed a deployment method of rolled-up type inflatable tube, made an prototype, and conducted a deployment experiment. The experimental results showed that the proposed method is much more simple and can deploy the tube more stably than the conventional methods, and it can control the deployment speed easily. The author conducted the numerical simulations of the deployment of the tube by using the commercial FEM code "LS-DYNA", which agrees well with the experimental results. The author inv … More estigated the shape control of membrane structures by changing the length of the cables which supports the structures at their boundaries, and proposed a shape control scheme based on the identification of the stiffness of the structural members as well as their unstressed shape. The numerical results showed that the proposed method can control the shape with less numbers of shape adjustment. The author applied these results to the analysis of the flight model of the spinning solar sail investigated by JAXA, Japan. He analyzed the effect of several parameters on the deployment behavior of the sail membrane, i.e. (1)the compressive stiffness of the membrane, (2)angular velocity, (3)the size of the membrane, and so on. From these results, he proposed three indices to evaluate the deployment motion of the sail membrane, ie. (1)the deployment ratio, (2)the cumulative strain energy density, and (3)the frequency of the maximum strain energy. He showed that these indices can be used for the comparison and the evaluation of the folding patterns as well as the deployment methods. Less