佐藤 泰貴

© 2016, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved. Many de-orbiting systems using deployable membranes are developed to keep the safety space environment. We have proposed a boom-membrane integrated space structure using tri-axial tubular CFRP booms. This paper describes detailed properties of the booms with and without the gravity compensation devices and fixed and free for rotation constraint of the stowage hub through the deployment experiments. We focus on the boom tip because the point where the membrane is applied by the tensile forces. In the experiments we measure the tip position and calculate the time history of deploying length and tip speed. As a result, the effects of the gravity compensation devices and rotation constraint of the stowage hub to deployment of the booms are clarified, as well as the validity of the hinge deployment model has been verified.

© 2015, American Institute of Aeronautics and Astronautics Inc. All rights reserved. This paper discusses the deformation properties of the solar sail IKAROS membrane to identify the possible causes of the phenomena observed by the flight data: the direction of the out-of-plane deformation. The flight data indicated that the direction of the out-of-plane deformation of the sail membrane was toward the Sun, although the solar pressure was applied from the Sun. This study hypothesized that the possible causes of the phenomenon is due to the initial curvature of the thin film devices on the sail and due to the circumferential slack induced by the bridges which connects each trapezoidal petal. The hypothesis was verified through geometrically nonlinear finite element analyses. The analysis results indicated that the sail membrane could deform in the Sun’s direction when the initial curvature of the thin film devices and the circumferential slack were simultaneously applied.

© 2015, American Institute of Aeronautics and Astronautics Inc. All rights reserved. The membrane-boom deployable structures which consist of self-deployable tri-axis CFRP boom with skew/spiral fold membrane wrapped around a single hub, have been developing for several small satellite missions as, solar sails, de-orbiting membrane systems, thin solar cell deployable membranes, and membrane antennas. Because the deployment properties of the membrane-boom structures depend on the self-deploying properties of the CFRP booms, the integration of membrane and booms is significant for designing the deployable structures. Also, the deploy-ability of the membrane-boom structures has to be evaluated by the ground testing and numerical simulations. This paper focuses on the dynamic properties of the membrane-boom deployable structures in the course of deployment through deployment experiments. Experimental results of the membrane-boom deployable structures models indicated the dynamic properties of membrane-boom deployable structures and non-linear buckling like properties for the deployable booms are discussed as well as to realize the simultaneous fold and deployment with simple holding/deploying mechanisms.

This paper addresses a simultaneous design optimization of the structure and actuator location for a plate model of space antenna to realize the high precision surface. The space antenna has an adaptive structure system to correct multiple surface error modes, which are induced in the space environment. The design optimization for the correction of the multiple surface error modes is formulated, where the weighting residual surface error vector is introduced to evaluate the contribution of the error modes. A constraint parameter of the actuator location is proposed to improve the performance of the design optimization. The results of the design optimization indicate that high performance is obtained by using the proposed constraint parameter, and thus, the effectiveness of the proposed parameter is verified.

This paper addresses the deformation properties of the IKAROS membrane to identify the IKAROS' higher out-of-plane stiffness, which was higher than expected. IKAROS' flight data showed that the out-of-plane deformation of the membrane was smaller than that predicted preflight by numerical simulations. A possible cause is the initial deformation of the IKAROS membrane, which is induced by the initial curvature of the thin film solar cells and the reflection control devices. In order to examine the effects of the initial deformation on the out-of-plane stiffness, nonlinear finite element analyses were carried out with shell elements for the 1/4 IKAROS membrane using the initial curvatures of the thin-film components. The results of the numerical simulations indicated that the on-orbit IKAROS membrane was nonflat due to the initial curvature of the thin-film components. The out-of-plane deformation with the initial deformation was found to be smaller than the deformation of the ideal flat membrane, and the numerical results qualitatively agreed with the IKAROS' flight data. As the initially deformed membrane increases the out-of-plane stiffness, which determines the deformation properties of the membrane, the bending stiffness is significant for the simulation of nonflat membrane structures. Based on the results, the mechanics of the higher out-of-plane stiffness of the IKAROS membrane was identified: it is the effects of the initial deformation of the membrane, which is globally propagated by the local deformation of initial curvatures of the thin film components.

Copyright ©2014 by the International Astronautical Federation. All rights reserved. The membrane-boom deployable structures which consist of self-deployable tri-axis CFRP boom with skew/spiral fold membrane wrapped around a single hub, have been developing for several small satellite missions as, solar sails, de-orbiting membrane systems, thin solar cell deployable membranes, and membrane antennas. Because the deployment properties of the membrane-boom structures depend on the self-deploying properties of the CFRP booms, the integration of membrane and booms is significant for designing the deployable structures. Also, the deploy-ability of the membrane-boom structures has to be evaluated by the ground testing and numerical simulations. This paper focuses on the dynamic properties of the membrane-boom deployable structures in the course of deployment through deployment experiments. Experimental results of the membrane-boom deployable structures models indicated the dynamic properties of membrane-boom deployable structures and non-linear buckling like properties for the deployable booms are discussed as well as to realize the simultaneous fold and deployment with simple holding/deploying mechanisms.

第29回宇宙構造・材料シンポジウム（2013年12月3日. 宇宙航空研究開発機構宇宙科学研究所 (JAXA)(ISAS)), 相模原市, 神奈川県資料番号: SA6000013001レポート番号: A1

Folded thickness of a large space membrane is determined based on the mechanical properties of a crease in a wrapping fold to identify a fold line induced by the wrapping fold. Wrapping fold experiments are performed to examine the configuration of fold line in detail. The experimental results indicate that the fold line induced by the wrapping fold deviates from the target straight fold line because the folded thickness is not equal to zero. To determine the folded thickness, the mechanical properties of a crease in the wrapping fold membrane are examined analytically. The folded thickness and the configuration of fold line are identified by the theoretical analysis in terms of the wrapped length of fold line, the tensile force, the membrane thickness, the radius of center hub, and the creasing force applied before wrapping. The results of the theoretical analysis are verified using the experimental results. A fold pattern, which consists of the fold line obtained by the theoretical analysis, is proposed, and the high packaging efficiency is realized by the proposed fold pattern. © 2013 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

This paper proposes a method to store a large solar-sail membrane while ensuring repeatability of its stored configuration. The feasibility and effectiveness of the method is verified through a series of sail-storage experiments using 10m-size membranes. Large membranes used as a solar sail should be stored compactly to save the launch volume; in addition, their stored configuration should be sufficiently predictable in order to guarantee reliable deployment in orbit. However, it is difficult to store a large membrane compactly with sufficient repeatability because of the finite thickness of the membrane. This paper classifies the existing and proposed folding patterns that can consider the finite-thickness of membranes. This paper then demonstrates the feasibility of "bulging roll-up" experimentally, and evaluates the repeatability of its stored configuration quantatively. © 2013 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

The present study proposes ... Features (i) stiffer for ground testing, (ii) Synchronous boom-membrane deployment, (iii) Resist launch vibration, (iv) Repeatable and simpler folding pattern, ... to be written!. Copyright© (2013) by the International Astronautical Federation.

Mechanics of a local buckling, which is induced by wrapping fold of a creased membrane, is discussed experimentally, theoretically, and numerically in this paper to examine the condition for the local buckling. The theoretical analysis is performed by introducing one-dimensional wrapping fold model, and the dominant parameters of the condition for the local buckling are obtained, which are expressed by the tensile force, the membrane thickness, and the radius of the center hub. The experimental results indicate that the interval of the local buckling is proportional to the diameter of the center hub, and the results are qualitatively agreement with the FEM results.

Wrapping fold analyses of a membrane retracted by guided-pin mechanisms are performed using a onedimensional model and FEM analyses to investigate the retraction properties for restoring forces, configuration of creases, and plastic deformation in the membrane. In the analyses, a wrapping fold model, which divides the wrapping fold membrane into the folded state and the transient process, is proposed. Analytical procedures for the folded state of the wrapping fold model are constructed considering the mechanical condition of the folded state. At first, we analyze the wrapping fold model by one-dimensional approximation to determine the retraction properties as a function of the contact force. Then, the retraction properties for the layer pitch and for the membrane thickness are examined using FEM analyses. As the results of these analyses, the configuration of the creases and the contact force are obtained for an arbitrary layer pitch. The Mises stress in the crease is evaluated to examine the existence of the plastic deformation. Comparing the results of these analyses, the applicability of the one-dimensional analyses is discussed. The analytical results are evaluated by experimental studies, and these results are in agreement qualitatively.

The deployment and retraction mechanisms for two-dimensional deployable membrane for spinning solar sail are proposed in this paper using wrapping fold for polygonal membrane with tensile forces. The fold and deployment of large-scale membrane sails are significant to realize the solar sails. The spinning solar sail is one of the concepts, which uses the centrifugal force to deploy the membrane. The structural and dynamic properties of the spinning solar sail are determined by the folding pattern and deployment mechanisms. The rotationally skew fold, which is proposed by authors, is one of the concepts for the solar sail membrane. However, the manufacturing and the folding of the rotationally skew fold are quite difficult due to the double corrugation properties. Therefore, we have developed folding and retraction mechanisms using wrapping fold with tensile forces by modifying the rotationally skew fold pattern with spiral fold. Experiments with the conceptual folding mechanisms for two-dimensional deployable membrane are demonstrated, and finally, the by optimizing the distribution of tensile forces and controlling the hinge deformation for the initial fold, the membrane have been successfully folded.