Research on Mechanical Characteristics of Modularized Membrane Deployable Structures

对于未来的空间结构系统，要求其具有多种功能、可扩展性和冗余性。模块化的膜展开结构有可能显示出新的结构概念，以满足这些要求。对它们的研究有必要澄清模块化结构的概念，并分析电缆和膜的力学特性。这两个问题都是当前结构工程中的难点问题，目前还没有建立起足够的研究方法。在本研究中，通过考虑模块化结构的概念，重新探讨了结构系统的意义，提出了一种基于膜张力场模型的有限元方法，并阐明了膜固有的皱折现象。模块化结构的概念经常出现在人工制品和自然界的事物中。在工件中，从制造、测试、运输和分析的角度来看，模块是基于每个功能安排的子系统。在自然界的事物中，它们的系统由相同和/或相似的模块组成，这些模块具有相同的功能。通过对二维桁架结构的分析，将相同的模块分层引入构件，揭示了不同于传统结构体系其他方向的可能性。针对起皱现象，研究了基于张力场模型的有限元分析方法，并采用非线性有限壳单元进行了严格的分析。在此基础上，提出了一种新的应力-应变张量修正方案，该方案对皱褶膜非常有效。还澄清了皱纹现象的各种特征，并指出膜的边界强烈影响现象。

For future space structure systems it is requested that they have variety of functions, extendibility, and redundancy. Modularized membrane deployable structures have some possibility to show new structure concepts to correspond to such requests. For their research it is necessary to clarify concepts of modularized structures, and also to analyze mechanical characteristics of cables and membranes. They are both difficult subjects in the present structure engineering, in which sufficient approaches are not established yet. In the present study, meanings of structure systems are reinvestigated though the consideration of concepts of modularized structures, and a new finite element approach based on the tension field model of membranes is proposed, and wrinkle phenomena inherent in membranes are clarified.Concepts of modularized structures are often seen in artifacts and things in nature. In artifacts it has been considered that modules are subsystems arranged based on each function from the viewpoints of manufacturing, test, transportation and analysis. In things in nature their systems consist of congruent and/or similar modules, which have the same functions. Introducing the same modules to artifacts hierarchically, possibility for other directions of structure systems, which are different from the conventional ones, is shown through the analysis of two-dimensional truss structures.Concerning wrinkle phenomena, analytical approaches using finite elements based on the tension field model are studied, and strict analyses using nonlinear finite shell elements are performed. Experimental analysis of square membranes is also carried out Consequently, a new modification scheme of the stress-strain tensor is proposed, which is quite effective for wrinkled membranes. Various characteristics of wrinkle phenomena are also clarified, and it is noted that boundaries of membranes strongly affect the phenomena.