Dynamics of Inflatable Space Structure

提出了一种充气膜结构展开动力学的数值分析方法，并编制了相应的数值计算程序。提出了薄膜自接触的数学模型和薄膜折线的粘弹塑性模型。这些模型的制定被实施到已经开发到去年的数字代码中。膜的破裂问题是近年来最热门的研究课题，而本文所分析的问题是其他研究者尚未研究过的。然而.本文的主要研究成果如下：（1）建立了局部屈曲膜动力学的数值计算方法，并编制了相应的数值计算程序。这种方法使我们能够执行精确地保持能量、线动量和角动量的数值时间积分，即时间积分是无条件稳定的。这是零重力条件下膜动力学计算的关键技术，也是目前比较困难的问题。(2)建立了充气气体与膜管相互作用的数学模型。该模型还精确地保持了能量守恒，从而导致数值稳定的积分。(3)膜的自接触的效果被实现到数字代码中。这也是获得准确模拟结果的关键数值技术。(4)本文建立了薄膜褶皱的粘弹塑性模型，模拟了褶皱的产生和发展，研究表明，薄膜和充气薄膜结构的动力特性可以用数值方法预测，而这在过去是不可能的。这是这项研究最重要的结果。

A numerical analysis method of deployment dynamics of inflatable membrane structures is proposed, and the numerical code is developed. A mathematical model of self-contact of the membrane and the visco-elastoplastic model of the fold line of the membrane are proposed. The formulation of these models is implemented into the numerical code that has already been developed until last year. The wrinkling problem f the membrane is the most popular research topics in these years, and the problem analyzed in this research has not investigated by other researchers yet. However. That problem will be the most serious problem to fabricate the large membrane structures in near future.The results of this research are summarized as follows; (1) Numerical method of the dynamics of membrane with partial wrinkling is formulated and a numerical code is developed. This method enables us to perform the numerical time integration that exactly conserves the energy, the linear momentum, and the angular momentum, i.e. the time integration is unconditionally stable. This is the key numerical technology to calculate the dynamics of the membrane in zero-gravity condition that has been quite difficult. (2) A mathematical model of the interaction between the inflation gas and the membrane tube is constructed. This model also conserves the energy exactly, which leads the numerically stable integration. (3) The effect of the self-contact of the membrane is implemented into the numerical code. This is also the key numerical technology to obtain the accurate results of the simulation. (4) A visco-elastoplastic model of the fold of the membrane is constructed, which is necessary to simulate the generation and growth of the fold.The research shows that the dynamic behavior of membranes and inflatable membrane structures can be predicted numerically, which has been understood impossible. That is the most important result of this research.