基于摄影测量的充气膜结构有限元建模方法

FINITE ELEMENT MODELLING OF INFLATABLE MEMBRANE STRUCTURE BASED ON PHOTOGRAMMETRY

  • 摘要: 为了对正常使用过程中的充气膜结构进行荷载和动态特性等进一步分析和安全评价,提出了基于摄影测量的在役充气膜结构有限元模型建立方法。首先,采用三维摄影测量法对正常使用过程中的充气膜结构外形进行测量,并利用压力传感器测得相应的充气内压。然后,基于测量的外形及内压,将连续的膜面离散为膜线,并将内压按从属面积分配到相应的节点上,应用引入线性调整理论的索杆体系找力分析理论对膜线的力密度进行计算。随后,基于杆系结构平衡矩阵理论和小变形假定,应用非线性协调矩阵广义逆法,对结构的零应力态进行求解。最后,将得到的零应力态作为初始模型,利用有限元软件对其进行充气数值模拟,得到正常使用状态下的充气膜结构有限元模型。通过ETFE气枕模型的测量试验,验证了所提出的方法。

     

    Abstract: In order to carry out the further analysis of an inflatable membrane structure during the phase of normal operation, a finite element modelling method for inflatable membrane structures is presented based on photogrammetry. The proposed method is divided into four steps. Firstly, the three-dimensional coordinates of the target points pasted on the external surface of an inflatable membrane structure are observed to build the membrane shape based on photogrammetry, and the internal pressure is measured by means of the pressure sensor. Secondly, after simulating the continuous membrane surface by the membrane links and by distributing the internal pressure to the according joint based on the measurement results, the force density of membrane link is calculated based on the force finding theory of a cable structure system with the linear adjustment theory. Thirdly, according to the equilibrium matrix theory and the small deformation assumption, the zero-stress state of inflatable membrane structures is solved by using the nonlinear generalized inverse matrix method. Fourthly, the finite element model of inflatable membrane structures during the process of normal operation can be built by introducing the internal pressure via ABAQUS based on the zero stress state. Finally, the proposed method is verified by the results of both measurement and calculation obtained from the model experiment of a triangular ETFE cushion.

     

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