Find-shaped Membrane Structure Based On The Geometric Nonlinear Finite Element Analysis

Membrane structure is an important branch of modern space structure system. For its rich and colorful forming, proper economical efficiency, outstanding architectural and structural characteristics, membrane structure is rapidly developed all over the world. The design of membrane structure which is different from traditional structures mainly contains four phases: project design, form-finding analysis, load analysis and cutting pattern. Form-finding analysis is the base and key of the design for membrane structure, which will influence whether the whole structure system is sound, economical and handsome.After summarizing the research on the form-finding of membrane structure home and abroad, this paper is based on the geometric nonlinear finite element theory, deeply works over the form-finding of membrane structure and discusses the following several aspects.Firstly, presents the geometric nonlinear finite element theory, educes the geometric nonlinear finite element equations of triangular membrane element and two-node cable element applied in the form-finding analysis according to U. L. The iteration approach and convergence criterion have been properly adopted to deal with such equations, which can accelerate the convergence of iteration calculation and improve the efficiency of form-finding calculation.Secondly, according to the geometric nonlinear finite element theory, an new design method for the form-finding of membrane structure-- combination of shape and state-- is innovatively put forward, drives the initial prestress on the membrane by pedestal shifting and temperature action to obtain the shape. The combination of shape and state is achieved meanwhile the aim of the form-finding is also come true exactly and rapidly. Then, basing on such method and considering the influence of support system, coordinated form-finding analysis is introduced to discuss how the support system affects the form-finding.Thirdly, the basic courses and disposals on ANSYS of such two form-finding methods are presented, which provides reference for software choosing during the form-finding analysis of membrane structure henceforth.Finally, according to the combination of shape and state method and its basic courses, this paper conducted the form-finding of three types of membrane structure engineering (membrane structure with rigid-flexible combined boundary, framework membrane structure, close combined membrane structure) by ANSYS, which can check up the rationality and validity of this method. Then, in term of the coordinated form-finding analysis method, this paper also conducted the form-finding of the same engineering above considering the support system. After the coordinated form-finding results are compared with the original form-finding results which were not take the support system into account, the significance of the coordinated form-finding is emphasized, which will provide reference for similar engineering.