Finite Element Analysis Of Large Span Cable Net And Reticulated Shell Structures

Spatial structure has applied in the construction of our country more and more,and the structure has gradually diversified,the span is growing,many researchers put forward various methods of spatial structure of experimental research and simulation analysis,which are very good to promote the development of the spatial structure.In this paper,the spatial structure is divided into flexible spatial structure and rigid space structure,and the finite element analysis of the cable structure and reticulated shell structure is carried out respectively.Cable structure is a flexible space tension structure which is not a definite geometric shape,so it's needed to apply pre-stressed force before the initial geometric state will be formed in order to withstand the role of external load.The determination of the shape of the cable network becomes a critical step in the analysis of the cable structure.The reticulated shell structure is a rigid spatial grid structure,which is the same as the traditional structure in terms of a fixed geometry,but the span is wider than the traditional structure one,and the force is more reasonable.When the reticulated shell structure is wider and wider,the material used is more and more lightweight,the stability problem becomes the most important problem of the reticulated shell structure,especially the single layer spherical reticulated shell.In this paper,the geometric stiffness matrix of nonlinear beam element is deduced,and the nonlinear finite element equation of space beam element is established.The main contents of this paper are divided into two parts,which are based on the FAST astronomical telescope main cable structure as an example to find the shape analysis and Kewitte(K8)single-layer spherical reticulated shell structure as an example of the nonlinear stability analysis.The main work of the study is divided into the following aspects:(1)Based on the large general finite element program ANSYS,the modeling program of FAST main cable structure is compiled by using APDL parameterized design language.(2)The inverse morphological method is used to analyze the initial form of the cable structure,and we need to solve the problem that the internal force distribution of the structure is not optimized by using same tension substitution method.(3)Using the finite element analysis software ANSYS,the nonlinear stability analysis of Kewitte(K8)single-layer spherical reticulated shell structure is carried out.The initial defects are considered and the state of the initial defect is not taken into account.Load-displacement curve,and to illustrate the initial defects on the stability of the reticulated shell structure.In this paper,the iterative method is discussed and applied to the initial morphological analysis of the cable structure.The results show that the inverse iterative method can be applied to the initial morphological analysis of the long span network structure.By comparing the initial defect and considering the nonlinear stability limitload factor in the case of the initial defect,and comparing the load factor under different initial defects,the conclusion is that the stability of the structure is worse when the initial defect value is bigger,Which has a certain theoretical reference for the stability design of large span reticulated shells.