Analysis On Non-linearity And Stochastic Flaw Of Reticulated Shell

Space grid structure is greatly developed in our country in the past two decades because of its reasonable stress, big coverage area, rich shape and so on, which makes it be more and more welcome and attractive. The structure has a fine prospect. And the double-layer reticulated spherical shell is one of the most widely applied space grid structure. In the same time the study of nonlinear theory of the double-layer reticulated shell structure is imperfect. Then further analysis on nonlinearity and structural parameters' affect on ultimate load-carrying capacity is necessary. This paper will complete this work.On the basis of review of development of grid structure and actuality and development of analysis of nonlinearity, nonlinearity of the double-layer reticulated shell structure is studied. Then bar element's tangential stiffness matrixes are deduced, which is based on the finite element method. The geometrical nonlinearity and material nonlinearity are both considered in the non-linear element stiffness matrix.After discussing method for integrating stiffness matrix and load embattle, they are integrated with'set-in-right-position'rule. The essential of solving the nonlinear structure is to solve nonlinear algebraic equations. In the paper, the equations are solved by the combination-of-incremental-and-iterative method. The essential of the instability is showed by mathematics method. A corresponding program is developed. Nonlinear load-displacement curve in complete-process analysis of a double-layer reticulated shell structure is traced out by the program. And the stochastic flaw has the influence on the bearing capacity, which can be considered, too. A calculate example is given to check the correctness of the program.Finally a fact double-layer reticulated spherical shell is analyzed. The change of parameters, such as ratio of height-span, shell's thickness, stochastic flaw and disposal of load so on is considered, and more than 200 results on ultimate load-carrying capacity are obtained. The function relationship between the parameters and the ultimate load-carrying capacity is established and the parameter influence on ultimate load-carrying capacity is analyzed respectively via the statistic of the result. Some conclusions rebound to engineering design.