The Buckling And Postbuckling Analysis Of Doubly-curved Composite Shells With Nonlinear Finite Element Method

Composite structures have been widely used in the aerospace and aeronautic structures due to their high specific properties, the doubly-curved composite shells played an important role in the airplane structures, the general failure model of which was buckling. Actually, some structures under buckling do not fail, still had a reasonable postbuckling strength, which should be full used in the designing. In a word, the buckling and postbuckling analysis of doubly-curved composite shells became an important problem for the engineering.According to the finite element package ABAQUS, The buckling and postbuckling response of doubly-curved composite shells with and without stiffeners is analyzed by using the nonlinear finite element method in this paper.Firstly, the buckling and postbuckling of doubly-curved composite shells subjected to transverse concentrate and uniform loads were simulated by using the finite element modeling. The equilibrium paths were obtained and the first ply failure loads were predicted based on the Tsai-Wu failure theory. The influence of geometric parameters and sequence of ply on the buckling and postbuckling response has been discussed in detail, and some valuable results are obtained.Secondly, the progressive damage model based on the Tsai-Wu failure theory was introduced to the finite element procedure for progressive failure analysis. The buckling and postbuckling of doubly-curved composite shell and cylindrical composite shell subjected to transverse concentrate loads were analyzed, the equilibrium paths and the progressive failure process were obtained. By using the spring elements for the boundary condition of cylindrical shell, the results obtained in this paper were better than the results of literatures comparing to the experiment data.Thirdly, the buckling and postbuckling of doubly-curved composite shells with stiffeners subjected to transverse uniform loads and combined loads were simulated by using the finite element modeling. The equilibrium paths and correlative curves of critical loading were obtained. The influence of geometric parameters of stiffeners on the buckling and postbuckling response has been discussed in detail and the results would be useful for the structure designing and application.