Post-Buckling Analysis Of Thin-Walled Stiffened Shells

Due to high specific strength and stiffness, thin-walled stiffened shells has been widely used in aircraft structures. The stability design of stiffened shell structures under axial compression has become the outstanding problems in the design of intensity. Meanwhile, in view of the lightweight design of stiffened cylindrical shell structure, the fast and efficient numerical analysis methods for solve post-buckling is urgently need. Therefore, the analysis methods of the stability of the thin-walled stiffened shell structure under axial compression was studied. The main works of this dissertation are given as follows:(1) Theoretically, the comparative study of three commonly used numerical analysis method of solving the post-buckling problem, Arc-length method, Implicit dynamic method, Explicit dynamic method, through the finite element analysis the stiffened shell structures under axial compression, and select explicit dynamic method is the best post-buckling numerical analysis method by the calculation cost and calculation precision.(2)For the buckling of cylindrical shell structure exhibits the characteristics of multi-modal, this dissertation proposed introducing initial geometrical defects by the coupling defect modal method, and given a simple formula to calculate the coupling effect.(3)The post-buckling behavior of thin-walled stiffened cylindrical shell structures under axial compression is studied based on FEA by nonlinear explicit dynamic method, and compared the critical buckling load with nonlinear implicit method when changes the structural geometric parameters, such as cylindrical shell ribs sectional aspect ratio, skin thickness, and the degree of density, and gives the scope of explicit dynamic analysis, Explicit nonlinear analysis can be fast and efficient analysis the post-buckling behavior of thin-walled stiffened cylindrical shell structures when the mass ratio of the ribs and the skin is greater than 0.4.(4) Adopted the enumeration method, and compared the critical buckling load of the four common reinforcement grid thin-walled stiffened shells. According to the optimum critical buckling load, the best reinforcement grid thin-walled stiffened shell is ISOGRID grille structure. Meanwhile, on the basis of equivalent stiffness method, the thin-walled stiffened cylindrical shell was equivalent to the smooth cylindrical shell in order to simplify the analysis model. It improved the analysis efficiency, decreased the difficulty of the analysis, and provided a fast post-buckling analysis method for the engineering application.