| Cylindrical shells are one of the shell structure commonly used in practice, and openings ofen exist on the shell wall. Stress concentration at the edge of the hole results in the reduction of the shell buckling load and the ultimate load-carrying capacity, as the discontinuity of the opening leads to the local disturbing in the displacement field and stress field. So study on buckling behavior of cylindrical shells with openings are of theoretical and practical value.The stability of shell structures with openings is closely related with the geometrical parameters, initial imperfections, material properties, the shape and the dimension of the opening, load modes and the boundary conditions. So it is very difficult to work out the buckling load of shell structures with openings by the classic analytical method, and numerical methods are widely employed in buckling analysis of shell structures for the purpose of practical application.The effect of circular openings and elliptic openings on the critical buckling load of cylindrical shell has been studied by numerous investigators in the past , but little work has been done in the rectangular cutouts shell. Numerical methods are adopted in this thesis to investigate the stability behavior of thin cylindrical shells with rectangular openings subject to axial compression.Firstly, geometrically nonlinear analysis are carried out to investigate the effect of geometric parameters on the stability behavior. The considered parameters include the circumferential angle, the height, the location in the meridional direction, relative location, the number of the openings and radius-to-thickness ratio of the shells. It is found that the buckling load of cylindrical shells with rectangular opening is mainly dependent on the circumferential angle.For cylindrical shell with rectangular openings, four types of reinforcement are proposed. The effects of various types of cutout reinforcement on the stability behavior are discussed through geometrically nonlinear analyses. It seems clear that the section size and configuration of the axial stiffener are important to improve the load-carrying capacity.It has also been shown that, thin cylindrical shells are sensitive to initial geometric imperfections. The effects of eigenmode-affine imperfections and axisymmetriccircumferential depressions on shell structures with unreinforced openings and reinforced openings are studied.Lastly, the effect of material nonlinearity on the stability behavior of cylindrical shells with rectangular openings subject axial compression is discussed, and the effect of initial imperfections on elastic-plastic stability behavior is also studied. |
