Search

Abstract: Assuming axisymmetric buckling and according to the adjacent equilibrium criterion, a buckling critical stress formula of a perfect tank wall is first obtained through analysis of elastic–plastic buckling carried out by J 2 plastic flow theory. Furthermore, combining the current tank seismic design standards and the results obtained in this paper, a new critical buckling stress formula of the tank wall is derived after correction for material plasticity by introducing a plasticity influence coefficient. Comparisons between the results obtained and those from the relevant formulas in the design standards of America, Japan, China and Europe are also performed. Our research shows that under interaction of high hydraulic and axial compression, the material properties of the tank wall change rapidly, and the buckling strength of the tank wall also decreases rapidly. The relation between the tank wall buckling critical stress and the hydraulic pressure is similar to Rotter''s semi-empirical formula. The results presented in this paper can provide technical support in further protection of large oil storage tanks. [Copyright &y& Elsevier]

Abstract: This paper focuses on the buckling of cylindrical shells under axial compression with small arbitrary thickness variations in the axial direction. General asymptotic formula of the buckling load, which is in terms of the thickness variation parameterεup to arbitrary order, is first derived by the perturbation expansion. Then effects led by three patterns of thickness variations on the buckling of axially compressed cylindrical shells, which are axisymmetric modal, local and stepwise variable, are, respectively investigated. Buckling loads of thin shells with axisymmetric modal thickness variation obtained from general analyses coincide with the Koiter''s results. Particularly, an analytical study on the buckling of cylindrical shells with stepwise variable thickness is carried out, because these thin-walled structures are widely used in actual engineering. In addition to the analytic investigation, numerical analyses and comparisons are also performed. [Copyright &y& Elsevier]

Abstract: This study focuses on the buckling of cylindrical shells under external pressure with general axisymmetric thickness imperfections. Firstly, the result of uniform thickness imperfection and recent study result of axisymmetric modal thickness imperfection are reviewed briefly. Secondly, asymptotic formulas of the buckling load, which are in terms of the thickness imperfection parameter up to arbitrary order, are determined through asymptotic analyses. The analyses are based on a system of linearized governing partial differential equations of perfect shells with variable thickness. Thirdly, the effects led by three patterns of thickness imperfections on the buckling of the laterally pressured cylindrical shells, which are uniform, axisymmetric modal and parabolic, are respectively investigated. Buckling loads of uniform and axisymmetric modal thickness imperfections coincide with the known results. In addition to the analytic investigation, numerical analyses and comparisons are also carried out. The analytical study results presented in the paper can be utilized to evaluate the stabilities of cylindrical shells under external pressure with general axisymmetric imperfections in thickness, once the thickness imperfection is known. [Copyright &y& Elsevier]