Modal analysis of the post-buckling behaviour of cylindrical steel panels under compression: Imperfection sensitivity and local2 interaction

In technical branches, such as chemical or petroleum industries, cylindrical steel tanks are essential structures used for storage of liquid products. Therefore, their safety and reliability is essential, because any failure might have dangerous consequences, in extreme cases may even lead to an environmental disaster. The aim of the presented paper is to show the results of the modal analysis concerning the cylindrical steel tank with self-supported roof which has been constructed in northern Poland. The investigation was carried out with the use of the FEM commercial computer program Abaqus. The values of natural frequencies, as well as the natural modes, for different levels of liquid filling (empty tank, partly filled and tank fully filled) were determined in the study. The results of the study clearly indicate that the increase in the liquid level leads to the substantial decrease in the natural frequencies of the structure.

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Buckling of Thin-Walled Long Steel Cylinders Subjected to Bending

Journal of Pressure Vessel Technology ◽

10.1115/1.4002902 ◽

2010 ◽

Vol 133 (1) ◽

Cited By ~ 9

Author(s):

Sotiria Houliara ◽

Spyros A. Karamanos

Keyword(s):

Structural Response ◽

Cylinder Wall ◽

Imperfection Sensitivity ◽

Bifurcation Instability ◽

Buckling Mode ◽

Cross Sectional ◽

Moment Capacity ◽

Thin Walled ◽

Cylindrical Steel ◽

Element Technique

The present paper investigates structural response and buckling of long unstiffened thin-walled cylindrical steel shells, subjected to bending moments, with particular emphasis on stability design. The cylinder response is characterized by cross-sectional ovalization, followed by buckling (bifurcation instability), which occurs on the compression side of the cylinder wall. Using a nonlinear finite element technique, the bifurcation moment is calculated, the post-buckling response is determined, and the imperfection sensitivity with respect to the governing buckling mode is examined. The results show that the buckling moment capacity is affected by cross-sectional ovalization. It is also shown that buckling of bent elastic long cylinders can be described quite accurately through a simple analytical model that considers the ovalized prebuckling configuration and results in very useful closed-form expressions. Using this analytical solution, the incorporation of the ovalization effects in the design of thin-walled cylinders under bending is thoroughly examined and discussed, considering the framework of the provisions of the new European Standard EN1993-1-6.

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Post-buckling Behavior of Stiffened Cross-Ply Cylindrical Shells

Journal of Applied Mechanics ◽

10.1115/1.2901599 ◽

1994 ◽

Vol 61 (4) ◽

pp. 998-1000 ◽

Cited By ~ 7

Author(s):

M. Savoia ◽

J. N. Reddy

Keyword(s):

Axial Compression ◽

Carrying Capacity ◽

Shell Theory ◽

Load Carrying Capacity ◽

Imperfection Sensitivity ◽

Buckling Modes ◽

Geometric Imperfection ◽

Buckling Behavior ◽

Load Carrying ◽

Post Buckling

The post-buckling of stiffened, cross-ply laminated, circular determine the effects of shell lamination scheme and stiffeners on the reduced load-carrying capacity. The effect of geometric imperfection is also included. The analysis is based on the layerwise shell theory of Reddy, and the “smeared stiffener” technique is used to account for the stiffener stiffness. Nu cylinders under uniform axial compression is investigated to merical results for stiffened and unstiffened cylinders are presented, showing that imperfection-sensitivity is strictly related to the number of nearly simultaneous buckling modes.

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Towards imperfection insensitive buckling response of shell structures-shells with plate-like post-buckled responses

The Aeronautical Journal ◽

10.1017/aer.2015.14 ◽

2016 ◽

Vol 120 (1224) ◽

pp. 233-253 ◽

Cited By ~ 26

Author(s):

S. C. White ◽

P. M. Weaver

Keyword(s):

Variable Stiffness ◽

Axial Stiffness ◽

Asymptotic Model ◽

Imperfection Sensitivity ◽

Asymptotic Results ◽

Buckling Mode ◽

Design Variables ◽

Non Linear ◽

Buckling Stability ◽

Post Buckling

ABSTRACTThe imperfection sensitivity of cylindrical panels under compression loading is shown to be not only reduced but effectively eliminated using stiffness tailoring techniques. Shells are designed with variable angle-tow (VAT) laminae, giving their laminates variable-stiffness properties over the surface co-ordinates. By employing an asymptotic model of the non-linear shell behaviour and a genetic algorithm, the post-buckling stability was maximised with respect to the VAT design variables. Results for optimised straight-fibre and VAT shells are presented in comparison with quasi-isotropic designs. In the straight-fibre case, small improvements in the post-buckling stability are shown to be possible but at the expense of the buckling load. In the VAT case, on the other hand, considerable improvements in the post-buckling stability are obtained and drops in axial stiffness and load associated with buckling are reduced to negligible levels. The improvements are shown to be a result of a benign membrane stress distribution prior to buckling and a localisation of the buckling mode. The asymptotic results are compared with non-linear finite-element analyses and are found to be in good agreement. Potential future multi-objective optimisation studies are discussed.

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