Buckling of cylindrical shells with stepwise wall thickness subjected to combined loading (original) (raw)
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Thin-Walled Structures, 1991
Buckling and postbuckling behaviour of perfect and imperfect cylindrical shells of finite length subject to combined loading of external pressure and axial compression are considered. Based on the boundary layer theory which includes the edge effect in the buckling of shells, a theoretical analysis for the buckling and postbuckling of circular cylindrical shells under combined loading is presented using a singular perturbation technique. Some interaction curves for perfect and imperfect cylindrical shells are given. The analytical results obtained are compared with some experimental data in detail, and it is shown that both agree well. The effects of initial imperfection on the interactive buckrng load and postbuckling behaviour of cylindrical shells have also been discussed NOTATION
Thin-Walled Structures, 2012
Metal cylindrical storage structures of significant size, such as silos and vertical-axis tanks, are almost always constructed from many short cylindrical shells of different thickness as the stress resultants on the wall progressively increase towards the base. The resulting increases in thickness are always made in step changes using metal sheets of uniform thickness because of the availability of such source materials. The result is a shell with a stepped wall with multiple discrete steps in thickness. Such shells are very susceptible to buckling under external pressure when empty or partially filled, but the buckling mode may involve only part of the shell height due to the changes in shell thickness. These changes must therefore be accounted for within the design process. A new method of determining the critical buckling resistance of such shells was recently developed, and although it has been shown to be valid, the methodology for its application in practical design has not been set out or shown. This paper therefore briefly describes the new method and demonstrates the manner in which it can be used to produce rapid, safe assessments of cylindrical shells with a wide range of patterns of wall thickness changes. The results are then suitable for direct introduction into such documents as the European standard on metal shells [1] and the ECCS Recommendations [2].
Buckling strength of the cylindrical shell and tank subjected to axially compressive loads
This paper aims to develop practical design equations and charts estimating the buckling strength of the cylindrical shell and tank subjected to axially compressive loads. Both geometrically perfect and imperfect shells and tanks are studied. Numerical analysis is used to evaluate buckling strength. The modeling method, appropriate element type and necessary number of elements to use in numerical analysis are recommended. According to the results of the para-metric study of the perfect shell, the buckling strength decreases significantly as the diameter-to-thickness ratio increases, while it decreases slightly as the height-to-diameter ratio increases. These results are different from those in the case of columns. The buckling strength of the perfect tank placed on an extremely soft foundation and a stiff foundation increases by up to 1.6% and 5.6%, respectively, compared with that of the perfect shell. The buckling strength of the shell and tank decreases significantly as the amplitude of initial geometric imperfection increases. Convenient and sufficiently accurate design equations and charts used for estimating buckling strength are provided.
The application of thin-walled cylindrical shells, as the essential structural members, has been known for engineers and functional duty of them is basic necessaries of modern industries. These structures are prone to fail by buckling under external pressure which could be happened during discharging or wind load. Although the buckling capacity of the shells depends principally on two geometric ratios of "length to radius" (L/R) and "radius to thickness" (R/t), but the effect of thickness variation on the behavior of the shells is complicated to be studied. On the other hand, the buckling strength of thin cylindrical shells is sensitive to the magnitude and shape of geometric imperfections.
Buckling of thin-walled cylindrical shells under axial compression
International Journal for Numerical Methods in Engineering, 2009
Lightweight thin-walled cylindrical shells subjected to external loads are prone to buckling rather than strength failure. The buckling of an axially compressed shell is studied using analytical, numerical and semi-empirical models. An analytical model is developed using the classical shell small deflection theory. A semi-empirical model is obtained by employing experimental correction factors based on the available test data in the theoretical model. Numerical model is built using ANSYS finite element analysis code for the same shell. The comparison reveals that the analytical and numerical linear model results match closely with each other but are higher than the empirical values. To investigate this discrepancy, non-linear buckling analyses with large deflection effect and geometric imperfections are carried out. These analyses show that the effects of non-linearity and geometric imperfections are responsible for the mismatch between theoretical and experimental results. The effect of shell thickness, radius and length variation on buckling load and buckling mode has also been studied. Copyright © 2009 John Wiley & Sons, Ltd.
Thin-Walled Structures, 1993
A new approach is extended to investigate the buckling and postbuckling behaviour of perfect and imperfect, stringer and ring stiffened cylindrical shells of finite length subject to combined loading of external pressure and axial compression. The formulations are based on a boundary layer theory which includes the edge effect in the postbuckling analysis of a thin shell. The analysis uses a singular perturbation technique to determine the buckling loads and the postbuckling equilibrium paths. Some interaction curves for perfect and imperfect stiffened cylindrical shells are given and compared well with experimental data. The effects of initial imperfection on the interactive buckling load and postbuckling behaviour of stiffened cylindrical shells have also been discussed.
Code 48 Buckling Stability of Thin Walled Cylindrical Shells Under Axial Compression
Light weight thin walled cylindrical shells subjected to external loads are prone to buckling rather than strength failure. In this paper, buckling investigation of thin walled cylindrical shells under axial compression is presented. Buckling failure is studied using analytical, numerical and semi empirical models. Analytical model is developed using Classical Shell small deflection theory. A Semi empirical model is obtained by employing experimental correction factors based on the available test data to the theoretical model. A finite elements model is built using ANSYS FEA Code for the same shell.
BUCKLING ANALYSIS OF SHELLS SUBJECTED TO COMBINTED LOADS
IAEME Publication, 2014
A semi-analytical isoparametric finite element with three nodes per element and five degrees of freedom per node has been used for the solution. Moderately thick shell theory has been used for the analysis. Second order strains with the in plane and transverse non-linear terms are used for the derivation of geometric matrix. Full Fourier expansion is used in the circumferential direction to overcome the coupling that arises due to material anisotropy and torque prestress. Comparison of the results obtained due to finite element is made with simplified solutions using two thin shell theories with and without shear deformation. The effects of combined load (axial compression and external pressure) on pre-buckling characteristics of composite circular cylindrical and conical shells of various geometric properties have been presented.
Buckling strength of thin cylindrical shells under localised axial compression
2002
The buckling strength of a thin cylindrical shell is important in many applications in civil engineering. On the one hand, current design rules are principally based on an empirical interpretation of test data and hence very simple loading conditions are applied. On the other hand, experimental and theoretical observations show significant stress non-uniformity and hence a deviation from the buckling strength expected under uniform load. Reliable quantification of this effect is still challengingly difficult. This paper explores a typical thin cylindrical silo shell under localized axial compression. Two different buckling phenomena are identified with corresponding, and distinct, buckling mode forms. The influence of geometric imperfections on the buckling strength of the shell is also considered.
2018
Buckling in cylindrical shells has been a major issue for researchers for more than a century. Cylindrical shells are often used in the production of aircrafts, racks, boilers, pipelines, cars, and some submarine structures. These structures may experience axial compression loads in their longevity and yield to buckling. Furthermore, these structures usually have disruptions, such as cutouts, which may have adverse effects on their stability. In the present paper using finite element method, the buckling of cylinders with circular cutout of AA508 aluminum alloy under loading is investigated. The effect of some geometric parameters such as cutout position and cutout size on the critical load of buckling of these shells was studied. According to the results, with increase in the diameter of cutout the critical load of buckling sharply decreases. The results of the numerical analysis are verified by a series of experimental tests.