Imperfection-sensitivity of eccentrically stiffened cylindrical shells.

The initial postbuckling behavior of axially stiffened cylindrical shells is studied with a view to ascertaining the extent to which various effects such as stringer eccentricity, load eccentricity, and barreling influence the imperfection-sensitivity of these structures to buckling. In most cases, when these effects result in an increase in the buckling load of the perfect structure, they increase its imperfection-sensitivity as well. In some instances, however, barreling can significantly raise the buckling load of the shell while reducing its imperfection-sensitivity. The analysis, which is based on Koiter’s general theory of postbuckling behavior and is made within the context of Ka´rma´n-Donnell-type theory, takes into account nonlinear prebuckling deformations and different boundary conditions.

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Mode Interaction of Axially Stiffened Cylindrical Shells: Effects of Stringer Axial Stiffness, Torsional Rigidity, and Eccentricity

Journal of Applied Mechanics ◽

10.1115/1.3157756 ◽

1981 ◽

Vol 48 (4) ◽

pp. 915-922 ◽

Cited By ~ 10

Author(s):

David Hui ◽

R. C. Tennyson ◽

J. S. Hansen

Keyword(s):

Torsional Rigidity ◽

Cylindrical Shells ◽

Mode Interaction ◽

Axial Stiffness ◽

Local Mode ◽

Postbuckling Behavior ◽

Imperfection Sensitivity ◽

Quartic Term ◽

Load Carrying ◽

Stiffened Cylindrical Shells

This paper deals with the effect of stringer axial stiffness, torsional rigidity, and eccentricity on the panel initial postbuckling behavior and mode interaction of axially stiffened cylindrical shells. As far as the local panel mode is concerned, the cylinder is taken to be integrally stiffened and the postbuckling redistribution of the axial load-carrying capacity between the skin and stringers is investigated. It is found that although the buckling analysis is more or less identical to previous analyses, there are significant changes in the quartic term of the potential energy of the local mode and hence, the imperfection-sensitivity of the structure is altered. These changes are due to the interaction between the stringers and the skin in the postbuckling analysis. In addition, to assess the effect of a nonlinear prebuckling state resulting from the presence of local imperfections, Koiter’s theory of amplitude modulation of the local mode is applied to an example problem of interest.

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Imperfection Sensitivity of Stiffened Cylindrical Shells Under Interactive Buckling

Applied Mechanics Reviews ◽

10.1115/1.3124418 ◽

1994 ◽

Vol 47 (6S) ◽

pp. S251-S255

Author(s):

Srinivasan Sridharan

Keyword(s):

Amplitude Modulation ◽

Cylindrical Shells ◽

Computational Modelling ◽

Local Buckling ◽

Second Order ◽

New Technique ◽

Local Mode ◽

Imperfection Sensitivity ◽

Stiffened Shells ◽

Stiffened Cylindrical Shells

In this paper some recent advances made in the understanding of the phenomena and computational modelling of the interaction of local and overall instabilities in stiffened cylindrical shells will be reviewed. These relate to two distinct categories of problems: (1) Axially compressed stringer-stiffened shells and (2) Ring-stiffened cylinders subjected to hydrostatic compression. The former have been analyzed with a novel methodology which employs finite elements in which the local buckling information is embedded. Comparisons of the results of the new technique with Abaqus - a well established nonlinear analysis program - reveals the validity of the underlying concepts of the new technique and efficacy of the new approach. It is shown, that provided all the key local buckling modes triggered in the interaction are considered and the modulation of local buckling amplitudes is accounted for, it is justifiable to neglect the mixed second order stresses and strains in the analysis. Imperfection-sensitivity of a stringer stiffened cylindrical shell structure is illustrated. In the case ring-stiffened cylinders subjected to hydrostatic pressure, it is shown that the amplitude modulation is the key factor in the interaction; it performs the function of capturing the contributions of several neighboring modes of the same longitudinal description as the fundamental local mode, but with differing circumferential wave numbers. An examination of the potential energy function indicates that the amplitude modulation is solely responsible for the presence of the nonvanishing cubic terms, which are dominant over the quartic terms. Once again, mixed second order fields evaluated with appropriate orthogonality conditions have little influence on the interaction and can be safely neglected. An example of an orthotropic layered shell under coincident and well separated critical stresses is presented.

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