Experimental and theoretical correlations for elastic buckling of axially compressed stringer stiffened cylinders

Abstract

A re-examination of some 240 past experiments on the general elastic buckling of axially loaded stringer stiffened cylinders suggests that the observed buckling behaviours exhibited a degree of imperfection sensitivity considerably higher than that so often ascribed to them. It is demonstrated how the underestimation of these experimental knock-downs may have resulted from the use of theoretical models insufficiently representative of test conditions. By incorporating a more precise modelling of the test shells the present analyses show how, contrary to a widely held belief, the potential knock-down factors for general elastic buckling can approach those of the isotropic cylinder. Furthermore, despite the relatively perfect nature of many of the test shells, the recently described 'reduced stiffness analysis' method provides lower bounds of the observed experimental scatter that are sufficiently reliable to recommend this method as a basis for future design.

Stability in Shells

“…Extensive comparisons of test loads and the predictions from the extended reduced stiffness method for a wide range of stiffened and unstiffened cylindrical shell geometries have shown similar levels of agreement, see for example Ref. [14].…”

Experimental and theoretical correlations for elastic buckling of axially compressed ring stiffened cylinders

“…The theoretical knock-down factor. p t h r which is defined as the ratio of the reduced stiffness, o f , to classical minimum critical stress, oCm Plh = a k / a c m (1) is, for this shell, found to be as low as 0.53, indicating considerable potential for imperfection sensitivity. This, as anticipated, is somewhat lower than the experimental knock-down factor, pexp, defined as Table 3 which for this shell is 0.69; aexp is the experimental buckling stress.…”

Comments on effective use of numerical modelling and extended classical shell buckling theory

“…to very similar treatment. Previous work on rib-reinforced cylinder buckling [1][2][3][4][5][6] recorded behaviours that have close similarities to those displayed by the cylinders comprised of composite materials [47][48][49][50][51][52][53][54] including the link with the influence of Poisson's ratio [5,46].…”

“…As opined at the start of this paper, the increasing interest in the use of rib-reinforced shells as a means for improving material efficiency might also benefit from reconsideration of the work undertaken by Ellinas [1][2][3][4][5][6], prior to the availability of reliable nonlinear numerical software. These earlier studies were undertaken using the original version of the RS method, in which just the linearized membrane energy terms were omitted.…”