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

Abstract

Re-examination of some 85 past experiments on the elastic buckling of axially loaded ring stiffened cylinders shows the existence of two distinctive behavioural regimes. Lightly stiffened cylinders, like isotropic cylinders, buckle into non-axisymmetric modes having long axial wavelengths at loads that are sensitive to the precise magnitudes of small initial imperfections. Heavily stiffened cylinders are characterised by snap buckling into axisymmetric modes which, for elastic behaviour at least, show only limited sensitivity to initial imperfections.Each of these characteristics is shown to be predicted by the recently developed 'reduced stiffness analysis' method, which, despite the relatively perfect nature of test specimens, predicts reliabk lower bounds to the experimental scatter. Taken together with the previously demonstrated empirical validity of the reduced stiffness analysis for the prediction of buckling modes and lower bounds to buckling loads for both isotropic and stringer Stiffened cylinders, the present comparisons provide further support to the recommendation that this method be considered as an alternative basis for future design.

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

“…The above reported studies have suggested that the axial load buckling behaviour of the isotropic cylinder can be viewed as simply a rather special case of the behaviour displayed by shells constructed from orthotropic fibre-reinforced composite materials. This echoes earlier suggestions that the behaviour of rib-reinforced cylinders could equally be seen as a generalization of the behaviour of the isotropic cylinder [1][2][3][4][5][6][31][32]. But what recent work exploiting the potential of 'high-fidelity' numerical experimentation shows, when interpreted within the framework of classical and its RS extension, is that this behaviour can be presented in a form of potential importance for design.…”

“…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.…”

“…We now know that both the linear and linearized membrane energy terms are eliminated as a result of imperfection stimulated mode coupling [46]. It would be useful if future research (see footnotes 6 and 7) could demonstrate with the help of the now refined RS model, together with the possibility of carefully controlled numerical experimentation, whether the important findings as to how best to optimize the axial load buckling performance for the rib-reinforced cylinders continue to apply [1][2][3][4][5]. This is especially important if as seems likely the benefits from the use of lightweight composites incorporating the use of optimal use of rib stiffening are to be eventually realized.…”

“…The following has been prompted by such an experience. Without of course providing any details, a recent request to review work developing reliable numerical analysis for the buckling behaviour of rib-reinforced circular cylinders subject to axial loading, including a very extensive list of references, was found to have completely ignored a body of work on this same subject [1][2][3][4][5][6] that some 40 years ago had attracted best paper awards from both the Institutions of Mechanical and Civil Engineers. Were it just the neglect of a few papers co-authored by the reviewer, it would certainly not have merited the following response.…”