The reversed "von Karman/Brazier effect" and a compendiary analytical solution

TL;DR

The paper investigates how cross-section ovalisation affects bending in cylindrical shells, focusing on a reversed behavior when ovalisation is prevented. Analytical formulae are developed using Donnell's shell equations and a beam-on-elastic-foundation model, with circumferential loading decomposed by Fourier analysis. Validation is provided through comparison with experimental tests and finite-element analyses, demonstrating accurate predictions for both imposed-ovalisation and reversed cases. The results offer practical tools for offshore engineering design, enabling assessment and mitigation of ovalisation effects with stiffeners and buckling arrestors.

Abstract

The goal of the present study is to offer some accurate analytical formulae for the evaluation of the here defined reversed "von Karman/Brazier's effect", which may appear at first sight anomalous and has previously been noticed and successively explained using both Finite Element analyses and approximate analytical formulations. The proposed analytical formulae, based on the previous contribution of one of the present authors and on the Donnell's equations for cylindrical shells can be helpful in emphasizing the possible impact that some arrangements may have in various fields and especially in offshore engineering and can assist design calculations.

Figures (9)

• Figure 1: Buckle arrestors.
• Figure 2: Typical four-point bending test arrangement.
• Figure 3: Circular cylindrical shell loaded by two opposite inward forces at the half-length section: coordinate system and notations.
• Figure 4: Beam-on-elastic foundation analogy.
• Figure 5: Axial stresses and resulting ovalising pressure.