Failure Behavior of Corrugated Pressure Cylindrical Shells with Variable Wall Thickness under Uniform External Pressure

Collapse behavior of corrugated stiffened pressure shells under external hydrostatic pressure considering actual fabrication imperfections: A reverse modeling technique

Experiments on cylindrical shells under pure bending and external pressure

Longitudinally stiffened corrugated cylindrical shells under uniform external pressure

Based on a systematic literature review, no design guidelines addressing practical issues related to steel circular hollow section (CHS) members under hydrostatic pressure have been documented thus far, except for the design recommendations proposed by the European standard EN 1993-1-6 concerning the strength and stability of shell structures. Considering that the existing codes are often outdated and subject to improvement, there is a growing demand for modern solutions that can accurately replicate the stability loss response of equipment subject to external pressure. The development of a more direct and simple method, augmented by reliable computational techniques, is advisable to avoid the numerous challenges associated with manual calculations. This approach will streamline the design process and mitigate the complexity of current practical or technical approaches. Thus, this research has formulated a method to predict design strength through the direct application of the critical elastic buckling stress, determined from Generalised Beam Theory (GBT) analyses, induced by hydrostatic pressure in custom-crafted equations, finely tuned for this specific objective. The authors present a formulation of GBT to analyze the elastic buckling behavior of CHS subject to both combined axial compression and external pressure. This work provides an extensive study of the behavior of circular cylindrical shells under external loading conditions. It first introduces the analyses of GBT and the theoretical and empirical formulas applicable to this objective. It then describes the steps involved in the development and validation of a numerical model that simulates the response of circular cylindrical shells under hydrostatic pressure, conducting an extensive parametric study using finite element analyses (FEAs). The results from available tests validate the finite element (FE) model. Upon achieving adequate agreement between the generated numerical and experimental results, new resistance reduction curves for cylindrical shell members are developed based on the results of the parametric study. Additionally, the study compares the existing provisions of EN 1993-1-6 for the design of cylindrical shells under hydrostatic pressure. Finally, a statistical approach is adopted to compare the responses of cylindrical shells calculated according to the EN 1993-1-6 code recommendations with those obtained through the newly proposed method.

The author deduced approximate formulae for calculating, the collapsing pressure of conical and spherical shells under uniform external pressure from the exact formulae for Cylindrical Shells, and showed that the results of collapsing experiments relating to elastic stability of mild-steel shells of the three typical shapes above mentioned can be represented by a single curve.

Buckling behavior of cylindrical steel tanks with concavity of vertical weld line imperfection

Buckling of cylindrical shells with stepwise variable wall thickness under uniform external pressure

This paper proposes a new type of shell, similar to a cylindrical shell, which has significantly higher buckling strength when subjected to an arbitrary combination of uniform external pressure and axial compression. The underlying principle consists in a slight modification of the perfect cylinder in order to counteract the natural deformations which get larger and larger and lead to the collapse of the structure. Such shells are called ASTER shells. The concept has been validated through experiments, then analyzed numerically in order to explain what was observed and to propose avenues for improvements. The shells were made of electrodeposited nickel. The material was characterized. The chosen specimens were carefully measured to characterize their thickness and initial imperfections, then tested under the various types of loading. Then they were analyzed using finite elements. Thus, we were able to compare the finite element predictions with the experimental results. This comparison shows that plasticity has a decisive influence on the critical load and that linear elastic dimensioning leads to a serious overestimation of the experimental critical load. Contrary to perfect cylindrical shells, this type of shell is not significantly affected by geometric imperfections: this is another advantage of this type of design. Finally, we propose a numerical analysis in order to optimize the choice of the shape and propose shapes which resist buckling much better than a smooth cylinder when subjected to uniform external pressure, axial compression or a combination of both.

Experiments on dented cylindrical shells under peripheral pressure

The large deflection of a spherical shell loaded with an inward radial point load and a uniform external pressure is investigated by supposing that the shell suffers small deflections from two known exact solutions to the equations for large deflection. These two exact solutions being of a segment whose curvature is completely reversed, for the region in the neighbourhood of the point of application of the point load, and of an unstressed sphere for the remainder of the shell.In the first part of the paper load-deflection curves are obtained for constant external pressures with varying inward point loads. It is found that for certain combinations of the values of pressure and point load, the shell becomes unstable. This is believed to be the first time that the stability of spherical shells under combinations of independently varying load system has been discussed.The results obtained in the first part of the paper are used in the second part to investigate the post-buckling behaviour of perfect and imperfect spherical shells under uniform external pressure acting alone. The behaviour predicted for a perfect shell agrees satisfactorily with the work of previous authors; the behaviour of shells with geometrical imperfection has received no previous satisfactory treatment. It is found that a geometrical imperfection of half the thickness can reduce the buckling pressure to about one-fifth of the classical value for perfect shells.Experiments are described on copper shells having regions thinned by acid etching. Their results are in good agreement with the theoretical predictions.

Global optimum design of externally pressurized isogrid stiffened cylindrical shells with added T-rings

On the theory of stability of cylindrical thin-walled shells under the action of external pressure

Plastic collapse of circular conical shells under uniform external pressure

Vibration and elastic instability of thin-walled domes under uniform external pressure

The solution of the stability problem of a circular sandwich ring under uniform external pressure is given in a refined statement. The need to determinate the precritical stresses in load-bearing layers in the refined statement with regard to the transverse compression of the core is established, which is the basis for the detection of the mixed flexural buckling forms (BFs) with more than two half-waves along the circumferential coordinate (n>2). It is found that sandwich structures with a determining parameter of transverse compression corresponding to the limit of transition from the mixed BFs to synphasic ones are the most efficient from the weight viewpoint.