Behavior Of Thin-walled Cylindrical Shells Research Articles

Determining the mechanical behavior of thin-walled cylindrical shells of cement composite containing graphene oxide and glass fibers with the help of fuzzy logic model and artificial neural network

Determining the mechanical behavior of thin-walled cylindrical shells of cement composite containing graphene oxide and glass fibers with the help of fuzzy logic model and artificial neural network

A semi-empirical modeling approach for predicting the deformational capacity of axially-compressed cylindrical shells based on a novel material stress-strain characterization method

Adoption of cylindrical shell structures for various load-resistance applications has enjoyed wide-spread acceptance in the field of civil, mechanical and aerospace engineering, mainly due to the exceptional structural efficiency of cylindrical shells to withstand significant longitudinal and circumferential in-plane loading without bending. However, where such in-plane loading conditions are compressive, cylindrical shells are likely to exhibit an unstable response characterized by localized out-of-plane deformation. Computerized numerical simulation is often required for accurate and efficient estimation of the strains and resultant stresses in cylindrical shells under loading, especially where the thickness of the shell is sufficient to evoke an inelastic buckling response in the structure. The buckling behavior of thin-walled cylindrical shells subjected to uniform axial compression has been studied in this paper using the finite element (FE) simulation method to assign respective material, geometric, loading and boundary properties to computer-generated cylindrical shell specimens. Extensive parametric analysis, consisting of approximately 720 FE runs, was then conducted based on a full-factorial empirical design, applying ample variations of the relevant parameters that influence the buckling response of axially-compressed cylindrical-shell structures. Nonlinear multiple regression techniques were then employed to derive the coefficients of nonlinear mathematical expressions, each developed as an arithmetic product of appropriate variable functions related to the respective functional sensitivities of the investigated parameters. Strain-hardening properties were incorporated into the mathematical expressions based on the shape constants of the Ndubuaku stress-strain model; which has proven to be remarkably useful for accurate parameterization of the stress-strain behavior over the full range of strains for a wide range of metallic materials, including materials with a well-defined yield plateau. Excellent predictions of FEA-derived values for the critical limit strain limit were obtained, and a simple statistical approach was presented to increase the conservativeness of the semi-empirical model as required.

Buckling behavior of a thin-walled cylinder shell with the cutout imperfections

ABSTRACTIn this work, the effects of geometric imperfections on the buckling behavior of thin-walled cylindrical shells under compression were investigated by both experimental and numerical methods. The imperfections were produced by one or two circular cutouts on the shell surface. The configuration of specimens was fabricated by the geometric imperfection parameter α, which was calculated using the circular cutout radius a, thickness t, and cylinder radius R. In the experimental investigation, a three-dimensional (3D) Digital Image Correlation Method, an optical instrument which utilized the full-field and noncontact measurement, was employed to obtain 3D displacement and strains, then the test data were analyzed and compared with the correlation technique that can determine the surface displacements of cylindrical shells. The further numerical simulations showed that parameter a played an important role in the buckling strengths of thin-walled specimens. In addition, the visualization effects of the geometric imperfections on the thin-walled shell structures were also demonstrated by using this optical method.

Composite cylindrical shells under static and dynamic axial loading: An experimental campaign

The results of an experimental investigation performed at the Politecnico di Milano inside the European project DAEDALOS on three composite cylindrical shells are here presented. At first, static buckling tests were performed under axial compression. Then, two types of dynamic tests were carried out: modal tests at different load levels before buckling and dynamic buckling tests applying an axial shortening of short duration. At the end, one shell was statically tested until final failure. The tests allow to understand the behavior of thin-walled cylindrical shells subjected to axial compression both in static and dynamic conditions. The results show the strength capacity of these structures to work in the post-buckling range with a capacity to sustain a load that is about 40% of the buckling load. The modal tests at different load levels allowed to observe that an increase of the load determines a reduction of the modal frequency and an increase of the damping. Large deformations are obtained before the final failure with out-of-plane displacements of almost 40mm and a shortening equal to about 26 times the buckling shortening.

Sloshing effect on the dynamic behavior of horizontal cylindrical shells

The present study investigates the effect of free surface motion of a fluid on the dynamic behavior of thin-walled cylindrical shells. This paper outlines a semi-analytical approach to dynamic analysis of a fluid-filled horizontal cylindrical shell taking into account free surface motion; sloshing. The aim of the method is to provide a general approach that can be used for both analysis and synthesis of fluid/structure interaction problems in horizontal cylindrical shells focusing on the dynamic interaction between a flexible structure and incompressible and inviscid flow. The approach is very general; it allows dynamic analysis of both uniform and non-uniform cylindrical shells and considers the fluid forces and includes the sloshing effect exerted on the structure. The hybrid method developed in this work incorporates a combination of the classic finite element approach and thin shell theory to determine the specific displacement functions. Mass and stiffness matrices of the shell are determined by precise analytical integration. A potential function is applied to develop the dynamic pressure due to the fluid. The kinetic and potential energies are evaluated for a range of fluid heights to find the influence of the fluid on the dynamic responses of the structure. The influence of physical and geometrical parameters on the fluid-structure system has been considered in the numerical solutions. When these results are compared with corresponding results available in the literature, both theoretical and experimental, very good agreement is obtained.

719 薄肉円筒部材の塑性座屈挙動に及ぼす形状および物性の影響(GS-3 座屈挙動,研究発表講演)

719 薄肉円筒部材の塑性座屈挙動に及ぼす形状および物性の影響(GS-3 座屈挙動,研究発表講演)

Behavior of thin-walled cylindrical shells subjected to local thermal shock

Behavior of thin-walled cylindrical shells subjected to local thermal shock

Some Observations on the Yoshimura Buckle Pattern for Thin-Walled Cylinders

A great deal of the behavior of thin-walled cylindrical shells loaded in axial compression can be explained by considering the Yoshimura buckle pattern as a three-dimensional space frame and observing the collapse of that space frame.