Experimental Investigations of Prebuckled Cylinders Under External Pressure

1979 ◽  
Vol 101 (2) ◽  
pp. 178-184 ◽  
Author(s):  
R. H. Knapp ◽  
C. Dumlao
Keyword(s):  
Circular Cylinder ◽  
External Pressure ◽  
Experimental Investigations ◽  
Structural Form ◽  
Corrugated Surface ◽  
Buckling Failure

The prebuckled cylinder is a geometrical idealization of the actual buckled surface of an axially compressed circular cylinder. It is a polyhedral representation of the cylinder in which flat triangular surfaces are joined to form an undulated (corrugated) surface. Such surfaces have been generally regarded as failed forms of the cylinder; however, recent experimental investigations show that the prebuckled cylinder is remarkably more resistant to buckling failure under external pressure than the true cylinder. The prebuckled cylindrical (PC) shell can now be regarded as a new, unfailed structural form to resist external pressure.

On the Nonlinear Analysis Methodologies for Thin Spherical Shells Under External Pressure with Different Finite-Element Codes

1989 ◽  
Vol 33 (04) ◽  
pp. 318-325
Author(s):  
Dario Boote ◽  
Donatella Mascia
Keyword(s):  
Finite Element ◽  
Numerical Procedure ◽  
External Pressure ◽  
Experimental Investigations ◽  
Nonlinear Analyses ◽  
Spherical Shells ◽  
Double Curvature ◽  
Load Carrying ◽  
Material Load ◽  
Structure Collapse

Submersible structures consist merely of simple and double curvature thin-walled shells. For this kind of structure, collapse occurs due to the combined nonlinear action of buckling and plasticity of material. Load-carrying capacity may then be assessed mainly by two approaches: experimental investigations and step-by-step numerical procedures. In nonlinear analyses, the results obtained are influenced by the magnitude of the load increment adopted. Solution procedures are then required in order to choose adequate parameters for material failure description as well as elastic nonlinearity. The aim of this paper is to carry out a suitable numerical procedure whose reliability does not depend on the finite-element code adopted.

Lobar Buckling of Thin-Walled Cylindrical and Truncated Conical Shells Under External Pressure

1974 ◽  
Vol 18 (04) ◽  
pp. 272-277
Author(s):  
C. T. F. Ross
Keyword(s):  
Finite Element ◽  
Circular Cylinder ◽  
Numerical Solutions ◽  
External Pressure ◽  
Element Solution ◽  
Conical Shells ◽  
Varying Thickness ◽  
Complex Boundary ◽  
Thin Walled ◽  
Unsymmetrical Loading

Numerical solutions have been produced for the asymmetric instability of thin-walled circular cylindrical and truncated conical shells under external pressure. The solutions for the circular cylinder have shown that the assumed buckling configurations of Nash [l]2 and Kaminsky [2] were quite reasonable for fixed ends. Comparison was also made of the finite-element solution of conical shells with other analyses. From these calculations, it was shown that the numerical solutions were superior to the analytical ones, as the former could be readily applied to vessels of varying thickness or those subjected to unsymmetrical loading or with complex boundary conditions.

scholarly journals Safety Analysis Using Lebesgue Strain Measure of Thick-Walled Cylinder for Functionally Graded Material under Internal and External Pressure

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
A. K. Aggarwal ◽  
Richa Sharma ◽  
Sanjeev Sharma
Keyword(s):  
Circular Cylinder ◽  
Functionally Graded Material ◽  
Safety Analysis ◽  
External Pressure ◽  
Functionally Graded ◽  
Transition Theory ◽  
Strain Measure ◽  
Graded Material ◽  
Homogeneous Cylinder ◽  
Walled Cylinder

Safety analysis has been done for thick-walled circular cylinder under internal and external pressure using transition theory which is based on the concept of generalized principal Lebesgue strain measure. Results have been analyzed theoretically and discussed numerically. From the analysis, it can be concluded that circular cylinder made of functionally graded material is on the safer side of the design as compared to homogeneous cylinder with internal and external pressure, which leads to the idea of “stress saving” that minimizes the possibility of fracture of cylinder.

scholarly journals Numerical Simulation of Multi-Span Greenhouse Structures

Agriculture ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 499
Author(s):  
María S. Fernández-García ◽  
Pablo Vidal-López ◽  
Desirée Rodríguez-Robles ◽  
José R. Villar-García ◽  
Rafael Agujetas
Keyword(s):  
Matrix Method ◽  
Local Buckling ◽  
External Pressure ◽  
Climatic Conditions ◽  
Wind Loads ◽  
Buckling Modes ◽  
First Order ◽  
Global Buckling ◽  
Computational Fluid Dynamics Cfd ◽  
Buckling Failure

Greenhouses had to be designed to sustain permanent maintenance and crop loads as well as the site-specific climatic conditions, with wind being the most damaging. However, both the structure and foundation are regularly empirically calculated, which could lead to structural inadequacies or cost ineffectiveness. Thus, in this paper, the structural assessment of a multi-tunnel greenhouse was carried out. Firstly, wind loads were assessed through computational fluid dynamics (CFD). Then, the buckling failure mode when either the European Standard (EN) or the CFD wind loads were contemplated was assessed by a finite element method (FEM). Conversely to the EN 13031-1, CFD wind loads generated a suction in the 0–55° region of the first tunnel and a 60% reduction of the external pressure coefficients in the third tunnel was not detected. Moreover, the first-order buckling eigenvalues were reduced (32–57%), which resulted in the need for a different calculation method (i.e., elastoplastic analysis), and global buckling modes similar to local buckling shape were detected. Finally, the foundation was studied by the FEM and a matrix method based on the Wrinkler model. The stresses and deformations arising from the proposed matrix method were conservative compared to those obtained by the FEM.

Development of a New Concept for Cylindrical Pressure Hulls

1980 ◽  
Vol 102 (3) ◽  
pp. 253-257 ◽  
Author(s):  
R. H. Knapp ◽  
R. T. Kudo ◽  
B. Auksmann
Keyword(s):  
Large Scale ◽  
Structural Form ◽  
Technical Feasibility ◽  
Acrylic Plastic ◽  
Initial Effort ◽  
Structural Concept ◽  
Buckling Failure ◽  
Design And Construction

The prebuckled cylindrical (PC) shell represents a new structural concept suitable for use in the undersea environment. The externally pressurized PC shell has been shown to be more resistant to buckling failure than a comparable “true” cylinder. The technical feasibility of this new concept has now been realized by the design and construction of a large-scale prototype made entirely of transparent acrylic plastic. The success of this initial effort offers encouragement to further pursue applications of this novel structural form to other uses in the ocean.

An Experimental Study of Transition and Film Boiling Heat Transfer in Liquid-Saturated Porous Bed

1986 ◽  
Vol 108 (1) ◽  
pp. 117-124 ◽  
Author(s):  
S. Fukusako ◽  
T. Komoriya ◽  
N. Seki
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Circular Cylinder ◽  
Boiling Heat Transfer ◽  
Heating Surface ◽  
Local Maximum ◽  
Nucleate Boiling ◽  
Film Boiling ◽  
Experimental Investigations ◽  
Porous Bed

Experimental investigations of transition and film boiling in a liquid-saturated porous bed are reported. The porous bed contained in a vertical circular cylinder is made up of packed spherical beads whose diameters range from 1.0 to 16.5 mm, while the depth of the bed overlying the heating surface varies from 10 to 300 mm. Water and fluorocarbon refrigerants R-11 and R-113 are adopted as testing liquids. Special attention is focused on the effect of the diameter of spherical beads on boiling heat transfer in the transition boiling region. It is found that for the small bead diameters the steady boiling heat transfer rises monotonically with temperature from nucleate boiling through the film boiling region, without going through a local maximum.

The Influence of Vortex Generators on the Drag and Heat Transfer From a Circular Cylinder Normal to an Airstream

1969 ◽  
Vol 91 (1) ◽  
pp. 91-99 ◽  
Author(s):  
T. R. Johnson ◽  
P. N. Joubert
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Circular Cylinder ◽  
Drag Coefficient ◽  
Angular Position ◽  
Vortex Generator ◽  
Vortex Generators ◽  
Experimental Investigations ◽  
Stagnation Line

Experimental investigations were carried out to examine the effect of vortex generators on drag and heat transfer from a circular cylinder in a crossflow. The cylinder was fitted with two rows of vortex generators which were symmetrically placed on either side of and parallel to the front stagnation line. One configuration of vortex generator was used and the angular position of the rows from the front stagnation line was varied. In the heat transfer runs the vortex generator position remained unvaried. Results are presented to show the variation of drag coefficient with Reynolds number for several angular positions of the generator rows. Results are also presented to show the variation of Nusselt number with Reynolds number both for a cylinder with and without generators. These show that both decreases in drag coefficient and increases in Nusselt number can be obtained when vortex generators are fitted.

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