Buckling and Post-buckling Behavior of a Pipe Subjected to Internal Pressure

1995 ◽  
Vol 62 (3) ◽  
pp. 595-600 ◽  
Author(s):  
D. M. Tang ◽  
M. A. Ilgamov ◽  
E. H. Dowell
Keyword(s):  
Internal Pressure ◽  
Coupling Effect ◽  
Elastic Shell ◽  
External Pressure ◽  
Static Deflection ◽  
Hollow Beam ◽  
Buckling Behavior ◽  
Post Buckling ◽  
The Subject ◽  
The One

It is well known that a thin elastic shell under external pressure may undergo buckling and collapse. Less well known is that a hollow beam under internal pressure may buckle as an Euler column. This is the subject of the present study. The buckled deflection and natural frequency about the buckled configuration of a vertical pipe with clamped (y-axis) and hinged (z-axis) boundary conditions at the lower support location, considering the influence of internal pressure and initial (manufactured) curvature, has been studied analytically and experimentally. The buckling and post-buckling behavior of the pipe beam with an initial static deflection depends upon the nonlinear coupling due to deflection in the two directions including the anisotropic boundary condition at the one support location. The coupling effects increase as the internal pressure and the initial static deflection increase. When the initial static deflection is zero, the coupling effect disappears. The theoretical results agree reasonably well with the experiments.

The Buckling Behavior of Pipes and Its Influence on the Axial Force Transfer in Directional Wells

2000 ◽  
Vol 122 (3) ◽  
pp. 129-135 ◽  
Author(s):  
Ergun Kuru ◽  
Alexander Martinez ◽  
Stefan Miska ◽  
Weiyong Qiu
Keyword(s):  
Internal Pressure ◽  
Axial Force ◽  
Current Theory ◽  
Pipe Diameter ◽  
Computer Simulator ◽  
Buckling Behavior ◽  
Force Transfer ◽  
Post Buckling ◽  
Support Conditions ◽  
The University

An experimental setup was built at the University of Tulsa to study buckling and post-buckling behavior of pipes constrained in straight horizontal and curved wellbores. Experiments were conducted to investigate the axial force transfer with and without static internal pressure. Different stages of buckling phenomena and their relation to the axial force, the pipe diameter (1/4 and 3/8 in.) and the pipe end-support conditions have also been investigated. Experimental results have shown that the buckling load is a strong function of the pipe diameter and the pipe end-support conditions. Static internal pressure appears to have insignificant influence on the buckling behavior of pipes. A brief review of recently developed mathematical models to predict buckling behavior of pipes in inclined, curved, and horizontal sections of wellbore is also presented. Applications of the current theory are presented by using recently developed computer simulator. Results of the theoretical analysis have confirmed the versatility and effectiveness of computer simulator for better understanding and solving buckling related problems in the field. [S0195-0738(00)00903-1]

The Elastic Instability of a Complete Spherical Shell

1962 ◽  
Vol 13 (2) ◽  
pp. 189-201 ◽  
Author(s):  
J.M.T. Thompson
Keyword(s):  
Spherical Shell ◽  
High Speed ◽  
Large Deflection ◽  
Elastic Shell ◽  
External Pressure ◽  
Maximum Pressure ◽  
Elastic Instability ◽  
Rotationally Symmetric ◽  
Post Buckling ◽  
Good Agreement

SummaryThe elastic instability of a complete spherical shell under uniform external pressure is studied experimentally and theoretically. The premature snapping of a thin elastic shell, made of polyvinyl chloride, is seen to be classical in nature. The experimental maximum pressure and pre-snapping bending deformation are correlated with the theoretical behaviour of an initially imperfect shell. The large deflection behaviour of a perfect shell is assessed experimentally, and the stable post-buckling states are observed to be rotationally symmetric. A fairly precise theoretical analysis of these states is performed, the use of a high-speed digital computer allowing a considerable advance over previous treatments. The experimental and theoretical post-buckling curves are in good agreement, yielding the first detailed correlation of post-snapping equilibrium states in the field of shell instability.

Koiter-Based Solution for the Initial Post-buckling Behavior of Moderately Thick Orthotropic and Shear Deformable Cylindrical Shells Under External Pressure

1997 ◽  
Vol 64 (4) ◽  
pp. 885-896 ◽  
Author(s):  
G. A. Kardomateas
Keyword(s):  
Cylindrical Shells ◽  
Shear Deformation Theory ◽  
External Pressure ◽  
Isotropic Case ◽  
Imperfection Sensitivity ◽  
Buckling Behavior ◽  
Load Carrying ◽  
Geometrical Imperfections ◽  
Post Buckling ◽  
Shear Deformable

The initial post-buckling behavior of moderately thick orthotropic shear deformable cylindrical shells under external pressure is studied by means of Koiter’s general post-buckling theory. To this extent, the objective is the calculation of imperfection sensitivity by relating to the initial post-buckling behavior of the perfect structure, since it is generally recognized that the presence of small geometrical imperfections in some structures can lead to significant reductions in their buckling strengths. A shear deformation theory, which accounts for transverse shear strains and rotations about the normal to the shell midsurface, is employed to formulate the shell equations. The initial post-buckling analysis indicates that for several combinations and geometric dimensions, the shell under external pressure will be sensitive to small geometrical imperfections and may buckle at loads well below the bifurcation predictions for the perfect shell. On the other hand, there are extensive ranges of geometrical dimensions for which the shell is insensitive to imperfections, and, therefore it would exhibit stable post-critical behavior and have a load-carrying capacity beyond the bifurcation point. The range of imperfection sensitivity depends strongly on the material anisotropy, and also on the shell thickness and whether the end pressure loading is included or not. For example, for the circumferentially reinforced graphite/epoxy example case studied, it was found that the structure is not sensitive to imperfections for values of the Batdorf length parameter z˜ above ≃270, whereas for the axially reinforced case the structure is imperfection-sensitive even at the high range of length values; for the isotropic case, the structure is not sensitive to imperfections above z˜ ≃ 1000.

scholarly journals On the subject of analyzing the post-buckling behavior of composite sandwich panels with thin skins of variable stiffness under longitudinal compression

2021 ◽  
Vol 2094 (4) ◽  
pp. 042056
Author(s):  
O V Mitrofanov ◽  
E V Nazarov
Keyword(s):  
Variable Parameter ◽  
Variable Stiffness ◽  
Practical Significance ◽  
Composite Sandwich Panels ◽  
Composite Sandwich ◽  
Rigid Filler ◽  
Buckling Behavior ◽  
Post Buckling ◽  
The Subject ◽  
Analytical Expressions

Abstract The use of variable stiffness panels can be considered as one of the measures to improve the weight efficiency of aircraft structures. The object of research in this work is three-layer panels of variable stiffness loaded with longitudinal compressive forces. The purpose of the work is to evaluate the overcritical behavior of the specified panels when geometrically nonlinear relations are used. The variable parameter of three-layered panels in the case under consideration is the height of the rigid filler, which varies linearly. An analytical solution of the problem of determining the stress-strain state by the Bubnov-Galerkin method is given. The deflection of a panel is represented by two terms, and the problem is reduced to the solution of a nonlinear system of two unknown equations with respect to the values of the deflection amplitudes. Analytical expressions for calculating membrane stresses are given. The practical significance of the work lies in the possibility of estimating the overcritical behavior of a three-layer panel of variable stiffness under compression and the possibility of constructing an algorithm for the optimal design of the panels.

On Establishing Buckling Knockdowns for Imperfection-Sensitive Shell Structures

2018 ◽  
Vol 85 (9) ◽  
Author(s):  
S. Gerasimidis ◽  
E. Virot ◽  
J. W. Hutchinson ◽  
S. M. Rubinstein
Keyword(s):  
Cylindrical Shells ◽  
Strong Dependence ◽  
Elastic Shell ◽  
External Pressure ◽  
Buckling Load ◽  
Spherical Shells ◽  
Nonlinear Buckling ◽  
Buckling Loads ◽  
Buckling Behavior ◽  
Global Buckling

This paper investigates issues that have arisen in recent efforts to revise long-standing knockdown factors for elastic shell buckling, which are widely regarded as being overly conservative for well-constructed shells. In particular, this paper focuses on cylindrical shells under axial compression with emphasis on the role of local geometric dimple imperfections and the use of lateral force probes as surrogate imperfections. Local and global buckling loads are identified and related for the two kinds of imperfections. Buckling loads are computed for four sets of relevant boundary conditions revealing a strong dependence of the global buckling load on overall end-rotation constraint when local buckling precedes global buckling. A reasonably complete picture emerges, which should be useful for informing decisions on establishing knockdown factors. Experiments are performed using a lateral probe to study the stability landscape for a cylindrical shell with overall end rotation constrained in the first set of tests and then unconstrained in the second set of tests. The nonlinear buckling behavior of spherical shells under external pressure is also examined for both types of imperfections. The buckling behavior of spherical shells is different in a number of important respects from that of the cylindrical shells, particularly regarding the interplay between local and global buckling and the post-buckling load-carrying capacity. These behavioral differences have bearing on efforts to revise buckling design rules. The present study raises questions about the perspicacity of using probe force imperfections as surrogates for geometric dimple imperfections.

“Channeling” the powers of God’s Word

2010 ◽  
Vol 4 (2) ◽  
pp. 135-156 ◽  
Author(s):  
Dorothea E. Schulz
Keyword(s):  
The Other ◽  
Border Zone ◽  
Focus Attention ◽  
Spiritual Power ◽  
New Materials ◽  
God's Word ◽  
Audio Recordings ◽  
Heated Debate ◽  
The Subject ◽  
The One

Starting with the controversial esoteric employment of audio recordings by followers of the charismatic Muslim preacher Sharif Haidara in Mali, the article explores the dynamics emerging at the interface of different technologies and techniques employed by those engaging the realm of the Divine. I focus attention on the “border zone” between, on the one hand, techniques for appropriating scriptures based on long-standing religious conventions, and, on the other, audio recording technologies, whose adoption not yet established authoritative and standardized forms of practice, thereby generating insecurities and becoming the subject of heated debate. I argue that “recyclage” aptly describes the dynamics of this “border zone” because it captures the ways conventional techniques of accessing the Divine are reassessed and reemployed, by integrating new materials and rituals. Historically, appropriations of the Qur’an for esoteric purposes have been widespread in Muslim West Africa. These esoteric appropriations are at the basis of the considerable continuities, overlaps and crossovers, between scripture-related esoteric practices on one side, and the treatment by Sharif Haidara’s followers of audio taped sermons as vessels of his spiritual power, on the other.

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