On the Propagation of Bulges and Buckles

1984 ◽  
Vol 51 (2) ◽  
pp. 269-277 ◽  
Author(s):  
E. Chater ◽  
J. W. Hutchinson
Keyword(s):  
Steady State ◽  
Critical Pressure ◽  
External Pressure ◽  
Instability Mode ◽  
Instability Modes ◽  
Buckle Propagation ◽  
State Propagation

Two examples illustrate the propagation of instability modes under quasi-static, steady-state conditions. The first is the inflation of a long cylindrical party balloon in which a bulge propagates down the length of the balloon. The second is the collapse of a long pipe under external pressure as a result of buckle propagation. In each example, there is a substantial barrier to the initiation of the instability mode. Once initiated, however, the mode will not arrest if the pressure is in excess of the quasi-static, steady-state propagation pressure. It is this critical pressure that is determined in this paper for each of the two examples.

A Global Energy Approach for Analysis of a Propagating Buckle in Submarine Pipelines

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
Mingqiao Tang ◽  
Jianghong Xue ◽  
Renhuai Liu
Keyword(s):  
Steady State ◽  
Transition Zone ◽  
Plastic Material ◽  
External Pressure ◽  
Thick Wall ◽  
Yield Coefficient ◽  
Rigid Plastic ◽  
Stretching Factor ◽  
Buckle Propagation ◽  
Membrane Stretching

This paper presents a unique approach to analyze the steady-state buckle propagation phenomenon in underwater pipelines. In previous work, we restudied the buckling of a very long pipeline subjected to external pressure and found that buckling happens only over a certain length of the pipeline. In this paper, the collapse mode of the pipeline obtained in previous studies is taken as the transition zone during steady-state buckle propagation. Kinematics in the transition zone is analyzed based on von Kármán–Donnell type of nonlinearity. Assuming linear elastic rigid plastic material properties, the mechanical responses in the transition zone are examined using the deformation theory. Two parameters, the yield coefficient and the membrane stretching factor, are introduced to depict the effects of transversal bending and the membrane stretching, respectively. Analytical solution of buckle propagation pressure is derived by considering the energy conversation calculated from shell theory. It is found that the buckle propagation performance is governed by the transversal bending, including the circumferential bending and longitudinal bending. The membrane stretching is significant only for thick wall pipeline, in particular when the ratio of radius-to thickness is small than ten. The analysis is in effect by comparing the obtained solutions with the well-established predictions and the experimental results.

SPECKLE STATISTICS IN THE PHOTON LOCALIZATION TRANSITION

2010 ◽  
Vol 24 (12n13) ◽  
pp. 1950-1988 ◽  
Author(s):  
Azriel Z. Genack ◽  
Jing Wang
Keyword(s):  
Steady State ◽  
Probability Distributions ◽  
Speckle Pattern ◽  
Frequency Variation ◽  
Localization Transition ◽  
Classical Waves ◽  
Speckle Patterns ◽  
The Many ◽  
Photon Localization ◽  
State Propagation

We review the statistics of speckle in the Anderson localization transition for classical waves. Probability distributions of local and integrated transmission and of the evolution of the structure of the speckle pattern are related to their corresponding correlation functions. Steady state and pulse transport can be described in terms of modes whose speckle patterns are obtained by decomposing the frequency variation of the transmitted field. At the same time, transmission can be purposefully manipulated by adjusting the incident field and the eigenchannels of the transmission matrix can be found by analyzing sets of speckle patterns for different inputs. The many aspects of steady state propagation are reflected in diverse, but simply related, parameters so that a single localization parameter encapsulates the character of transport on both sides of the divide separating localized from diffusive waves.

On symmetric intrusions in a linearly stratified ambient: a revisit of Benjamin's steady-state propagation results

2021 ◽  
Vol 929 ◽  
Author(s):  
M. Ungarish
Keyword(s):  
Steady State ◽  
Control Volume ◽  
Gravity Current ◽  
Head Loss ◽  
Stability Criteria ◽  
Ambient Fluid ◽  
Height Ratio ◽  
Stagnation Line ◽  
Volume Analysis ◽  
State Propagation

Previous studies have extended Benjamin's theory for an inertial steady-state gravity current of density $\rho _{c}$ in a homogeneous ambient fluid of density $\rho _{o} < \rho _{c}$ to the counterpart propagation in a linearly stratified (Boussinesq) ambient (density decreases from $\rho _b$ to $\rho _{o}$ ). The extension is typified by the parameter $S = (\rho _{b}-\rho _{o})/(\rho _{c}-\rho _{o}) \in (0,1]$ , uses Long's solution for the flow over a topography to model the flow of the ambient over the gravity current, and reduces well to the classical theory for small and moderate values of $S$ . However, for $S=1$ , i.e. $\rho _b = \rho _c$ , which corresponds to a symmetric intrusion, various idiosyncrasies appear. Here attention is focused on this case. The control-volume analysis (balance of volume, mass, momentum and vorticity) produces a fairly compact analytical formulation, pending a closure for the head loss, and subject to stability criteria (no inverse stratification downstream). However, we show that plausible closures that work well for the non-stratified current (like zero head loss on the stagnation line, or zero vorticity diffusion) do not produce satisfactory results for the intrusion (except for some small ranges of the height ratio of current to channel, $a = h/H$ ). The reasons and insights are discussed. Accurate data needed for comparison with the theoretical model are scarce, and a message of this paper is that dedicated experiments and simulations are needed for the clarification and improvement of the theory.

Ruga mechanics of soft-orifice closure under external pressure

2021 ◽  
Vol 477 (2249) ◽  
Author(s):  
Hanxun Jin ◽  
Alexander K. Landauer ◽  
Kyung-Suk Kim
Keyword(s):  
Surface Layer ◽  
Limit Load ◽  
Phase Evolution ◽  
External Pressure ◽  
Soft Material ◽  
Buckling Mode ◽  
Cross Sectional ◽  
Threefold Symmetry ◽  
Instability Modes ◽  
Symmetry Mode

Here, we report the closure resistance of a soft-material bilayer orifice increases against external pressure, along with ruga-phase evolution, in contrast to the conventional predictions of the matrix-free cylindrical-shell buckling pressure. Experiments demonstrate that the generic soft-material orifice creases in a threefold symmetry at a limit-load pressure of p / μ  ≈ 1.20, where μ is the shear modulus. Once the creasing initiates, the triple crease wings gradually grow as the pressure increases until the orifice completely closes at p / μ  ≈ 3.0. By contrast, a stiff-surface bilayer orifice initially wrinkles with a multifold symmetry mode and subsequently develops ruga-phase evolution, progressively reducing the orifice cross-sectional area as pressure increases. The buckling-initiation mode is determined by the layer's thickness and stiffness, and the pressure by two types of the layer's instability modes—the surface-layer-wrinkling mode for a compliant and the ring-buckling mode for a stiff layer. The ring-buckling mode tends to set the twofold symmetry for the entire post-buckling closure process, while the high-frequency surface-layer-wrinkling mode evolves with successive symmetry breaking to a final closure configuration of two- or threefold symmetry. Finally, we found that the threefold symmetry mode for the entire closure process provides the orifice's strongest closure resistance, and human saphenous veins remarkably follow this threefold symmetry ruga evolution pathway.

Nonlinear Stability Analysis of the Vaulted Roofs With Corrosion Defects of Oil Storage Tank

2009 ◽  
Author(s):  
Baosheng Dong ◽  
Xinwei Zhao ◽  
Hongda Chen ◽  
Jinheng Luo ◽  
Zhixin Chen ◽  
...  
Keyword(s):  
Spherical Shell ◽  
Nonlinear Stability ◽  
Storage Tank ◽  
Critical Pressure ◽  
External Pressure ◽  
Shallow Spherical Shell ◽  
Nonlinear Stability Analysis ◽  
Spherical Shells ◽  
Oil Storage ◽  
Oil Storage Tank

The vaulted roofs of oil storage tank are usually designed as the shallow spherical shells subjecting to a uniform external pressure, which have been widely observed that these shallow spherical shells undergo various levels of corrosion in their employing conditions. It is important to assess the stability of these local weaken shallow spherical roofs due to corrosion for preventing them from occurring unexpected buckling failure. In this paper, the uniform eroded part of a shallow spherical oil tank vaulted roof is simplified as a shallow spherical shell with elastic supports. Based on the simplification, a general pathway to calculate the critical pressure of eroded shallow spherical shell is proposed. The modified iteration method considering large deflection of the shell is applied to solve the problem of nonlinear stability of the shallow spherical shells, and then the second-order approximate analytical solution is obtained. The critical pressure calculated by this method is consistent with the classical numerical results and nonlinear finite element method, and the calculation errors are less than 10%. It shows that it is feasible to apply the method proposed here.

Effect of Weather, Age, and Cyclic Pressurizations on Structural Performance of Acrylic Plastic Spherical Shells Under External Pressure Loading

1982 ◽  
Vol 104 (2) ◽  
pp. 190-200
Author(s):  
J. D. Stachiw ◽  
R. B. Dolan
Keyword(s):  
Surface Layer ◽  
Critical Pressure ◽  
External Pressure ◽  
Thin Surface Layer ◽  
Ambient Atmosphere ◽  
Plastic Shell ◽  
Spherical Shells ◽  
Acrylic Plastic ◽  
Operational Life ◽  
Physical And Chemical

Weathering, aging, and cyclic application of stresses to acrylic plastic degrades its physical properties. The rate of degradation must be known if the useful life of load-carrying acrylic structures is to be predicted with accuracy. Physical and chemical tests conducted by the authors on thick spherical shells indicate that the weathering affects only a thin surface layer of material, which after 10 years is still less than 0.020 in. thick. Similarly, pollutants in the ambient atmosphere of the pressure chamber affect the surface layer of the spherical shell facing the interior of the chamber. The physical and chemical properties of the thin surface layer affected by weathering differed significantly from those in the middle of 2.5-in.-thick Plexiglas G plate; the decrease in properties was: 40 percent in tensile elongation, 34 percent in flexure strength, 21 percent in tensile strength, and 79 percent in molecular weight. Since the interior body of the thick plastic shell is not affected by weathering or chemical attack and the affected surface layers are very thin, the ability of the shell to carry compressive loads is not significantly diminished after 10 years of service. Only an 11 percent decrease of critical pressure was observed in spherical shells with thickness of 1 in. subjected to 10 years of weathering and 2000 pressure cycles of 8 hour duration each to 30 percent of its original critical pressure. Based on the preceding data it appears safe to extend the operational life from 10 to 20 years of all acrylic plastic spherical shells with bearing surfaces normal to spherical surface designed on the basis of ANSI/ASME PVHO-1 Safety Standard for external pressure service.

Effects of Diameter to Thickness Ratio and External Pressure on the Velocity of Dynamic Buckle Propagation in Offshore Pipelines

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Z. Omrani ◽  
K. Abedi ◽  
A. R. Mostafa Gharabaghi
Keyword(s):  
Finite Element ◽  
Numerical Study ◽  
Element Model ◽  
External Pressure ◽  
Thickness Ratio ◽  
Small Scale ◽  
Element Analysis ◽  
Models Comparison ◽  
Buckle Propagation ◽  
Exerted Pressure

In this paper, a numerical study of the dynamic buckle propagation, initiated in long pipes under external pressure, is presented. For a long pipe, due to the high exerted pressure, local instability is likely to occur; therefore, the prevention of its occurrence and propagation are very important subjects in the design of pipelines. The 3D finite element modeling of the buckle propagation is presented by considering the inertia of the pipeline and the nonlinearity introduced by the contact between its collapsing walls. The buckling and collapse are assumed to take place in the vacuum. The numerical results of the nonlinear finite element analysis are compared with the experimental results obtained by Kyriakides and Netto (2000, “On the Dynamics of Propagating Buckle in Pipelines,” Int. J. Solids Struct., 37, pp. 6843–6878) from a study on the small-scale models. Comparison shows that the finite element results have very close agreement with those of the experimental study. Therefore, it is concluded that the finite element model is reliable enough to be used for nonlinear collapse analysis of the dynamic buckle propagation in the pipelines. In this study, the effects of external pressure on the velocity of dynamic buckle propagation for different diameter to thickness ratios are investigated. In addition, the mathematical relations, based on the initiation pressure, are derived for the velocity of buckle propagation considering the diameter to thickness ratio of the pipeline. Finally, a relation for the buckle velocity as a function of the pressure and diameter to thickness ratio is presented.

Collapse and Buckle Propagation of Sandwich Pipes: A Review

2013 ◽  
Author(s):  
Chen An ◽  
Menglan Duan ◽  
Segen F. Estefen
Keyword(s):  
Failure Modes ◽  
Oil And Gas ◽  
Research Work ◽  
External Pressure ◽  
Mechanical And Thermal Properties ◽  
Structural Resistance ◽  
Buckle Propagation ◽  
Collapse Behavior ◽  
Elastoplastic Constitutive Model ◽  
Core Materials

Sandwich pipes (SP) can be an effective solution for ultra-deepwater submarine pipelines, combining high structural resistance with thermal insulation. Most research work on this subject has been conducted at the subsea technology laboratory (LTS) of COPPE/UFRJ, with the aim of developing qualified pipes to transport deepwater oil and gas, especially for the pre-salt reservoirs at Offshore Brazil. This article reviewed most of the research done in recent years (2002–2012) on the buckling, collapse and buckle propagation of SP, which emphasized on the development of theoretical, experimental and numerical methods adopted to analyze such structural behavior of SP with different core materials. The main mechanical and thermal properties of the previously considered core materials were also given, together with the elastoplastic constitutive model for each material. The experimental and numerical results of collapse and buckle propagation under external pressure for SP were summarized. A general discussion of the mechanical failure modes of SP under external pressure was also provided. Besides, some suggestions for future work on collapse behavior and buckle propagation of SP were given.

The Dynamic, Steady-State Propagation of an Antiplane Shear Crack in a General Linearly Viscoelastic Layer

1985 ◽  
Vol 52 (4) ◽  
pp. 853-856 ◽  
Author(s):  
J. R. Walton
Keyword(s):  
Stress Intensity Factor ◽  
Steady State ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Shear Crack ◽  
Antiplane Shear ◽  
Viscoelastic Layer ◽  
Crack Speed ◽  
Universal Dependence ◽  
State Propagation

In a previous paper, the dynamic, steady-state propagation of a semi-infinite antiplane shear crack was considered for an infinite, general linearly viscoelastic body. Under the assumptions that the shear modulus is a positive, nonincreasing continuous and convex function of time, convenient, closed-form expressions were derived for the stress intensity factor and for the entire stress distribution ahead of and in the plane of the advancing crack. The solution was shown to have a simple, universal dependence on the shear modulus and crack speed from which qualitative and quantitative information can readily be gleaned. Here, the corresponding problem for a general, linearly viscoelastic layer is solved. An infinite series representation for the stress intensity factor is derived, each term of which can be calculated recursively in closed form. As before, a simple universal dependence on crack speed and material properties is exhibited.

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