Pipe Bend Analysis by Thin Shell Theory

1986 ◽  
Vol 53 (1) ◽  
pp. 173-180 ◽  
Author(s):  
J. F. Whatham
Keyword(s):  
Computer Program ◽  
Thin Shell ◽  
Shell Theory ◽  
Factor Versus ◽  
Pipe Bend ◽  
Pipe Elbow ◽  
Wide Range ◽  
Out Of Plane ◽  
Plane Bending ◽  
Thin Shell Theory

Thin shell theory is applied to pipe bends terminated by flanges or flange-ended tangent pipes and subjected to any end loading, either in-plane or out-of-plane. Graphs of flexibility factor versus pipe bend characteristic are presented for in-plane bending of a wide range of pipe elbows terminated by flanges or short flange-ended tangents. Experimental results verify the thin shell solutions for in-plane and out-of-plane bending of a flanged pipe elbow. The capabilities of a computer program BENDPAC are also described.

Flexibility and Stress Factors of Pipe Bends—An Analysis by the Finite Ring Method

1977 ◽  
Vol 99 (2) ◽  
pp. 281-290 ◽  
Author(s):  
H. Ohtsubo ◽  
O. Watanabe
Keyword(s):  
Thin Shell ◽  
Shell Theory ◽  
Pipe Wall ◽  
Finite Ring ◽  
Stress Factors ◽  
Bending Moments ◽  
Pipe Wall Thickness ◽  
Out Of Plane ◽  
Ring Method ◽  
Thin Shell Theory

The present paper investigates the flexibility and stress factors for the pipe bends when they are connected with straight pipes and subjected to out-of-plane as well as in-plane bending moments, to which the conventional methods are not directly applicable. The stress analysis is carried out by the use of a new finite ring element method which is based on the general thin shell theory incorporating shear strain. The numerical results obtained for flexibility and stress factors are compared with the code formula. The influence of initial deflections and the variation of the pipe wall thickness is also studied.

Local loads on a toroidal shell

1992 ◽  
Vol 27 (2) ◽  
pp. 59-66 ◽  
Author(s):  
D Redekop ◽  
F Zhang
Keyword(s):  
Cylindrical Shell ◽  
Shell Theory ◽  
Elastic Shell ◽  
Toroidal Shell ◽  
Pipe Bend ◽  
Local Loads ◽  
Simply Supported ◽  
Linear Elastic ◽  
Wide Range ◽  
Theory Solution

In this study the effect of local loads applied on a sectorial toroidal shell (pipe bend) is considered. A linear elastic shell theory solution for local loads is first outlined. The solution corresponds to the case of a shell simply supported at the two ends. Detailed displacement and stress results are then given for a specific shell with loadings centred at three positions; the crown circles, the extrados, and the intrados. These results are compared with results for a corresponding cylindrical shell. The paper concludes with a table summarizing results for characteristic displacements and stresses in a number of shells, covering a wide range of geometric parameters.

Turbulence-Induced Vibration Analysis of an Open Curved Thin Shell

2010 ◽  
Author(s):  
Mitra Esmailzadeh ◽  
Aouni A. Lakis
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Root Mean Square ◽  
Thin Shell ◽  
Shell Theory ◽  
Pressure Field ◽  
Mean Square Displacement ◽  
Mean Square ◽  
Cross Spectral Density ◽  
Thin Shell Theory

A method is presented to predict the root mean square displacement response of an open curved thin shell structure subjected to a turbulent boundary-layer-induced random pressure field. The basic formulation of the dynamic problem is an efficient approach combining classic thin shell theory and the finite element method. The displacement functions are derived from Sanders’ thin shell theory. A numerical approach is proposed to obtain the total root mean square displacements of the structure in terms of the cross-spectral density of random pressure fields. The cross-spectral density of pressure fluctuations in the turbulent pressure field is described using the Corcos formulation. Exact integrations over surface and frequency lead to an expression for the total root mean square displacement response in terms of the characteristics of the structure and flow. An in-house program based on the presented method was developed. The total root mean square displacements of a curved thin blade subjected to turbulent boundary layers were calculated and illustrated as a function of free stream velocity and damping ratio. A numerical implementation for the vibration of a cylinder excited by fully developed turbulent boundary layer flow was presented. The results compared favorably with those obtained using software developed by Lakis et al.

Effect of Load Angle on Limit Load of Polyethylene Miter Pipe Bends

2010 ◽  
Author(s):  
Tarek M. A. A. EL-Bagory ◽  
Maher Y. A. Younan ◽  
Hossam E. M. Sallam ◽  
Lotfi A. Abdel-Latif
Keyword(s):  
Crack Depth ◽  
Bending Moment ◽  
Limit Load ◽  
Factor H ◽  
Pipe Bend ◽  
Combined Load ◽  
Specific Loading ◽  
Out Of Plane ◽  
Plane Bending ◽  
Load Angle

The aim of this paper is to investigate the effect crack depth a/W = 0 to 0.4 and load angle (30°,45°,and 60°) on the limit load of miter pipe bends (MPB) under out-of-plane bending moment with a crosshead speed 500 mm/min. The geometry of cracked and uncracked multi miter pipe bends are: bend angle, α = 90°, pipe bend factor, h = 0.844, standard dimension ratio, SDR = 11, and three junctions, m = 3. The material of the investigated pipe is a high-density polyethylene (HDPE), which is applied in natural gas piping systems. Butt-fusion welding is used to produce the welds in the miter pipe bends. An artificial crack is produced by a special cracking device. The crack is located at the crown side of the miter pipe bend, such that the crack is collinear with the direction of the applied load. The crack depth ratio, a/W = 0, 0.1, 0.2, 0.3 and 0.4 for out-of-plane bending moment “i.e. loading angle φ = 0°”. For each out-of-plane bending moment and all closing and opening load angles the limit load is obtained by the tangent intersection method (TI) from the load deflection curves produced by the specially designed and constructed testing machine at the laboratory. For each out-of-plane bending moment case, the experimental results reveals that increasing crack depth leads to a decrease in the stiffness and limit load of MPB. In case of combined load (out-of-plane and in-plane opening; mode) higher load angles lead to an increase in the limit load. The highest limit load value appears at a loading angle equal, φ = 60°. In case of combined load (out-of-plane and in-plane closing; mode) the limit load decreases upon increasing the load angle. On the other hand, higher limit load values take place at a specific loading angle equal φ = 30°. For combined load opening case; higher values of limit load are obtained. Contrarily, lower values are obtained in the closing case.

Stress and flexibility factors for multi-mitred pipe bends subjected to internal pressure combined with external loadings

1972 ◽  
Vol 7 (2) ◽  
pp. 97-108 ◽  
Author(s):  
M P Bond ◽  
R Kitching
Keyword(s):  
Internal Pressure ◽  
Large Diameter ◽  
Pipe Bend ◽  
Bending Tests ◽  
Bending Load ◽  
Out Of Plane ◽  
Thin Walled ◽  
Plane Bending ◽  
Internal Pressures ◽  
Stress Patterns

The stress analysis of a multi-mitred pipe bend when subjected to an internal pressure and a simultaneous in-plane or out-of-plane bending load has been developed. Stress patterns and flexibility factors calculated by this analysis are compared with experimental results from a large-diameter, thin-walled, three-weld, 90° multi-mitred bend which was subjected to in-plane bending tests at various internal pressures.

A NEW KIND OF SINGULAR STIFF PROBLEMS AND APPLICATION TO THIN ELASTIC SHELLS

1995 ◽  
Vol 05 (01) ◽  
pp. 47-66 ◽  
Author(s):  
D. CAILLERIE ◽  
E. SANCHEZ-PALENCIA
Keyword(s):  
Asymptotic Behavior ◽  
Local Structure ◽  
Thin Shell ◽  
Spectral Properties ◽  
Shell Theory ◽  
Stiff Problems ◽  
Medium Frequency ◽  
Limit Solution ◽  
General Configuration ◽  
Thin Shell Theory

We consider the asymptotic behavior of the solution of a class of problems involving a small parameter ε and ε2. This generalizes the “singular stiff” problems arising in classical thin shell theory. The new problems appear in theory of composite shells, when the local structure implies coupling between membrane stresses and flexions. According to specific hypotheses, this kind of problems contains singular perturbations and penalty problems where the limit solution belongs to a subspace G1 of the general configuration space V. In addition to the coercive problem, spectral properties are considered in the small and medium frequency ranges, including spectral families in the case without compactness.

Free vibration of bi-material cylindrical shells

2016 ◽  
Vol 230 (15) ◽  
pp. 2637-2649 ◽  
Author(s):  
Saeed Sarkheil ◽  
Mahmud S Foumani ◽  
Hossein M Navazi
Keyword(s):  
Exact Solution ◽  
Cylindrical Shell ◽  
Free Vibration ◽  
Boundary Conditions ◽  
State Space ◽  
Thin Shell ◽  
Shell Theory ◽  
Circular Cylindrical Shell ◽  
Space Technique ◽  
Thin Shell Theory

Based on the Sanders thin shell theory, this paper presents an exact solution for the vibration of circular cylindrical shell made of two different materials. The shell is sub-divided into two segments and the state-space technique is employed to derive the homogenous differential equations. Then continuity conditions are applied where the material of the cylindrical shell changes. Shells with various combinations of end boundary conditions are analyzed by the proposed method. Finally, solving different examples, the effect of geometric parameters as well as BCs on the vibration of the bi-material shell is studied.

Theory of thin elastic shells applied to pipe bends subjected to bending and internal pressure

1972 ◽  
Vol 7 (4) ◽  
pp. 285-293 ◽  
Author(s):  
J A Blomfield ◽  
C E Turner
Keyword(s):  
Internal Pressure ◽  
Shell Theory ◽  
Coupling Effect ◽  
Governing Equations ◽  
Elastic Shells ◽  
Out Of Plane ◽  
Plane Bending

A consistent set of equations for the in-plane and out-of-plane bending of pipe bends is derived from the equations of shell theory with a correction for the coupling effect of internal pressure. The resulting governing equations are solved numerically and compared with other experimental and theoretical solutions.

Vibration of Shallow Shells: A Review With Bibliography

1997 ◽  
Vol 50 (8) ◽  
pp. 431-444 ◽  
Author(s):  
K. M. Liew ◽  
C. W. Lim ◽  
S. Kitipornchai
Keyword(s):  
Thin Shell ◽  
Shell Theory ◽  
Free Vibration Analysis ◽  
Review Article ◽  
Shallow Shells ◽  
First Order ◽  
Recent Developments ◽  
Thick Shells ◽  
Thin Shell Theory ◽  
Introductory Review

This review article documents recent developments in the free vibration analysis of thin, moderately thick, and thick shallow shells. An introductory review of the studies in Kirchhoff-Love classical thin shell theory is given. The development of studies in moderately thick shells incorporating the effects of transverse shear deformation and rotary inertia is detailed. This review article mainly focuses on research advances in vibration studies since the 1970s using the classical Kirchhoff-Love, first-order, and higher-order theories. The validity and range of applicability of these theories are examined. There are 163 references listed at the end of the article.

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