Stability of Vertically Bent Pipelines Buried in Sand

2004 ◽  
Vol 126 (3) ◽  
pp. 382-390 ◽  
Author(s):  
Sahel N. Abduljauwad ◽  
Hamdan N. Al-Ghamedy ◽  
Junaid A. Siddiqui ◽  
Ibrahim M. Asi ◽  
Naser A. Al-Shayea
Keyword(s):  
Internal Pressure ◽  
Three Dimensional ◽  
Computer Software ◽  
Specific Weight ◽  
Bend Angle ◽  
Element Analysis ◽  
Minimum Cover ◽  
Dimensional Finite Element ◽  
The Stability ◽  
Three Dimensional Finite Element

This paper discusses the stability of underground pipelines with preformed vertical bends buried in sandy soil. More specifically, the minimum cover height required to prevent the pipe from bowing under the action of forces due to temperature change and internal pressure is estimated. The variables considered include the pipe and soil materials, diameter, thickness, overburden height, bend radius, bend angle, internal pressure, fluid specific weight, and temperature variation. A comprehensive three-dimensional finite element analysis is carried out. The results are extracted from the output obtained. These results are put in a database which is used to develop general regression models to determine the relationships among the different variables. Different buckling modes are also considered. All of these results and models are entered into a computer software program for ready access.

Structural Stability Evaluation for Lifting Lug Design of Large Marine Engine by Finite Element Analysis

2007 ◽  
Vol 353-358 ◽  
pp. 2855-2859
Author(s):  
W.C. Lee ◽  
Chae Sil Kim ◽  
J.B. Na ◽  
D.H. Lee ◽  
S.Y. Cho ◽  
...  
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Design Procedure ◽  
Steel Structures ◽  
Stability Evaluation ◽  
Element Analysis ◽  
Marine Engines ◽  
Dimensional Finite Element ◽  
The Stability ◽  
Three Dimensional Finite Element

Since most marine engines are generally very huge and heavy, it is required to keep safety from accidents in dealing them. Several types of lifting lugs have been used to assemble hundred ton–large steel structures and carry the assembled engines. Recently a few crashes have been occurred in carrying engines due to breaking down the lugs. Although the stability evaluation of the lifting lug has therefore been very important for safety, systematic design procedure of the lugs, which includes the structural analysis considering stability, has few reported. This paper describes the three dimensional finite element structural modeling for a lifting lug, the studies for determining the reasonable loading and boundary conditions, and the stability evaluation with the results of structural analyses. It should be very helpful for designing the other types of lifting lugs with safety.

J-R Curves From Circumferentially Through-Wall-Cracked Pipe Tests Subjected to Combined Bending and Tension—Part II: Experimental and Analytical Validation

1998 ◽  
Vol 120 (4) ◽  
pp. 412-417 ◽  
Author(s):  
N. Miura ◽  
G. M. Wilkowski
Keyword(s):  
Internal Pressure ◽  
Three Dimensional ◽  
Combined Loading ◽  
Element Analysis ◽  
Dimensional Finite Element ◽  
Estimation Scheme ◽  
Materials Used ◽  
Three Dimensional Finite Element ◽  
Η Factor ◽  
J Estimation

In Part I (Miura and Wilkowski, 1998) of this paper, the theory of the two η-factor solutions for circumferentially through-wall-cracked pipes subjected to combined bending and tension due to internal pressure was presented. These solutions seemed to give reasonable predictions by comparing with the existing simplified J-estimation scheme. It was also ascertained that the J would be underestimated if the effect of the internal pressure was not properly considered. Consequently, this paper presents the application of these solutions to full-scale pipe tests. The tests were performed at 288°C (550°F) under combined bending and internal pressure. The materials used for the tests were both carbon steel and stainless steel. The effect of combined loading on the J-R curves was determined and compared to C(T) specimen J-R curves. The solutions were then verified by using three-dimensional finite element analysis.

Cover Requirement and Stability of Horizontally Bent Buried Pipelines

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
Hamdan N. Al-Ghamedy ◽  
Sahel N. Abduljauwad ◽  
Junaid A. Siddiqui ◽  
Naser A. Al-Shayea ◽  
Ibrahim M. Asi
Keyword(s):  
Regression Models ◽  
Three Dimensional ◽  
Specific Weight ◽  
Elastic Instability ◽  
Buried Pipelines ◽  
Element Analysis ◽  
Buckling Modes ◽  
Dependent Variables ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

A method of calculating soil cover requirements for horizontally bent buried pipelines is described. In sequence, the results of a comprehensive three-dimensional finite element analysis are used to develop regression models for two dependent variables: maximum allowed temperature change and minimum overburden height. Other variables considered include the pipe diameter and thickness, the radius and angle of the bend, the internal pressure, the fluid specific weight, and the material used. Relationships among the different variables are determined. Finally, the results are checked with respect to several buckling modes to consider elastic instability conditions.

Three-Dimensional Finite Element Analysis of Several Internal and External Pelvis Fixations

2000 ◽  
Vol 122 (5) ◽  
pp. 516-522 ◽  
Author(s):  
J. M. Garcı´a ◽  
M. Doblare´ ◽  
B. Seral ◽  
F. Seral ◽  
D. Palanca ◽  
...  
Keyword(s):  
Finite Element ◽  
Pelvic Ring ◽  
Three Dimensional ◽  
Fixation Method ◽  
Individual Treatment ◽  
Element Analysis ◽  
Sacroiliac Screws ◽  
Dimensional Finite Element ◽  
The Stability ◽  
Three Dimensional Finite Element

The Finite Element Method (FEM) can be used to analyze very complex geometries, such as the pelvis, and complicated constitutive behaviors, such as the heterogeneous, nonlinear, and anisotropic behavior of bone tissue or the noncompression, nonbending character of ligaments. Here, FEM was used to simulate the mechanical ability of several external and internal fixations that stabilize pelvic ring disruptions. A customized pelvic fracture analysis was performed by computer simulation to determine the best fixation method for each individual treatment. The stability of open-book fractures with external fixations at either the iliac crests or the pelvic equator was similar, and increased greatly when they were used in combination. However, external fixations did not effectively stabilize rotationally and vertically unstable fractures. Adequate stabilization was only achieved using an internal pubis fixation with two sacroiliac screws. [S0148-0731(00)00905-5]

Three-Dimensional Versus Axisymmetric Finite-Element Analysis of a Cylindrical Vessel Inlet Nozzle Subject to Internal Pressure—A Comparative Study

1978 ◽  
Vol 100 (2) ◽  
pp. 134-140 ◽  
Author(s):  
J. B. Truitt ◽  
P. P. Raju
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Comparative Study ◽  
Internal Pressure ◽  
Three Dimensional ◽  
Element Analysis ◽  
Stress Indices ◽  
Modeling Techniques ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

This paper presents a comparative study between a three-dimensional and an axisymmetric finite-element analysis of a reactor pressure-vessel inlet nozzle subject to internal pressure. A quarter-symmetric section of the nozzle is modeled with a three-dimensional quadratic isoparametric finite element. This comparative study proves that the axisymmetric analysis is unconservative if based upon common axisymmetric modeling techniques. This inadequacy, for the PWR vessel inlet nozzle studied herein, can be offset by a modification of the modeling techniques, i.e., if the value of the radius of the equivalent spherical vessel is taken as 3.2 instead of, say, 2. The results of the three-dimensional finite-element analysis are also compared with those of a photo-elastic stress analysis and with the stress indices indicated by the ASME Section III Code. These additional comparisons, based upon a continuous distribution of hoop and tangential stress indices in both the transverse and longitudinal planes, shows good agreement between the three-dimensional finite-element and photoelastic analyses. The ASME Section III stress indices are found to be relatively conservative.

Finite Element Analysis of Nonuniformity of Tires with Imperfections5

2007 ◽  
Vol 35 (3) ◽  
pp. 226-238 ◽  
Author(s):  
K. M. Jeong ◽  
K. W. Kim ◽  
H. G. Beom ◽  
J. U. Park
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Three Dimensional ◽  
Element Model ◽  
Radial Force ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Dimensional Finite Element ◽  
Force Variation ◽  
Three Dimensional Finite Element

Abstract The effects of variations in stiffness and geometry on the nonuniformity of tires are investigated by using the finite element analysis. In order to evaluate tire uniformity, a three-dimensional finite element model of the tire with imperfections is developed. This paper considers how imperfections, such as variations in stiffness or geometry and run-out, contribute to detrimental effects on tire nonuniformity. It is found that the radial force variation of a tire with imperfections depends strongly on the geometrical variations of the tire.

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