A FE Model to Predict the Stress Concentration Factors in the Tensile Armor Wires of Flexible Pipes Inside End Fittings

2013 ◽  
Author(s):  
José Renato M. de Sousa ◽  
George C. Campello ◽  
Fabiano Bertoni ◽  
Gilberto B. Ellwanger
Keyword(s):  
Stress Concentration ◽  
High Stress ◽  
Axial Stiffness ◽  
Fe Model ◽  
Acceptance Test ◽  
Stress Distributions ◽  
High Stress Concentration ◽  
Flexible Pipes ◽  
The Wire ◽  
Stress Concentration Factors

In this work, a bidimensional finite element (FE) approach is proposed to estimate the stresses induced in the tensile armor wires inside end fittings (EF) of flexible pipes. This approach accounts for the residual stresses caused by the mounting procedure and the deformed configuration of the wire. The resin and its interaction with the wires are also addressed. A parametric study was performed aiming at investigating the influence of three parameters on the stress state along the wire, i. e., the contact conditions between the resin and the wire inside the EF, the stress levels induced during the factory acceptance test (FAT) or the offshore leak test (OLT) and the resin elastic properties. The study pointed that high stress concentration is induced in the transition between the flexible pipe’s body and the EF and the stress distribution along the wire may be significantly affected by these parameters. Moreover, the apparent axial stiffness of the wire is also modified by its anchoring conditions, which may lead to non-uniform stress distributions among the wires of the tensile armor layers.

Embedded Elliptical Crack at a Corner

1978 ◽  
Vol 100 (1) ◽  
pp. 28-33
Author(s):  
A. S. Kobayashi ◽  
A. F. Emery ◽  
W. J. Love ◽  
A. Antipas
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Stress Concentration ◽  
High Stress ◽  
Elliptical Crack ◽  
Stress Distributions ◽  
High Stress Concentration ◽  
Magnification Factors ◽  
Elliptical Cracks ◽  
Circular Cracks

A procedure for estimating the stress intensity factor of an embedded elliptical crack near the corner in a region of high stress concentration such as pressurized or thermally shocked nozzle-to-cylinder junction is discussed. The procedure is then used to analyze two hypothetical embedded circular cracks near the corner of a nozzle-to-cylinder junction where stress distributions in the uncracked junction are known. Also shown are two new stress intensity magnification factors for two embedded elliptical cracks, i.e., b/a = 0.2 and 0.982, close to a free corner, i.e., a/h = b/h = 0.9.

scholarly journals Thermo-mechanical stress analysis of dissimilar material joints using FEM

2020 ◽  
Vol 4 (2) ◽  
pp. 147-154
Author(s):  
Somnath Somadder
Keyword(s):  
Stress Concentration ◽  
Numerical Investigation ◽  
High Stress ◽  
Dissimilar Materials ◽  
Theory Of Elasticity ◽  
Dissimilar Material ◽  
Stress Distributions ◽  
High Stress Concentration ◽  
Thermal Expansion Coefficients ◽  
The Difference

Abstract: This article presents numerical investigation of isotropic dissimilar material joints. Dissimilar material joints are broadly used in in various structures, including offshore, nuclear, electronic packaging, IC chip and spacecraft various fields of science and technology. In bi-material joints two different material are bonded with common interface region. High stress concentration occur at the interface of the joint under thermo-mechanical loadings due to the difference in the elastic properties and the thermal expansion coefficients of dissimilar materials. The stresses acting along the interface of dissimilar material joints are very important to determine whether the structure is reliable or not for operation. The main purpose of this research is to provide finite element solutions to predict the stress distribution at the interface of the joint based on the theory of elasticity. Keywords: Numerical Investigation, Dissimilar material joints, Stress concentration, Stress distributions, Theory of elasticity.

New Power Transmission Chain Design

1986 ◽  
Vol 108 (3) ◽  
pp. 255-261
Author(s):  
Y. Kin ◽  
R. Dubrovsky
Keyword(s):  
Stress Concentration ◽  
Power Transmission ◽  
High Stress ◽  
Variable Loading ◽  
Experimental Stress Analysis ◽  
High Stress Concentration ◽  
Concentration Factors ◽  
Stress Concentration Factors ◽  
A Chain ◽  
Very High

Precision multiple roller power transmissions are investigated in this work. These chains transfer significant power and move with very high velocity. They are subjected to variable loading with strong vibration and impact components, and require forced stream lubrication. Because of these severe working conditions, chain life is limited by the fatigue, and the chain plates are the weakest elements in many cases. It is shown that fatigue life is significantly decreased by fretting action, high stress concentration in the plates, and the impossibility of maintaining a uniform force distribution across the multiple lines of a chain. The results of the performed experimental stress analysis under static and variable loading are given for the different plate geometries. The plates with a variety of stress reducers located in different areas are investigated, and theoretical and effective stress concentration factors are determined. Based on that, new plate chain designs are proposed. These new designs use fewer lines to transfer the same power as conventional chains.

Comparison on Stress Concentration Factors of Y/T Tubular Joints Between Numerical and Parametric Formulation Results

2005 ◽  
Author(s):  
Stefano Baratella ◽  
Dario Boote ◽  
Fabio Petrillo ◽  
Fabrizio Stefani
Keyword(s):  
Stress Concentration ◽  
Numerical Models ◽  
High Stress ◽  
Bending Moment ◽  
Steel Structures ◽  
Element Analysis ◽  
High Stress Concentration ◽  
Wide Range ◽  
Long Time ◽  
Stress Concentration Factors

The action of environmental loads such as wind and waves on offshore steel structures is locally emphasized by complex tubular connections, giving place to high stress concentration in correspondence of welds between pipe elements. This phenomenon, which heavily influences the fatigue life of the joint and, as a consequence, the operability of the whole platform, can be quantified by the Stress Concentration Factor. SCF can be determined either by experimental approach, numerical analysis and parametrical formulas developed mainly in the seventies-eighties by specialized authors like Kuang, Wordsworth, Smedley and Efthymiou. Even though these formulas, quoted as reference in the main world recognized rules, represented for a long time a useful tool for the designers of most projects, some discrepancies have been found to exist among them. A research has then been jointly promoted by University of Genoa and RINA Industry in order to compare the results of the parametric formulas with those coming from a finite element analysis performed on very refined numerical models made of brick elements. In this investigation attention has been focused on Y/T type joints; a wide range of configurations has been analysed by varying the most important parameters defining the geometry of the joint. Each configuration has been loaded by axial force and in/out of plane bending moment.

scholarly journals The Effect of Implant Length and Diameter on Stress Distribution around Single Implant Placement in 3D Posterior Mandibular FE Model Directly Constructed Form In Vivo CT

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7344
Author(s):  
Akikazu Shinya ◽  
Yoshiki Ishida ◽  
Daisuke Miura ◽  
Akiyoshi Shinya
Keyword(s):  
High Stress ◽  
Three Dimensional ◽  
Clinical Situation ◽  
Mechanical Analysis ◽  
Fe Model ◽  
High Stress Concentration ◽  
Implant Placement ◽  
Implant Therapy ◽  
Mandibular First Molar

A three-dimensional (3D) finite element (FE) model of the mandibular bone was created from 3D X-ray CT scan images of a live human subject. Simulating the clinical situation of implant therapy at the mandibular first molar, virtual extraction of the tooth was performed at the 3D FE mandibular model, and 12 different implant diameters and lengths were virtually inserted in order to carry out a mechanical analysis. (1) High stress concentration was found at the surfaces of the buccal and lingual peri-implant bone adjacent to the sides of the neck in all the implants. (2) The greatest stress value was approximately 6.0 MPa with implant diameter of 3.8 mm, approx. 4.5 MPa with implant diameter of 4.3 mm, and approx. 3.2 MPa with implant diameter of 6.0 mm. (3) The stress on the peri-implant bone was found to decrease with increasing length and mainly in diameter of the implant.

On the Axisymmetric Response of a Damaged Flexible Pipe

2014 ◽  
Author(s):  
José Renato M. de Sousa ◽  
Carlos Magluta ◽  
Ney Roitman ◽  
George C. Campello
Keyword(s):  
Finite Element ◽  
Analytical Model ◽  
Load Capacity ◽  
High Stress ◽  
Experimental Tests ◽  
Theoretical Models ◽  
Experimental Measurements ◽  
Fe Model ◽  
Flexible Pipe ◽  
High Stress Concentration

This work focuses on the structural analysis of a damaged 9.13″ flexible pipe to pure and combined axisymmetric loads. A set of experimental tests was carried out considering one up to ten broken wires in the outer tensile armor of the pipe and the results obtained are compared to those provided by a previously presented finite element (FE) model and a traditional analytical model. In the experimental tests, the pipe was firstly subjected to pure tension and, then, the responses to clockwise and anti-clockwise torsion superimposed with tension were investigated. In these tests, the induced strains in the outer armor were measured. Moreover, the axial elongation of the pipe was monitored when the pipe is subjected to tension, whilst the twist of the pipe was measured when torsion is imposed. The experimental results pointed to a slight decrease in the stiffness of the pipe with the increasing number of broken wires and, furthermore, a redistribution of forces among the intact wires of the damaged layer with high stress concentration in the wires close to the damaged ones. Both theoretical models captured these features, but, while the results obtained with the FE model agreed well with the experimental measurements, the traditional analytical model presented non-conservative results. Finally, the results obtained are employed to estimate the load capacity of the pipe.

On the Structural Response of a Flexible Pipe With Damaged Tensile Armor Wires

2011 ◽  
Author(s):  
Jose´ Renato M. de Sousa ◽  
George C. Campello ◽  
Antoˆnio Fernando B. Bueno ◽  
Eduardo Vardaro ◽  
Gilberto B. Ellwanger ◽  
...  
Keyword(s):  
Mechanical Response ◽  
High Stress ◽  
Three Dimensional ◽  
Structural Response ◽  
Experimental Tests ◽  
Element Model ◽  
Axial Stiffness ◽  
Stress Concentrations ◽  
Flexible Pipe ◽  
Flexible Pipes

This paper studies the structural response of a 6.0″ flexible pipe under pure tension considering two different situations: the pipe is intact or has five wires broken in its outer tensile armor. A three-dimensional nonlinear finite element model devoted to analyze the local mechanical response of flexible pipes is employed in this study. This model is capable of representing each wire of the tensile armors and, therefore, localized defects, including total rupture, may be adequately represented. Results from experimental tests are also presented in order to validate the theoretical estimations. The theoretical and experimental results indicate that the imposed damage reduced the axial stiffness of the pipe. High stress concentrations in the wires near the damaged ones were also observed and, furthermore, the stresses in the inner carcass and the pressure armor are affected by the imposed damage, but, on the other hand, the normal stresses in the wires of the inner tensile armor are not.

Fracture Assessments of High Pressure Vessel Components Having Longitudinal Holes

2017 ◽  
Author(s):  
Yu Xu ◽  
Kuao-John Young
Keyword(s):  
High Pressure ◽  
Stress Concentration ◽  
Fracture Mechanics ◽  
Pressure Vessel ◽  
High Stress ◽  
Pressure Vessels ◽  
Crack Face ◽  
High Pressure Vessel ◽  
High Stress Concentration ◽  
Critical Locations

Small size longitudinal holes are common in components of high pressure vessels. In fracture mechanics evaluation, longitudinal holes have not drawn as much attention as cross-bores. However, longitudinal holes become critical at certain locations for such assessments because of high stress concentration and short distance to vessel component wall. The high stress concentration can be attributed to three parts: global hoop stress that is magnified by the existence of the hole, local stresses due to pressure in the hole, and crack face pressure. In high pressure vessel design, axisymmetric models are used extensively in stress analyses, and their results are subsequently employed to identify critical locations for fracture mechanics evaluation. However, axisymmetric models ignore longitudinal holes and therefore cannot be used to identify the critical location inside the holes. This paper is intended to highlight the importance of including longitudinal holes in fracture mechanics evaluation, and to present a quick and effective way of evaluating high stress concentration at a longitudinal hole using the combined analytical solutions and axisymmetric stress analysis results, identifying critical locations and conducting fracture mechanics evaluation.

Reduction of Stress Concentration Due to Interference Fits in an Infinite Plate With Two Holes

1978 ◽  
Vol 100 (4) ◽  
pp. 369-373
Author(s):  
T. Iwaki ◽  
K. Miyao
Keyword(s):  
Exact Solution ◽  
Stress Concentration ◽  
Elastic Properties ◽  
High Stress ◽  
Infinite Plate ◽  
Concentration Effects ◽  
Numerical Examples ◽  
High Stress Concentration ◽  
External Forces

This paper contains an exact solution for stresses which are produced in an infinite plate with two holes of different sizes by interference fits. It is assumed that the plate and the interference-fitted ring have the same elastic properties and are perfectly bonded to each other. Numerical examples of the solution are worked out and the interference fits are found useful for reducing the high-stress concentration effects which are induced in an infinite plate with two holes by external forces.

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