An Investigation of the Bisymmetric Hydrostatic Collapse of Flexible Pipes Based on Equivalent Layer Approaches

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
José Renato M. de Sousa ◽  
Marcelo K. Protasio ◽  
Luís Volnei S. Sagrilo ◽  
Djalene Maria Rocha
Keyword(s):  
Numerical Models ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Collapse Mechanism ◽  
Fe Model ◽  
Flexible Pipe ◽  
Flexible Pipes ◽  
Dimensional Finite Element ◽  
Equivalent Ring ◽  
Three Dimensional Finite Element

Abstract The hydrostatic collapse strength of a flexible pipe is largely dependent on the ability of its carcass and/or pressure armor to resist radial loading and, therefore, its prediction involves an adequate modeling of these layers. Hence, initially, this work proposes a set of equations to estimate equivalent mechanical properties for these layers, which allows their modeling as equivalent orthotropic cylinders. Particularly, equations to predict the equivalent ring bend stiffness are obtained by simulating several two-point static ring tests with a three-dimensional finite element (FE) model based on beam elements and using these results to form datasets that are analyzed with a symbolic regression (SR) tool. The results of these analyses are the closed-form equations that best fit the provided datasets. After that, these equations are used in conjunction with a three-dimensional shell FE model (FEM) and a previously presented analytical model to study the bisymmetric hydrostatic collapse mechanism of flexible pipes. The predictions of these models agreed well with the collapse pressures obtained with numerical models and in experimental tests thus indicating the potential use of this approach in the design of flexible pipes.

Equivalent Layer Approaches to Predict the Bisymmetric Hydrostatic Collapse Strength of Flexible Pipes

2018 ◽  
Author(s):  
José Renato M. de Sousa ◽  
Marcelo K. Protasio ◽  
Luis V. S. Sagrilo
Keyword(s):  
Three Dimensional ◽  
Experimental Tests ◽  
Fe Model ◽  
Flexible Pipe ◽  
Collapse Mechanisms ◽  
Collapse Strength ◽  
Flexible Pipes ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Radial Loading

The hydrostatic collapse strength of a flexible pipe is largely dependent on the ability of its carcass and pressure armor to resist radial loading and, therefore, its prediction involves an adequate modeling of these layers. Hence, initially, this work proposes a set of equations to estimate equivalent thicknesses and physical properties for these layers, which allows their modeling as equivalent orthotropic cylinders. These equations are obtained by simulating several two-point static ring tests with a three-dimensional finite element (FE) model based on beam elements and using these results to form datasets that are analyzed with a symbolic regression (SR) tool. The results of these analyses are the closed-form equations that best fit the provided datasets. After that, these equations are used in conjunction with a three-dimensional shell FE model and a previously presented analytical model to study the dry and wet hydrostatic collapse mechanisms of a flexible pipe. The predictions of these models agreed quite well with the collapse pressures obtained in experimental tests thus indicating that the use of the equivalent approach is promising.

An Experimental and Numerical Study on the Axial Compression Response of Flexible Pipes

2010 ◽  
Author(s):  
Jose´ Renato M. de Sousa ◽  
Paula F. Viero ◽  
Carlos Magluta ◽  
Ney Roitman
Keyword(s):  
Axial Compression ◽  
Failure Modes ◽  
Mechanical Response ◽  
Numerical Study ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Mechanical Analysis ◽  
Fe Model ◽  
Flexible Pipe ◽  
Flexible Pipes

This paper deals with a nonlinear three-dimensional finite element (FE) model capable of predicting the mechanical response of flexible pipes subjected to axisymmetric loads focusing on their axial compression response. Moreover, in order to validate this model, experimental tests carried out at COPPE/UFRJ are also described. In these tests, a typical 4″ flexible pipe was subjected to axial compression until its failure is reached. Radial and axial displacements were measured and compared to the model predictions. The good agreement between all obtained results points that the proposed FE model is efficient to estimate the response of flexible pipes to axial compression and, furthermore, has potential to be employed in the identification of the failure modes related to excessive axial compression as well as in the mechanical analysis of flexible pipes under other types of loads.

An Experimental and Numerical Study on the Axial Compression Response of Flexible Pipes

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
José Renato M. de Sousa ◽  
Paula F. Viero ◽  
Carlos Magluta ◽  
Ney Roitman
Keyword(s):  
Axial Compression ◽  
Failure Modes ◽  
Mechanical Response ◽  
Numerical Study ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Mechanical Analysis ◽  
Fe Model ◽  
Flexible Pipe ◽  
Flexible Pipes

This paper deals with a nonlinear three-dimensional finite element (FE) model capable of predicting the mechanical response of flexible pipes subjected to axisymmetric loads focusing on their axial compression response. Moreover, in order to validate this model, experimental tests are also described. In these tests, a typical 4 in. flexible pipe was subjected to axial compression until its failure is reached. Radial and axial displacements were measured and compared to the model predictions. The good agreement between all results points out that the proposed FE model is effective to estimate the response of flexible pipes to axial compression and; furthermore, has potential to be employed in the identification of the failure modes related to excessive axial compression as well as in the mechanical analysis of flexible pipes under other types of loads.

On the Coupled Extensional–Torsional Response of Flexible Pipes

2009 ◽  
Author(s):  
He´ctor E. M. Merino ◽  
Jose´ R. M. de Sousa ◽  
Carlos Magluta ◽  
Ney Roitman
Keyword(s):  
Cross Sections ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Axial Rotation ◽  
Analytical Models ◽  
Fe Model ◽  
Flexible Pipe ◽  
Torsional Response ◽  
Flexible Pipes ◽  
Axial Twist

In this paper, the coupled extensional-torsional behavior of a 4″ flexible pipe is studied. The pipe was subjected to pure tension and two different boundary conditions were considered: ends free and prevented from axially rotating. The response of the pipe is predicted with a three-dimensional nonlinear finite element (FE) model. Some aspects of the obtained results are discussed, such as: the effect of restraining the axial rotation at the extreme sections of the model; the effect of friction or adhesion between the layers of the pipe on the induced axial rotation (or torque) and elongation; and the reduction to simple plane behavior usually assumed by analytical models. The numerical results are compared to the ones measured in experimental tests performed at COPPE/UFRJ. Reasonable agreement is observed between all results pointing out that the analyzed pipe is torque balanced and that friction mainly affects the axial twist or torque led by the applied tension. Moreover, the cross-sections of the pipe remain straight with the imposed load, but different axial rotations are found in each layer.

scholarly journals Condensation method in practical modal analysis of hull vibration with application of 3D FE model

2019 ◽  
pp. 162-169
Author(s):  
Valeriy Sutyrin
Keyword(s):  
Modal Analysis ◽  
Three Dimensional ◽  
Element Model ◽  
Fe Model ◽  
Structural Elements ◽  
Natural Vibrations ◽  
Condensation Method ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Analytical Approaches

This paper gives modal analysis results for mid-body of a refrigerator carrier ship by means of combined three-dimensional finite-element model with 1.5 million DOF. The study estimates the error of modal analysis for the ship structure if its boundary conditions are specified in advance, i.e. approximately, as well as analyses the gain in time offered by structuring the analytical model as per reduction (condensation) method. Analytical approaches thus transformed can be successfully applied in filtering lower frequencies and modes of natural vibrations for structural elements and joints of hull in the direct vicinity of exciting force application points.

scholarly journals Evaluation of the Effects of the Chincup Appliance on the Craniofacial Structures by the Finite Element Analysis

2017 ◽  
Vol 7 ◽  
pp. 219-223
Author(s):  
Beril Demir Karamanli ◽  
Hülya Kılıçoğlu ◽  
Armagan Fatih Karamanli
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Fe Model ◽  
Analysis Method ◽  
Class Iii ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Clinical Changes

Aims The aim of this study is to evaluate the effects of the chincup appliance used in the treatment of Class III malocclusions, not only on the mandible or temporomandibular joint (TMJ) but also on all the craniofacial structures. Materials and Methods Chincup simulation was performed on a three-dimensional finite element (FE) model. 1000 g (500 g per side) force was applied in the direction of chin-condyle head. Nonlinear FE analysis was used as the numerical analysis method. Results By the application of chincup, stresses were distributed not only on TMJ or mandible but also on the circummaxillary sutures and other craniofacial structures. Conclusions Clinical changes obtained by chincup treatment in Class III malocclusions are not limited by only mandible. It was seen that also further structures were affected.

On the Axial Holding Capacity of Torpedo Bases in Clay

2017 ◽  
Author(s):  
José Renato M. de Sousa ◽  
Rachel G. B. C. Genzani ◽  
Elisabeth C. Porto ◽  
Alexandre T. Borges ◽  
Emmanuel F. Nogueira ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Free Fall ◽  
Fe Model ◽  
Well Drilling ◽  
Soft Clays ◽  
Axial Capacity ◽  
Accurate Design ◽  
Dimensional Finite Element ◽  
One Year ◽  
Three Dimensional Finite Element

A torpedo base is a type of conductor casing that embeds into the seabed mainly by free fall using its own weight as driving energy. One of the advantages of this concept is to install the conductor casing before the dynamic positioned (DP) drillship arrival at the location. This reduces the time of the well drilling leading to significant cost saving. However, the need to withstand the challenging loads of the ultra-deep water scenarios pushed the typical torpedo base design to its limit and, consequently, modifications to its original geometry and more accurate design models are needed. Therefore, in this work, a new torpedo base, designed to sustain high axial loads in very soft clays, is analyzed with a three-dimensional finite element (FE) model. This model accounts for the setup-effects of the soil with the use of a previously proposed analytical approach to estimate the stress state of the soil at any time after the installation of the base. The results obtained indicate that the axial holding capacity of the base varies along time. The holding capacity increase rapidly at the beginning of the installation, but this rate reduces after the first days. Depending on soil characteristics, full axial capacity may be reached more than one year after the installation of the base. Moreover, the use of more than four fins welded to the shaft of the conductor casing modifies the shear zone along the base, but does not contribute to a significant increase in the axial holding capacity.

Backcalculation of Thermally Deformed Concrete Pavements

2000 ◽  
Vol 1716 (1) ◽  
pp. 64-72 ◽  
Author(s):  
Samir N. Shoukry
Keyword(s):  
Thermal Gradient ◽  
Concrete Slab ◽  
Three Dimensional ◽  
Plain Concrete ◽  
Slab Thickness ◽  
Fe Model ◽  
Concrete Pavements ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Falling Weight

Nonlinear explicit three-dimensional finite element (3-D FE) modeling is used to investigate the performance of the falling weight deflectometer (FWD) test in the evaluation of layer moduli of jointed plain concrete pavements (JPCP) subjected to nonlinear thermal gradient through the slab thickness. Concrete slab separation from the base, in-plane friction at the concrete-base interface, the gravitational forces, and the interface characteristics between dowel bars and surrounding concrete are all represented in the 3-D FE model. Experimental verification of the model is obtained through comparison of the 3-D FE generated response to ( a) the FWD measured deflection basin and ( b) the measured response of an instrumented rigid pavement section located in Ohio to a loaded truck moving at 21.8 m/s (48 mph). Several cases of linear and nonlinear thermal gradients are applied to the model, and deflection basins are obtained. Two backcalculation programs, MODULUS 5.0 and EVERCALC 4.0, are used for prediction of the layer moduli in each case, and the values are compared. The results indicate that thermal curling of the slab due to negative thermal gradient has little effect on the accuracy of backcalculated moduli. Warping of the slab due to positive thermal gradient greatly influences the measured FWD deflection basin and leads to significant errors in the backcalculated moduli. These errors may be minimized if the time an FWD test is conducted falls between the late afternoon and midmorning (from 5:30 p.m. to 9:30 a.m. during summer in West Virginia).

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.

Residual Stress Prediction for Non-Axisymmetric Vessel Penetration Welds

2008 ◽  
Author(s):  
Kazuo Ogawa ◽  
Nobuyoshi Yanagida ◽  
Koichi Saito
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Three Dimensional ◽  
Measurement Data ◽  
Fe Model ◽  
Stress Distributions ◽  
Dimensional Finite Element ◽  
Stress Prediction ◽  
Three Dimensional Finite Element ◽  
Good Agreement

Residual stress distribution in an oblique nozzle jointed to a vessel with J-groove welds was analyzed using a three-dimensional finite element method. All welding passes were considered in a 180-degree finite element (FE) model with symmetry. Temperature and stress were modeled for simultaneous bead laying. To determine residual stress distributions at the welds experimentally, a mock-up specimen was manufactured. The analytical results show good agreement with the experimental measurement data, indicating that FE modeling is valid.

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