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.

Numerical Analysis of a Flexible Pipe With Damaged Tensile Armor Wires

2009 ◽  
Author(s):  
Jose´ Renato M. de Sousa ◽  
Aline Nacif Pinho ◽  
Gilberto Bruno Ellwanger ◽  
Edison C. P. Lima
Keyword(s):  
Mechanical Response ◽  
High Stress ◽  
Three Dimensional ◽  
Element Model ◽  
Axial Rotation ◽  
Flexible Pipe ◽  
High Stress Concentration ◽  
Flexible Pipes ◽  
Localized Defects ◽  
Nonlinear Finite Element Model

This paper focus on the structural analysis of a 2.5″ flexible pipe with one up to five broken wires in its outer tensile armor. The pipe is supposed to be under pure tension and the effect of the number of ruptured wires on its response is discussed. A three-dimensional nonlinear finite element model devoted to analyze the local mechanical response of flexible pipes is proposed and employed in all performed analyses. This model is capable of representing each wire of the tensile armors and, therefore, localized defects, including total rupture, may be adequately represented. The obtained results pointed to high stress concentration in the wires near the damaged ones as well as a significant increase in the axial rotation of the pipe. Moreover, the stresses in the inner carcass and the pressure armor are also affected by the rupture of wires in the outer tensile armor.

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.

Investigation on Mechanical Properties of Fibreglass Reinforced Flexible Pipes Under Torsion

2018 ◽  
Author(s):  
Pan Fang ◽  
Yuxin Xu ◽  
Shuai Yuan ◽  
Yong Bai ◽  
Peng Cheng
Keyword(s):  
Mechanical Behavior ◽  
Torsion Angle ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Load Condition ◽  
Element Model ◽  
Flexible Pipe ◽  
Torsional Load ◽  
Flexible Pipes ◽  
The Impact

Fibreglass reinforced flexible pipe (FRFP) is regarded as a great alternative to many bonded flexible pipes in the field of oil or gas transportation in shallow water. This paper describes an analysis of the mechanical behavior of FRFP under torsion. The mechanical behavior of FRFP subjected to pure torsion was investigated by experimental, analytical and numerical methods. Firstly, this paper presents experimental studies of three 10-layer FRFP subjected to torsional load. Torque-torsion angle relations were recorded during this test. Then, a theoretical model based on three-dimensional (3D) anisotropic elasticity theory was proposed to study the mechanical behavior of FRFP. In addition, a finite element model (FEM) including reinforced layers and PE layers was used to simulate the torsional load condition in ABAQUS. Torque-torsion angle relations obtained from these three methods agree well with each other, which illustrates the accuracy and reliability of the analytical model and FEM. The impact of fibreglass winding angle, thickness of reinforced layers and radius-thickness ratio were also studied. Conclusions obtained from this research may be of great practicality to manufacturing engineers.

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.

Finite Element Analysis of a Flexible Pipe Interlocked Carcass Under Tension Loads

2021 ◽  
Author(s):  
Fernando Geremias Toni ◽  
Rodrigo Provasi ◽  
Clóvis de Arruda Martins
Keyword(s):  
Finite Element ◽  
Failure Modes ◽  
Three Dimensional ◽  
Element Model ◽  
Cylindrical Layer ◽  
Stress Concentrations ◽  
Flexible Pipe ◽  
Element Analysis ◽  
Realistic Representation ◽  
Three Dimensional Finite Element

Abstract To correctly model the structural behavior of a flexible pipe, the contribution of all the layers must be completely understood, among them the interlocked carcass. That carcass is a metallic layer designed to provide radial stiffness to a flexible pipe, mainly supporting pressure differentials and thus preventing failure modes such as collapse and crushing, but its behavior under other loads is worth of investigation. This paper contributes to understanding the carcass behavior under tension. Given its complex helical and interlocked geometry, modelling the carcass through the Finite Element Method is a challenging task, not only due to the large size of the models, but also due to the nonlinearities and convergence difficulties that arise from the self-contacts at the interlocking. For these reasons, most works developed over the past decades have adopted an equivalent layer approach, in which the carcass is replaced by an orthotropic cylindrical layer with equivalent mechanical properties. Although practical, this approach disregards the effects from the interlocking, such as stiffness variations and stress concentrations. Therefore, aiming a more realistic representation and a better understanding of the mechanical behavior of the interlocked carcass, this work presents four different carcass finite element models to analyze this layer under tension loads. The first one is a complete three-dimensional finite element model of an interlocked carcass discretized with second order isoparametric solid elements and surface-to-surface contact elements. The second model consists of a version of the first one with the addition of an inner polymeric sheath. As for the third and fourth models, it was adopted the simplifying ring hypothesis, that is, a carcass with 90 degree lay angle, thus allowing the axisymmetric modelling of the two previous configurations, representing a substantial computational gain by using two-dimensional meshes. The results of those models are then presented and compared, and the validity of the adopted simplifying hypothesis is verified.

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.

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.

Bending Analysis of a Flexible Pipe With Broken Tensile Armor Wires

2015 ◽  
Author(s):  
José Renato M. de Sousa ◽  
Carlos Magluta ◽  
Ney Roitman ◽  
George C. Campello
Keyword(s):  
Mechanical Response ◽  
High Stress ◽  
Experimental Tests ◽  
Analytical Models ◽  
Force Distribution ◽  
Experimental Measurements ◽  
Fe Model ◽  
Flexible Pipe ◽  
High Stress Concentration ◽  
Bending Loads

In this work, the mechanical response of a damaged 2.5″ flexible pipe under combined tensile and bending loads is studied. A set of experimental tests was carried out either considering the pipe intact or with one up to four broken wires in its outer tensile armor. In these tests, the deflections along the pipe as well as the strains in its outer tensile armor wires were measured thus allowing estimating the bending stiffness of the pipe and the force distribution among the wires, respectively. The results obtained are compared to those provided by a previously presented finite element (FE) model and analytical models. The numerical and analytical predictions agreed well with the experimental measurements pointing to a negligible 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.

Simplified Finite Element Models to Study the Dry Collapse of Straight and Curved Flexible Pipes

2016 ◽  
Vol 138 (2) ◽  
Author(s):  
Alfredo Gay Neto ◽  
Clóvis de Arruda Martins ◽  
Eduardo Ribeiro Malta ◽  
Rafael Loureiro Tanaka ◽  
Carlos Alberto Ferreira Godinho
Keyword(s):  
Finite Element ◽  
Failure Modes ◽  
Computational Cost ◽  
Three Dimensional ◽  
Element Model ◽  
External Pressure ◽  
Flexible Pipe ◽  
Flexible Pipes ◽  
Simplified Modeling ◽  
Good Agreement

Dry collapse is one of the possible failure modes of flexible pipes. It refers to the situation in which no damage occurs in the flexible pipe external sheath. In this scenario, all layers of the pipe withstand the external pressure loading in a deep-water application. Such a situation is addressed in this work, which proposes some simplified modeling techniques to represent straight and curved flexible pipes subjected to external pressure, undergoing dry collapse during simulation procedure. The results of the proposed models are compared to other reference results, from a fully three-dimensional (3D) finite element model. Good agreement has been got, even with the proposed simplifications with a large reduction in computational cost when compared to full 3D model.

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