Effect of Material Plasticity and Metallic Layer Profiles on the Crushing Resistance of Flexible Pipes

2013 ◽  
Author(s):  
Marcel Sato ◽  
Rafael L. Tanaka ◽  
Elson L. Albuquerque ◽  
Rafael G. Morini ◽  
Carlos A. F. Godinho
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Experimental Comparison ◽  
Squeezing Effect ◽  
Flexible Pipe ◽  
3D Finite Element ◽  
Typical Situation ◽  
Flexible Pipes ◽  
Radial Strength ◽  
Polymeric Layer

This paper presents a numerical 3D finite element model to simulate a flexible pipe under crushing-traction condition, which is a typical situation found during its laying operation. This model considers the geometry of some layers from the flexible pipe, responsible of providing the most contribution to its radial strength (e.g., interlocked carcass, internal polymeric layer, pressure armor, and external polymeric layer) and geometry of laying system shoes. It also considers the flexible pipe initial ovalization and the squeezing effect due to the tensile armor layers under traction. A numerical-experimental comparison is presented, in order to show the model validity.

Finite Element Analysis of Flexible Pipes Under Compression

2014 ◽  
Author(s):  
Eduardo Ribeiro Malta ◽  
Clóvis de Arruda Martins
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
High Strength ◽  
Element Model ◽  
Large Displacements ◽  
Flexible Pipe ◽  
Element Analysis ◽  
Flexible Pipes ◽  
Compressive Loads ◽  
Surface Vessel

Axial compressive loads can appear in several situations during the service life of a flexible pipe, due to pressure variations during installation or due to surface vessel heave. The tensile armor withstands well tension loads, but under compression, instability may occur. A Finite Element model is constructed using Abaqus in order to study a flexible pipe compound by external sheath, two layers of tensile armor, a high strength tape and a rigid nucleus. This model is fully tridimensional and takes into account all kinds of nonlinearities involved in this phenomenon, including contacts, gaps, friction, plasticity and large displacements. It also has no symmetry or periodical limitations, thus permitting each individual wire of the tensile armor do displace in any direction. Case studies were performed and their results discussed.

Finite Element Analysis of Flexible Pipes Under Axial Compression: Influence of the Sample Length

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Eduardo Ribeiro Malta ◽  
Clóvis de Arruda Martins
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Inner Core ◽  
High Sensitivity ◽  
Element Model ◽  
Sample Length ◽  
Flexible Pipe ◽  
Element Analysis ◽  
Flexible Pipes

In order to study the axial compressive behavior of flexible pipes, a nonlinear tridimensional finite element model was developed. This model recreates a five layer flexible pipe with two tensile armor layers, an external polymeric sheath, an orthotropic high strength tape, and a rigid inner core. Using this model, several studies were conducted to verify the influence of key parameters on the wire instability phenomenon. The pipe sample length can be considered as one of these parameters. This paper includes a detailed description of the finite element model itself and a case study where the length of the pipe is varied. The procedure of this analysis is here described and a case study is presented which shows that the sample length itself has no practical effect on the prebuckling response of the samples and a small effect on the limit force value. The postbuckling response, however, presented high sensitivity to the changes, but its erratic behavior has made impossible to establish a pattern.

Thermal Effects on the Anchoring of Flexible Pipe Tensile Armors

2015 ◽  
Author(s):  
Olaf O. Otte Filho ◽  
Rafael L. Tanaka ◽  
Rafael G. Morini ◽  
Rafael N. Torres ◽  
Thamise S. V. Vilela
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Thermal Effects ◽  
Current Model ◽  
Element Model ◽  
Small Scale ◽  
Flexible Pipe ◽  
System A ◽  
Flexible Pipes ◽  
Better Than

In the design of flexible pipes, predict the anchoring behavior on end fittings is always challenging. In this sense, Prysmian Surflex has developed a finite element model, which should help the end fitting design as well the prediction of the structural behavior and the acceptable maximum loads. The current model considers that the contact between armor-resin is purely cohesive and has been suitable for the design of end fittings [1] and [2]. But tests and new studies [3] and [4] indicate that only cohesive assumption would not be the best approach. Experimental data from prototype tests also show that the current model would not predict acceptable results for loads higher than those used in previous projects. This document will describe a study developed considering the friction and thermal contraction, instead of the cohesive phenomenon in the anchoring behavior analysis. Small scale tests were conducted in order to understand the anchoring relation between the resin and the wire used in the tensile armor. For this purpose, a special test device was developed to simulate an enclosure system. A parametric study was also performed to identify the cooling temperatures, coefficients of friction and contact properties parameters taken from small scale tests. The finite element model considers the thermal effects during exothermic curing. Using the new parameters obtained, a second model was developed. This model consists of only one real shaped bended wire inside an end fitting cavity. To validate the model, samples were tested on laboratory according anchoring design. The results of this round of tests were studied and corroborate the argument that use friction and thermal effects is better than use only the cohesive condition.

Helical Wire Behavior of Unbonded Flexible Pipes Under Bending

2015 ◽  
Author(s):  
Yutian Lu ◽  
Huibin Yan ◽  
Yong Bai ◽  
Peng Cheng
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Axial Strain ◽  
Bending Moment ◽  
Element Model ◽  
Flexible Pipe ◽  
Slip Mechanism ◽  
Flexible Pipes ◽  
Bending Behavior ◽  
Unbonded Flexible Pipes

The bending behavior of unbonded flexible pipe is governed by the response of the helical wires in the tensile armor to bending. The behavior of the helical wire, especially the axial strain, is influenced by the slip mechanism as a result of an increasing curvature under bending. In the present paper, two limit curves are considered with a certain curvature. A 3-D finite element model using ABAQUS is developed to simulate the practical behavior of the helical wires under bending. By comparing the FEA and theoretical results, a basic conclusion about the real slip path of the helical wire between two limit curves is introduced. A hysteretic bending moment-curvature relationship induced by the slip mechanism is obtained from the finite element model as well.

Finite Element Analysis of Flexible Pipes Under Compression: Influence of the Sample Length

2015 ◽  
Author(s):  
Eduardo Ribeiro Malta ◽  
Clóvis de Arruda Martins
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
High Strength ◽  
Element Model ◽  
Sample Length ◽  
Flexible Pipe ◽  
Element Analysis ◽  
Flexible Pipes ◽  
The Stability

In order to study the compressive behavior of flexible pipes, a nonlinear tridimensional finite element model was developed. This model recreates a five layer flexible pipe with two tensile armor layers, an external polymeric sheath, an orthotropic high strength tape and a rigid inner nucleus. Using this model, several studies are being conducted to verify the influence of key parameters on the wire instability phenomenon. The pipe sample length can be considered one of these parameters and its variation causes significant change at the stability response of the tensile layers. This article includes a detailed description of the finite element model itself and a case study where the length of the pipe is changed. The procedure of this analysis is here described, along with the results.

Finite Element Analysis of Flexible Pipes Under Compression: Influence of the Friction Coefficient

2016 ◽  
Author(s):  
Eduardo Ribeiro Malta ◽  
Clóvis de Arruda Martins
Keyword(s):  
Finite Element ◽  
Friction Coefficient ◽  
Finite Element Model ◽  
High Strength ◽  
Element Model ◽  
Flexible Pipe ◽  
Element Analysis ◽  
Frictional Contacts ◽  
Flexible Pipes ◽  
Nonlinear Finite Element Model

In order to study the compressive behavior of flexible pipes, a nonlinear Finite Element model was developed. This fully tridimensional model recreates a five layer flexible pipe with two tensile armor layers, an external polymeric sheath, an orthotropic high strength tape and a rigid inner nucleus. The friction coefficient is known as a key parameter in determining the instability response of flexible pipes tensile armor. Since the featured model includes all nonlinear frictional contacts between the layers, it has been used to conduct several experiments in order to investigate its influence on the response. This article includes a description of the Finite Element Model itself and a case study where the friction between the layers of the pipe is changed. The procedure of this analysis is here described, along with the results.

Finite Element Model and Bending for Marine Composite Flexible Pipes

2013 ◽  
Vol 690-693 ◽  
pp. 314-317 ◽  
Author(s):  
Man Wang ◽  
Rui Xiang Bai ◽  
Mao Jun Zhou
Keyword(s):  
Finite Element ◽  
Stress Response ◽  
Optimal Design ◽  
Model Building ◽  
Element Model ◽  
Flexible Pipe ◽  
Flexible Pipes ◽  
Layer Composite ◽  
Bending Load ◽  
Marine Composite

The parameterizationmodeling of typical composite flexible pipe is studied by ANSYS two-developmentlanguage APDL, which established the model building of the spiral self-lockinglayer and scanning division meshes. The stress response of the typicalfive-layer composite flexible pipe was calculated under bending load byadopting the no slip assumptions. It is easy to modify the parameters offlexible pipe structure by using the parameterization modeling. Theparameterization modeling can be used for the optimal design of flexible pipe.

Residual Stress Evaluation and Buckling Analysis of Carcass Layers in Flexible Pipes Using 3D Finite Element Model

2015 ◽  
Author(s):  
Minggang Tang ◽  
Jun Yan ◽  
Jinlong Chen ◽  
Zhixun Yang ◽  
Qianjin Yue
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Finite Element Model ◽  
Critical Pressure ◽  
Element Model ◽  
Forming Process ◽  
Cold Forming ◽  
3D Finite Element ◽  
3D Finite Element Model ◽  
Flexible Pipes

A carcass layer plays an important role in unbonded flexible pipes to resist the high level of external pressure without buckling collapse. The layer is made of an interlocked helically wound metal wire of profiled section that cold-deformed by a series of rollers. In typical design and analysis process of the carcass layer, the initial stress is always assumed to be zero. During the carcass layer manufacturing (a cold forming process), the metal strap is however subjected to varies of squeezing and bending and deformations to take “S” shape, and then the profiled wire to a cycling sequence of bending, squeezing and twisting deformations, which take it beyond its material elastic limit. The residual stress is therefore introduced and could has effect on the critical pressure of the carcass layer. This paper presents a 3D finite element model to investigate the detailed residual stress distribution and variation during the forming process of the carcass layer. A study case using a 3D ring model is presented to systemically study the influence of imperfections, especially the residual stress, on the critical pressure of carcass layers.

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

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
Alfredo Gay Neto ◽  
Clóvis de Arruda Martins ◽  
Eduardo Ribeiro Malta ◽  
Rafael Loureiro Tanaka ◽  
Carlos Alberto Ferreira Godinho
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
3D Models ◽  
External Pressure ◽  
Finite Element Models ◽  
Flexible Pipe ◽  
Collapse Pressure ◽  
Flexible Pipes ◽  
Polymeric Layer ◽  
Collapse Failure

When the external sheath of flexible pipes experiences damage, seawater floods the annulus. Then, the external pressure is applied directly on the internal polymeric layer, and the load is transferred to the interlocked carcass, the innermost layer. In this situation, the so-called wet collapse failure of the interlocked carcass can occur. Simplified methodologies to address such a scenario, using restricted three-dimensional (3D) finite element models, are presented in this work. They are compared with full 3D models, studying both straight and curved flexible pipes scenarios. The curvature of the flexible pipe is shown to be important for wet collapse pressure predictions.

Finite Element Analysis of Flexible Pipes Under Compression: Influence of the Friction Coefficient

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Eduardo Ribeiro Malta ◽  
Clóvis de Arruda Martins
Keyword(s):  
Finite Element ◽  
Friction Coefficient ◽  
Finite Element Model ◽  
High Strength ◽  
Element Model ◽  
Flexible Pipe ◽  
Element Analysis ◽  
Frictional Contacts ◽  
Flexible Pipes ◽  
Nonlinear Finite Element Model

In order to study the compressive behavior of flexible pipes, a nonlinear finite element model was developed. This fully tridimensional model recreates a five-layer flexible pipe with two tensile armor layers, an external polymeric sheath, an orthotropic high strength tape, and a rigid inner nucleus. The friction coefficient is known as a key parameter in determining the instability response of flexible pipes’ tensile armor. Since the featured model includes all nonlinear frictional contacts between the layers, it has been used to conduct several experiments in order to investigate its influence on the response. This article includes a description of the finite element model itself and a case study where the friction between the layers of the pipe is changed. The procedure of this analysis is described here, along with the results.

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