Parallelized Element-by-Element Architecture for Structural Analysis of Flexible Pipes Using Macro Finite Elements

2017 ◽  
Author(s):  
Fernando Geremias Toni ◽  
Clóvis de Arruda Martins
Keyword(s):  
Structural Analysis ◽  
Finite Elements ◽  
Degrees Of Freedom ◽  
Local Analysis ◽  
Present Moment ◽  
Flexible Pipe ◽  
Computational Performance ◽  
Flexible Pipes ◽  
Oil And Natural Gas ◽  
Global Stiffness Matrix

Flexible pipes are employed to transport oil and natural gas from the seabed to the floating units, and vice versa. These pipes are made of concentric layers of different geometries, materials and structural functions in order to withstand a series of static and dynamic loads from its adverse operating environment. The local analysis is an important stage in the design of a flexible pipe and consists in determining the stresses and strains distributions along its layers. Multipurpose finite element packages, such as ANSYS and ABAQUS, are commonly used in this task, but present many limitations for their generic nature, varying from the absence of specific tools for model creation to heavy restrictions of the number of degrees-of-freedom to make computational processing feasible. Over the past years, several macro finite elements were formulated by PROVASI & MARTINS specifically for modeling a flexible pipe, allowing a reduction in the total number of degrees-of-freedom. However, until the present moment, there is no parallel processing software that efficiently implements these elements for large model applications. Aiming greater computational performance, the macro elements can be combined with the element-by-element (EBE) method, which is characterized by the global stiffness matrix elimination, is highly parallelizable, scalable and shows a memory consumption that grows linearly with the number of elements in the model. In this context, a parallelized architecture for structural analysis of flexible pipes that explores the EBE method and macro finite elements has been developed, being of great interest for design applications in the industry.

Parallelized Element-by-Element Solver for Structural Analysis of Flexible Pipes Using Finite Macroelements

2020 ◽  
Author(s):  
Fernando Geremias Toni ◽  
Clóvis de Arruda Martins
Keyword(s):  
Structural Analysis ◽  
Degrees Of Freedom ◽  
Large Scale ◽  
Memory Consumption ◽  
Large Matrix ◽  
Flexible Pipes ◽  
Problem Description ◽  
Global Stiffness Matrix ◽  
Simulation Time ◽  
Matrix Bandwidth

Abstract Due to the number of layers and their respective geometrical complexities, finite element analyzes of flexible pipes usually require large-scale schemes, with a high number of elements and degrees-of-freedom. If proper precautions are not taken, such as suitable algorithms and numerical methods, the computational costs of these analyzes may become unfeasible to the current computational standards. Finite macroelements are finite elements formulated for the solution of a specific problem considering and taking advantage of its particularities, such as geometry patterns, in order to obtain computational advantages, as reduced number of degrees-of-freedom and ease of problem description. The element-by-element method (EBE) also fits very well in this context, since it is characterized by the elimination of the global stiffness matrix and its memory consumption grows linearly with the number of elements, besides being highly parallelizable. Over the last decades, several works regarding the EBE method were published in the literature, but none of them directly applied to flexible pipes. Due to the contact elements between the layers, problems with flexible pipes are usually characterized by very large matrix-bandwidth, making the implementation of EBE method more challenging, so that its efficiency and scalability are not compromised. Therefore, this work presents a parallelized implementation of an element-by-element architecture for structural analysis of flexible pipes using finite macroelements, consisting of an extension of a previous work from the same authors. New synchronization algorithms were developed, with scalability improvements, the methodology was extended to other finite macroelements and comparisons were made with a well-stablished FEM software, with significant gains in simulation time and memory consumption.

Optimization of Flexible Pipes Dynamic Analysis Using Artificial Neural Networks

2016 ◽  
Author(s):  
Victor Chaves ◽  
Luis V. S. Sagrilo ◽  
Vinícius Ribeiro Machado da Silva
Keyword(s):  
Dynamic Analysis ◽  
Fem Simulation ◽  
Training Data ◽  
Local Analysis ◽  
Flexible Pipe ◽  
Nonlinear Fem ◽  
Irregular Wave ◽  
Flexible Pipes ◽  
Artificial Neural ◽  
Hybrid Methodology

Irregular wave dynamic analysis is an extremely computational expensive process on flexible pipes design. One emerging method that aims to reduce these computational costs is the hybrid methodology that combines Finite Element Analyses (FEA) and Artificial Neural Network (ANN). The proposed hybrid methodology aims to predict flexible pipe tension and curvatures in the bend stiffener region. Firstly using short FEA simulations to train the ANN, and then using only the ANN and the prescribed floater motions to get the rest of the response histories. Two approaches are developed with respect to the training data. One uses an ANN for each sea state in the wave scatter diagram and the other develops an ANN for each wave incidence direction. In order to evaluate the accuracy of the proposed approaches, a local analysis is applied, based on the predicted tension and curvatures, to calculate stresses in tension armour wires and the corresponding flexible pipe fatigue lifes. The results are compared to those from full nonlinear FEM simulation.

Effect of Tension on Collapse Performance of Flexible Pipes

2018 ◽  
Author(s):  
Marcelo Miyazaki ◽  
Laurent Paumier ◽  
Fabien Caleyron
Keyword(s):  
Finite Elements ◽  
Failure Modes ◽  
Cost Model ◽  
Negative Influence ◽  
External Pressure ◽  
Flexible Pipe ◽  
Test Protocol ◽  
Specific Test ◽  
Flexible Pipes ◽  
Finite Elements Model

This paper investigates the effect of tension on collapse performance of flexible pipes. In the design of flexible pipelines for offshore field developments, one of the failure modes being associated with external pressure and bending loadings is the hydrostatic collapse. In accordance with standards, TechnipFMC methodology for flexible pipe collapse resistance determination ensures a robust design. The model has an analytical basis, leading to a fast and straightforward use. It has been validated with more than 200 tests performed on all possible pipe constructions on straight and curved configurations. TechnipFMC and IFP Energies nouvelles have also developed and improved over the past few years a Finite Elements Model dedicated to flexible riser studies. It takes full advantage of the structure periodicities such that a whole riser can be studied with a short length and low CPU cost model associated to specific periodicity conditions. The model is able to represent bent risers in various configurations (bending cycles, internal and external pressure, axial tension, torsion) and has been used for collapse prediction of flexible risers under tension. Additionally, a specific test protocol has been developed to be able to carry out a collapse test associated to tension. The purpose of this paper is to present the collapse test result, the specific development of the model for collapse and tension and the corresponding calculations performed with the Finite Elements Model on several structures, demonstrating that there is no negative influence of tension on collapse mode. It also gives a better understanding on the interaction between tension in the armor layers and collapse phenomenon.

Effect of Installation on Collapse Performance of Flexible Pipes

2017 ◽  
Author(s):  
Fabien Caleyron ◽  
Vincent Le Corre ◽  
Laurent Paumier
Keyword(s):  
Finite Elements ◽  
Failure Modes ◽  
External Pressure ◽  
Residual Effects ◽  
Cyclic Plasticity ◽  
Flexible Pipe ◽  
Collapse Resistance ◽  
Flexible Pipes ◽  
Offshore Field ◽  
Finite Elements Model

This paper investigates the effect of installation on collapse performance of flexible pipes. In the design of flexible pipelines for offshore field developments, one of the critical failure modes being associated with external pressure and bending loadings is the hydrostatic collapse. In accordance with standards, Technip methodology for flexible pipe collapse resistance determination ensures a robust and competitive design. The model has an analytical basis, leading to a fast and straightforward use. It has been validated with more than 200 tests performed on all possible pipe constructions on straight and curved configurations. As the industry is moving to deeper and deeper water, there is a greater need to understand all factors which could affect collapse. This includes residual effects due to the high installation loads from the laying system. As a consequence, Technip has performed several collapse tests on samples previously submitted to a loading representative of installation conditions (tension and crushing). Moreover, Technip and IFP Energies Nouvelles have developed and improved over the past few years a Finite Elements model dedicated to collapse prediction. The model accounts for the detailed geometry of the wires (carcass, pressure vault, spiral), ovalization, cyclic plasticity, contacts and residual stresses due to manufacturing. It allows to evaluate the effect of installation on the ovalization and plasticity of each layer and the collapse performance of the flexible pipe. The purpose of this paper is to present the collapse tests results and the corresponding calculations performed with the Finite Elements Model on several cases representative of Technip flexible pipes portfolio.

Flexible Pipe Systems Configurations for the Pre-Salt Area

2010 ◽  
Author(s):  
Judimar Clevelario ◽  
Fabio Pires ◽  
Claudio Barros ◽  
Terry Sheldrake
Keyword(s):  
Water Injection ◽  
High Strength Steels ◽  
High Strength ◽  
Pilot Project ◽  
Local Analysis ◽  
Flexible Pipe ◽  
Pipe System ◽  
Flexible Pipes ◽  
Unbonded Flexible Pipes ◽  
Global And Local

Unbonded flexible pipes are being considered as an actual solution for the following developments for the Brazilian Pre-Salt area. This technology is already being successfully used in the first EWT installed in the Brazilian Pre-salt and being qualified for the first Pre-salt Pilot Project development. However, unlikely the current project developments in water depths around 1500m, the free catenary configuration is not always an applicable option not only due to the 2500m water depth but also to the presence of contaminants such as CO2 and H2S in the conveyed fluids which in certain applications make the use of conventional high strength steels unfeasible, making the use of sour service armour wires mandatory. This paper presents the result of the global and local analysis performed for different applications such as 4″ gas lift, 6″ water injection, 6″ production and 9.13″ Gas export structures designed specifically for the ultra deep water in Brazilian Pre-Salt area. The aim of this study was to verify the feasibility of the free hanging catenary configuration and determine the most suitable flexible pipe system configuration for different applications, confirming that the flexible pipes are an adequate solution for the Pre-Salt even when the service life requirements exceeds 20 years and associated safety factors.

Bonded Flexible Pipe Model Using Macroelements

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
Rodrigo Provasi ◽  
Fernando Geremais Toni ◽  
Clóvis de Arruda Martins
Keyword(s):  
Finite Element ◽  
Degrees Of Freedom ◽  
Structural Behavior ◽  
Small Displacement ◽  
Relative Movement ◽  
Memory Consumption ◽  
Flexible Pipe ◽  
Pipe Model ◽  
Flexible Pipes ◽  
Compliant Behavior

Flexible pipes are structures composed by many layers that vary in composition and shapes. The structural behavior of each layer is defined by the role it must play. The construction of flexible pipes is such that the layers are unbounded, with relative movement between them. Even though this characteristic is what enables its high bending compliant behavior, if the displacements involved are small, a bonded analysis is interesting to grasp the general characteristics of the problem. The bonded hypothesis means that there is no movement relative between layers, which is fine for a small displacement analysis. It also creates a lower bound for the movement, since when considering increasingly friction coefficient values, it tends to the bonded situation. The main advantage of such hypothesis is that the system becomes linear, leading to fast solving problems (when compared to full frictional analysis) and giving insights to the pipe behavior. The authors have previously developed a finite element based one called macroelements. This model enables a fast-solving problem with less memory consumption when compared to multipurpose software. The reason behind it is the inclusion of physical characteristics of the problem, enabling the reduction in both number of elements and memory used and, since there are less elements and degrees-of-freedom, faster solved problems. In this paper, the advantages of such model are shown by using examples that are representative of a simplified, although realistic, flexible pipe. Comparisons between the macroelement model and commercial software are made to show its capabilities.

Artificial Neural Networks Applied to Flexible Pipes Fatigue Calculations

2015 ◽  
Author(s):  
Victor Chaves ◽  
Luis V. S. Sagrilo ◽  
Vinícius Ribeiro Machado da Silva ◽  
Mario Alfredo Vignoles
Keyword(s):  
Neural Networks ◽  
Artificial Neural Networks ◽  
Computational Cost ◽  
Local Analysis ◽  
Flexible Pipe ◽  
Training Time ◽  
Flexible Pipes ◽  
Dynamic Analyses ◽  
Artificial Neural ◽  
Hybrid Methodology

Flexible pipes play an important role in offshore oil exploitation activities nowadays. However, time-domain flexible pipe irregular wave dynamic analyses are extremely computational expensive. One of the various existing methods to reduce computational costs in dynamic analyses is the hybrid methodology that combines dynamic Finite Element Analyses (FEA) and Artificial Neural Networks (ANN). This paper presents a novel application of this methodology for flexible pipes fatigue calculations. In order to decrease computational cost involved in these analyses the proposed hybrid methodology aims to predict tension and curvatures in the bend stiffener region. Firstly using short FEA simulations to train the ANN, and then using only the ANN and the prescribed floater motions to get the rest of the response histories. With the predicted tension and curvatures, a local analysis is applied to calculate stresses in tensile armour wires and the corresponding fatigue lives. To evaluate the optimal ANN a sensibility study is developed for some key parameters as: training time length, neurons on hidden layer and delay length. A full FEA is also performed in order to evaluate the accuracy of the proposed hybrid methodology, comparing both full FEA flexible pipe fatigue results and those obtained using the hybrid methodology.

scholarly journals Burst pressure prediction of fiber-reinforced flexible pipes with arbitrary generatrix

2021 ◽  
Vol 16 ◽  
pp. 155892502199081
Author(s):  
Guo-min Xu ◽  
Chang-geng Shuai
Keyword(s):  
Transfer Matrix ◽  
Linear Equations ◽  
Burst Pressure ◽  
Fiber Reinforced ◽  
Flexible Pipe ◽  
Theoretical Derivation ◽  
Design And Optimization ◽  
Flexible Pipes ◽  
Novel Method ◽  
Winding Angle

Fiber-reinforced flexible pipes are widely used to transport the fluid at locations requiring flexible connection in pipeline systems. It is important to predict the burst pressure to guarantee the reliability of the flexible pipes. Based on the composite shell theory and the transfer-matrix method, the burst pressure of flexible pipes with arbitrary generatrix under internal pressure is investigated. Firstly, a novel method is proposed to simplify the theoretical derivation of the transfer matrix by solving symbolic linear equations. The method is accurate and much faster than the manual derivation of the transfer matrix. The anisotropy dependency on the circumferential radius of the pipe is considered in the theoretical approach, along with the nonlinear stretch of the unidirectional fabric in the reinforced layer. Secondly, the burst pressure is predicted with the Tsai-Hill failure criterion and verified by burst tests of six different prototypes of the flexible pipe. It is found that the burst pressure is increased significantly with an optimal winding angle of the unidirectional fabric. The optimal result is determined by the geometric parameters of the pipe. The investigation method and results presented in this paper will guide the design and optimization of novel fiber-reinforced flexible pipes.

Sign in / Sign up

Export Citation Format

Share Document