Numerical and Experimental Study of Damaged Sandwich Pipe Under External Pressure

2014 ◽  
Author(s):  
João Fabrício Machado de Castilho ◽  
Ilson Paranhos Pasqualino
Keyword(s):  
Experimental Study ◽  
Three Dimensional ◽  
Mechanical Damage ◽  
High Strength ◽  
Good Alternative ◽  
External Pressure ◽  
Small Scale ◽  
Fe Model ◽  
Steel Tubes ◽  
Initiation Pressure

Studies on sandwich pipes, which comprise two concentric high strength steel tubes and a suitable annular material have shown good results due to their improved strength under external pressure and therefore they have been indicated as a good alternative for application in brazilian pre-salt scenario as gas and oil exportation pipelines. After installation on seabed a sandwich pipe can undergo mechanical damage caused by possible impacts of an anchor or some dropped heavy objects. When this happens, its strength under external pressure can be significantly reduced. This paper presents a numerical and experimental study of the reduced strength under external pressure (initiation pressure) of a damaged sandwich pipe. To this end, small scale sandwich pipe models were manufactured using steel tubes and PVDF in the annular space. Mechanical damages were simulated on the external surface of the models to collapse them under external pressure. The test results were compared to a three dimensional FE model simulating both the initiation pressure and the propagation pressure of the tested samples. A parametric study was carried out to analyze the sandwich pipe performance under damaged conditions.

Numerical Modeling of Tube Hydropiercing Using Phenomenological and Micro-Mechanical Damage Criteria

2013 ◽  
Vol 549 ◽  
pp. 172-179 ◽  
Author(s):  
Amir Hassannejadasl ◽  
Daniel E. Green
Keyword(s):  
Experimental Studies ◽  
Three Dimensional ◽  
Equivalent Plastic Strain ◽  
Mechanical Damage ◽  
High Strength ◽  
Dimensional Finite Element ◽  
Steel Dp600 ◽  
Three Dimensional Finite Element ◽  
Jc Model ◽  
Damage Criteria

Hydropiercing is an efficient way of piercing holes in mass produced hydroformed parts with complex geometries. By driving piercing punches radially into a hydroformed and fully pressurized tube, holes will be pierced and extruded into the tube-wall. Recent experimental studies have shown that the formability of advanced high strength steel (AHSS) tubes can be increased with the application of internal pressure. In this study, three-dimensional finite element simulations of a tube hydropiercing process of a dual phase steel (DP600) were performed in LS-DYNA, using phenomenological, micromechanical and combined damage criteria. Damage was included in the numerical analysis by applying constant equivalent plastic strain (CEPS), the Gurson-Tvergaard-Needleman (GTN), and the Extended GTN (GTN+JC) model. In order to calibrate the parameters in each model, a specialized hole-piercing fixture was designed and piercing tests were carried out on non-pressurized tube specimens. Of the various ductile fracture criteria, the results predicted with the GTN+JC model, such as the punch load-displacement, the roll-over depth, and the quality of the clearance zone correlated the best with the experimental data.

Experimental Study on Bearing Capacity of Q690 High-Strength Steel Tubes under Axial Load

2014 ◽  
Vol 638-640 ◽  
pp. 101-104
Author(s):  
Yi Liang Peng ◽  
Guo Tian Li ◽  
Xuan Min Han ◽  
Lei Chen
Keyword(s):  
Experimental Study ◽  
Bearing Capacity ◽  
High Strength Steel ◽  
Axial Load ◽  
High Strength ◽  
Steel Grade ◽  
Stability Factor ◽  
Steel Tubes ◽  
Steel Members ◽  
The Stability

With the rapid development of power transmission and transformation projects in China, steel supporting structure has already became the most popular structural form for these structures. However, the limit of steel grade used for current substation supporting structures is normally Q420, compared with that of Q690 used in other countries. When the high-strength steel is used, the geometric parameters of section for members become smaller, and the stability of members is the most important factors to influence the bearing capacity of structures. The stability factor for axial loaded steel members in current 《Code for design of steel structures》(GB50017-2003) was derived based on the experimental results for steel members with lower steel grade, the results are inevitably different from those for high-strength steel members. To make the calculations of Q690 high-strength steel tubes more accurate and reasonable, this paper conducts experimental study on the bearing capacity of Q690 high-strength steel tubes under axial load to provide scientific basis for practical design of these structures.

Propagation of Buckles in Sandwich Pipes Under External Pressure

2005 ◽  
Author(s):  
I. P. Pasqualino ◽  
M. I. Lourenc¸o ◽  
T. A. Netto
Keyword(s):  
Three Dimensional ◽  
Nonlinear Behavior ◽  
Element Model ◽  
External Pressure ◽  
Core Material ◽  
Small Scale ◽  
Ongoing Research ◽  
Scale Models ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

Sandwich pipes have been considered feasible conceptions for ultra deepwater pipelines, since they are capable to work at low temperatures and withstand high hydrostatic pressures. Sandwich pipelines are composed by inner and outer metallic pipes and a suitable core material which must provide high compression strength and good thermal insulation. The aim of this ongoing research is to study the quasi-static propagation of buckles in sandwich pipes. In this paper, a three-dimensional finite element model considering material and geometric nonlinear behavior is presented. The mesh discretization is determined through a detailed mesh sensitivity analysis. Some experiments with small scale models combining aluminum pipes and polypropylene as core material were carried out to calibrate the numerical model. The propagation pressure is evaluated under different bonding conditions between pipe layers.

Radial Buckling of Tensile Armor Wires in Subsea Flexible Pipe—Numerical Assessment of Key Factors

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
Alireza Ebrahimi ◽  
Shawn Kenny ◽  
Amgad Hussein
Keyword(s):  
Three Dimensional ◽  
External Pressure ◽  
Axial Stiffness ◽  
Parameter Study ◽  
Fe Model ◽  
Key Factors ◽  
Flexible Pipe ◽  
Analysis And Design ◽  
Axial Forces ◽  
Out Of Plane

Flexible pipes can be used as risers, jumpers, and flowlines that may be subject to axial forces and out-of-plane bending motion due to operational and environmental loading conditions. The tensile armor wires provide axial stiffness to resist these loads. Antibirdcaging tape is used to provide circumferential support and prevent a loss of stability for the tension armor wires, in the radial direction. The antibirdcaging tape may be damaged where a condition known as “wet annulus” occurs that may result in the radial buckling (i.e., birdcaging mechanism) of the tensile armor wires. A three-dimensional continuum finite element (FE) model of a 4 in. flexible pipe is developed using abaqus/implicit software package. As a verification case, the radial buckling response is compared with similar but limited experimental work available in the public domain. The modeling procedures represent an improvement over past studies through the increased number of layers and elements to model contact interactions and failure mechanisms. A limited parameter study highlighted the importance of key factors influencing the radial buckling mechanism that includes external pressure, internal pressure, and damage, related to the percentage of wet annulus. The importance of radial contact pressure and shear stress between layers was also identified. The outcomes may be used to improve guidance in the engineering analysis and design of flexible pipelines and to support the improvement of recommended practices.

Reliability Analysis of Corroded Pipelines Under External Pressure

2017 ◽  
Author(s):  
A. P. Teixeira ◽  
O. G. Palencia ◽  
C. Guedes Soares
Keyword(s):  
Reliability Analysis ◽  
Three Dimensional ◽  
External Pressure ◽  
Design Methods ◽  
Sensitivity Analyses ◽  
Structural Safety ◽  
Small Scale ◽  
Collapse Pressure ◽  
Collapse Probability ◽  
Subsea Pipelines

This paper aims at assessing the reliability of pipelines with corrosion defects subjected to external pressure. Several design methods that explicitly account for the effect of corrosion damages on the collapse pressure of pipelines are considered. In particular, semi-empirical design equations derived from small-scale experiments and three-dimensional non-linear finite element analyses and design code methods currently used in practice are adopted. First, the design methods are analyzed and their predictions compared and then used to formulate the reliability problem of corroded pipelines subjected to external pressure. The reliability analysis adopts the state-of-the art stochastic models to characterize the uncertainty on the main parameters influencing the structural safety of corroded subsea pipelines. Parametric and sensitivity analyses are then performed for different levels of corrosion damages to identify the influence of the various parameters on the collapse probability of corroded pipelines under external pressure.

Numerical Simulation of Friction Stir Spot Welding

2016 ◽  
Vol 834 ◽  
pp. 43-48 ◽  
Author(s):  
Marius Adrian Constantin ◽  
Ana Boşneag ◽  
Monica Iordache ◽  
Claudiu Bădulescu ◽  
Eduard Niţu
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Spot Welding ◽  
Frictional Heating ◽  
Three Dimensional ◽  
High Strength Steels ◽  
High Strength ◽  
Friction Stir Spot Welding ◽  
Fe Model ◽  
Friction Stir

Friction Stir Spot Welding (FSSW) is a solid state joining process that relies on frictional heating and plastic deformation realized at the interaction between a non-consumable welding tool that rotates on the contact surfaces of the workpieces. Friction Stir Spot Welding (FSSW) is an evolving technique that has received considerable attention from automotive industries to replace electric resistance spot welding, which shows poor weldability for advanced high-strength steels as well as aluminium alloys. Because of the interest shown by the industry towards this process, an attempt to optimize it is imperative. But the experiments are often time consuming and costly. To overcome these problems, numerical analysis has frequently been used in the last years. The purpose of this paper is to develop a three-dimensional fully coupled thermal-stress finite element (FE) model of FSSW process for thin aluminium alloy Al 6061-T6. Numerical simulation being helpful for better understanding and observation of the influence of input parameters on the resulting phenomena. It is described the algorithm and are presented the activities needed to be performed in order to develop a valid numerical model for FSSW. The validation of the numerical model being achieved by comparing the resulted temperatures from the numerical simulation with the experimentally determined temperatures for the same material

Predicted Behaviour of Partially Restrained Connection with Cold Formed High Strength Steel by 3D Finite Element Modelling

2011 ◽  
Vol 250-253 ◽  
pp. 1734-1743
Author(s):  
Syaril Taufik ◽  
Shahrizan bin Baharom ◽  
Robert Y. Xiao
Keyword(s):  
Finite Element ◽  
High Strength Steel ◽  
Load Capacity ◽  
Three Dimensional ◽  
High Strength ◽  
Contact Element ◽  
Fe Model ◽  
Ultimate Load Capacity ◽  
The Moment ◽  
Partially Restrained

Thispaper investigates the behavior prediction of partially restrained (PR) connection with high strength steel bythree-dimensional nonlinear finite-element (FE) analyses. The connectionmodel is such that angle cleats are represented by radiuses corner section shell elements. The full interaction between angle and beam and/or column is simulated by contact element. The analysis results of the moment- rotation relationship and behaviour characteristic of the connection with high strength steel are compared and discussed. It is found that contact element and strength enhancement of the corner regions employed to the model are very important parameters for accurate prediction of PR connection behaviour with cold-formed high strength steel. The moment capacity prediction of top and seat angle connections based on EC3 has been shown to be reasonable compared with FE modeling. Theproposed connection FE model is capable of predicting the ultimate load capacity and the plastic strain pattern with good accuracy. The model presented gives excellent results for increasing the connection capacity significantly due to employed higher strength steel section.

Collapse Mechanism of Unbounded Metal-Composite Pipes Under Hydrostatic Pressure

2008 ◽  
Author(s):  
Ilson Paranhos Pasqualino ◽  
Flavio Antoun Netto ◽  
Theodoro Antoun Netto
Keyword(s):  
Thermal Insulation ◽  
Progressive Failure ◽  
Composite Layer ◽  
External Pressure ◽  
Small Scale ◽  
Plastic Behavior ◽  
Collapse Mechanism ◽  
Fe Model ◽  
Metal Composite ◽  
Composite Pipes

Metal-composite pipes are feasible alternatives for deepwater applications where thermal insulation and structural behavior requirements must be met. They are composed of an inner metal pipe and an outer structural composite layer which act in combination to provide excellent structural strength and additional thermal insulation. In this work, the mechanical behavior of such pipes under external pressure is investigated through numerical analyses and experimental tests. Small scale models were tested under external pressure to calibrate a finite element based numerical model. The FE model incorporates nonlinear kinematics, progressive failure analyses of the composite layer, and metal elastic-plastic behavior. Unbounded interface between metal and composite was assumed through frictionless surface-based contact model in other to obtain a conservative estimate of the metal-composite pipe performance under external pressure.

Numerical and Experimental Study of a Flexible Pipe Under Torsion

2010 ◽  
Author(s):  
He´ctor E. M. Merino ◽  
Jose´ Renato M. de Sousa ◽  
Carlos Magluta ◽  
Ney Roitman
Keyword(s):  
Experimental Study ◽  
Finite Element ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Nonlinear Finite Element ◽  
Analytical Models ◽  
Fe Model ◽  
Pure Torsion ◽  
Flexible Pipe ◽  
Torsional Loads

The torsional behavior of a 4″ flexible pipe is here studied. The pipe was subjected to clockwise and anticlockwise torsion and also to torsion combined with tension. For pure torsion, two different boundary conditions were considered: ends free to elongate and prevented from elongating. When tensional and torsional loads are imposed to the pipe, only analyses with ends prevented from elongating are carried out. In all cases, the response of the pipe is predicted with a three-dimensional nonlinear finite element (FE) model and with a classical analytical model. Experimental tests performed at COPPE/UFRJ are also employed to validate the theoretical estimations. The obtained results point out that the pipe is torque balanced for clockwise torsion, but it is not balanced for anti-clockwise torsion. Moreover, analytical models for axissymetric analyses assume that the layers of a flexible pipe are subjected to the same twist and elongation, but the FE results state that this hypothesis holds only for anti-clockwise torsion. Therefore, some differences were found between the FE and analytical models mainly when clockwise torsion is considered. Finally, due to its ability to deal with friction and adhesion between layers, the FE estimations agreed quite well with the experimental measures.

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