Strength Analyses of Sandwich Pipes for Ultra Deepwaters

2004 ◽  
Vol 72 (4) ◽  
pp. 599-608 ◽  
Author(s):  
Segen Farid Estefen ◽  
Theodoro Antoun Netto ◽  
Ilson Paranhos Pasqualino
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Ultimate Strength ◽  
Thermal Insulation ◽  
Research Work ◽  
Element Model ◽  
Material Behavior ◽  
Core Material ◽  
Small Scale ◽  
Mechanical Resistance

Design requirements for pipelines regarding both ultimate strength and flow assurance in ultra deepwater scenarios motivated the development of a new sandwich pipe which is able to combine high structural and thermal insulation properties. In this concept, the annulus is filled with low cost materials with adequate thermal insulation properties and good mechanical resistance. The aim of this research work is to perform small-scale laboratorial tests and to develop a finite element model to evaluate the structural performance of such sandwich pipes with two different options of core material. After calibrated in view of the experimental results, a three-dimensional finite element model incorporating nonlinear geometric and material behavior is employed to perform strength analyses of sandwich pipes under combined external pressure and longitudinal bending. Ultimate strength envelopes for sandwich pipes are compared with those generated for single-wall steel pipes with equivalent collapse pressures. The study shows that sandwich pipe systems with either cement or polypropylene cores are feasible options for ultra deepwater applications.

scholarly journals Experimental and Numerical Investigations of Ultimate Strength of Imperfect Stiffened Plates of Different Slenderness

2020 ◽  
Vol 27 (4) ◽  
pp. 120-129
Author(s):  
Krzysztof Woloszyk ◽  
Yordan Garbatov ◽  
Jakub Kowalski ◽  
Leszek Samson
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Ultimate Strength ◽  
Compressive Force ◽  
Initial Imperfection ◽  
Element Model ◽  
Stiffened Plates ◽  
Structural Behaviour ◽  
Middle Cross Section ◽  
Geometrical Imperfections

AbstractThe objective of this study is to analyse the behaviour of compressed stiffened plates of different slenderness using experimental and numerical methods. The presented results are part of a long-term project to investigate the ultimate strength of geometrically imperfect structures subjected to different degradation phenomena, including corrosion degradation and locked cracks. Several specimens were subjected to a uniaxial compressive force, and the most important quantities related to the structural behaviour were captured and analysed. A finite element model, accounting for material and geometrical nonlinearities and initial geometrical imperfections, was developed using the commercial software ANSYS. The residual welding-induced stresses were measured in the middle cross-section for two specimens. The initial imperfection was identified by employing a close-range photogrammetry approach. It was concluded that the numerical analyses, based on the finite element model, predict the ultimate strength of stiffened plates accurately, although some deviations were also observed. The detailed analysis with the indication of possible uncertainty is presented, and several conclusions are derived.

Simulation of Thermo-Mechanical Models for Hot Formed Parts by Numerical Experiments

2014 ◽  
Vol 663 ◽  
pp. 668-674
Author(s):  
Azman Senin ◽  
Zulkifli Mohd Nopiah ◽  
Muhammad Jamhuri Jamaludin ◽  
Ahmad Zakaria
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Prediction Accuracy ◽  
Research Work ◽  
Deformation Characteristic ◽  
Element Model ◽  
Forming Limit ◽  
Prototype Model ◽  
New Production ◽  
Element Analysis

The Finite-Element Analysis (FEA) is a prediction methodology that facilitates product designers produced the part design with manufacturing focused. With the similar advantages, manufacturing engineers are capable of build the first actual car model from the new production Draw Die. This approach has eliminated the requirement to manufacture the prototype model from soft tool parts and soft tool press die. However, the prediction accuracy of FEA is a major topic of research work in automotive sector's practitioners and academia as current accuracy level is anticipated at 60%. The objective of works is to assess the prediction accuracy on deformation results from mass production stamped parts. The Finite-element model is developed from the CAD data of the production tools. Subsequently, finite-element model for production tools is discretized with shell elements to avoid computation errors in the simulation process. The sheet blank material with 1.5 mm and 2.0 mm thickness is discredited by shell (2D modeling) and solid elements (3D modeling) respectively. The input parameters for the simulation model for both elements are attained from the actual setup at Press Machine and Production Tool. The analysis of deformation and plastic strain are performed for various setup parameters. Finally, the deformation characteristic such as Forming Limit Diagram (FLD) and thinning are compared for all simulated models.

Behaviour of cold-formed steel built-up I-section columns composed of four U-profiles

2018 ◽  
Vol 22 (3) ◽  
pp. 613-625 ◽  
Author(s):  
M Anbarasu ◽  
M Venkatesan
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Ultimate Strength ◽  
Element Model ◽  
Cross Sectional ◽  
Direct Strength Method ◽  
The North ◽  
Compression Members ◽  
Cross Sectional Dimension ◽  
Cold Formed Steel

This work reports numerical results concerning the cold-formed steel built-up I-section columns composed of four U-profiles under axial compression. A finite element model is developed by using the software program ABAQUS. The developed model includes geometric, material nonlinearities and geometric imperfections. The finite element model was verified against the experimental results reported in the cold-formed steel built-up open section columns. In the parametric study, the sections are analysed with several cross-sectional dimension ratios and lengths, in order to assess their influence on the buckling behaviour and ultimate strength of cold-formed steel built-up I-section columns. After presenting and discussing the numerical parametric results, the article shows that the current direct strength method in the North American Specification for cold-formed steel compression members design curve fails to predict adequately the ultimate strength of some of the columns analysed and addresses the modification proposed on current direct strength method curves, providing improved predictions of all the numerical ultimate strength available. The proposed method is also assessed by reliability analysis.

A FINITE ELEMENT MODEL FOR COMPRESSIVE ICE LOADS BASED ON A MOHR-COULOMB MATERIAL AND THE NODE SPLITTING TECHNIQUE

2021 ◽  
pp. 1-33
Author(s):  
Hauke Herrnring ◽  
Søren Ehlers
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Material Behavior ◽  
Double Pendulum ◽  
Strain Rates ◽  
Splitting Technique ◽  
Structure Interaction ◽  
Node Splitting ◽  
Brittle Mode

Abstract This paper presents a finite element model for the simulation of ice-structure interaction problems, which are dominated by crushing. The failure mode of ice depends significantly on the strain rate. At low strain rates the ice behaves ductile, whereas at high strain rates ice reacts in brittle mode. This paper focuses on the brittle mode, which is the dominating mode for ship-ice interactions. A multitude of numerical approaches for the simulation of ice can be found in the literature. Nevertheless, the literature approaches do not seem suitable for the simulation of continuous ice-structure interaction processes at low and high confinement ratios in brittle mode. Therefore, this paper seeks to simulate the ice-structure interaction with the finite element method (FEM). The objective of the here introduced Mohr-Coulomb Nodal Split (MCNS) model is to represent the essential material behavior of ice in an efficient formulation. To preserve mass and energy as much as possible, the node splitting technique is applied, instead of the frequently used element erosion technique. The intention of the presented model is not to reproduce individual cracks with high accuracy, because this is not possible with a reasonable element size, due to the large number of crack fronts forming during the ice-structure interaction process. To validate the findings of the model, the simulated maximum ice forces and contact pressures are compared with ice-extrusion and double pendulum tests. During validation, the MCNS model shows a very good agreement with these experimental values.

Crystallographic effects during micromachining — A finite-element model

2015 ◽  
Vol 29 (22) ◽  
pp. 1550119
Author(s):  
Shin-Hyung Song ◽  
Woo Chun Choi
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Chip Formation ◽  
Orthogonal Cutting ◽  
Element Model ◽  
Material Behavior ◽  
Face Centered Cubic ◽  
Work Material ◽  
User Material Subroutine ◽  
Crystallographic Orientations

Mechanical micromachining is a powerful and effective way for manufacturing small sized machine parts. Even though the micromachining process is similar to the traditional machining, the material behavior during the process is much different. In particular, many researchers report that the basic mechanics of the work material is affected by microstructures and their crystallographic orientations. For example, crystallographic orientations of the work material have significant influence on force response, chip formation and surface finish. In order to thoroughly understand the effect of crystallographic orientations on the micromachining process, finite-element model (FEM) simulating orthogonal cutting process of single crystallographic material was presented. For modeling the work material, rate sensitive single crystal plasticity of face-centered cubic (FCC) crystal was implemented. For the chip formation during the simulation, element deletion technique was used. The simulation model is developed using ABAQUS/explicit with user material subroutine via user material subroutine (VUMAT). Simulations showed that variation of the specific cutting energy at different crystallographic orientations of work material shows significant anisotropy. The developed FEM model can be a useful prediction tool of micromachining of crystalline materials.

Bodner-Partom Constitutive Model and Nonlinear Finite Element Analysis

1990 ◽  
Vol 112 (3) ◽  
pp. 287-291 ◽  
Author(s):  
F. A. Kolkailah ◽  
A. J. McPhate
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Plastic Strain ◽  
Constitutive Model ◽  
Finite Element Model ◽  
Numerical Technique ◽  
Element Model ◽  
Material Behavior ◽  
Model Parameters ◽  
Elastic Plastic

In this paper, results from an elastic-plastic finite-element model incorporating the Bodner-Partom model of nonlinear time-dependent material behavior are presented. The parameters in the constitutive model are computed from a leastsquare fit to experimental data obtained from uniaxial stress-strain and creep tests at 650°C. The finite element model of a double-notched specimen is employed to determine the value of the elastic-plastic strain and is compared to experimental data. The constitutive model parameters evaluated in this paper are found to be in good agreement with those obtained by the other investigators. However, the parameters determined by the numerical technique tend to give response that agree with the data better than do graphically determined parameters previously used. The calculated elastic-plastic strain from the model agreed well with the experimental strain.

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.

Stress Concentration Factors of Dented Pipelines

2006 ◽  
Author(s):  
Bianca de Carvalho Pinheiro ◽  
Ilson Paranhos Pasqualino ◽  
Se´rgio Barros da Cunha
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Numerical Model ◽  
Finite Element Model ◽  
Internal Pressure ◽  
Element Model ◽  
Small Strain ◽  
Small Scale ◽  
Concentration Factors ◽  
Stress Concentration Factors

A nonlinear finite element model was developed to assess stress concentration factors induced by plain dents on steel pipelines subjected to cyclic internal pressure. The numerical model comprised small strain plasticity and large rotations. Six small-scale experimental tests were carried out to determine the strain behavior of steel pipe models during denting simulation followed by the application of cyclic internal pressure. The finite element model developed was validated through a correlation between numerical and experimental results. A parametric study was accomplished, with the aid of the numerical model, to evaluate stress concentration factors as function of the pipe and dent geometries. Finally, an analytical formulation to estimate stress concentration factors of dented pipelines under internal pressure was proposed. These stress concentration factors can be used in a high cycle fatigue evaluation through S-N curves.

Ultimate strength of columns laterally braced by girt–diaphragm systems

1989 ◽  
Vol 16 (3) ◽  
pp. 227-238 ◽  
Author(s):  
Bruno Massicotte ◽  
Denis Beaulieu ◽  
André Picard
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Ultimate Strength ◽  
Parametric Study ◽  
Design Method ◽  
Element Model ◽  
Structural System ◽  
Industrial Buildings ◽  
Stabilizing Effect ◽  
Stability Statistics

This paper deals with the stabilizing effect of girts and cladding on columns in light industrial buildings. The construction aspects of such systems are briefly reviewed and a description of their behavior is presented. Solutions available to determine column strength in column–girt–diaphragm systems are reviewed. The use of a finite-element-based software is proposed as the only practical way to analyze this type of structural system. Results of a large parametric study using a finite element model are presented and a method to evaluate the ultimate strength of actual columns is introduced. Finally, a simple hand design method is derived. Key words: diaphragm, design, finite element, girt, column, stability, statistics.

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