A Comprehensive Parametric Finite Element Study on the Development of Strain Concentration in Concrete Coated Offshore Pipelines

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
N. Nourpanah ◽  
F. Taheri
Keyword(s):  
Plastic Deformation ◽  
Finite Element ◽  
Biaxial Stress ◽  
Combined Loading ◽  
Nonlinear Phenomena ◽  
Fe Model ◽  
Modeling Framework ◽  
Offshore Pipelines ◽  
Strain Concentration ◽  
Bending Load

The strain concentration at the field joint (FJ) of the commonly used concrete coated offshore pipelines is considered and discussed in this paper. The details of a 3D finite element (FE) modeling framework, developed using the commercial software ABAQUS, are presented. The numerical results are verified against the experimental results available in the literature. The FE model considered in this study captures several nonlinear phenomena associated with the problem, including the plastic deformation of the steel and anticorrosion layer (ACL) material, the cracking and crushing of the concrete, and also the large deformation effects. The developed FE framework is subsequently used to perform a parametric study to assess the effect of each influencing parameter on the strain concentration factor (SCF) developed within the FJ region. The influence of the geometric features of the coated pipe and the relevant mechanical properties of the materials as well as various combined loading scenarios are investigated. Results indicate that pipeline diameter, thickness, and coating thickness affect the SCF more than the strength of either concrete coating or ACL. Also, the postyield properties of the steel, especially the strain hardening capacity, may significantly influence the SCF. The combination of the internal pressure loading (causing a biaxial stress state) or tensile loading with the primary bending load is found to also increase the SCF significantly after steel yielding is initiated. Moreover, these combined loading scenarios cause different and more severe plastic deformation patterns in the FJ.

scholarly journals Finite element modelling of microstructural changes during equal channel angular drawing of pure aluminium

2021 ◽  
Author(s):  
Serafino Caruso ◽  
Stano Imbrogno
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Finite Element ◽  
Size Variation ◽  
Fe Model ◽  
Pure Aluminium ◽  
Continuous Dynamic Recrystallization ◽  
Research Activities ◽  
Hardness Change ◽  
Continuous Dynamic

AbstractGrain refinement by severe plastic deformation (SPD) techniques, as a mechanism to control microstructure (recrystallization, grain size changes,…) and mechanical properties (yield strength, ultimate tensile strength, strain, hardness variation…) of pure aluminium conductor wires, is a topic of great interest for both academic and industrial research activities. This paper presents an innovative finite element (FE) model able to describe the microstructural evolution and the continuous dynamic recrystallization (CDRX) that occur during equal channel angular drawing (ECAD) of commercial 1370 pure aluminium (99.7% Al). A user subroutine has been developed based on the continuum mechanical model and the Hall-Petch (H-P) equations to predict grain size variation and hardness change. The model is validated by comparison with the experimental results and a predictive analysis is conducted varying the channel die angles. The study provides an accurate prediction of both the thermo-mechanical and the microstructural phenomena that occur during the process characterized by large plastic deformation.

scholarly journals Design and analysis of concrete-filled tubular flange girders under combined loading

2021 ◽  
pp. 136943322110015
Author(s):  
Rana Al-Dujele ◽  
Katherine Ann Cashell
Keyword(s):  
Finite Element ◽  
Axial Force ◽  
Failure Modes ◽  
Numerical Study ◽  
Combined Loading ◽  
Torsional Stiffness ◽  
Fe Model ◽  
Combined Effects ◽  
Element Analysis ◽  
Hollow Section

This paper is concerned with the behaviour of concrete-filled tubular flange girders (CFTFGs) under the combination of bending and tensile axial force. CFTFG is a relatively new structural solution comprising a steel beam in which the compression flange plate is replaced with a concrete-filled hollow section to create an efficient and effective load-carrying solution. These members have very high torsional stiffness and lateral torsional buckling strength in comparison with conventional steel I-girders of similar depth, width and steel weight and are there-fore capable of carrying very heavy loads over long spans. Current design codes do not explicitly include guidance for the design of these members, which are asymmetric in nature under the combined effects of tension and bending. The current paper presents a numerical study into the behaviour of CFTFGs under the combined effects of positive bending and axial tension. The study includes different loading combinations and the associated failure modes are identified and discussed. To facilitate this study, a finite element (FE) model is developed using the ABAQUS software which is capable of capturing both the geometric and material nonlinearities of the behaviour. Based on the results of finite element analysis, the moment–axial force interaction relationship is presented and a simplified equation is proposed for the design of CFTFGs under combined bending and tensile axial force.

Finite Element Modelling of Static and Fatigue Failure of Composite Repair System in Offshore Pipe Risers

2014 ◽  
Vol 875-877 ◽  
pp. 1063-1068 ◽  
Author(s):  
Park Hinn Chan ◽  
Kim Yeow Tshai ◽  
Michael Johnson ◽  
Hui Leng Choo
Keyword(s):  
Finite Element ◽  
Internal Pressure ◽  
Low Cycle Fatigue ◽  
Failure Mechanisms ◽  
Repair System ◽  
Fe Model ◽  
Composite Surface ◽  
Composite Repair ◽  
Bending Load ◽  
Static Conditions

The static and cyclic failure mechanisms of offshore pipe riser repaired with a designated laminate orientation of carbon/epoxy (C/E) system were studied. The finite element (FE) model takes into account failure mechanisms of the composite sleeve inter-layer delamination, debonding at the steel riser-composite surface interface, and the maximum permissible strain of the repaired riser. Design conditions of the combined static loads (coupled internal pressure, longitudinal tensile and transverse bending) were determined through a limit state analysis [1,2]. The limiting static bending load that causes catastrophic failure under a coupled internal pressure and tensile loadings was determined through Virtual Crack Closure Technique (VCCT). The effects of cyclic bending, mimicking the typical scenarios experienced in pipe riser exposed to dynamic subsea environment, were evaluated and compared against the static conditions. The low cycle fatigue of the composite repair system (CRS) is simulated using a direct cyclic analysis within a general purpose FE program, where the onset and fatigue delamination/disbonding growth are characterized through the Paris Law.

Numerical Analysis of High Pressure Cold Bend Pipe to Investigate the Behaviour of Tension Side Fracture

2012 ◽  
Author(s):  
Celal Cakiroglu ◽  
Amin Komeili ◽  
Samer Adeeb ◽  
J. J. Roger Cheng ◽  
Millan Sen
Keyword(s):  
Finite Element ◽  
High Pressure ◽  
Internal Pressure ◽  
Experimental Studies ◽  
Element Model ◽  
Combined Loading ◽  
Element Analysis ◽  
Bend Pipe ◽  
Bending Load ◽  
Bending Loads

The cold bend pipelines may be affected by the geotechnical movements due to unstable slopes, soil type and seismic activities. An extensive experimental study was conducted by Sen et al. in 2006 to understand the buckling behaviour of cold bend pipes. In their experiments, it was noted that one high pressure X65 pipe specimen failed under axial and bending loads due to pipe body tensile side fracture which occurred after the development of a wrinkle. The behaviour of this cold bend pipe specimen under bending load has been investigated numerically to understand the conditions leading to pipe body tension side fracture following the compression side buckling. Bending load has been applied on a finite element model of the cold bend by increasing the curvature of it according to the experimental studies conducted by Sen [1]. The bending loads have been applied on the model with and without internal pressure. The distribution of the plastic strains and von Mises stresses as well as the load–displacement response of the pipe have been compared for both load cases. In this way the experimental results obtained by Sen [1] have been verified. The visualization of the finite element analysis results showed that pipe body failure at the tension side of the cold bend takes place under equal bending loads only in case of combined loading with internal pressure.

scholarly journals A Novel Method for High Temperature Fatigue Testing of Nickel Superalloy Turbine Blades with Additional NDT Diagnostics

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1392
Author(s):  
Dominik Kukla ◽  
Mateusz Kopec ◽  
Ryszard Sitek ◽  
Aleksander Olejnik ◽  
Stanisław Kachel ◽  
...  
Keyword(s):  
Finite Element ◽  
High Temperature ◽  
Fatigue Testing ◽  
Turbine Blades ◽  
Nickel Superalloy ◽  
Fe Model ◽  
Destructive Testing ◽  
High Temperature Fatigue ◽  
Bending Load ◽  
Novel Method

In this paper, a novel method for high temperature fatigue strength assessment of nickel superalloy turbine blades after operation at different times (303 and 473 h) was presented. The studies included destructive testing (fatigue testing at temperature 950 °C under cyclic bending load), non-destructive testing (Fluorescent Penetrant Inspection and Eddy Current method), and finite element modelling. High temperature fatigue tests were performed within load range from 5200 to 6600 N using a special self-designed blade grip attached to the conventional testing machine. The experimental results were compared with the finite element model generated from the ANSYS software. It was found that failure of turbine blades occurred in the area with the highest stress concertation, which was accurately predicted by the finite element (FE) model.

Numerical Investigation on the Fatigue Behavior of the Multi-Planar Tubular DX-Joint under Combined Loads

2014 ◽  
Vol 1006-1007 ◽  
pp. 11-17
Author(s):  
Gui Jie Liu ◽  
Yu Zhang ◽  
Basit Farooq
Keyword(s):  
Finite Element ◽  
Hot Spot ◽  
Fatigue Behavior ◽  
Combined Loading ◽  
Element Analysis ◽  
Hot Spot Stress ◽  
Bending Load ◽  
Weld Toe ◽  
Plane Bending ◽  
Stress Concentration Factors

The stress concentration factors (SCFs) is used in the fatigue design for calculating hot-spot stress. However a major issue can be noted that the majority of research results are focused on the SCF distribution of uni-planar tubular joints subjected to the single basic load. By aiming to find the solution of this problem, the distribution of SCFs at the weld toe of a multi-planar tubular DX-joint which is subjected to the two set of the balanced combined loading components at the end of in-plane braces is studied by the finite element method. Thus it is concluded that for the axial plus in-plane bending load case, hot-spot stress location varies between saddle and crown position; while the location is invariably at the saddle position under combined axial plus out-of-plane bending loads. At last the API RP2A equation for predicting hot-spot stress is used for comparison with the finite element analysis results. Meanwhile the distribution of SCFs is also provided, that information indicates the-hot spot location along the weld toe affects the crack initiation.

scholarly journals Finite Element Modeling of Microstructural Changes During Equal Channel Angular Drawing of Pure Aluminium

2021 ◽  
Author(s):  
SERAFINO CARUSO ◽  
Stano Imbrogno
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Finite Element ◽  
Size Variation ◽  
Fe Model ◽  
Pure Aluminium ◽  
Continuous Dynamic Recrystallization ◽  
Research Activities ◽  
Hardness Change ◽  
Continuous Dynamic

Abstract Grain refinement by severe plastic deformation (SPD) techniques, as a mechanism to control microstructure (recrystallization, grain size changes,…) and mechanical properties (yield strength, ultimate tensile strength, strain, hardness variation…) of pure aluminium conductor wires, is a topic of great interest for both academic and industrial research activities. This paper presents an innovative finite element (FE) model able to describe the microstructural evolution and the continuous dynamic recrystallization (CDRX) that occur during equal channel angular drawing (ECAD) of commercial 1370 pure aluminium (99.7% Al). A user subroutine has been developed based on the continuum mechanical model and the Hall-Petch (H-P) equations to predict grain size variation and hardness change. The model is validated by comparison with the experimental results and a predictive analysis is conducted varying the channel die angles. The study provides an accurate prediction of both the thermo-mechanical and the microstructural phenomena that occur during the process characterised by large plastic deformation.

Failure Analysis of Plastic Pipe Reinforced by Cross Helically Wound Steel Wire Subjected to Internal Pressure and Bending Load

2016 ◽  
Author(s):  
Jie Zhang ◽  
Jianfeng Shi ◽  
Jinyang Zheng
Keyword(s):  
Internal Pressure ◽  
Steel Wire ◽  
Operating Conditions ◽  
Combined Loading ◽  
Design Parameters ◽  
Fe Model ◽  
Plastic Pipe ◽  
Bending Load ◽  
Calculation Results ◽  
Bending Loads

Plastic pipe reinforced by cross helically wound steel wire (PSP) has been widely used in the transportation of petroleum, natural gas, municipal water, etc. In some serious occasions, PSP suffers from bending load caused by operating conditions such as ocean wave, pipeline laying and geological sedimentation, besides internal pressure. Thus, to understand the strength of PSP under the complex loads is crucial for ensuring safety. In this study, a finite element (FE) model of PSP was proposed by taking both internal pressure and bending load into consideration. By gradually increasing the bending load, the strength of PSP was obtained by taking the break of steel wires as the failure criterion. Then, combined loading tests were conducted to verify the proposed model. The results show that the applied bending loads bear a nonlinear relationship with the increasing deformation. By comparing experimental results and FE model calculation results, good agreement was obtained. Based on the verified FE model, the limit bending load and the effects of design parameters and internal pressure on the strength of PSP were discussed.

Elasto-Plastic Deformation of Colony Boundaries in Pearlite Microstructure by Finite Element Analyses

2015 ◽  
Vol 786 ◽  
pp. 33-36
Author(s):  
L. Roslan ◽  
Tetsuya Ohashi ◽  
Yohei Yasuda ◽  
Chikara Suruga
Keyword(s):  
Plastic Deformation ◽  
Finite Element ◽  
Plastic Strain ◽  
Finite Element Analyses ◽  
Strain Concentration ◽  
Colony Boundary

Elasto-plastic tensile deformations in multi-colony structures are studied by finite element analyses to investigate how the deformation in multi-colony structures influence the strain concentration around colony boundary. The results obtained from plastic strain distributions show that plastic strain concentrates around colony boundary when there is a large difference of deformation between adjacent colonies and around the point where boundaries of differently aligned colonies meet.

Finite Element Analysis on Plastic Deformation Behaviors of Ti-3Al-2.5V Tubes under Axial Compression

2015 ◽  
Vol 639 ◽  
pp. 551-558 ◽  
Author(s):  
Tao Huang ◽  
Mei Zhan ◽  
Jin Qiang Tan ◽  
Jing Guo ◽  
He Yang
Keyword(s):  
Plastic Deformation ◽  
Finite Element ◽  
Flow Stress ◽  
Friction Coefficient ◽  
Axial Compression ◽  
High Performance ◽  
Fe Model ◽  
Deformation Degree ◽  
Element Analysis ◽  
Deformation Behaviors

With the requirement of aviation and aerospace fields for high-strength Ti-3Al-2.5V titanium alloy bent tubes with high-performance, it is great significance to research the plastic deformation of Ti-3Al-2.5V tubes under compression to obtain desired flow stress curves. A finite element (FE) model of axial compression of Ti-3Al-2.5V tubes was established in this study. Using this model, deformation behaviors of Φ12 mm × t0.9 mm Ti-3Al-2.5V tubes with different ratios of thickness to height (t/h) compressed under different frictions were analyzed. It is shown that the non-uniform deformation degree of the tubes increases with the decrease of t/h and the increase of friction coefficient. This means that a large t/h value and small friction can help to attain a uniaxial compression condition to obtain desired flow stress curves. Such compression conditions for the Φ12 mm × t0.9 mm Ti-3Al-2.5V tube is that, t/h is not less than 0.6 and the friction coefficient is not greater than 0.05

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