scholarly journals Analysis of Crack Behaviour in Pipeline System Using FAD Diagram Based on Numerical Simulation under XFEM

2020 ◽  
Vol 10 (17) ◽  
pp. 6129
Author(s):  
S. Montassir ◽  
K. Yakoubi ◽  
H. Moustabchir ◽  
A. Elkhalfi ◽  
Dipen Kumar Rajak ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Structural Integrity ◽  
Pipeline System ◽  
Extended Finite Element ◽  
Steel Pipes ◽  
Long Time ◽  
Numerical Tools ◽  
Cracked Structures ◽  
Element Method

For a long time, cracked structures have triggered various researchers to develop a structural integrity approach and design models to address the fracture problems. In the present study, a pipeline with an axial semi-elliptical surface defect was examined in detail. Recent works have highlighted the use of the classical finite element method (CFEM) as numerical tools to solve the fracture mechanics; however, this approach comes with a few difficulties in the modelling aspects. To overcome this issue, we proposed the use of the extended finite element method (XFEM), which was implemented in the commercial version of Abaqus software. Moreover, we have used the results based on this technique in the volumetric method to estimate the stress intensity factors (SIFs). Then, this parameter was employed to build the failure assessment diagram (FAD). The FAD curve was used in the current investigation because it is one of the conventional methods for the evaluation of flaws in steel pipes. The XFEM simulations enable us to draw an FAD curve that can be used as a practical reference for defect evaluation in pipeline systems in the industrial world.

scholarly journals An Extended Finite Element Method (XFEM) Study on the Elastic T-Stress Evaluations for a Notch in a Pipe Steel Exposed to Internal Pressure

Mathematics ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 507
Author(s):  
K. Yakoubi ◽  
S. Montassir ◽  
Hassane Moustabchir ◽  
A. Elkhalfi ◽  
Catalin Iulian Pruncu ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Internal Pressure ◽  
Extended Finite Element Method ◽  
Research Study ◽  
Extended Finite Element ◽  
T Stress ◽  
Cracked Structures ◽  
Element Method

The work investigates the importance of the K-T approach in the modelling of pressure cracked structures. T-stress is the constant in the second term of the Williams expression; it is often negligible, but recent literature has shown that there are cases where T-stress plays the role of opening the crack, also T-stress improves elastic modeling at the point of crack. In this research study, the most important effects of the T-stress are collected and analyzed. A numerical analysis was carried out by the extended finite element method (X-FEM) to analyze T-stress in an arc with external notch under internal pressure. The different stress method (SDM) is employed to calculate T-stress. Moreover, the influence of the geometry of the notch on the biaxiality is also examined. The biaxiality gave us a view on the initiation of the crack. The results are extended with a comparison to previous literature to validate the promising investigations.

A Benchmark Study on Applying Extended Finite Element Method to the Structural Integrity Assessment of Subsea Pipelines at HPHT Service Conditions

2018 ◽  
Author(s):  
Ankang Cheng ◽  
Nian-Zhong Chen
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Extended Finite Element Method ◽  
Structural Integrity ◽  
Future Application ◽  
Extended Finite Element ◽  
Integrity Assessment ◽  
Service Conditions ◽  
Subsea Pipelines ◽  
Element Method

Structural integrity assessment for subsea pipelines at high pressure high temperature (HPHT) service conditions is one of the most challenging research topics in offshore engineering sector. This paper is to introduce an extended finite element method (XFEM) based numerical approach for structural integrity assessment for subsea pipelines serving HPHT reservoir. A 3D model of a quarter of subsea pipe section with an external semi-elliptical surface crack located at the weld toe is built and the crack propagation under fatigue load is simulated using the XFEM. Results are presented and investigated from both geometric and mechanical aspects. Theoretical basis and limitation for this technique are discussed. Suggestions are given for future application of the XFEM technique based on fracture mechanics when assessing the structural integrity of subsea pipelines at HPHT service conditions.

PWSCC Assessment by Using Extended Finite Element Method

2015 ◽  
Vol 06 (03) ◽  
pp. 1550007
Author(s):  
Sung-Jun Lee ◽  
Sang-Hwan Lee ◽  
Yoon-Suk Chang
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Extended Finite Element Method ◽  
Structural Integrity ◽  
Displacement Function ◽  
Driving Mechanism ◽  
Extended Finite Element ◽  
Control Rod ◽  
Head Penetration ◽  
Element Method

The head penetration nozzle of control rod driving mechanism (CRDM) is known to be susceptible to primary water stress corrosion cracking (PWSCC) due to the welding-induced residual stress. Especially, the J-groove dissimilar metal weld regions have received many attentions in the previous studies. However, even though several advanced techniques such as weight function and finite element alternating methods have been introduced to predict the occurrence of PWSCC, there are still difficulties in respect of applicability and efficiency. In this study, the extended finite element method (XFEM), which allows convenient crack element modeling by enriching degree of freedom (DOF) with special displacement function, was employed to evaluate structural integrity of the CRDM head penetration nozzle. The resulting stress intensity factors of surface cracks were verified for the reliability of proposed method through the comparison with those suggested in the American Society of Mechanical Engineering (ASME) code. The detailed results from the FE analyses are fully discussed in the manuscript.

Application of the Extended Finite Element Method (XFEM) to Simulate Crack Propagation in Pressurized Steel Pipes

2017 ◽  
Author(s):  
Meng Lin ◽  
Sylvester Agbo ◽  
J. J. Roger Cheng ◽  
Nader Yoosef-Ghodsi ◽  
Samer Adeeb
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Crack Propagation ◽  
Extended Finite Element Method ◽  
Crack Depth ◽  
External Loading ◽  
Extended Finite Element ◽  
The Maximum Principle ◽  
Steel Pipes ◽  
Element Method

The extended finite element method (XFEM) has recently become a very effective method to investigate the propagation of cracks in various structures under complex loading conditions. However, its use in the pipeline industry has been limited. This paper aims to apply XFEM to model our previous experimental results on NPS 12 grade of X52 steel pipes in which circumferential cracks with different sizes were pre-machined near the middle length and then eccentric tension was applied to the pressurized pipe specimens. Our previous experiments showed that the propagation of a surface crack was affected by the original crack configuration, the internal pressure level, and the external loading applied. The crack depth showed greater influence than the crack length on the burst load and the tensile strain capacity of the pipe. In this paper, the fracture criterion for modelling crack propagation using XFEM was defined by two damage parameters, the maximum principle stress and the fracture energy. The values of the damage parameters were varied until excellent agreement was obtained between one of our previous experiments and its numerical model. Then, this set of damage parameters was used to model another one of the experiments for verification. This paper describes our methodology for validation of XFEM and the adequate values of the damage parameters required to model crack propagation in X52 pipes.

scholarly journals A mesh-independent framework for crack tracking in elastodamaging materials through the regularized extended finite element method

2021 ◽  
Author(s):  
Elena Benvenuti ◽  
Nicola Orlando
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Damage Evolution ◽  
Extended Finite Element Method ◽  
Mesh Adaptivity ◽  
Extended Finite Element ◽  
Evolution Law ◽  
Crack Paths ◽  
Original Crack ◽  
Element Method

AbstractWe propose a formulation for tracking general crack paths in elastodamaging materials without mesh adaptivity and broadening of the damage band. The idea is to treat in a unified way both the damaging process and the development of displacement discontinuities by means of the regularized finite element method. With respect to previous authors’ contributions, a novel damage evolution law and an original crack tracking framework are proposed. We face the issue of mesh objectivity through several two-dimensional tests, obtaining smooth crack paths and reliable structural results.

Sign in / Sign up

Export Citation Format

Share Document