Simulation of Ductile Crack Propagation in Pipeline Steels Using Cohesive Zone Modeling

2012 ◽  
Author(s):  
Andrew Dunbar ◽  
Xin Wang ◽  
Bill (W. R. ) Tyson ◽  
Su Xu
Keyword(s):  
Crack Propagation ◽  
Cohesive Zone ◽  
Infinite Plate ◽  
Cohesive Zone Modeling ◽  
Opening Angle ◽  
Small Scale ◽  
Propagation Characteristics ◽  
Ductile Crack ◽  
Drop Weight Tear Test ◽  
Zone Modeling

This paper presents recent results of numerical studies on stable crack extension of high toughness steels typical of those in modern gas pipelines using cohesive zone modeling. Two sets of materials are modeled. The first material set models a typical structural steel, with variable toughness described by four traction-separation (TS) laws. The second set models an X70 pipe steel, with three different TS laws. For each TS law, there are three defining parameters: the maximum cohesive strength, the final separation and the work of separation. The specimens analyzed include a crack in an infinite plate (small-scale yielding, SSY) and a standard drop-weight tear test (DWTT). Fracture propagation characteristics and values of crack-tip opening angle (CTOA) are obtained from these two types of specimens. It is shown that cohesive zone models can be successfully used to simulate ductile crack propagation and to numerically measure CTOAs. The ductile crack propagation characteristics and CTOAs obtained from SSY and DWTT specimens are compared for each set of steels. In addition, the CTOA results from numerical cohesive zone modeling of DWTT specimens of X70 steel are compared with those from laboratory tests.

Study of influence of various loading parameters on crack propagation by using Cohesive Zone Modeling (CZM) approach

2012 ◽  
Vol 2 (1) ◽  
Author(s):  
Riaz Ahmed ◽  
Md. Arifuzzaman
Keyword(s):  
Crack Propagation ◽  
Cohesive Zone ◽  
Cohesive Zone Modeling ◽  
Dynamic Crack Propagation ◽  
Dynamic Crack ◽  
Simulation Code ◽  
Static Mode ◽  
Mass Scaling ◽  
Zone Modeling ◽  
Nonlinear Crack

AbstractCohesive Zone Modeling (CZM) is one of the most promising tools to investigate nonlinear crack propagation in present time. In this study, CZM approach is used to investigate the influence of various type of loading parameters in nonlinear crack propagation. These parameters include loading velocity, mass scaling, maximum strength of cohesive element and displacement jump. For this investigation, we used DYNA3D as a dynamic crack simulation code. Simulation outcomes were compared with the experimental results, where an experimental observation for Arcan test Mode I case was made in MTS machine. Note that, the experiment was performed in quasi-static mode. As DYNA3D is used to simulate dynamic crack propagation, this comparison reflects the deviation of crack parameters for quasi-static and dynamic crack propagation. Finally we checked, whether DYNA3D can be used for quasi-static crack propagation or not.

Comparison of Through-Wall and Complex Crack Behaviors in Dissimilar Metal Weld Pipe Using Cohesive Zone Modeling

2013 ◽  
Author(s):  
Do-Jun Shim ◽  
David Rudland ◽  
Frederick Brust
Keyword(s):  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Cohesive Zone Modeling ◽  
Zone Model ◽  
Ductile Crack ◽  
Dissimilar Metal ◽  
Ductile Crack Growth ◽  
Zone Modeling ◽  
Dissimilar Metal Weld ◽  
Metal Weld

Cohesive zone modeling has been shown to be a convenient and effective method to simulate and analyze the ductile crack growth behavior in fracture specimens and structures. Recently, authors have applied the cohesive zone model to simulate the ductile fracture behavior of a through-wall cracked pipe test consisting of a single material. In this paper, cohesive zone modeling has been applied to simulate the ductile crack growth in dissimilar metal weld pipe tests that was recently conducted by the U.S. NRC. Two crack types, i.e. through-wall and complex cracks, were simulated in the work. This paper describes how the cohesive parameters were determined and discusses in detail about the finite element modeling of the cohesive zone model. Various fracture parameters were compared between the finite element analyses and the experiments to validate the model. The results of the cohesive zone models showed good agreement with the pipe test results. Furthermore, the results of the cohesive zone model demonstrate that the fracture toughness (J at crack initiation, Jinit.) of the complex cracked pipe can be significantly lower (factor of 0.41) than that of the through-wall cracked pipe.

Cohesive zone modeling of crack propagation influenced by martensitic phase transformation

2018 ◽  
Vol 712 ◽  
pp. 564-573 ◽  
Author(s):  
Sally Issa ◽  
Sara Eliasson ◽  
Alexander Lundberg ◽  
Mathias Wallin ◽  
Håkan Hallberg
Keyword(s):  
Phase Transformation ◽  
Crack Propagation ◽  
Cohesive Zone ◽  
Martensitic Phase ◽  
Martensitic Phase Transformation ◽  
Cohesive Zone Modeling ◽  
Zone Modeling

Cohesive Zone Modeling of Ductile Crack Growth in Circumferential Through-Wall-Cracked Pipe Tests

2011 ◽  
Author(s):  
Do-Jun Shim ◽  
Mohammed Uddin ◽  
Frederick Brust ◽  
Gery Wilkowski
Keyword(s):  
Crack Growth ◽  
Cohesive Zone ◽  
Bending Moment ◽  
Growth Behavior ◽  
Cohesive Zone Modeling ◽  
Crack Growth Behavior ◽  
Ductile Crack ◽  
Element Analysis ◽  
Ductile Crack Growth ◽  
Zone Modeling

Cohesive zone modeling has been shown to be a convenient and effective method to simulate and analyze the ductile crack growth behavior in fracture specimens and structures. However, the cohesive zone modeling has not been applied to simulate the ductile crack growth behavior of a circumferential through-wall cracked pipe. In this paper, cohesive zone modeling has been applied to simulate the ductile crack growth of a past through-wall-cracked pipe test that was conducted during Degraded Piping Program. The ABAQUS code was used for the three-dimensional finite element analysis. The bending moment at crack initiation, maximum bending moment, crack extension, and J-integral values were calculated from the finite element analysis. These results were compared with the experimental results. In addition, results obtained from an existing J-estimation scheme (LBB.ENG2) were provided for comparison. All results showed reasonable agreement. The results of the present study demonstrate that the cohesive zone modeling can be applied to simulate the ductile crack growth behavior of a through-wall cracked pipe.

Effect of Separation on Ductile Crack Propagation Behavior During Drop Weight Tear Test

2010 ◽  
Author(s):  
Takuya Hara ◽  
Taishi Fujishiro
Keyword(s):  
Crack Propagation ◽  
Ductile Fracture ◽  
Fracture Resistance ◽  
High Strength ◽  
Opening Angle ◽  
Ductile Crack ◽  
Line Pipe ◽  
Propagation Behavior ◽  
Drop Weight ◽  
Drop Weight Tear Test

The demand for natural gas using LNG and pipelines to supply the world gas markets is increasing. The use of high-strength line pipe provides a reduction in the cost of gas transmission pipelines by enabling high-pressure transmission of large volumes of gas. Under the large demand of high-strength line pipe, crack arrestability of running ductile fracture behavior is one of the most important properties. The CVN (Charpy V-notched) test and the DWTT (Drop Weight Tear Test) are major test methods to evaluate the crack arrestability of running ductile fractures. Separation, which is defined as a fracture parallel to the rolling plane, can be characteristic of the fracture in both full-scale burst tests and DWTTs. It is reported that separations deteriorate the crack arrestability of running ductile fracture, and also that small amounts of separation do not affect the running ductile fracture resistance. This paper describes the effect of separation on ductile propagation behavior. We utilized a high-speed camera to investigate the CTOA (Crack Tip Opening Angle) during the DWTT. We show that some separations deteriorate ductile crack propagation resistance and that some separations do not affect the running ductile fracture resistance.

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