Defect Assessments of Pipelines Using Constraint Designed SE(T) Specimens

2004 ◽  
Author(s):  
Sebastian Cravero ◽  
Claudio Ruggieri
Keyword(s):  
Plane Strain ◽  
Driving Force ◽  
Fracture Behavior ◽  
Strong Support ◽  
Crack Tip ◽  
Primary Objective ◽  
Potential Applicability ◽  
Pressurized Pipelines ◽  
Crack Tip Constraint ◽  
Fracture Specimens

This work presents a numerical investigation of crack-tip constraint for SE(T) specimens and axially surface cracked pipes using plane-strain, nonlinear computations. The primary objective is to gain some understanding of the potential applicability of constraint designed fracture specimens in defect assessments of pressurized pipelines and cylindrical vessels. The present study builds upon the J-Q approach using plane-strain solutions to characterize effects of constraint on cleavage fracture behavior for fracture specimens and cracked pipes. Under increased loading, each cracked configuration follows a characteristic J-Q trajectory which enables comparison of the corresponding crack-tip driving force. The results provide a strong support to use constraint-designed SE(T) specimens in fracture assessments of pressurized pipes and cylindrical vessels.

Integrity Assessments of Pipelines Using SE(T) Specimens

2004 ◽  
Author(s):  
Sebastian Cravero ◽  
Claudio Ruggieri
Keyword(s):  
Plane Strain ◽  
Fracture Behavior ◽  
Strong Support ◽  
Crack Tip ◽  
Primary Objective ◽  
Potential Applicability ◽  
Pressurized Pipelines ◽  
Crack Tip Constraint ◽  
Integrity Assessments ◽  
Fracture Specimens

This work presents a numerical investigation of crack-tip constraint for SE(T) specimens and axially surface cracked pipes using plane-strain, nonlinear computations. The primary objective is to gain some understanding of the potential applicability of constraint designed fracture specimens in defect assessments of pressurized pipelines and cylindrical vessels. The present study builds upon the J-Q approach using plane-strain solutions to characterize effects of constraint on cleavage fracture behavior for fracture specimens and cracked pipes. Under increased loading. each cracked configuration follows a characteristic J-Q trajectory which enables comparison of the corresponding crack-tip driving force. The results provide a strong support to use constraint-designed SE(T) specimens in fracture assessments of pressurized pipes and cylindrical vessels.

Numerical Correlation of Fracture Behavior in Axially Cracked Pipelines Using Constraint Designed Fracture Specimens

2005 ◽  
Author(s):  
Sebastian Cravero ◽  
Claudio Ruggieri
Keyword(s):  
Plane Strain ◽  
Cleavage Fracture ◽  
Driving Force ◽  
Fracture Behavior ◽  
Crack Tip ◽  
Primary Objective ◽  
Potential Applicability ◽  
Pressurized Pipelines ◽  
Further Development ◽  
Fracture Specimens

This work explores applications of constraint designed fracture specimens in defect assessments of pressurized pipelines and cylindrical vessels. The primary objective is to gain some understanding of the potential applicability of SE(T) specimens in defect assessments of pressurized pipelines and cylindrical vessels. The present study builds upon the J-Q approach using plane-strain solutions to characterize effects of constraint on cleavage fracture behavior for fracture specimens and cracked pipes. Under increased loading, each cracked configuration follows a characteristic J-Q trajectory which enables comparison of the corresponding crack-tip driving force. A key outcome of this investigation is that toughness data measured using SE(T) specimens appear more applicable for cleavage fracture predictions of pressurized pipelines and cylindrical vessels than standard, deep notch fracture specimens under bend loading. The results encourage further development of constraint-designed SE(T) specimens for fracture assessments of pressurized pipes and cylindrical vessels.

Constraint Effects on Ductile Crack Growth in SE(T) and SE(B) Specimens With Implications for Assessments of Tearing Resistance

2012 ◽  
Author(s):  
Claudio Ruggieri
Keyword(s):  
Crack Growth ◽  
Crack Tip ◽  
Stable Crack Growth ◽  
Primary Objective ◽  
Crack Growth Resistance ◽  
Tensile Fracture ◽  
Width Ratio ◽  
Cell Parameters ◽  
Crack Tip Constraint ◽  
Fracture Specimens

This work addresses a two-parameter description of crack-tip fields in bend and tensile fracture specimens incorporating the evolution of near-tip stresses following stable crack growth with increased values of the J-integral. The primary objective is to examine the potential coupled effects of geometry and ductile tearing on crack-tip constraint as characterized by the J-Q theory which enables more accurate correlations of crack growth resistance behavior in conventional fracture specimens. Plane-strain, finite element computations including stationary and growth analyses are described for SE(B) and clamped SE(T) specimens having different notch depth to specimen width ratio in the range 0.2 ≤ a/W≤0.5. A computational cell methodology to model Mode I crack extension in ductile materials is utilized to describe the evolution of J with Δa for the fracture specimens. Laboratory testing of an API 5L X70 steel using deeply cracked C(T) specimens is used to measure the crack growth resistance curve for the material and to calibrate the cell parameters. The present results provide additional understanding of the effects of constraint on crack growth which contributes to further evaluation of crack growth resistance properties of pipeline steels using SE (T) and SE(B) specimens.

Correlation of Fracture Behavior in Circumferentially Cracked Pipes Under Combined Load Conditions Using SENT Specimens: Effects on J-R Resistance Curves

2008 ◽  
Author(s):  
Sebastian Cravero ◽  
Richard E. Bravo ◽  
Hugo A. Ernst
Keyword(s):  
Q Methodology ◽  
Fracture Behavior ◽  
Biaxial Loading ◽  
Crack Tip ◽  
Combined Loading ◽  
Combined Loads ◽  
Loading Effects ◽  
Resistance Curves ◽  
Crack Tip Constraint ◽  
Fracture Specimens

Single edge cracked under tension (SENT) specimens appear as an alternative to conventional fracture specimens to characterize fracture toughness of circumferentially cracked pipes. The similarities of stress and strains fields between SENT specimens and cracked pipes are now well known. However, these similarities are not so well established for the case of circumferentially cracked pipes under combined loading conditions (i.e. internal pressure plus bending). This work presents a numerical analysis of crack-tip constraint of circumferentially surface cracked pipes and SENT specimens using full 3D nonlinear computations. The objective is to examine combined loading effects on the correlation of fracture behavior for the analyzed crack configurations. The constraint study using the J-Q methodology and the h parameter gives information about the fracture specimen that best represents the crack-tip conditions on circumferentially flawed pipes under combined loads. Additionally, simulations of ductile tearing in a surface cracked plate under biaxial loading using the computational cell methodology demonstrate the negligible effect of biaxial loadings on resistance curves.

Evaluation of Crack Tip Constraint in Pipes Subjected to Combined Loading

2008 ◽  
Author(s):  
Sebastian Cravero ◽  
Richard E. Bravo ◽  
Hugo A. Ernst
Keyword(s):  
Internal Pressure ◽  
Q Methodology ◽  
Fracture Behavior ◽  
Crack Tip ◽  
Combined Loading ◽  
Single Edge ◽  
Combined Loads ◽  
Loading Effects ◽  
Crack Tip Constraint ◽  
Fracture Specimens

Single edge cracked under tension (SENT) specimens appear as an alternative to conventional fracture specimens to characterize fracture toughness of circumferentially cracked pipes. The similarities of stress and strains fields between SENT specimens and cracked pipes are now well known. However, these similarities are not so well established for the case of circumferentially cracked pipes under combined loading conditions (i.e. internal pressure plus tension, internal pressure plus bending, etc.). This work presents a numerical analysis of crack-tip constraint of circumferentially surface cracked pipes and SENT specimens using full 3D nonlinear computations. The objective is to examine combined loading effects on the correlation of fracture behavior for the analyzed crack configurations. The constraint study using the J-Q methodology and the h parameter gives information about the fracture specimen that best represents the crack-tip conditions on circumferentially flawed pipes under combined loads.

Correlation of Fracture Behavior in Circumferentially Cracked Pipes and Fracture Specimens Including Ductile Tearing

2014 ◽  
Author(s):  
Diego F. B. Sarzosa ◽  
Claudio Ruggieri
Keyword(s):  
Finite Element ◽  
Crack Growth ◽  
Fracture Behavior ◽  
Crack Depth ◽  
Crack Tip ◽  
Primary Objective ◽  
Crack Growth Resistance ◽  
Tensile Fracture ◽  
Ductile Tearing ◽  
Fracture Specimens

This work addresses a two-parameter description of crack-tip fields in bend and tensile fracture specimens incorporating the evolution of near-tip stresses following stable crack growth with increased values of the crack driving force as characterized by the J-integral. The primary objective of this study is to assess the coupled effects of geometry and ductile tearing on crack-tip constraint, as characterized by the J – Q theory, to correlate fracture behavior in circumferentially cracked reeled pipes and common fracture specimens. 3-D finite element computations including stationary and growth analyses were conducted for 3P SE(B) and clamped SE(T) specimens having different notch depth (a) to specimen width (W) ratio. Additional 3-D finite element analyses were also performed for circumferentially cracked pipes with a surface flaw having different crack depth (a) over pipe wall thickness (t) ratios. A cell methodology to model Mode I crack extension in ductile materials was utilized to describe the evolution of J with the evolving near-tip opening stresses. Laboratory testing of an API 5L X70 steel using deeply cracked C(T) specimens was used to measure the crack growth resistance curve for the material and to calibrate the cell parameter defined by the initial void fraction, f0. The present results provide further understanding of crack growth resistance measurements in pipeline steels using SE(T) and SE(B) specimens while eliminating some restrictions against the use of shallow cracked bend specimens in defect assessment procedures.

Characterization of creep crack-tip constraint levels for pressurized pipelines with axial surface cracks

2017 ◽  
Vol 114 ◽  
pp. 98-109 ◽  
Author(s):  
Lianyong Xu ◽  
Xingfu Zhang ◽  
Lei Zhao ◽  
Yongdian Han ◽  
Hongyang Jing
Keyword(s):  
Crack Tip ◽  
Surface Cracks ◽  
Creep Crack ◽  
Pressurized Pipelines ◽  
Crack Tip Constraint ◽  
Axial Surface

Numerical Analyses of Ductile Fracture Behavior in 2D Plane Strain and Axisymmetric Models Using the Complete Gurson Model

2009 ◽  
Author(s):  
Jie Xu ◽  
Zhiliang Zhang ◽  
Erling O̸stby ◽  
Ba˚rd Nyhus ◽  
Dongbai Sun
Keyword(s):  
Crack Growth ◽  
Fracture Behavior ◽  
Large Scale ◽  
Crack Tip ◽  
Ductile Crack ◽  
Geometry Dependence ◽  
Ductile Crack Growth ◽  
Scale Yielding ◽  
Resistance Curves ◽  
Crack Tip Constraint

Ductile crack growth plays an important role in the analyses of fracture behavior of structures. A strong geometry dependence of ductile crack growth resistance emerges under large scale yielding conditions. This geometry dependence is associated with different levels of crack tip constraint. However, an independent relationship between the fracture resistance and crack tip constraint has also been observed in experimental studies for selected specimen geometries. To verify these results, crack growth resistance curves for plane strain, mode I crack growth under large scale yielding have been computed using the complete Gurson model. Single edge notched bending (SENB) and tension (SENT) specimens with three different crack geometries have been selected for the numerical analyses. Specimen size effect on ductile crack growth behavior has also been studied. In addition, the SENT specimen appears as an alternative to conventional fracture specimens to characterize fracture toughness of circumferentially cracked pipes due to its similar geometry constraint ahead of the crack tip with that of cracks in pipes. 2D axisymmetric models have been carried out to investigate the effect of biaxial loading (axial tension combined with internal pressure) on the resistance curves for pipes with long internal circumferential cracks under large scale yielding conditions.

Further Insights on J-R Curve Behavior in Pipeline Steels Using Low Constraint Fracture Specimens

2013 ◽  
Author(s):  
Diego F. B. Sarzosa ◽  
Claudio Ruggieri
Keyword(s):  
Crack Growth ◽  
Crack Tip ◽  
Stable Crack Growth ◽  
Primary Objective ◽  
Crack Growth Resistance ◽  
Tensile Fracture ◽  
Width Ratio ◽  
Pipeline Steels ◽  
Cell Parameters ◽  
Fracture Specimens

This work addresses a two-parameter description of crack-tip fields in bend and tensile fracture specimens incorporating the evolution of near-tip stresses following stable crack growth with increased values of the J-integral. The primary objective is to examine the potential coupled effects of geometry and ductile tearing on crack-tip constraint as characterized by the J-Q theory which enables more accurate correlations of crack growth resistance behavior in conventional fracture specimens. Plane-strain, finite element computations including stationary and growth analyses are described for SE(B) and clamped SE(T) specimens having different notch depth to specimen width ratio in the range 0.2≤ a/W≤0.5. A computational cell methodology to model Mode I crack extension in ductile materials is utilized to describe the evolution of J with Δa for the fracture specimens. Laboratory testing of an API 5L X70 steel using deeply cracked C(T) specimens is used to measure the crack growth resistance curve for the material and to calibrate the cell parameters. The present results provide additional understanding of the effects of constraint on crack growth which contributes to further evaluation of crack growth resistance properties of pipeline steels using SE (T) and SE(B) specimens.

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