Cell Model Predictions of Ductile Fracture in Damaged Pipelines

“…CTOD (Crack Tip Opening Displacement) test is an effective method for evaluating the fracture properties of materials and welded joints [8]. In the CTOD test, the test material or welded joint was made into a sample with prefabricated crack, then plus an external force to measure the CTOD value(crack tip opening displacement), and the CTOD value reflected the strength of the material or welded joint toughness.…”

Section: Pipeline Steel Unilateral Notched Tensile Testmentioning

confidence: 99%

Application of GTN Model in Tensile Fracture of Pipeline Steel

Lian

Zhang

et al. 2018

KEM

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In this paper, the macroscopic mechanical behavior of tensile fracture of X70 pipeline steel is combined with the evolution of mesoscopic pores. The ABAQUS finite element software was used to analyze the variation of pore volume fraction in the tensile failure process of unilateral notched specimens with Gurson-Tvergaard-Needleman (GTN) mesoscopic damage model. Combined with the unilateral notched tensile test and the numerical simulation results, the damage mechanics model of pipeline steel based on void volume fraction is established. The results show that the volume fraction of pores is a mesomechanical parameter based on the damage of the micro-holes in the metallic plastic material, which is a bridge between the mesoscopic damage characteristics and the macro-mechanical parameters. Establishing the damage mechanics model of high strength pipeline steel with hole volume fraction as damage variable can truly reflect the macro-meso-mechanics behavior of X70 pipeline steel during unilateral notching.

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“…The integrity assessment of such cracked pipe structures often utilises fracture mechanics-based engineering critical assessment procedure outlined in engineering standards. [12][13][14] Such constraint difference will impose a marked effect on the measured J-Δa curve. Standard material testing methods 5-7 employ specimens with deep through-thickness crack under high crack-front constraints to measure the material J-Δa curve.…”

Section: Introductionmentioning

confidence: 99%

“…11 The geometry and plasticity-induced constraint loss can lead to significant differences in the near tip stress triaxiality between a surface crack front and a deeply cracked fracture specimen. [12][13][14] Such constraint difference will impose a marked effect on the measured J-Δa curve. [15][16][17][18] Capelle et al 19 have studied the role of constraint on the shift of the ductile-to-brittle transition temperature.…”

Section: Introductionmentioning

confidence: 99%

An η‐compliance method to estimate the J‐Δa curve for pipes with a circumferential surface crack

Parool

Qian

Koh

2017

Fatigue Fract Eng Mat Struct

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This paper presents an η‐compliance method to measure the J‐Δa curve for pipes with a circumferential surface crack, using the experimentally recorded load versus the crack mouth opening displacement (CMOD) relationship. This study modifies the η method commonly practiced for standard through‐thickness fracture specimens to measure the energy release rate, J, from P‐CMOD curve for pipes with a circumferential surface crack. The non‐dimensional parameter η for the surface‐cracked pipes derives from elastic–plastic finite element analyses. The relationship between the crack size and the CMOD‐based compliance, coupled with crack profiles interpolated linearly between the fatigue crack profile and the crack profile after ductile tearing, allows determining the crack depth corresponding to the measured CMOD compliance. The measured location‐specific J‐Δa curves indicate consistency with the fracture resistance curve measured from through‐thickness fracture specimens at small crack extension levels. The difference between the fracture resistances becomes significantly larger as the crack extends beyond 0.5 mm.

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Cell Model Predictions of Ductile Fracture in Damaged Pipelines

Cited by 4 publications

References 0 publications

Evaluation of CTOD resistance curves in clamped SE(T) specimens with weld centerline cracks

Evaluation of CTOD resistance curves in clamped SE(T) specimens with weld centerline cracks

Application of GTN Model in Tensile Fracture of Pipeline Steel

An η‐compliance method to estimate the J‐Δa curve for pipes with a circumferential surface crack

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