Constraint effect on the ductile crack growth resistance of circumferentially cracked pipes

Xu, Jie; Zhang, Z.L.; O̸stby, Erling; Nyhus, Bård; Sun, Dong

doi:10.1016/j.engfracmech.2009.11.005

Cited by 49 publications

(37 citation statements)

References 22 publications

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“…3b, which is equivalent to the initially 90 degree intercept method. The same procedure using a fixed node to calculate CTOD has been utilized in [32][33][34][35][36]. The results will be used to propose approximate CTOD models that can be utilized to estimate the CTOD based on given loadings and temperatures.…”

Section: Resultsmentioning

confidence: 99%

Effect of low temperature tensile properties on crack driving force for Arctic applications

Dahl

Ren

Akselsen

et al. 2018

Theoretical and Applied Fracture Mechanics

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Many petroleum companies expand their activities further north towards the Arctic region, resulting in design temperatures down to −60• C, which is much lower than what is usual for most current petroleum installations. As properties of steels are temperature dependent, it is of great interest to evaluate the effects of low temperature on the crack driving force in steels. The present work investigates these effects numerically using finite element (FE) models of single-edge-notchedtension (SENT) specimens with crack depths 0.1 ≤ a/W ≤ 0.5. The effects of Lüders strain, yield strength and crack depth on the crack tip opening displacement (CTOD) and the relation between CTOD and crack mouth opening displacement (CMOD) are studied, and it is shown that an increase in yield strength and Lüders strain, as a result of Arctic temperature, intensifies the crack driving force. It is also shown that the crack depth has very little influence on the effect of Lüders strain on the CTOD. An approximate model that can be used to estimate the CTOD based on yield strength, Lüders strain and loading is proposed for gross stress levels σ G /σ y ≤ 0.5 and a crack depth a/W = 0.5. It is finally shown that the tensile properties have a more significant effect on the CTOD-CMOD relation than the crack depth for a SENT specimen.Mange petroleumsselskaper utvider sine aktiviteter nordover mot arktiske områder. Dette fører til designtemperaturer ned til −60• C, noe som er mye lavere enn det som er vanlig for de fleste nåvaerende petroleumsinstallasjoner. Ettersom egenskapene til stål er temperaturavhengige, er det av stor interesseå evaluere effektene av lav temperatur på den drivende kraften for sprekkvekst i stål. Dette arbeidet undersøker disse effektene numerisk ved hjelp av elementmetoden med modeller av single-edge-notched-tension (SENT)-bruddprøver med sprekkdybder 0.1 ≤ a/W ≤ 0.5. Effektene av Lüders tøyning, flytespenning og sprekkdybde på sprekkspissutvidelsen (CTOD) og sammenhengen mellom CTOD og sprekkmunningsutvidelsen (CMOD) er studert, og det er påvist at økt flytespenning og Lüders tøyning, som et resultat av arktisk temperatur, fører til økt drivende kraft for sprekkvekst. Det er også vist at sprekkdybden har liten innflytelse på effekten av Lüders tøyning på CTOD. Det er foreslått en omtrentelig modell som kan bli brukt tilå estimere CTOD basert på flytespenning, Lüders tøyning og last for bruttospenningsnivåer σ G /σ y ≤ 0.5 og sprekkdybde a/W = 0.5. Det er til slutt påvist at materialets strekkegenskaper har en større virkning på CTOD-CMOD-forholdet enn sprekkdybden for en SENT-prøve.i ii PrefaceThe work presented here is a Master's thesis written at Department of Engineering Design and Materials at Norwegian University of Science and Technology (NTNU). The thesis work is carried out as a part of SMACC (Studies of materials behavior for future cold climate applications), which is a research project with several industry partners, and with SINTEF and NTNU as research partners.The author wishes to thank SINTEF fo...

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Section: Resultsmentioning

confidence: 99%

Effect of low temperature tensile properties on crack driving force for Arctic applications

Dahl

Ren

Akselsen

et al. 2018

Theoretical and Applied Fracture Mechanics

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“…In literature, several (numerical) studies indicate that the constraint in SENT specimens is comparable to pipe specimens [14,50]. Additionally considering the previously published correspondence in constraint between pipe and wide plate specimens [17], it was therefore expected for wide plate and SENT specimens to experience a similar constraint.…”

Section: Discussionmentioning

confidence: 99%

Comparison of girth weld tearing resistance obtained from Curved Wide Plate and Single Edge Notch Tensile testing

Verstraete

Waele

Minnebruggen

et al. 2015

Engineering Fracture Mechanics

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a b s t r a c tCurved Wide Plate and Single Edge Notch Tensile tests are commonly considered for girth weld defect assessment. It is however not clear which test yields the least conservative estimate of the tearing resistance. A combined numerical-experimental procedure has been established to measure the crack extension, based on the direct current potential drop technique. This procedure appears accurate with respect to testing standards. In addition, the tearing resistance of the SENT specimens appears noticeably lower compared to wide plate specimens. This implies that SENT testing introduces conservatism in a girth weld defect assessment.

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“…Nyhus et al 23,24 pointed out that the geometry constraint of SENT specimen is closer to the pipe than SENB specimen. Xu et al 25 pointed out that the SENT specimens are the good representation of flawed pipes and can be used in the assessment of pipes. Larrosa and Ainsworth 26 found that it will reduce the excessive conservatism in fracture assessment when the fracture behavior of the test specimen with a similar constraint was used.…”

Section: 11mentioning

confidence: 99%

“…17,[23][24][25][26] Chiesa et al 17 found that the constraint state of the pipeline with a/W = 0.75 is correspond to the SENT specimen with a/W = 0.6. Nyhus et al 23,24 pointed out that the geometry constraint of SENT specimen is closer to the pipe than SENB specimen.…”

Section: 11mentioning

confidence: 99%

The matching of crack-tip constraint between standard and non-standard specimen

Yang

2018

Advances in Mechanical Engineering

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The matching of crack-tip constraint is a key issue for the developing of accurately structure integrity assessment method. For more and more non-standard specimens with different constraint states were used in the scientific research, it is especially significant to establish the matching of constraint between standard specimen and non-standard specimen. In this article, the single edge-notched bend specimens with various constraint states were selected, and the unified constraint parameter A p under different J-integrals was calculated by finite element analysis. And then, based on the J-A p curves, the matching of crack-tip constraint between different specimens was studied, and the matching specimens were given. In order to confirm the reliability of results, some experiments focused on the matching specimens were performed. The experiment results showed that the matching is valid. For the fracture properties of matching specimens are matching also, it is significant to the accurate assessment of structural integrity.

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Constraint effect on the ductile crack growth resistance of circumferentially cracked pipes

Cited by 49 publications

References 22 publications

Effect of low temperature tensile properties on crack driving force for Arctic applications

Effect of low temperature tensile properties on crack driving force for Arctic applications

Comparison of girth weld tearing resistance obtained from Curved Wide Plate and Single Edge Notch Tensile testing

The matching of crack-tip constraint between standard and non-standard specimen

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