Residual stress induced crack tip constraint

Liu, J.; Zhang, Z.L.; Nyhus, Bård

doi:10.1016/j.engfracmech.2008.03.010

Cited by 35 publications

(28 citation statements)

References 27 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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“…Liu et al (2008) studied a one-dimensional residual stress field perpendicular to the crack plane in single edge notched tension and bending specimens. They showed that residual stress can enhance the crack-tip constraint and defined a parameter R to characterize the effect.…”

Section: ¼0mentioning

confidence: 99%

“…Understanding how residual stresses along with the presence of known or worst case defects affect the limit life without unnecessary conservation is crucial for the industry. Most recently, the residual stress-induced crack-tip constraint has been investigated by Liu et al (2008) by using single edge notched bending specimens and a one-dimensional residual stress field. A new parameter R was proposed.…”

Section: Introductionmentioning

confidence: 99%

Effect of residual stresses on the crack-tip constraint in a modified boundary layer model

Ren

Zhang

Nyhus

2009

International Journal of Solids and Structures

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a b s t r a c tResidual stresses play a crucial role in structural integrity assessment. In this study, a large cracked cylinder with a weld in the center is applied to investigate the effect of residual stresses on the cracktip constraint. A modified boundary layer model with a remote displacement-controlled elastic K-field and T-stress under small scale yielding has been used to simulate the problem. A two-dimensional tensile residual stress field due to the weld is introduced into the model by the so-called eigenstrain method. It has been shown that the residual stresses can significantly elevate the crack-tip constraint and thus increase the probability for cleavage fracture. The constraint parameter R introduced by the authors can be used to rank the crack-tip constraint induced by the bi-axial residual stresses. The R value decreases with the increase in the applied J-integral. The residual stress-induced constraint is also coupled with the T-stress. The R value becomes smaller with larger T-stress.

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“…It is now well understood that crack tip constraints due to specimen geometries, loading modes and yield strength mismatches as well as residual stresses [1][2][3][4][5][6][7][8][9][10] affect the stress distribution around a crack and consequently preclude the use of a single parameter characterization of the crack tip stress field. A second parameter based on the elastic T-stress has been proposed by Betegon and Hancock [11] to describe the crack tip stress field.…”

Section: Introductionmentioning

confidence: 99%

Effects of crack depth and specimen size on ductile crack growth of SENT and SENB specimens for fracture mechanics evaluation of pipeline steels

Zhang

O̸stby

et al. 2009

International Journal of Pressure Vessels and Piping

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Residual stress induced crack tip constraint

Cited by 35 publications

References 27 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

Effect of residual stresses on the crack-tip constraint in a modified boundary layer model

Effects of crack depth and specimen size on ductile crack growth of SENT and SENB specimens for fracture mechanics evaluation of pipeline steels

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