Full-range stress–strain behaviour of contemporary pipeline steels: Part I. Model description

Hertelé, Stijn; Waele, Wim De; Denys, Rudi; Verstraete, Matthias

doi:10.1016/j.ijpvp.2012.01.006

Cited by 35 publications

(18 citation statements)

References 13 publications

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“…The measured engineering stress-strain data was converted to true stress-logarithmic strain data using standard procedures [21]. Using the tensile data of the tested X70 pipeline steel, an improved estimate for the hardening exponent given by Annex F of API 579 [42] provides the strain hardening exponent at the test temperature as n % 13, which characterizes relatively well the hardening behavior typically observed in similar pipeline grade steels [43,44]. The two adjustment factors in the Gurson yield condition given by Eq.…”

Section: Finite Element Models For Crack Growth Analysismentioning

confidence: 99%

J –CTOD relations in clamped SE(T) fracture specimens including 3-D stationary and growth analysis

Sarzosa

Souza

Ruggieri

2015

Engineering Fracture Mechanics

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Section: Finite Element Models For Crack Growth Analysismentioning

confidence: 99%

J –CTOD relations in clamped SE(T) fracture specimens including 3-D stationary and growth analysis

Sarzosa

Souza

Ruggieri

2015

Engineering Fracture Mechanics

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“…The stress-strain curve in the pipe axial direction shows a pronounced two-stage strain hardening behavior as often observed for high strength linepipe steel. It can be parametrically described on the basis of the UGent stress-strain model, developed to describe such behavior [40]. Summarized, the following materials have been simulated for each of the considered specimens (SCWP, UP and PP), forming angles (20°, 30°and 40°) and flaw depths (4.0 mm, 5.0 mm, 6.0 mm, 7.0 mm and 8.0 mm) resulting in a total of 540 simulations: material anisotropy (r TRD /r LRD = 1.00, 1.02 and 1.04) and weld strength overmatch (À5%, 0%, +5%, +10%).…”

Section: Hill's 1948 Yield Criterionmentioning

confidence: 99%

Effects of specimen geometry and anisotropic material response on the tensile strain capacity of flawed spiral welded pipes

Minnebruggen

Hertelé

Thibaux

2015

Engineering Fracture Mechanics

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“…This model has two strain hardening stages, each independently characterized by a different strain hardening exponent (Figure 4). Previous work has shown that, in contrast with the more conventional Ramberg-Osgood model, the 'UGent' model is capable to accurately describe the full strain hardening behaviour up to necking of line pipe steels (provided there is no discontinuous yielding) [20]. Indeed, above a Y/T-ratio threshold of 0.80, these steels tend to show two strain hardening stages as described by the 'UGent' stress-strain model.…”

Section: Framework For Strain-based Assessment Of Girth Weld Flawsmentioning

confidence: 99%

Combined numerical-experimental framework for strain based design and flaw assessment of girth welds

Hertelé¹,

Denys²,

Minnebruggen³

et al. 2013

SCAD

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An increasing number of transmission pipelines have to be installed and operated in harsh conditions, due to the diminishing reserves of exploited fossil fuel sources. Under certain environment related circumstances, longitudinal plastic strains are imposed. When tensile, these may induce failure in girth welds in conjunction with the inevitable presence of weld defects. A large number of factors related to environment, material, geometry and operating conditions influence the tensile strain capacity and, hence, the acceptability of girth weld flaws. Therefore, a project specific development of guidelines in this strain based context is recommended. This paper provides systematic frameworks on (a) how to design pipelines under strain based conditions, and (b) how to assess girth weld flaws that were detected using non destructive testing. Attention is given to several technical and economical aspects related to the selection and qualification of pipe and weld metals, and to the evaluation of flaw acceptability. Both frameworks comprise a combined experimental-numerical approach, collecting project development reports from literature with research carried out at Soete Laboratory. Concretely, four in-house realizations are adopted: the UGent equation for strain capacity, the curved wide plate tension test, the UGent stress-strain equation and a finite element model of full scale pressurized pipe tension testing. The proposed frameworks aim to facilitate in performing thorough and economically justifiable strain based design and assessment processes.Keywords: girth weld; weld flaw; strain based design; strain based assessment; project approach INTRODUCTIONThe availability of fossil fuel reserves decreases [1]. As a consequence, transport pipelines are installed and operated in increasingly challenging circumstances. Such pipelines may suffer from plastic strains that are being imposed under (partially) displacement controlled loading. Their structural integrity is to be judged in a strain based context, which considers strain as an evaluation quantity rather than stress. In this respect, the tensile strain capacity of the structure (i.e. the tensile strain level corresponding with failure of the structure) should exceed the strain demand (i.e. the strain level resulting from the imposed conditions).The strain based evaluation of pipelines under displacement controlled loading can be considered at two stages. First, devoted choices are to be taken during the design stage, prior to the construction of the pipeline. This aspect is referred to as a 'strain based design'. Second, the girth welds that connect pipe sections potentially contain weld flaws. A fracture mechanics based evaluation of their acceptability requires a method for strain based flaw assessment.To date, there are no standardized procedures for the strain based design of pipelines and their girth welds. Further, strain based assessment procedures for girth weld flaws have been developed during the last decade, but all of them show limitations...

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Full-range stress–strain behaviour of contemporary pipeline steels: Part I. Model description

Cited by 35 publications

References 13 publications

J –CTOD relations in clamped SE(T) fracture specimens including 3-D stationary and growth analysis

J –CTOD relations in clamped SE(T) fracture specimens including 3-D stationary and growth analysis

Effects of specimen geometry and anisotropic material response on the tensile strain capacity of flawed spiral welded pipes

Combined numerical-experimental framework for strain based design and flaw assessment of girth welds

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