Dynamic Crack Propagation in Line Pipe

Maxey, W.A.

doi:10.1007/978-94-009-8594-0_5

Cited by 17 publications

(12 citation statements)

References 2 publications

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“…Under this same routine and as close as possible to the actual conditions of a burst test. According to the assumption of Maxey et al [31], only the portion of the pipeline downstream of the crack tip is constantly charged by the gas pressure. Using this same routine, the internal pressure is imposed to a certain distance ahead of the crack tip.…”

Section: Loadingmentioning

confidence: 99%

The CTOA as a Parameter of Resistance to Crack Extension in Pipes Under Internal Pressure

Amara

Pluvinage²,

Capelle

et al. 2016

Fracture at All Scales

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Different methods of CTOA measurements are described: Optical microscopy coupled with digital image correlation, analytical analysis of experimental load-displacement curves or simulation by Finite Element method. Using a Modified Compact Tension (MCT) specimen at room temperature, tests are performed to measure the value of the CTOA of API 5L X65 pipe steel. The influence of thickness on CTOA has been studied and explained through a "triaxial stress constraint". Crack extension is modelled by the finite element method using the CTOA criterion coupled with the node release technique. Crack velocity, arrest pressure and crack extension at arrest have been determined. Values of the CTOA are not intrinsic to materials. Like other measures of fracture toughness, it is sensitive to geometry and loading mode. This sensitivity can be described by a constraint parameter. For the thickness effect, the constraint parameter T z is very appropriate.

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Section: Loadingmentioning

confidence: 99%

The CTOA as a Parameter of Resistance to Crack Extension in Pipes Under Internal Pressure

Amara

Pluvinage²,

Capelle

et al. 2016

Fracture at All Scales

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“…Two datasets are considered in this assessment of the BTCM. The ¿ rst involves the dataset that underlies the development and empirical calibration of the BTCM [15]. Given the many disposable parameters involved, and their use in tuning the calibration, the BTCM should correctly calculate the required toughness across that dataset.…”

Section: Limitations and Key Assumptions Inherentmentioning

confidence: 99%

Arresting Propagating Shear in Pipelines

Leis¹

2015

Izv. vysš. učebn. zaved., Čern. metall.

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Abstract.The consequences of what has been termed running ductile fracture require that pipelines be designed to arrest propagation, and so avoid major incidents due to this type of failure. Approaches to characterize pipeline response and their resistance to such failure to ensure arrest rely on semi-empirical models developed in the mid-1970s. Continuing reliance on such semi-empirical models, which were calibrated using fullscale tests done on segments of pipelines, persists because this failure process involves three interacting nonlinearities, and so is complex. These nonlinearities include: 1) plastic À ow and tearing instability, 2) soil-structure interaction, and 3) expansion wave response and decompression in the pressurizing media. This paper ¿ rst reviews the history and related developments that represent almost 40 years invested in fracture-based approaches to quantify propagating shear in pipelines. Graphical evidence of the full-scale failure process and related phenomenology lead to an alternative hypothesis to quantify this failure process that is based on plastic collapse rather than fracture. It is shown that the phenomenology does not support a fracture-controlled process, and that instead the metrics of arrest should reÀ ect the À ow properties of the steel. Finally, aspects of fracture-based approaches are related to the collapse-based concept as the basis to understand the success that at times has been achieved using fracture-based approaches. Surrogates for CVN energy that has been used in the BTCM as a measure of fracture resistance are reevaluated as functions of the À ow response, which provides the basis to rationalize the historic successes on the fracture-based formulation. Finally, remaining gaps and issues are addressed.

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“…9 because of the effect of no backfill. This effect had been investigated by Battelle's Columbus Laboratories and it is reported 5) that the crack velocity in the case of no backfill increases 1.38 times the crack velocity in the case of backfill conditions. This "1.38" is only the mean value for the pipe having 30 inches of soil or sand cover and this value may vary with the pipe size, the operating pressure, and the backfill depth.…”

Section: The Effect Of No Backfillmentioning

confidence: 99%