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Direct Comparison of Single-Specimen Clamped SE(T) Test Methods on X100 Line Pipe Steel

Published

Author(s)

Timothy S. Weeks, Enrico Lucon

Abstract

The clamped single edge-notched tension (SE(T)) specimen has been widely used in a single-specimen testing scheme to generate fracture resistance curves for high strength line-pipe steels. The SE(T) specimen with appropriate notch geometry is a low-constraint specimen designed to reduce conservatism in the measurement of fracture toughness. The crack driving force is taken as either the J-integral or crack tip opening displacement (CTOD) and it is generally accepted that the two are interchangeable and equivalent using a simple closed form solution. However, the assumption that they are interchangeable, and to what extent, hasn’t been previously investigated experimentally on the same SE(T) specimen. This paper presents multiple test methods that were simultaneously employed on the same SE(T) specimens. The instrumentation includes: clip-gauges to measure surface crack mouth opening displacements (CMOD) and CTOD by the double-clip-gauge method; strain-gage arrays for direct J-integral measurements; and direct-current potential-drop (DCPD) instrumentation for supplementary crack size measurement. A direct comparison of ductile crack-growth resistance curves generated using J-integral and CTOD is presented here where each represent a different experimental and analytical approach. The two methods are in reasonable agreement over a narrow range of crack growth, differing slightly at initiation and diverging with increasing crack growth. Analysis of the supplementary instrumentation (i.e., strain gages, extensometers and DCPD) will be provided in a future publication.
Proceedings Title
Proceedings of the 10th International Pipeline Conference
Conference Dates
September 29-October 3, 2014
Conference Location
Calgary

Citation

Weeks, T. and Lucon, E. (2014), Direct Comparison of Single-Specimen Clamped SE(T) Test Methods on X100 Line Pipe Steel, Proceedings of the 10th International Pipeline Conference, Calgary, -1, [online], https://doi.org/10.1115/IPC2014-33695 (Accessed July 24, 2024)

Issues

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Created September 29, 2014, Updated November 10, 2018