SYMPOSIA PAPER Published: 01 January 1983
STP37309S

J-Integral Analysis of Surface Cracks in Pipeline Steel Plates

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A capability for direct experimental evaluation of the J-integral in surface-cracked members under elastic-plastic deformation is useful for providing understanding of the driving force for fracture. In addition, such a capability makes it possible to evaluate analytical and numerical predictions of J. Experimental procedures have been developed for direct evaluation of J at the root of surface cracks from quantities measured at the specimen surfaces. These procedures rely on the assumption that the line J-integral around the root of a surface flaw is sufficiently path-independent for practical purposes. Arguments in favor of this assumption are made.

Experimentally measured J-integral results are presented for specimens containing surface cracks. Several specimens of pipeline steel 16 mm thick and 75 to 100 mm wide, containing surface cracks varying in length from 31 to 48 mm and in depth from 5.6 to 10.5 mm, were loaded in tension, and the J-integral was evaluated. Plots of measured J as a function of applied stress show a parabolic dependence followed by a nonlinear region and a vertical asymptote at the stress corresponding to net section yield. The experimental results are used to evaluate a simplified line-spring model for predicting J, and the model results compare favorably with the experimental data.

Author Information

King, RB
Fracture and Deformation Division, National Bureau of Standards, Boulder, Colo.
Cheng, Y-w
Fracture and Deformation Division, National Bureau of Standards, Boulder, Colo.
Read, DT
Fracture and Deformation Division, National Bureau of Standards, Boulder, Colo.
McHenry, HI
Fracture and Deformation Division, National Bureau of Standards, Boulder, Colo.
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Details
Developed by Committee: E08
Pages: I-444–I-457
DOI: 10.1520/STP37309S
ISBN-EB: 978-0-8031-4869-7
ISBN-13: 978-0-8031-0727-4