Full Content is available to subscribers

Subscribe/Learn More  >

Crack Tip Opening Angle: Measurement and Modeling of Fracture Resistance in Low and High Strength Pipeline Steels

[+] Author Affiliations
Ph. P. Darcis

NIST, Materials Reliability Division, Gaithersburg, MD

G. Kohn, A. Bussiba, J. D. McColskey, C. N. McCowan

NIST, Materials Reliability Division, Boulder, CO

R. Fields

NIST, Metallurgy Division, Gaithersburg, MD

R. Smith, J. Merritt

DOT/PHMSA, Washington, DC

Paper No. IPC2006-10172, pp. 159-168; 10 pages
  • 2006 International Pipeline Conference
  • Volume 3: Materials and Joining; Pipeline Automation and Measurement; Risk and Reliability, Parts A and B
  • Calgary, Alberta, Canada, September 25–29, 2006
  • Conference Sponsors: Pipeline Division
  • ISBN: 0-7918-4263-0
  • Copyright © 2006 by ASME


Crack tip opening angle (CTOA) is becoming one of the more widely accepted properties for characterizing fully plastic fracture. In fact, it has been recognized as a measure of the resistance of a material to fracture, in cases where there is a large degree of stable-tearing crack extension during the fracture process. This type of steady-state fracture resistance takes place when the CTOA in a material reaches a critical value, as typically occurs in low-constraint configurations. Our current research has applied the CTOA concept as an alternative or an addition to the Charpy V-notch and the drop weight tear test (DWTT) fracture energy in pipeline characterization. A test technique for direct measurement of CTOA was developed, using a modified double cantilever beam (MDCB) specimen. A digital camera and image analysis software are used to record the progression of the crack tip and to estimate CTOA using the crack edges adjacent to the crack tip. A steady-state CTOA has been successfully measured on five different strength grades of gas pipeline steel (four low strength grades and one high strength grade: X100). In addition, two-dimensional finite element models (2D FEMs) are used to demonstrate the sequence of the fracture process and the deformation mechanisms involved. The CTOA measurements and models are correlated and agree well.

Copyright © 2006 by ASME



Interactive Graphics


Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature

Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal

Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In