ISSN: 0090-3973
Published Online: 4 December 2008
Page Count: 6

Evaluating the Onset of Tearing in Elastic-Plastic Fracture Toughness Testing Using In Situ Optical Microscopy

Melcher, Ryan J.
Los Alamos National LaboratoryCessna Aircraft Company,NMKS,

(Received 16 June 2008; accepted 23 October 2008)

Abstract

Fracture toughness, in the sense of material resistance to ductile tearing from an initial sharp defect, is a common metric for structural integrity assessments of engineering components. While standardized test methods are well-suited for repeatable estimation of this metric, physical observation of crack-tip opening displacement (CTOD) and tearing may provide a supplemental means of evaluating the onset of tearing with greater accuracy in ductile materials. In contrast to previously documented methods of physical CTOD measurement, in situ optical microscopy on standard sidegrooved fracture toughness specimens presents an easily implemented, cost-effective tool for observing tearing onset. As an additional benefit, quantitative measurements of CTOD from in situ optical microscopy also provide a means of cross-checking standard J-integral results as determined from load-displacement test data.

Keywords:
fracture toughness, crack-tip opening displacement, optical microscopy

Paper ID: JTE101943
DOI: 10.1520/JTE101943
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