SEDL / STP / STP1114-EB / STP16848S

Specimen Size Requirements for Elastic-Plastic Crack Growth Resistance Curves

Gordon, JR
Manager, Edison Welding Institute, Columbus, OH

Jones, RL
Head, U.K. Admiralty Research Establishment, Holton Heath, Poole

Pages: 21    Published: Jan 1991

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Abstract

This paper presents the results of an experimental program to study size and geometry effects in CTOD R-curves. The results were obtained from room temperature unloading compliance R-curve tests on different sized single-edge-notch bend (SENB) specimens made from HY100 steel. The crack growth resistance was measured in terms of conventional CTOD, δ^o, (that is, as defined in BS 5762), CTOD corrected for crack growth, δ^R, and CTOD derived using a double clip gage arrangement δ^dc. It was found that all the CTOD R-curves exhibited upswings after crack extensions corresponding to approximately 17% of the initial uncracked ligament. Moreover, the slope of the CTOD R-curve increased dramatically after crack extensions corresponding to approximately 45% of the initial ligament. Apart from the R-curves obtained from the smaller specimens, normalizing the crack growth axis by dividing the crack extension by the initial ligament resulted in normalized CTOD R-curves which were in reasonable agreement over the entire crack growth range studied (that is, 60% of the initial uncracked ligament).