Since Crack tip opening displacement (
CTOD) has been proposed as a fracture mechanics parameter
CTOD in 1960s
CTOD is widely used in steel structure industries for toughness evaluation of the materials and/or defect assessment of the welded structures based on the fitness for service standard. National standard in each country and also ISO standard have been established which is a similar procedure to the firstly standardized DD19 in British Standard Institution in 1972. The
CTOD calculation is composed of plastic hinge model which assumes rotational deformation around the specific point. Standard range of crack length to width ratio (
a0/
W) is limited to be from 0.45 to 0.5. In the last 15 years, the discussion of
CTOD has revived at a chance of the J based
CTOD proposal in ASTM. The J based
CTOD is capable of
CTOD calculation in the wide
a0/
W range.
CTOD evaluation using single edge notched tension (SENT) specimen with a sallow crack is also desired by industries at the same time. However, the capability of rotational
CTOD evaluation in the wide
a0/
W range has not completely been concluded, yet. In this study, aiming to propose the new calculation method of
CTOD, the rotational deformation is examined in the
a0/
W range from 0.05 to 0.70, and the applicability of rotational
CTOD calculation for a shallow cracked specimen is discussed.
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