Comparative study of CTOD-resistance curve test methods for SENT specimens

A comparative study is performed in this paper on the crack-tip opening displacement (CTOD) resistance curve test methods developed for single edge-notched tension (SENT) specimens in the end-clamped conditions. Different J-integral conversion methods and double clip gage methods, including CANMET, ExxonMobil and BS 8571 test procedures, are evaluated experimentally using SENT test data for both low and high strain hardening steels. Results show that the J-conversion methods with different m factors determine different CTOD-R curves, while the double clip gage methods determine similar results. In particular, the two-type CTOD-R curves differ significantly for high strain hardening steels. The CTOD test methods are quantitatively compared, two typical methods are identified, physical meaning of CTODs is analyzed, and applications of CTOD toughness are discussed.