Comparing unloading compliance and d-c EP technique during SENT testing

Several procedures for SENT testing (DNV, ExxonMobil, and CANMET) are currently used in the industry and more recently a British Standard (BS8571:2014) has been published. In these procedures, either the d-c EP method or the unloading compliance technique are used to determine the start of ductile tearing and crack growth to arrive at fracture resistance CTOD R and J-R curves. This paper compares crack growth predictions where both the unloading compliance and d-c EP techniques were used simultaneously during SENT tests. Other unique aspects of the comparative methodologies, pros and cons of each of the two methods, and guidelines for fracture resistance curve development from SENT testing are also discussed.