Single edge notched tension (SENT) specimen with clamped ends has been accepted in the oil and gas industry as a low-constraint fracture test specimen to directly determine fracture toughness or resistances in low constraint conditions. Different SENT test methods have been developed, including DNV-RP-F108 test practice, CANMET J-resistance curve test procedure, ExxonMobil CTOD test procedure, and others. Based on these methods, a SENT test standard BS 8571 was developed and published in December of 2014. However, the stress intensity factor K used in BS 8571 was a very complicated function and difficult to use. Moreover, the present author found that this complicated K solution is correct only for a/W≤0.6, but incorrect for deep cracks of a/W>0.6. In order to obtain a simple and accurate K solution for the clamped SENT specimen, this paper revisits this topic. Using the crack compliance method, the desired K solution is obtained. Results show that the proposed K solution and its curve fit are very accurate over a wide range of crack sizes, and validated by existing finite element results of K for the SENT specimens.

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