A Wide Range Stress Intensity Factor Solution for Single Edge Notched Tension Specimen With Clamped Ends

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.