Consideration of a proposed SBAD method for BS7910

Concerns have been published about the cases of non-conservatism when the BS 7910 option 2 Failure Assessment Curve (FAC) is used in the Strain Based Analysis and Design (SBAD) regime. An assessment of these concerns has been made using an analytical solution for the Crack Driving Force (CDF) associated with an infinite notched strip. It was shown that the option 2 FAC could underpredict the CDF for this case and that the level of error was bigger for lower levels of strain hardening. A modification to the option 2 FAC is proposed. The modification has been studied in other publications and has been shown to provide conservatism in all cases investigated to-date.