Sam,

Yes, I misunderstood you.

To properly use FEA to correlate SIF with Sec VIII Div 2 appendix 4 or SEC III SUBSECTION NB requirements, use either brick or shell elements.For additional details, you need to use the paper by Hechmer and Hollinger, which in case you don't have and need, I can send it to you.However the paper by Hechmer and Hollinger won't throw any light on how to get the B31 type SIF values.The philosophy for doing so is something like this : get the "peak stess" and use the correlation 2i= CAESAR II*K2.Boundary condition that you need to use in your FEA model and the subsequent fine tunings need very good judgement.

Regards