Calculating SIF using FEA
Calculating SIF using FEA
(OP)
Suppose we need to calculate SIF at a tee junction and the vonmisses stress at a tee junction is calculated then to calculate the SIF how should be the other FEA model against which comparison should be made and what stress value to be obtained from the other stress model i.e. will it be vonmisses or some thing else?
Thanks and Regards
Parijat Bandyopadhyay





RE: Calculating SIF using FEA
NC suggests that an empirical relationship i=C2K2/2 may be used to determine the SIF, where C2 (primary+secondary stress) and K2 (peak stress) are the stress indices from class 1.
This EPRI Report gives some background on SIF's.
Also, the stress indices represent stress intensity (Tresca) not equivalent stress (von Mises).
RE: Calculating SIF using FEA
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Your approach is applicable to pressure vessel type components, not piping component design.
The SIF (Stress Intensification Factor) cannot be compared to calculated FEA stress concentration stresses or even empirical stress concentration factors. The Piping SIF's listed in the code have been corrected so that comparisons can be made to the fatuige limits of a circumferential butt weld, not straight pipe (this is why pipie to pipe butt welds do not have a stress concentration factor, a stroke of genius by Mr. Markl as you don't have to evaluate every single butt joint in your system).
Your only B31 code compliant option in developing new SIF's is to test in accordance with the above standard.
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