Membrane plus Bending At Component Level

[LS_SMS]

Folks, I am using 2023 ASME Sec. III, Div. 5 for high temperature components. A common theme throughout BPVC is to sum at the component level. For example, Pm + Pb should be summed at the component level for the 6 stress components, before deriving stress intensity to check against the allowables. However, some of the criteria in Sec. III, Div. 5 require that bending be divided by K before summation with membrane (e.g., HBB-3223, Eqn 5, image below).




I use ANSYS and to my knowledge, there is no way to tell ANSYS to first divide bending by K before deriving stress intensity. So ANSYS calculates membrane + bending at the component level and shares it with the user, but without the effects of K. So I think the only way around this is to extract the 6-component stress tensor from ANSYS for membrane and separately for bending. Then I would have to divide the bending components by K to comply with code. And then I would sum the bending tensor with the membrane tensor. Lastly, I would determine the stress intensity. All of this would have to be done manually in Excel. Is my thinking correct? It sure would be nice if there was a way to include K in ANSYS beforehand, but I don't think it's possible.

 

[TGS4]

Your thinking is correct. This needs to be manually, be that with Excel or equivalent. Can't be accomplished within your FE software.

 

[LS_SMS]

Thanks for the feedback. I was afraid that would be the answer. Oh well!

 

[LS_SMS]

If I extracted Pm and Pb stress intensity from the software, and did the summation directly on stress intensity, rather than the components, would it be conservative? In other words, I would do this...
S_int_Pm + S_int_Pb

Since stress intensity is always positive, could I conclude that the approach is conservative? If not conservative, please share an example for my curiosity.