Changing Principal Stress Direction in Sec. VIII, Div. 2 1

[m_ridzon]

Hi folks, newb here, but I've been stalking the forum for a little while now. I am doing a fatigue analysis per 2017 BPVC, Sec. VIII, Div. 2, Part 5.5.3. From everything I can tell in v2017, I am to use equivalent stress range (i.e., von Mises) for the calculation of alternating stress. However, it was brought to my attention that older versions (e.g., 1989) required the consideration of varying principal stress direction to calculate the alternating stress intensity (i.e., Tresca) in its mandatory Appendix 5. So it seems that Sec. VIII, Div. 2 changed somewhere along the line from Tresca to von Mises. But my main question is...can someone confirm that v2017 does NOT require any consideration of varying principal stress directions as was the case in older versions?

 

[TGS4]

You calculate the stress ranges on the component level, and then calculate the von Mises of the range, and not the range of the von Mises. This will consider the varying principal stress direction.

 

[m_ridzon]

You calculate the stress ranges on the component level, and then calculate the von Mises of the range, and not the range of the von Mises. This will consider the varying principal stress direction.

Perfect! I thought it would wash out that way, but needed confirmation. Thanks!