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Fatigue evaluation - ASME BPVC VIII DIV 3 KD-300

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bday

Mechanical
Nov 3, 2021
3
Hi,
question on the type of the stresses needs to be considered.

for simplicity lets say that equivalent alternating stress intensity is equal to the alternating stress intensity - so without mean stress correction
f1_e8hbq5.jpg


where:
alternating stress intensity = range of the shear stress
f2_eyaqzx.jpg


assuming that SN data are expressed in Stress amplitude vs Number of Cycles - shall we divide calculated alternating stress intensity by half (to have amplitude stress) and then compare this value with SN data?

or for some reasons alternating stress intensity (shear stress range) shall be directly compared with SN data.

Thanks
bday
 
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please, "stress intensity" has a specialised meaning, within damage tolerance. Maybe this is "ESL" (English as a Second Language) issue, but your sentence works well without "intensity" ... "for simplicity lets say that equivalent alternating stress is equal to the alternating stress - so without mean stress correction"
or possibly "magnitude" ... "for simplicity lets say that equivalent alternating stress magnitude is equal to the alternating stress magnitude - so without mean stress correction"

to your question, it may be your industry but I'd use 1/2 the maximum principal stress as a fatigue cycle.


another day in paradise, or is paradise one day closer ?
 
Good point.
However - this is ASME DIV3 nomenclature
 
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