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"...in a fatigue analysis, only Ktn can be used..." - Peterson

"...in a fatigue analysis, only Ktn can be used..." - Peterson

"...in a fatigue analysis, only Ktn can be used..." - Peterson

(OP)

Does anybody understand the subject statement from Peterson?

Here's the complete sentence from "Stress Concentration Factors" 2nd edition:

"In addition, in a fatigue analysis, only Ktn can be used to calculate the stress gradient correctly."

The implication is that for a fatigue analysis, Ktg can not be used to calculate stress gradient correctly.  This does not make sense to me since for the couple of examples that I worked out, the final stress value is the same whether I get it from Ktn x stress on net cross section or Ktg x stress on gross cross section.

What am I missing?
 

RE: "...in a fatigue analysis, only Ktn can be used..." - Peterson

i agree with your peak stress calc (either Ktn*net area or Ktg*gross area).

 

RE: "...in a fatigue analysis, only Ktn can be used..." - Peterson

(OP)
Thanks for the post rb1957!  

So you agree that, by extension, Peterson's statement doesn't make sense?

RE: "...in a fatigue analysis, only Ktn can be used..." - Peterson

i'd have to read it in context ... you have a pg number ?

RE: "...in a fatigue analysis, only Ktn can be used..." - Peterson

(OP)
In my paper copy, it is Page 8 at the top.  This is about the middle of section "1.2.1 Selection of Nominal Stresses".

 

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