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# Fatigue - Kt for a spotfaced hole

## Fatigue - Kt for a spotfaced hole

(OP)
Hi folks.

I'm doing fatigue analysis for an open spotfaced hole. As a first approach I was looking the Peterson's Chart 3.1 "Stress concentration factors Kt for a stepped flat tension bar with shoulder fillets" taking "H" as 2 times my thickness but I'm not convinced due to "h" in the chart should be infinite (for my case).

Does anyone can suggest another kt approach and how to combine it to the kt=3 (open hole)?

Thanks.

### RE: Fatigue - Kt for a spotfaced hole

the Kt for the spotface should be quite distant from the Kt for the hole.

"h" seems a relative innocent parameter ... only used to set the nominal stress (P/hd) ...

I'd look at how deep the spotface is compared to the thickness under the spotface, this'd be H/d.
and you should be able to get r/d.

### RE: Fatigue - Kt for a spotfaced hole

Time to switch to FEA I think.

Otherwise, Patterson has a calculation for plotting the stress concentration as a distance from the hole I recall, which will give you something better than 3 for the hole.

### RE: Fatigue - Kt for a spotfaced hole

NACA TN2073 has the stress distribution due to a hole

### RE: Fatigue - Kt for a spotfaced hole

Castorena...

I think the latest Peterson's Stress Concentration Factors [book] would have methods to calculate the Kt of spot-face + centered hole.

Regards, Wil Taylor

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