Fall 2012 ME 395 - GSI Josh Lacey

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 Calculation KQ

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Posts : 13
Join date : 2012-10-01

PostSubject: Calculation KQ   Fri Oct 05, 2012 3:03 pm

When calculating KQ, is the Force value we use the critical force where fracture of the bar begins and is the stress that we use the critical stress value where fracture begins?
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GSI Overlord

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Join date : 2012-08-30

PostSubject: Re: Calculation KQ   Fri Oct 05, 2012 3:52 pm

If you look at the lecture slides on page 9, you'll see how you can pick off P_Q with a 95% confidence interval from your load vs. COD plots. This P_Q value is the critical force you need to plug into the K_Q equation.

I'm not exactly sure what you mean by critical stress...there's no stress in the K_Q equation. If you are referring to the stress term in meeting the conditions for K_Ic, that is the yield stress of the aluminum given as a 0.2% offset as specified by the ASTM E399 standard.
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Calculation KQ
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