Fatigue Testing: Calculating ΔK vs da/dN from R & Max Stress

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arehman1289
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Hello Everybody,

Im doing my lab report on Fatigue testing for a Single Edge Notched Tension (SENT) sample and need to plot ΔK vs da/dN for a series of a vs N readings at different R and maximum stress values (attached in the picture). I've just been given one equation for Ki and told that I need to use ASTM E647 for assistance (attached equation). However after hours of going through it I was unable to figure out how to get ΔK vs da/dN from the data and information. Any step by step help would be highly appreciated. Please please.

Thanks
 

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There is a discussion of this starting on page 9-147 in MIL-HDBK-5H. That handbook has been superseded, but it is full of good information AND is available online. Just search MIL-HDBK-5H to find a copy. This figure summarizes two pages of step by step discussion that should help you.
DaDN.jpg