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# Stress Intensity Factor for Elliptical Cracks

1. ### pbeary

4
Hi, I just wanted some clarification with respect to a few equations relating stress intensity factor to semi-elliptical and quarter-elliptical cracks in solids.

The equations I have according to my notes are $K_{I_{(\varphi=\frac{\pi}{2})}}=1.12\frac{\sigma \sqrt{\pi a}}{\Phi}$ and $K_{I_{(\varphi=0)}}=1.12\frac{\sigma \sqrt{\pi \frac{a^{2}}{c}}}{\Phi}$

The problem is, from a diagram I have, it seems the first one is the quarter-elliptical (corner) crack and the latter is the edge. Is this correct? I am confused as it states the semi-elliptical crack first then the corner crack, though you would expect the explanations to be in the same order...

Here is the diagram btw.

### Staff: Mentor

The diagram is of a semi-elliptical crack. The two expressions are for different locations on the root, and they are of the same order (assuming I'm understanding your comment/question).

a is the same order as a2/c

3. ### pbeary

4
Hi, thanks for the reply, cleared everything right up for me.

Guess this can be closed now.