Stress Intensity Factor for Elliptical Cracks

pbeary

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 [itex]K_{I_{(\varphi=\frac{\pi}{2})}}=1.12\frac{\sigma \sqrt{\pi a}}{\Phi}[/itex] and [itex]K_{I_{(\varphi=0)}}=1.12\frac{\sigma \sqrt{\pi \frac{a^{2}}{c}}}{\Phi}[/itex]

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.


Thanks in advance!

Astronuc

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

pbeary

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

Guess this can be closed now.