how to determine the yield point of steel plate?

[daleacyr]

I deal with beams all the time. But steel plate... not so much.

I have a 12" square (approx) 1/4" steel plate that is securely attached on all four edges.
The plate will be subject to glancing blows from loads on a forklift.

How do I determine the yield point of the center of the square plate, given plate thickness and length/width?

[daleacyr]

Nevermind. I found the series of equations for flat plates.
Can't seem to get it to work tho...