Non-linear analysis?

No

I'd better qualify that answer - rereading your post I may have misinterpreted it.

What ProMech will do is treat the materials as springs of stiffness equal to the youngs modulus. If the yield stress of the part is exceeded, ProMech will not model the plastic deformation (Elastic deformation disappears when the stress is removed, plastic deformation remains after the stress is removed) or breakage of the part.

That's why you have to look at the results to see if any areas exceed the yield stress in order to decide whether the part will fail in reality.

Incidentally, for the stress on a part to equal the youngs modulus, the part would have to be stretched to twice it's original length (By the stress=Youngs modulus*Strain formula). Unless you're dealing in elastomers (Which ProMech won't model properly anyway) you're not going to find parts surviving that sort of treatment .

My bad.
I meant yield strength.
But thanks for the reply.
Alex,