Hi I'm Alan, from Argentina... I'm having a little issue when I try to simulate a simple design. I will post some pics to be more clear.

Here is how a fixed the piece and where is the force acting (12000N), it's a simple traction problem.

As you can see the max stress is about 2000 MPa in both pictures. The tensile stress to break AISI1045 is about 785 MPa (so it would explote haha), but this piece is real, have the same dimensions, same material, and it break's with a force about 17000N with the same fixture and point of aplication of the force.In the simulation it seems that the piece will break with 12000N... but in the real world this isn't true.

So, what am I doing wrong?

Thanks!