bolted metal plate strips - wrong stress on shell
Dear ladies and gentleman.
I have a problem with my structural analysis.
I want to simulate 2 metal plates which are bolted together, as you can see in the following picture.
The one end is fixed. On the other end there is a force into the direction of the plate strip (5000N). There is also a force in the direction of the bolt (5000N) on the upper und on the bottom side of the plate.
At first I made a hand calculation. The section of the plate is 40mmx5mm.
So I get a normal stress on the upper side of the left plate of about -125N/mm^2 and a normal stress on the bottom side of about 175 N/mm^2.
The right plate shoud have stress about 25 N/mm^2.
I have modelled this at first with 3D elements and got also these results.
Now I wanted to model it with shells and a beam instead of the bolt. But now I get results, which can not be true.
You can see my geometry at the picture bellow:
I connected the circular ring shell, wich presents the bolthead with the plate with a bonded contact. Also the 2 rectangular plates which presents one plate are bonded together. The areas of the 2 plates which are bolted together are connected with a frictional contact. The endpoint of the beam is connected with the "bolthead" with a fixed joint.
At the first step I obtained the bolt pretension and on the second step I obtained the forces on the plate.
So I get normal stresses as you can see bellow:
The results on the right plates are correct. But I think my results for the left plate are incorrect. But I have no idea what I did wrong.
Maybe I need more integration points for the shell? But unfortunately I did not find, where I could change this in ANSYS?
I am really looking forward for answers and ideas.
Thank you very much