Simulating bolt connection between structural members

[drAle85]

Hi I'm trying to simulate two square pipes inserted into each other and connected with a bolt connection. The contact between the pipes is separation and the aligned holes are connected with a bolt connection.

The inner Pipe is fixed at the bottom (green on the image). The outer pipe somehow remains a free body (red in the image). 

Definitely I'm doing something wrong, but I'm not sure what is it.

[hamid.sh. · Accepted solution]

Compare with this, or share your file please:

[drAle85]

Ok I got it now. You use two bolts in order to make the connection between the elements.

I have used one Bolt only on the outer sides of the outer tube. This does not provide enough information to the contact of the inner tube, since the bolt is only a virtual part.

The final product will however use a single bolt so it seems I will  have to model it explicitly.

Thank you for your help and especially on the speed of the answer.

[hamid.sh.]

@drAle85 No, I don't think the number of bolts has effect in that regard (i.e. on DOF), and as such you still don't have your solution. I had used two bolts just for practical reasons, but with one single bolt this model is fully constrained if properly set up. See the attached file with one bolt which is still fully green. Compare in more depth, or if you share your file perhaps someone will point out the problem. 

[drAle85]

Yes, you are correct. For constraint purposes, it works well with a single bolt connection on only one hole.

In the real product, a single bolt should go through both holes. I have tried to model it explicitly with a pin and have also put separation contact between all of the elements and fixed the bottom of the inner pipe. It still is not fully constrained... I have uploaded the model here so if anyone has a tip, it would be great.