Bolt Preload for Piping connection

I’ve already replied to the first 2 of your questions on YouTube so I’ll just comment on that last issue. It might be caused by the way those rings were modeled in FreeCAD, they were not meant to be merged so there can be some small misalignment causing incorrect compound part creation.

1 Like

Hi Matej,
Do you think the problem is what you thought it was for not getting correct contact pressure?

The mesh of involved sub-parts is merged if you create a compound part. In this case, there is no need for contact. In such cases, the contact stresses are not meaningful values. You can try to see if the parts are connected (merged) using the View->Exploded View tool.

@Matej I tried to just make compound of (bolt + shank + nut) for each bolt and the ChannelSection and LSection are separate.

Then as per @FEAnalyst Youtube video, I added tied constraint between bolt head and upper surface, nut face and bottom surface. I added PreTension for 4 bolts but I am getting failed result after nearly 600seconds and using 8cpus.

File is attached here
P5701178.zip (8.0 MB)

What am I doing wrong?

It doesn’t converge because of the contact between L section and channel section. If you change the interaction to tied, it will work.

Yes I tried and it converged in 2.3seconds. But when I change interaction to tied, I lost contact pressure which you can only get in surface to surface contact connection.

Is there a way to achieve contact pressure as per this post CalculiX-Examples/thermal.inp at master · calculix/CalculiX-Examples · GitHub

Thanks
Dharmit

Tied contact has to be of a surface-to-surface type and you can obtain the contact pressure with it.

2 Likes