Huge Displacement & Rotations Due to Sustained Load

Hi,

I have modeled a horizontal duct with a 90 Deg bend and both end are fixed (only movements in X, Y & Z directions are restrained while it is free to rotate). (refer to attached model). I am trying to find out whether the stress due to thermal expansion at the bend would be acceptable since the duct is restrained at both ends.

Looking at the displacement under sustained load, I realise that the displacement in downwards direction and the rotations around X & Z axis are too large (i.e. displacement in Y-direction (vertical axis) : -142544100mm).

However, Caesar II returns more reasonable results for the displacement and rotations under sustained load if I change the restraint conditions at both ends to anchors.

Could you please advice whether there is something wrong with my input?

Thanks and regards,

Steve

Results for both models sound reasonable. The question is not what Caesar II is doing, the question is what are you doing. What boundary conditions do you want?
Lacking RYs at each end will affect your thermal loads. The missing RX & RZ restraints affect your weight run.

Steve, if you do not want to restrict the rotation downward, your duct will drop. This you want, this you'll have, there is no wonder.

Regards,