CFD Online Discussion Forums - Bridgman Paradox?! Masters thesis

Hello!

Im working on my masters thesis, where Im looking into something that some would say is an unexpected answer.

The setup is very simple:
Attachment 31199

Step 1: Faced with the seemingly trivial physical problem with a pressurized chamber with a bar protruding the chamber walls through sealing glands, most people opts for solution 1; no resulting axial force; T =0.

Step 2: By reversing the pressure, there is 100% agreement that solution 2 gives the right answer. A compression force corresponding to the overall pistion effect.

Step 3: Most people agree that lowering external pressure to negative gives a suction force and corresponding tension in the piston of T =∆pA.
Then, the question is: Is not step 3 identical to step 1?

And here are some screenshots from Openfoam:
Attachment 31200

Attachment 31201

Attachment 31202

Attachment 31203

So, Why is there no axial force in the rod when pressure is applied from inside? The rod will fracture. Do you have an idea about why?

Any ideas and/or suggestions are appreciated! :)