RENAMED: Mesh Group Error. Pressure gives 0 results

[Roland]

Dear FEM forum,

I am trying to FEM analyze the bottom of a cylindrical steel tank (placed at angles, hence the plate is elliptical). The bottom is flat. I want to find out how to reinforce the bottom. My plan is to first analyze a single plate, followed by analyzing the placement of ribs of various sizes. I get stuck already at the very beginning: supposing no reinforcement ribs at all. Hence a flat elliptical plate only.

The issue arises with the application of the pressure. If I assume a force boundary condition that is equally distributed over the single plate face, then I do indeed find solutions. A soon as I replace the force by a pressure, I get stuck.

I take the plate: 2000 mm diameter, flat placed in X-Y
I apply a material: general steel
I apply a ElementGeometry2D: 5 mm thickness
I apply Constraint displacement: Outer circle fixed in X, Y and Z
I apply FEMMeshGmsh
I apply ConstraintPressure
I run CalculiXccxTools: write .inp file, run Calculix.

No error messages. But no result either. That is: no displacement at all, no stresses, no nothing.

In contrast, if I apply a force onto the plate, then there is a reasonable calculation result indeed. However, that provides no solution for me in the further analysis, because as soon as I place ribs, I am getting multiple faces of unequal size, so that each face 'faces' a different force.

I upload some files as illustration.

Would you have any suggestions?

Greetz

Roland

On:
OS: Windows 10 (10.0)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.18356 (Git)
Build type: Release
Branch: master
Hash: 12335c7d52376c140c5328d57902d2c0afdeb588
Python version: 3.6.8
Qt version: 5.12.1
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: English/United Kingdom (en_GB)

[Roland]

Dear FEM Forum,

It is solved, by taking the latest version 19-pre. The error was that 19-pre (that I installed in November 2019) did not produce a 'grouped' mesh. The issue is described/discussed here: https://forum.freecadweb.org/viewtopic. ... 1&p=211244 (post by bernd » Tue Jan 23, 2018 7:52 pm)

With the latest 19-pre it does work indeed.

Best regards,

Roland

[bernd]