Undesired cylindrical constraints behaviour - Hydrostatic Analysis

Bug Reports
1

Hello!

First post here :slight_smile: I have to say that I’m fairly new to PrePoMax/CalculiX but I love it! Thanks to the developpers for this free piece of software!

I’m currently testing PrePoMax by comparing analysis’ results with the Nastran In-CAD module for Autodesk Inventor. More specifically, I’m analysing the shell of an open-top water tank when full. To check the robustness of PrePoMax (v2.2.9-dev), I compared the results for the following analysis:

  • Full 3D solid analysis - Shell nodes of tank free
  • Partial (1 deg revolution) 3D solid analysis - cylindrical constraints
  • Full shell analysis - cylindrical constraints on shell
  • Partial (1 deg revolution) shell analysis - cylindrical constraints on shell
  • 2D axisymmetric of tank of half cross-section. (On a side note, the draftsman did not generate the shell on the positive side of the radial axis, causing nonpositive Jacobian errors, I simply reversed the normal of the plane to solve the error, ignoring the “negative Z” warning.)

For the full shell model analysis, I get non-expected displacements results. I restricted the shell nodes in the revolution direction (theta or T) based on a cylindrical coordinate system but free in the R direction, and it seem the model reacts as if it’s a rectangular coordinate system. Am I doing something wrong? Is it a bug?

Thanks!

Capture d’écran 2025-01-21 144954
Capture d’écran 2025-01-21 144954994×713 201 KB

2

Did you select the local CSYS when defining the BC ? Can you share the .pmx file ?

3

Yes I selected the local CSYS for the BC. As a new user I can’t add attachements, here is a link to the pmx file :

The link will expire after 3 downloads or in 3 days.

Thanks!

4

removed (mistake) … :sweat_smile: