Element definition (eg. Type=Mass, Type=T3D2) in combination with composite option on *shell section card (*ERROR in changekon)

[hkuhl]

Hi all, I ran into another issue with defining an element Type=Mass. In fact, that problem seems to be somewhat independend from the type of element that is created (I tried Type=Mass and Type=T3D2 [Truss]) element). As soon as I use the option “composite” on the shell card, I get the follwoing error message:

*ERROR in changekon: element type unknown: element: 1000000 type: MASS

When I reduce the number of composite layers to one, the model runs with no problem.

A similar Issue has been reported here: https://calculix.discourse.group/t/layered-shell-composite-with-spring-element/414

A solution seems to be to edit the file "changekon.f".

To replicate the issue please review the attached input file:

Composite Option with manual Element definition.zip

The fix of this bug, if it is one, would be highly appreciated.

[victorkemp]

That also happens with GAPUNI and S4.

[hkuhl]

I just noticed a similar issue with DISTRIBUTING COUPLING using ELEMENT,TYPE=DCOUP3D. The model does not solve as soon as I define more than one layer in the shell section (with only one layer defined, it works). But this time I do not get an error message, just the information "Job failed - no results exist." Composite Option with ELEMENT,TYPE=DCOUP3D.txt

[victorkemp]

In changekon.f, a few elements appear to be omitted from the list, and would cause that error when used with composites. They are:

• S3
• S4
• S4R
• M3D3
• CPS3
• CPE3
• CAX3
• T2D2
• T3D2
• T3D3
• GAPUNI
• SPRING1
• SPRING2
• MASS
• Uxxxx (depending on the name),
• U1
• US3

I think that code is just finding the number of nodes of the expanded+original element so most of them are probably easy to add, like S4 would have 4+11=15 nodes, S4R would have 4+8=12 and MASS would have 1.

It looks like DCOUP3D is being treated the same as D (network element) with 3 nodes instead of 1? Maybe that's why it fails??

[victorkemp]

Hello Guido. I see you've added the other element types to changekon.f (except 2D beam and truss?), however it still doesn't work because iponor is not updated. Here's an example that does now solve in the current development version but the solution's mesh is wrong because the elements' shapes are messed up and the beams are disconnected from each other as you can see in the attached picture.

This problem is resolved in my pull request: https://github.com/Dhondtguido/CalculiX/pull/41

composite_and_B31.inp.txt