How to use Z88 in FEM?

[AhmedER]

I get no results either. I need to have a closer look. This may take some time.

To try if your z88 runs in FreeCAD you could do the following.

- start FreeCAD
- go to start wb
- load 3D FEM example
- activate the analysis
- add an solver z88 object
- select the z88 solver
- click on the run analysis button
- a new result object should be created. You should get the same deformations as with Calculix

bernd

I did and it works with the 3D FEM example. When retrying my truss problem I noticed the following text in the Report view

"Edge femmesh will be exported as 3D truss element nr 4
{'ISFLAG': '1', 'INTORD': '0', 'INTOS': '0', 'IHFLAG': '0'}
Multiple beamsections for Z88 not yet supported!"

Does this mean that it doesn't support 2D beam elements and it converts it to 3D for analysis? Or does it mean that it just fails to analyze them entirely?

[Kunda1]

@bernd does Z88 have a unit test ?

[bernd]

no, there is no unit test at the moment.

multiple beamsections not supported means you only can define one beam sections for all your 1D elements. The multiple beam sections are not implemented for z88 in FreeCAD.

Just saw it on your sceen, you have two beamsection objects, there can only be one for z88 atm.

bernd

[Kunda1]

no, there is no unit test at the moment.

Should I open a FEM ticket for this ?

[bernd]

no, there is no unit test at the moment.

Should I open a FEM ticket for this ?

you could, but it is not somewhere near the top of my todo

[bernd]

i would cal it fem solver calculix, and we will collect all z88 related stuff there.

[Kunda1]

i would cal it fem solver calculix, and we will collect all z88 related stuff there.

issue #3118

[AhmedER]

no, there is no unit test at the moment.

multiple beamsections not supported means you only can define one beam sections for all your 1D elements. The multiple beam sections are not implemented for z88 in FreeCAD.

Just saw it on your sceen, you have two beamsection objects, there can only be one for z88 atm.

bernd

Even after I deleted one of the two beam elements and the error line disappeared I still get no results.

Instead this error appears
"Base.FreeCADError: PyArg_ParseTuple failed. Invalid arguments used with setNodeByScalars"

[bernd]

Z88 in FreeCAD uses for 1D meshes a truss element, thus you should use seg2 elments and not have nodes between the edgends. Furthermore as far as i know constraint displacement is not supported. But anyway I could your example not get to run. What you could do is to check the error log of z88 it is in the working directory and its name is z88r.log

I attached an example from Z88 homepage. It runs in calculix and in z88

bernd

[bernd]

updated the file from last post.

CalculiX gives max deflection of 64.6 mm
Z88 gives max deflection of 134.0 mm

Would be good to know which is correct of why the other is wrong ...

b2--z88examples--seg2_updated.fcstd

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