Create new output data in FEM

About the development of the FEM module/workbench.

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EmviiP
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Create new output data in FEM

Post by EmviiP » Thu Jun 10, 2021 6:56 pm

Hi I'm new to FreeCAD
I was trying to follow the FEM tutorial "Modelling of Post-tensioned Concrete", but I noticed that there are some properties / node data that I don't know how was made

For example the property "reinforcement ratio_x" , how is that made.
I know I can make a user defined formula in the gui but that only creates a single data array. How would I add multiple of my own data arrays/properties that I can look at in a post-processer like Paraview?
chrisb
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Re: Create new output data in FEM

Post by chrisb » Thu Jun 10, 2021 8:27 pm

Moved to FEM forum.
A Sketcher Lecture with in-depth information is available in English, auf Deutsch, en français, en español.
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bernd
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Re: Create new output data in FEM

Post by bernd » Fri Jun 11, 2021 5:22 am

Hi and welcome to FreeCAD FEM.

Which FreeCAD version are you on?

Have you tried the FEM example GUI on utilities menu? There is a reinforcement material example.
EmviiP
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Re: Create new output data in FEM

Post by EmviiP » Fri Jun 11, 2021 1:03 pm

Hi Bernd
I'm on the newest FreeCAD version 0.19.2

Yes I have tried the 2D RC Wall example but it does not show me how it adds new node data.

See attached image Image (https://imgur.com/a/QwATm8U)
As you can see there is no data in the Peeq property. I would like to learn how i could create that data and how I could create my own data for working on in post in Paraview.

I feel like I'm really bad at explaining my problem but I hope you kinda understand what I'm looking for.
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bernd
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Re: Create new output data in FEM

Post by bernd » Fri Jun 11, 2021 3:00 pm

you can add pictures in the post. This way they will be there even in a few years ...

the picthure from the last post:
RWTjakr.png
RWTjakr.png (46.57 KiB) Viewed 873 times
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bernd
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Re: Create new output data in FEM

Post by bernd » Fri Jun 11, 2021 3:02 pm

- to fill the PEER data you need to make a nonlinear material analysis and deform the structure in a way there will be peeq stress. As said use the exammple files. If you run the nonlinear material example there will be PEEQ strain filled in. If you run the reinforced material example the reinforced strain will be filled. If you run a thermomechanical analysis the temperature will be filled in. E.T.C. ...

- Which node data do you miss in the result object?
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bernd
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Re: Create new output data in FEM

Post by bernd » Fri Jun 11, 2021 3:04 pm

EmviiP wrote: Fri Jun 11, 2021 1:03 pm I feel like I'm really bad at explaining my problem but I hope you kinda understand what I'm looking for.
That is true. I have not yet understand 100% what your problem is.
EmviiP
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Re: Create new output data in FEM

Post by EmviiP » Fri Jun 11, 2021 8:22 pm

Okay my bad for using a bad example, I should not have used peeq.
What if I wanted to look at strain energy density in post, how would I go about adding that to the output?
I Know I could define it in the user defined formula but that only allows for one set of data. What if I for whatever reason wanted to also output some other not pre-defined data sets?
I'm thinking I probably have to use python and then operate on the result object and add the strain energy density as a property? I'm just guessing here.
Again I'm very sorry for my confusing questions :?
I just want to know how I can add my own outputs that are not predefined, like I can see Von mises, displacement and so on are.
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bernd
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Re: Create new output data in FEM

Post by bernd » Fri Jun 11, 2021 9:22 pm

this is possible, just add another attribute to the result object by python. This could be done python on runtime.

But be aware this will not be exported to vtk. For this recompiling FreeCAD and changes in Cpp would be needed.

Means the question is, what would you do with such a result?

I am on the way. Later on I may post a simple example how to add new attributes to the result object during run time.
EmviiP
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Re: Create new output data in FEM

Post by EmviiP » Fri Jun 11, 2021 11:33 pm

Oh I was not aware it would be that involved.
If it is not possible to export it to vtk then I might as well just use the "user defined formula" part. Hower, if it is not too much trouble i would still like to see your example on how to add new attributes to the result object during run time.
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