## Temperate dependent material properties

A forum to discuss the implementation of a good Materials system in FreeCAD
makkemal
Posts: 395
Joined: Wed Apr 29, 2015 12:41 pm
Location: South Africa
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### Temperate dependent material properties

I really like that material are being handled as a section on it's own.
This is really important

I am working on calculix gas sections
http://www.feacluster.com/CalculiX/ccx_ ... ode74.html

To do this I need material properties as a function of temperature

Code: Select all

``````*FLUID CONSTANTS
1.0022E9,1.69532E-11,270
1.0045E9,1.84135E-11,300
1.0131E9,2.28232E-11,400
1.0292E9,2.66931E-11,500
1.0506E9,3.01677E-11,600
1.0745E9,3.33396E-11,700
1.0982E9,3.62717E-11,800
1.1204E9,3.90084E-11,900
1.1405E9,4.15824E-11,1000
1.1583E9,4.40182E-11,1100
1.1739E9,4.63352E-11,1200
1.1976E9,4.85486E-11,1300
1.1997E9,5.06708E-11,1400
1.2104E9,5.27117E-11,1500
1.2199E9,5.46798E-11,1600
1.2284E9,5.65822E-11,1700
1.2361E9,5.84249E-11,1800
1.2431E9,6.02131E-11,1900
1.2495E9,6.19512E-11,2000
``````
Column 1 to three are the following value:

• Specific heat at constant pressure.
• Dynamic viscosity.
• Temperature.

How would this fir into the current framework ?
I am not sure how to handle this ?

Thanks
Michael
bernd
Posts: 8349
Joined: Sun Sep 08, 2013 8:07 pm
Location: Zürich, Switzerland

### Re: Temperate dependent material properties

good question ... ATM I have no idea. How does other libraries or software handle this.

I see two possibilities for the mathematics
- table with values (range is given due to the values)
- some function and a given range.
JRickF
Posts: 1
Joined: Mon Jul 08, 2019 4:49 pm

### Re: Temperate dependent material properties

I, too, would like to see a database of temperature-dependent material properties in FreeCAD, specifically, thermal conductivity as a function of temperature. For some earlier projects, I gathered the NIST data for the materials that they have measured and wrote a python class to provide access to these data (https://www.cv.nrao.edu/~rfisher/Cryoge ... _data.html) . I'd be happy to share this code and participate in a discussion on how to integrate it into FreeCAD. I'm pretty new to FreeCAD so I'll need lots advice about contribution protocols.

After integrating the NIST data into FreeCADD I assume that one will need some new code to do the right things with it in the FEM module -- presumably an iterative solution code.

Before I retired I did some work with AutoCAD CFD, and their method for specifying temperature-dependent material properties was a user-supplied look-up table. This would be more general than my NIST data python code.

Cheers,
Rick