At first i want to introduce myself: i studied material science at Montanuniversität Leoben 24 years ago, and since them i’m working in a steel producing factory.
since some weeks i have to do small FEM calculations, and so i found calculix and prepomax → i have to say “Thank you” for your work!

So now my problem: i want to do coupled, or uncoupled temperature-displacement calculations. for testing reasons i tried a small geometry and did the calculation with one of
the steels in the program - no temeprature dependence of the material parameters - it worked.
But: when i created a “new” steel with temeprature dependent parameters (calculatet with JMatPro) i get unbelivable results; somtimes the calculation stops, or the
diplacements are “exploding” at some points.

so i have questions: can you give me a hint and are there constraints concerning the temperature-dependent parameters of the material ( i have the calculated parameters
from ~1400°C down to 25°C).

Maybe there’s some mistake/typo in your data. Can you share it ? Possibly also with the PrePoMax model. You could use some hosting website and paste the link here.

I’m surprised that CalculiX allows this, in Abaqus temperature and other independent variables have to be specified in ascending order and I would stick to that approach.

Instead of heat transfer step followed by coupled temperature-displacement one, I would use two coupled steps.

Is that supposed to simulate a specific process or is it just an abstract test ?

is just an abstract Test, but following i want to do a more complex structure and at first i wanted to get shure, that the calculation do not stop or bring “satisfying” results when it runs in the night;-)

I see. Temperature-dependent properties should work fine and the values you have look good. Maybe apart from this abrupt change in elastic properties which may cause convergence issues:

Yes, steel getting almost zero Young’s modulus at 1475 degrees is clearly liquefying. Iron-carbon phase diagram can show it for different types of steel.

and yes - it’s a phase transition. I will cut the properties at high temperatures to eliminate the liquid phase But i have a second transition (solid-solid) from ~550 to ~650°C. I think there i have to smoothen the properties to get convergence in the calculation.