How can I transform the force or pressure data calculated by openfoam into the initial stress condition of calculix?

1

Hi, everyone.
Now, I am doing the coupling between openfoam and calculix by precice. I am dealing with the pre-stretched membrane. But now, the couped simulation diverged at the first time step. I guess that there is an initial force on the membrane in openfoam but I don’t set this in calculix, which makes the simulation diverged. So I want to put the force or pressure data calculated by openfoam at the first time step as the initial stress condition of calculix. How can I do it? The force and pressure files are attached as following.

force_pressure
force_pressure1657×502 660 KB

2

There are tools that can convert pressure results from OpenFOAM to load acting on the surface of the model but I don’t think there are any existing tools that could convert such results to initial stress condition. You may have to write a script for that or use the aforementioned approach, run a simulation with these loads and then use the obtained stresses as initial condition.

1 Like
3

Thank you so much.
If I don’t misunderstand, you mean that I can do as following steps.
Step1, convert pressure results from OpenFOAM to load acting on the surface of the model
Step2, use these load data to conduct simulation in calculix to get the stresses
Step3, apply stesses as initial condition.
For the step 1, could you recommend one tools for me to convert pressure to load?

4

PrePoMax (open-source pre- and postprocessor for CalculiX) has such a feature.

5

Thank you so much. I’ll try it. Have a nice day!

6

hi, it seems CGX capable to map loads from existing results format (*frd files).

Sets will be created if defined in the openFoam file. Results can be used for mapping purposes. For further details see “How to map loads” in the appendix.

If the master values are not available in either inp or frd format but in any other format which can be read by cgx (isaac, openFoam …) you may write them in frd format with the ”send” command to be usable as a master.

more detail can be found in CalculiX GraphiX (CGX) documentation.

7

Thank you so much. Now I am learning PrePoMax and plan to use it. I will also try your suggestion.