Import voltages 1

[vepawz]

I'm trying to transfer voltages between two coupled thermal-electric analyses. Any suggestions?

I tried going the pre-defined field route but I can only import 'epot' as a field variable to modify material properties using USDFLD. So, not helpful.

I also can't use DISP to import voltages since I don't want it as a boundary condition but more as an initial value.

Any help is appreciated. Thanks!

 

[FEA way]

You can’t use initial conditions (predefined field for initial step) for this purpose because in coupled thermal-electrical analysis only steady-state electrical currents are considered. Import capability (Predefined Field —> Initial state) won’t work as well since it doesn’t support coupled thermal-electrical elements.

However there is another way to do it. You can define analytical (mapped) field to map electrical potential from previous analysis to next one. This capability is described in the „Creating mapped fields from output database mesh data”. To do it in this case you should follow these steps:
- open .odb file with results from first analysis, switch to EPOT at the last frame
- create second viewport, tile viewports vertically and in the new viewport open CAE model for second analysis, continue with this viewport selected
- create new boundary condition for the first step, select Electrical/Magnetic category and choose Electric potential, select whole model as a region, type magnitude of 1 and click the „Create Analytical Field” button
- choose Mapped field, select „ODB mesh” as Data source and select Viewport 1 (the one with .odb file from previous analysis opened) as Viewport to map, click Ok
- in the Edit Boundary Condition window change the Distribution to AnalyticalField-1 (the one just created)

 

[vepawz]

Thanks for reply. But won't this apply a boundary condition i.e. the voltages at the selected nodes will remain fixed for the entire analysis? I want to define only the initial values of voltages at all nodes; the voltages should be able to be updated throughout the analysis.

Now that I think more about what you said, once I import voltages as bcs, I could create a second step (of the coupled thermal-electric kind as well). This way the bcs from first step would serve as initial conditions for the second step.

Do you think that this would work?

 

[FEA way]

Exactly, you can turn this boundary condition off in the second step. I'm afraid that it's the only way to do it since Abaqus doesn't support initial voltage in any form (due to the fact that it ignores transient current effects in thermal-electrical simulations, like I've mentioned before).

 

[vepawz]

Yes, thank you.

Since I'm using input files to do all this, I'll have to resort to using DISP subroutine to prescribe voltages. Is there an easier way around the subroutine?

 

[FEA way]

Even when you've been working directly in the input file so far, you can still import such file to CAE (File --> Import --> Model and set filter to .inp files). Then make sure that everything was imported CAE correctly (some more advanced options tend to disappear when they are not supported in CAE) and use the procedure described above to create mapped field with voltage. But if you still don't want to use CAE then I think that you could read voltage from nodes in previous analysis, save it to text file and then apply it to nodes in new analysis.