General Mechanical

General Mechanical

How to run a coupled field transient?

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    • rezam
      Subscriber

      @peteroznewman

      Hello

      I am going to run a coupled transient analysis which calculates the deviation in atomic concentration from an initial value due to the combined effect of diffusion, electromigration (electrical), thermomigration (thermal), and Stress migration (structural). I found an example in demo ANSYS website as "electromigration in solder ball) - chapter 47.

      I followed steps and wanted to calculate the voltage deviation ( electrical resistivity calculation). but the issue I have is that the output parameters dont change over time.

      APDL commands in WB.

    • Bill Bulat
      Ansys Employee
      Hi. I think that physically, the VOLT and TEMP responses will reach steady state long before the end of the transient at 5.4e5 seconds, and that we should expect their calculated values to be constant over the duration of the transient. Now, the CONC DOF varies much more slowly. For example, in TD47 which you mentioned, the calculated response of the concentration is seen to vary gradually and significantly over the very long 6.3e7 second (2 year) transient:
      How does your calculated CONC look?
      If you download the MAPDL input file for TD47, solve it, and, using POST26, plot the time variation of calculated TEMP and VOLT at one of the nodes, you will see that they are constant (very small variations are probably attributable to "numerical noise" from time integration):


      Time integration should probably be turned off for structural and thermal DOFs in runs like these (e.g., TIMINT,OFF,STRUCT and TIMINT,OFF,THERM).
      I hope this helps.
      Kind regards,
      Bill
    • rezam
      Subscriber
      Dear Bill
      Thanks for your prompt reply.
      I went through a paper attached above. This paper claims that resistance (or Voltage) changes over the time ( figure below). Could you please take a look on this paper ? I also want to know more on POST26, and MAPDL. I dont know how you got VOLT vs. time in MAPDL. Is it possible to share your file here with me.
      Look forward to hearing from you at your earliest convenience.

      Thanks Reza


    • rezam
      Subscriber
      Dear Bill
      Thanks for your prompt reply.

      Antonova, Looman - 2017 - Finite Elements for Electromigration Analysis.pdf
      618.32KB
      I went through a paper attached above. This paper claims that resistance (or Voltage) changes over the time ( figure below). Could you please take a look on this paper ? I also want to know more on POST26, and MAPDL. I dont know how you got VOLT vs. time in MAPDL. Is it possible to share your file here with me.


      Look forward to hearing from you at your earliest convenience.

      Thanks Reza
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