LS Dyna

LS Dyna

UNV file support in LS-Dyna

    • shravanumesh
      Subscriber

      I have a .unv result file from a hot forging simulation from another software. This file contains elements as well as respective temperature data.

      I want to import this file into LS-Dyna with temperature mapping. When I try to import it as an I-DEAS (UNV) file, only geometry data is imported. I could not find the temperature data on it.

      Is there a particular method to import it properly? Am I overlooking any option?

      Kindly let me know. Thank you.

    • Jim Day
      Ansys Employee
      How exactly have you done your importing of the I-DEAS universal data into LS-DYNA?
      From an LST software standpoint (LS-DYNA, LS-PrePost), I believe the only handling of I-DEAS universal files is via LS-PrePost (File>Import>IDEA-S Universal File). Offhand, I don't know the extent of that capability.
      What process do you hope to simulate with LS-DYNA after you import the data from the universal file?
    • shravanumesh
      Subscriber
      I have the end result of a structural+thermal simulation from another software. I want to import only the thermal simulation results to LS Dyna and conduct ICFD considering those thermal results. Is this possible?
    • Jim Day
      Ansys Employee
      Sorry ... I just want to understand where you're going with this. So you have a (deformed) structural geometry with a temperature distribution. What is the purpose of the subsequent ICFD analysis?
    • shravanumesh
      Subscriber
      My initial step of analysis would be the time of contact between workpiece and tool. So I can simulate that by keeping the two in contact and conducting thermal analysis.
      I want to conduct the thermal analysis of the entire forging process but it is difficult to do it with structural simulation in LS Dyna. So my idea is to extract UNV data at certain timestamps and check the results in LS Dyna after using ICFD.
      I would like to include the extreme case (deformed part) as well to compare how effective cooling is. (I am conducting a comparison between simulation with and without ICFD)
      I hope my motive is clear but feel free to ask more.
      Thank you for your prompt replies!
    • Jim Day
      Ansys Employee
      This forum doesn't allow passing of models (except those in the public domain) so it more or less forces a somewhat abstract discussion. That being the case, it still is not clear to me why you're taking the approach you're taking.
      There is a thermal solver in LS-DYNA (*CONTROL_SOLUTION, SOLN=1 or 2) that has nothing to do with ICFD. It allows a thermal-only analysis (steady-state or transient) or a coupled mechanical-thermal analysis. If you don't want to do a full-on coupled mechanical-thermal analysis, you may be able to break the phases of your simulation into pieces, invoking only the thermal solver or only the mechanical solver (driven by prescribed temperatures) in each piece of the simulation. For example, *LOAD_THERMAL_D3PLOT allows temperatures computed in a prior LS-DYNA thermal-only analysis to be used to load an LS-DYNA mechanical-only analysis.
      Explain to me why a third party code or ICFD analysis in LS-DYNA is necessary.
      Or perhaps the best way to clarify things is for you to point me to an application on the web, say from dynalook.com, that is similar to yours.
    • shravanumesh
      Subscriber
      Thank you for your suggestion regarding dividing my simulation. I will try to achieve my aim with this method.
      Why ICFD?: I am designing cooling channels for a tool in hot forging process so I need a thermo mechanical simulation. I tried to simulate the mechanical bulk forming in 3D in LS-Dyna but I have been having issues with contact, remeshing etc. I found it easier to simulate (mechanical part) in another software but that software does not have CFD capabilities (thermal part). Hence I am implementing ICFD in LS-Dyna.
      Why UNV?: My workpiece is initially in contact with several tools in the simulation and thus has a varied temperature profile. I am assuming it would be faster to take UNV temperature data instead of conducting a thermal simulation of the entire machine. Please feel free to correct me if my approach is not feasible.
      There are not many examples of bulk metal forming for LS-Dyna. Regarding cooling, there is an example for tool cooling that I have derived from. I am sorry that I cannot provide you a proper reference.
    • Jim Day
      Ansys Employee
      I'm getting a better idea of your situation now.
      Do I understand correctly that your original intent would be to import a snapshot of the temperature distribution in your near-rigid tool in order to do a design study of the cooling channels in the tool using ICFD in LS-DYNA? In other words, the ICFD analysis would not involve any mechanical response of the tool (no stresses or deformation). You just want to study cooling trends using ICFD. Is that right?
    • shravanumesh
      Subscriber
      Yes, that is my approach.
    • Jim Day
      Ansys Employee
      I spoke to our ICFD team.
      "There is a new keyword available in versions Dev/R13, called ICFD_INITIAL_TEMPNODE which allows the user to give an initial temperature for each internal node ID of the ICFD surface mesh. So he may be using that but it may involve some codding and file manipulation on his behalf which, I agree, could be cumbersome. The keyword ICFD_INITIAL also allows the user to use *DEFINE_FUNCTION to define a temperature but again, not great for what he wants to do."
      To be continued.
    • shravanumesh
      Subscriber
      Thank you so much for the information! This answers my question. I will give it a try keeping my time limitation in mind and update here if it is feasible.

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