I am getting 20 lakh sec as a solving time in radioss

Shrikant Sawant
Shrikant Sawant New Altair Community Member
edited December 2020 in Community Q&A

I am getting 20 lakh sec as a solving time in radioss. I am unable to rectify my mistakes. I have done element check but zero error has found and I have done model check. I am attaching FEM file below. Please help me in this case

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Answers

  • Mathieu Nové_20389
    Mathieu Nové_20389 New Altair Community Member
    edited November 2020

    Hi,

    You have a very bad mesh size quality.

    The smaller solid element is 0.091786mm and 66% of your model has element size lower than 1mm.

    You can see this information in the 0000.out / 0001.out or in the model checker with HyperMesh. Attached screenshots of the 3 methods.

    Mathieu

  • Andy_20955
    Andy_20955 New Altair Community Member
    edited December 2020

    Hi,

    For an explicit analysis like Radioss, the smaller the elements the smaller the timestep.  The smaller the time step the more cycles an analysis needs to run to solve and thus longer run time. 

    Some possible solutions,

    -Increase mesh size

    - run using more cores and the -np option.  So if you have a machine (or a cluster) with 20 cores in the CPU use -np 20.  Your

    - Shorten simulation time

    - increase time of load application (for static analysis)

    -use mass scaling /DT/NODA/CST, but not too much because then it changes the dynamics of your simulation.  Looking at your *0.out file you can see you have a only a few nodes < 1.5e-8.  So you could use 1.5*0.9 = 1.35-e8 for your time step up to may even 1.5e-8.  How much mass that can be added without changing the results depends on the simulation.

    /DT/NODA/CST

    0.9 1.35e-8

     

          TIME STEP       NODE NUMBER
      1.0485157361978E-08          31313
      1.1067017188659E-08          14700
      1.1296881178866E-08          29782
      1.1367257309381E-08          14815
      1.2129559673374E-08          15404
      1.2244650098704E-08          13402
      1.2655623756470E-08          15445
      1.2690038688843E-08          15493
      1.2707462889747E-08          13429
      1.2858554447847E-08          30020
      1.3305910671615E-08          29766
      1.3362628573182E-08          13579
      1.3543796525879E-08          30238
      1.3657003889043E-08          15315
      1.3873096137125E-08          15602
      1.3940235732351E-08          31925
      1.4107382793890E-08          29209
      1.4124196487242E-08          31123
      1.4128107416908E-08          31813
      1.4235348864991E-08          14614
      1.4281498065994E-08          15534
      1.4301371183887E-08          15346
      1.4343475736192E-08          15372
      1.4418790017203E-08          13775
      1.4739680553764E-08          30862
      1.4967510040948E-08          31984
      1.5100483928929E-08          29777

     

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