General Mechanical

General Mechanical

Nonlinear Unconvergence Issue

    • Autonewbie
      Subscriber

      Hi

      I am running a static nonlinear of pulling a rob with large displacement and bilinear properties but it cannot converge as below... I am not sure what are missing...


    • peteroznewman
      Subscriber
      It looks like it was converging. Did it stop or did you interrupt the solution? If it stopped, what was the error message in the Solution Output? If you stopped or interrupted it, start the Solve again.n
    • Autonewbie
      Subscriber
      Hi Peter, nI guess you are right... But I stop it after it run more than 3 hours for this setup. Wonder how could speed up with any setting? n
    • peteroznewman
      Subscriber
      Best to start the solver then sleep on it. That way, you give it 8 hours to run without interruption. I have had nonlinear models that ran for days.nTo speed up the model without changing your hardware, you must reduce the number of nodes in the mesh. Use large element size in areas of low stress gradient, reserving small elements in areas of high stress gradient where you care about the results. Replace solid elements with shell elements or beam elements. You can also reduce the run time by replacing bonded contact with Shared Topology and limiting the size of faces that have Remote Points attached to them.nIf you can change your hardware, then you need to know how much RAM this model needed. If the model did not run in-core but ran out-of-core, then you should install more RAM if your motherboard supports it. If the model already was running in-core, then adding more RAM will not speed up the solution.nIf your computer has a HDD for storage, then you can speed up the solution by installing a SSD and saving the model on that new drive.nIf you can change the computer and replace it with a new computer, get one with a faster CPU clock frequency. For example, if your current computer CPU frequency is 1.8 GHz and you get a computer with a 3.6 GHz clock, your model will take half the time to complete. If you change the computer, you can also get more cores. For example, if your current computer has 2 cores, and you get a computer with 4 cores, your model will complete in less time, but it won't be exactly cut in half because the performance does not scale linearly with cores the way it does with clock frequency. You could get a computer with 8 cores, but you can only use 8 cores if you have an ANSYS HPC license. The free student license will only run on 4 cores.n
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