oka wear calculations have poor repeatability

supermaker
supermaker Altair Community Member
in Community Q&A

When using the OKA model for GPU-based wear calculations in EDEM, the wear depth results are inconsistent when calculating the same model twice. However, the results are consistent when using the Archard model.

image.png

This is the first calculation

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I just roll back the time step to the beginning and click on start the second run.

image.png

Obviously the second calculation is larger than the first, with an error of 5.5%. Sometimes it is smaller than the first.😓

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Best Answers

  • Stephen Cole
    Stephen Cole
    Altair Employee
    Answer ✓

    Hi,

    It looks like the mesh is quite coarse, I'd recommend making the geometry mesh about the same size as the particles if looking at wear. I'd also make sure you are using the default settings in the simulator Advanced Settings, also recommend using Double Precision to test if that makes a difference.


    Regards

    Stephen

  • PrasadAvilala
    PrasadAvilala
    Altair Employee
    Answer ✓

    Hi,

    In addition to Stephen Cole comments, I want to add another point i.e

    the another reason for difference of wear in 2 simulation are the way particles created and rotated the drum i.e if you create material and rotate the drum as a sequence of operation then there is a possibility of difference is due to factory settings( random generation creates particles each time at different position and orientation which may lead small difference in results) However the error in your simulation is in 6th or 7th decimal and it might be negligible I feel.

    Thanks,

    Prasad A

Answers

  • Stephen Cole
    Stephen Cole
    Altair Employee
    Answer ✓

    Hi,

    It looks like the mesh is quite coarse, I'd recommend making the geometry mesh about the same size as the particles if looking at wear. I'd also make sure you are using the default settings in the simulator Advanced Settings, also recommend using Double Precision to test if that makes a difference.


    Regards

    Stephen

  • PrasadAvilala
    PrasadAvilala
    Altair Employee
    Answer ✓

    Hi,

    In addition to Stephen Cole comments, I want to add another point i.e

    the another reason for difference of wear in 2 simulation are the way particles created and rotated the drum i.e if you create material and rotate the drum as a sequence of operation then there is a possibility of difference is due to factory settings( random generation creates particles each time at different position and orientation which may lead small difference in results) However the error in your simulation is in 6th or 7th decimal and it might be negligible I feel.

    Thanks,

    Prasad A

  • supermaker
    supermaker Altair Community Member
    edited January 23
    https://community.altair.com/discussion/comment/188959#Comment_188959

    Hi,

    However, I noticed that for the same model, the calculation results of the Archard model exhibit excellent repeatability, with the curves perfectly overlapping. This seems a bit strange.

    Thanks,

    zhou

  • supermaker
    supermaker Altair Community Member
    https://community.altair.com/discussion/comment/188959#Comment_188959

    However, the Archard model exhibits excellent repeatability, with virtually no deviation and perfect overlap. Why is this the case?

  • PrasadAvilala
    PrasadAvilala
    Altair Employee

    Hi,

    If Archard wear is giving consistent results, then there might be so many factors i.e Is the wear being dominant due to abrasive or Impact, if it is impact dominant it is obvious that Archard wear can't show much improvement as Archard wear is based abrasive wear dominant behavior.

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