Negative Volume - Hourglass

Altair Forum User
Altair Forum User
Altair Employee
edited October 2020 in Community Q&A

Hello,

 

I am studying the compression of a soft material (hyperelastic) with RADIOSS.

But it seems like a hourglass effect happens during the compression (as you can see on the attached screenshots).

- I used [Ismstr] =2 and [Isolid] =1

- with /DT/BRICK/CST    0.67   0.0001

- material=LAW42 (Ogden) nu=0.495 (incompressible)

I can send you the .RAD files if possible.

I am trying full integration [Isolid] =12, but the computation time is really (really) increased even if the result seems better (for the begining of the compression).

 

I also got a poblem as the script in the other screenshot. I do not really know where it comes from... If you can help me please?

 

Thanks,

 

Corentin

<?xml version="1.0" encoding="UTF-8"?>Erreur apres remaillage v2.3.PNG

<?xml version="1.0" encoding="UTF-8"?>Animation (VonMises).png

<?xml version="1.0" encoding="UTF-8"?>Animation (VonMises)2.png

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Answers

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2017

    Hi Corentin 

    Please update with Isolid=24 (HEPH forulation) which is an improved reduced integration element with physical hourglass stabilization, which will run faster than the fully integrated solid elements. And moreover please ensure that the material parameters are correct. If the issue persist, please share the model files.

    In HyperView, please go to Preferences> Option> Performance> click on Accelerated Graphics check box for fixing the graphics issue.

     

     

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2017

    Hi George,

    Thank you. It is actually faster with  Isolid=24 (HEPH formulation). I have to check material parameters now because there is still hourglass effect (as you can see on the attached screenshot).

    The computation with  Isolid=12 (full integration, no hourglass) give a better result, but is really longer (4*longer). By the way, it seems that material parameters are fine, I guess.

     

    And even if I tried to change preferences option, I cant 'apply' because the same error messages come up... Then I can't actually select this option.

     

    Best regards,

     

    Thanks,

     

    Corentin

    <?xml version="1.0" encoding="UTF-8"?>screenshot v2.6.png

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2017

    Hi Corentin,

    Please share the model file so that we can have a workaround on the parameters.

    I think updating graphics card will fix the issue of HyperView error. Can you please update the drivers and update the status.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited November 2020

    Hi George,

    Thanks for your help. There are .rad files (with  Isolid=12 (full integration, no hourglass)), wich is my best result.

     

    I do not know what means 'update the drivers and update the status'. But I will try to figure it out.

     

    Best regards,

     

    Thanks again,

     

    Corentin

    <?xml version="1.0" encoding="UTF-8"?>screenshot v2.7.png

    Unable to find an attachment - read this blog

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited March 2017

    Hi Corentin,

    Please check and ensure that the material parameters used in the model are correct. Any wrong or unclear data provided during material characterization will lead to uncertain results. I have changed the material law to /MAT/LAW33, which is a foam material, and the same simulation is attached along.Please review it and let me know whether you looking for such a behavior of the material?.

    I was suggesting you to update the graphics driver of the system, which will fix the HyperView issue.

    Unable to find an attachment - read this blog

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