non linear elastic

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

Hey,

I tried to do to NL elastic Simulation. (followed the steps from the video https://altairuniversity.com/analysis/structural/nonlinear/nlstat-tutorial-pressure-load-on-a-chair/)

but I don't get convergence.

The model works actually with elastic material law. So I don't know what I have to change.

Can someone have a look, please?)

 

Furthermore, I just have the 'yield strength', 'ultimate strength' and 'elongation at break'. so actually it would be enough to put a bilinear material law. is that somehow possible or is there just the way with the table?

 

 

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Answers

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2018

    Hi,

     

    Thank you for sharing the files. I will check and update you soon.

     

    Some suggestions:

     

    1) If you have friction applied, remove friction and run again. 

    2) From the .out file I see that maximum plastic strain is 0.8 which is beyond the small deformation for this problem. Try to run the same model with LGDISP which is for large strain problems and check if this helps. 

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2018

    Hello,

    I tried without friction but it doesn't help

    If I use LGDISP the optistruct changes to radioss and i get problems with the interface type2. ( master nodes and slave nodes are dependent on each other) It's because I used Freeze contact for connecting different fine meshes. I read something about  SpotFlag= 25 in TYPE2 . That is not available in Optistruct, right?

    What is the easiest way to solve the problem?

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2018

    Hi @Oli

     

    Are you using NLSTAT with LGDISP?

     

    if yes this will not convert to RADIOSS in the background.

     

    You need to add LGDISP to the exisiting NLSTAT type and change the NLPARAM to NLPARAM(LGDISP) in loadcase.

     

    ALso, gap elements are not supported with NLSTAT LGDISP. instead use freeze contacts. 

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