creation stiffness matrix

ElineH
ElineH Altair Community Member
edited October 2020 in Community Q&A

Hi,

 

I was wondering how the creation of the stiffness matrix is defined. I don't mean how I implement it but I mean how OptiStruct knows how to generate a stiffness matrix. I was looking in the documentation for this but couldn't find it. Can someone help me?

 

Thank you

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Answers

  • FaroukM
    FaroukM Altair Community Member
    edited April 2020

    Hi Eline,

     

    You can do PARAM -> POST_V1 and then select -5. you will have Stiffness and Mass matrices (op2 file). But I don't know how to read them ...

     

    If you have any idea how to read *k.op2 or convert it to an ASCII file, please let me know.

     

    Thank you,

  • eit56611
    eit56611 Altair Community Member
    edited April 2020

    I would like to know how to export full global stiffness and mass matrices in Optistruct to an ASCII file as well. PARAM > POST > POST_V1 set to -5 seems to be outputting some mass and stiffness files to op2 format but they are binary and thus not human readable. Any help is appreciated; thank you.

     

    For some reason, PARAM > EXTOUT > DMIGPCH doesn't output the full global matrices.

  • FaroukM
    FaroukM Altair Community Member
    edited April 2020
    Altair Forum User said:

    I would like to know how to export full global stiffness and mass matrices in Optistruct to an ASCII file as well. PARAM > POST > POST_V1 set to -5 seems to be outputting some mass and stiffness files to op2 format but they are binary and thus not human readable. Any help is appreciated; thank you.

    I'm looking for the same thing. I found python package 'pyNastran' to read op2 file.

    https://pynastran-git.readthedocs.io/en/latest/

     

    I'm exploring this package ... I will let you know if I found something ;)

    Altair Forum User said:

    For some reason, PARAM > EXTOUT > DMIGPCH doesn't output the full global matrices.

    Yeah indeed, it's a reduced matrices ....!

  • adrian_aquino
    adrian_aquino Altair Community Member

    @FaroukM did you find how to use pyNastran to read stiffness and mass matrices?

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