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creation stiffness matrix

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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FaroukM

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

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

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

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

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

adrian_aquino

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