Extract full System Matrices K M D

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

Hello,

 

I need to extract the System Matrices K (stiffness) M (mass) and D (damping) of an optistruct model. I know I can do it with PARAM,EXTOUT,DMIGPCH and the definition of an ASET1. To obtain the complete matrices, I wa ssimply adding all nodes to the ASET1. It works but I have the following Problem:

 

When I solve the Eigenvalue Problem with the obtained Matrices, I am missing the 6 rigid body modes. Probably because the ASET1 is a boundary set which means no RBMs.

 

Do I have any Option to obtain the full Matrices including the rigid Body modes?

 

Thank you in advance,

Gesa Popesa

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Answers

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited November 2018

    Hi @Gesa Popesa

     

    I checked on OptiStruct document and I don't see a way to get the rigid body modes. 

     

    I need to check with the experts. I will get back to you soon.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited November 2018

    Okay, let s wait what the experts say!

     

    Thank you for your support!

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