How to define Inertia reference point.

David_Lindberg_1
David_Lindberg_1 Altair Community Member
edited May 2023 in Community Q&A

Hi,
I'm trying to verify the mass data (mass, CM, Inertia) for the flexible bodies that I've imported to MV. According to the info bar (see picture) the inertia data is with respect to the body system and the CM is wrt to the global system. 
image
As default, the body system marker is coincident with the global system. I'd like the body system to have origin at the CM of the part, so that I instead get the inertia data presented wrt to the CM of the part. 

This can be changed, however, when I change the body system marker location, then the part is translated in space. Thus, what I've accomplished is instead a translation/rotation of the part. Not the change of the reference point for Inertia presentation. 

Is there a way forward within MV, or should I instead work with GRDPNT parameter in Nastran (optistruct?)

Cheers,
David


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Best Answer

  • Praful
    Praful
    Altair Employee
    edited May 2023 Answer ✓

    Hello David - For a flex body, the Body Coordinate System is a reference frame that positions the body. The inertia properties are derived from the flex h3d file.

    You may obtain the inertia data with respect to the CG or any other point and coordinate system using Tools > CG/Inertia Summary

    image

    In the new MotionView interface (within the new HyperWorks image), the entity editor for the flex body shows the information as you expect, w.r.t the CG coordinate system

    image

    Regards

    Praful

     

Answers

  • Praful
    Praful
    Altair Employee
    edited May 2023 Answer ✓

    Hello David - For a flex body, the Body Coordinate System is a reference frame that positions the body. The inertia properties are derived from the flex h3d file.

    You may obtain the inertia data with respect to the CG or any other point and coordinate system using Tools > CG/Inertia Summary

    image

    In the new MotionView interface (within the new HyperWorks image), the entity editor for the flex body shows the information as you expect, w.r.t the CG coordinate system

    image

    Regards

    Praful

     

  • David_Lindberg_1
    David_Lindberg_1 Altair Community Member
    edited May 2023
    Praful Prabhu_20784 said:

    Hello David - For a flex body, the Body Coordinate System is a reference frame that positions the body. The inertia properties are derived from the flex h3d file.

    You may obtain the inertia data with respect to the CG or any other point and coordinate system using Tools > CG/Inertia Summary

    image

    In the new MotionView interface (within the new HyperWorks image), the entity editor for the flex body shows the information as you expect, w.r.t the CG coordinate system

    image

    Regards

    Praful

     

    Thank you Praful!

    Regards,
    David

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