What units should I choose? How can I read the analysis results correctly?

Betül Özer
Betül Özer Altair Community Member
edited April 2021 in Community Q&A

Hello, I selected gram, mm, ms and N units in the Hypermesh program. I could not understand what the unit of the first frequency value that came out of the modal analysis was. I attach the picture of the analysis result. I would be very happy if you could say numerical values ​​together with their units.

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I'm still not very good at studying units and analysis results. I hope I will learn :)

 

Actually, I have one more question. I want to choose my units ton, mm, s and N. But there is no undertone of hypermesh either. Or I don't know. He will be very happy if you help. I am adding the relevant images.

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Regards,

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Answers

  • Simon Križnik
    Simon Križnik Altair Community Member
    edited April 2021

    Hi,

     

    the unit of the frequency value is Hertz (Hz), which is also defined as cycles per second (s-1).

    A very small (near 0) frequency value indicates a rigid body mode.

    The tonne unit is MGG (megagram) in Hypermesh.

  • Betül Özer
    Betül Özer Altair Community Member
    edited April 2021
    Simon Križnik said:

    Hi,

     

    the unit of the frequency value is Hertz (Hz), which is also defined as cycles per second (s-1).

    A very small (near 0) frequency value indicates a rigid body mode.

    The tonne unit is MGG (megagram) in Hypermesh.

    Thank you, so when I select tonne (mgg), N, mm and s, will i read in MPa on my result screen?imageFor example is this 43.62 MPa?

  • Betül Özer
    Betül Özer Altair Community Member
    edited April 2021
    Simon Križnik said:

    Hi,

     

    the unit of the frequency value is Hertz (Hz), which is also defined as cycles per second (s-1).

    A very small (near 0) frequency value indicates a rigid body mode.

    The tonne unit is MGG (megagram) in Hypermesh.

    imageIs this 82.8214 Hz? (I select mgg, N, mm and s)

  • Simon Križnik
    Simon Križnik Altair Community Member
    edited April 2021
    Betül Özer said:

    Thank you, so when I select tonne (mgg), N, mm and s, will i read in MPa on my result screen?imageFor example is this 43.62 MPa?

    Glad to help.

    Following tonne (mgg), N, mm, s units should give MPa.

    Always follow a consistent set of units:

    https://www.altairuniversity.com/wp-content/uploads/2012/04/Student_Guide_55-57.pdf

  • Simon Križnik
    Simon Križnik Altair Community Member
    edited April 2021
    Betül Özer said:

    imageIs this 82.8214 Hz? (I select mgg, N, mm and s)

    Yes, the frequency units are always Hz.

    You need to make sure to use consistent units for stiffness and mass in order to get the correct frequency result.

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