damping coefficient

Nancy Jewel Mcdonie
Nancy Jewel Mcdonie Altair Community Member
edited June 11 in Community Q&A

Hi all, 

I'm so confuse between these parameters: 

  • uniform structural damping coefficient 
  • viscous damping
  • critical damping ratio

Can anyone make it clear for me?

Thanks. 

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Answers

  • Rajashri_Saha
    Rajashri_Saha
    Altair Employee
    edited June 11

    Hi Nancy,

    You can define Structural damping by specifying the value in PARAM, G card. Structural damping is related to displacement of the system.

    Viscous damping is related to velocity of the system. Water, oil and air can generate viscous drag forces. While doing Transient analysis, you can use PARAM, W3 and PARAM, W4 to convert structural damping to viscous damping.

    Critical damping ratio= Actual damping force/Critical Damping force. This value is half of Structural damping value. If you are using Structural damping as 0.06 then Critical damping will be 0.03. You can define this in SDAMPING card while doing MFRF with TYPE=CRIT.

    image

    Hope this clarifies your query.

    Thanks

    Rajashri

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