MFLUID as MODAL BASE for a MODAL FREQUENCY RESPONSE

Altair Forum User
Altair Forum User
Altair Employee
edited April 2021 in Community Q&A

Hello,

 

I have an enclosed volume with a fluid inside.

And I have to apply an Acceleration PSD to it.

So:
1) I am using MFLUID with VMOPT 2 in order to obtain a good modal base for my analysis.

2) To simulate the pressure, I am using a PLOAD4.


I've made several tests for this Analysis to work, but my RMS Von Mises is incredibly high.

I tested:
1) Normal Modes of the Structure with and without MFLUID: all is OK and I can see a reduction of the Frequency.

2) Modal Frequency Response without MFLUID is OK: the RMS values are pretty low - around 4-6 MPa.

3) BUT the Modal Frequency Response with MFLUID gives me HUGE RMS values.
4) I checked the Eigenvector Values of the Normal Modes Analysis - with and without MFLUID. The analysis with MFLUID has numbers around 1000 times higher.

 

Question: is there some way of obtaining a good Modal Base for a Modal Response Analysis, by using the MFLUID card?

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Answers

  • Rahul Rajan_21763
    Rahul Rajan_21763 New Altair Community Member
    edited July 2016

    Could you share us .fem file?Which version of Optistruct you are using?

  • Rex_22369
    Rex_22369 Altair Community Member
    edited April 2021

    I am facing the same problem, so do we need active the MFluid during the modal frequency response simulation?

    Thanks if you can give me suggestion!

     

     

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