Transient analysis: results are not as expected

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

Dear all,

I'm analyzing the vibrational behavior of a sub-group into a Gear box. First of all I ran the modal analysis and I found that 3 and 4 vibrational mode are in a range of frequencies that could create some problems. Now I'm running a Transient analysis assigning to some nodes a sinusoidal force whose frequency corresponds to 3 and 4 vibrational mode. I observed that displacement are extremely low and, thinking that there was something wrong with assigned damping, I removed it from the params of the analysis. So, theoretically, I should expect very high displacement if system running at resonance frequency, but that does not happen. I've attached the Optistruct model. Please help me to understand how I'm wrong.

To assign the force in TABLEID1 card I used a sampling rate equal to

 

fi/10

 

 

 

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Answers

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited October 2018

    Hi @Ferrari248F1AQ

     

    What is the load type? In your model, the load type on TLOAD1 is left blank.

     

     

    <?xml version="1.0" encoding="UTF-8"?>tload1.png

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited October 2018

    Hi Prakash, 

    thanks for you answer. In my case the load type is LOAD for each card.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited October 2018

    Hi,

     

    Can you share your calculations?

     

    I did some back-end calculations and the displacements are in the same range. 

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