Setting a load in a Direct Frequency Response Analysis

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

Hello,

I have a doubt, and I was wondering if someone here could help.

 

I am setting up a Direct Frequency Response Analysis, and I want to set an oscillating load. I've read the documentation and some tutorials, however, I can't find the solution.

 

The load I want to apply is:

 

force (time)=A+B*cos(wt)

A and B are constants, and w is the angular frequency.

 

If A=0, the proccess would be (I think):

- Set a unit load in the given direction, with load type DAREA, and magnitude 1.

- Set a TableD1 load collector, with a range of frequencies and y=B

- Set Freqi and Rload2 load collectors, and a freq resp (direct) loadstep accordingly.

 

(I would be grateful if someone can confirm that is correct)

 

However, when A is not zero, I have no idea what I should do.

 

One more thing, is there a way to view the applied load in Hyperview? If there was, I could see for myself what I am doing. EDIT: I think I found a way to do this, with the global output request OLOAD, not sure it it'll work though.

 

Thanks for your attention, hope someone can help!

 

Regards

 

 

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Answers

  • tinh
    tinh Altair Community Member
    edited June 2016

    Hi,

    In your case to combine loads, using DLOAD may be helpful

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited June 2016

    I will answer to myself in case it's useful for someone. 

    Firstly, if you want to introduce a time-dependant force (instead of frequency dependant) you should do a Transient Analysis (not a Direct Frequency Response Analysis).

    Secondly, you can't introduce a force=A+B*sin(wt). You have to apply A and B*sin(wt) as two different forces, and then combine those two, using the DLOAD method as suggested above.

     

    Thanks

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