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Frequency response analysis FEMAP

Experimenter
Experimenter

Good day,

 

I am trying to run a frequency/harmonic analysis and I get an error message which says: A Tstep card in case control has an invalid set ID of 1.

I have checked as a reference the video - https://www.youtube.com/watch?v=aRduXRq4TkA.

The video does not show how to insert results from a previous modal analysis.

I did not perform such analysis.

 

I therefore have a number of questions:

* What does the Tstep card refer to and how to solve this error?

* I understand that the harmonic analysis can be based on a modal analysis, or run independently. How can either option be selected?

* Are there any online examples showing all the steps required to perform a harmonic analysis?

 

Thanks

Best regards 

 

 

8 REPLIES

Re: Frequency response analysis FEMAP

Phenom
Phenom
Have you looked at the examples via Help | Examples? There are these:
Modal Frequency Analysis of the Hinge Model
Frequency Response of Tower with Seismic Excitation
Also, a TSTEP entry is typically for transient analysis, not for frequency response. Are you sure you have chosen analysis type 4: Frequency / Harmonic Response when you setup the analysis.

Re: Frequency response analysis FEMAP

Experimenter
Experimenter

Good day, thanks for your message.

Yes, I had a look to the examples but I still was not able to solve this test.

Its true, trying with 4.Frequency/harmonic response the TSTEP warning is not a problem anymore.

Now,I get a new error message: USER FATAL MESSAGE 6683 (FRRD1A).

But it looks like more realistic.

Best regards

 

Re: Frequency response analysis FEMAP

Phenom
Phenom
It is important you do those examples in full, as the error suggests you either have not selected appropriate analysis (harmonic load) frequencies compared to the natural frequencies, or you haven't selected any mode frequencies at all (in which case it may have defaulted to first 10 modes, which may be good enough, if you think the results are OK).

Re: Frequency response analysis FEMAP

Experimenter
Experimenter

Hi ,

I am quite new with FEMAP-NASTRAN and I am still struggling around with my test cases.
In the .f06 I get the following error:
*** USER INFORMATION MESSAGE 480 (XSEMIN)
JOB TERMINATED DUE TO LACK OF SOL, COMPILE, OR LINK CARDS IN THE EXECUTIVE CONTROL SECTION.
But I am not sure what they mean with that and how to correct it. Can someone shed some light over that issue?.
Best regards


 

Re: Frequency response analysis FEMAP

Phenom
Phenom

Yes, it means you have not selected any analysis type (eg. statics, modes, frequency response etc.).

 

If you are new to Femap, then you should start with (all) the simple example problems.  Follow each step.  Then it will become easier for you to understand the basics of how it works, and why things may be going wrong.  This will be time well spent. 

I realise the examples are very geometrically simple models, but they do cover quite a few procedural points related to analysis setup, which is what your questions have been related to so far.

Re: Frequency response analysis FEMAP

Experimenter
Experimenter

Good day,

The modal and harmonic simulation has been succesfully performed.

Now, I am interpretating the results. The chart says plate top xy shear stress vs set value.

It is not clear for me what "set value" means.

Regards

 

 

Re: Frequency response analysis FEMAP

Phenom
Phenom
In Femap, "Set Value" typically means things like:
1. "Time" in a transient analysis;
2. "Proportion of Load" in non-linear static analysis;
3. "Frequency" in frequency response analysis;

So if things are as they should be, choosing "set value" in a Vector vs Output Set chart should produce a result vs frequency.

Re: Frequency response analysis FEMAP

Experimenter
Experimenter

Thanks, that makes sense.

What I have is a value (displacement, shear stress, acc,...) vs frequency.

Very good :-)