Learning Forum

[Pedro Argote]

I am performing an harmonic analysis, I can obtain the logical results and I would like to ask you a basic doubt in order to clarify the obtained result interpretation. In a full method harmonic analysis, when I introduce a discrete excitation, I mean an excitation of 0,5 mm as amplitude at a specified frequency, for example at 9 Hz (considering that the amplitude value is 0 for the rest of frequencies). If the first natural frequency of my structure appears at 15 Hz, should I ontain any stress or displacement results at the frequency of 9 Hz?

I know that at that frequency I will not have any amplification and the stress or displacement results should keep low. I thought I would obtain any result different to zero, but I did not gat them. So, my question is that if the frequency of my excitation is far from the natural frequencies of the structure, should I get results in a Full Method or in a Modal Superposition Harmonic Analysis?

Thank you very much for your help!

[Dave Looman]

Both full and mode-sup harmonic should give non-zero results at 9 hz.  At very low frequencies the result will approach a static solution, but will not be zero.  

[Ruturaj Gavali]

Hey Pedro!

Please see if the Ansys videos below are helpful:

Performing Mode Superposition Harmonic Analysis

Performing Harmonic Analysis with Full Method

Correctly Interpreting Harmonic Results

Thanks!

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