Measured displacement and obtaining frequency spectrum

[MiamiVipul]

I am measuring mid-span displacement of a rotating shaft using a displacement sensor. I would like to see the frequency spectrum of the lateral vibration of the shaft. Could somebody please let me know any examples that are available in Sound and Vibration Toolbox V3.1 to convert the displacement measurements to Frequency-amplitude plane and get the spectrum; looking for a quick fix without building everything from scratch.

Thanks a lot.

MiamiVipul.

[Jordan_D]

Hi MiamiVipul,

It sounds to me like you have a waveform in the time domain (amplitude vs. time) and you would like to see it in the frequency domain (frequency vs. amplitude). If this is the case then you might want to take a look at the LabVIEW Spectral Measurements Express VI or some of the Baseband FFT functions from the Sound and Vibration Toolkit. Those VI's should help you speed up your development. Keep me posted if you have more questions.

[preston_johnson]

If you are interested in the more formal rotating machinery functions such as order tracking, orbit plots, bode plots, shaft centerline, and so forth, you may want to consider upgrading your Sound and Vibration Toolset to the Sound and Vibration Measurement Suite.  https://www.ni.com/en-us/shop/product/labview-sound-and-vibration-toolkit.html  Take a look at the resources tab for additional links on the affore mentioned page. 

The order analysis functions in the toolset are built for rotating machinery measurements.  The Sound and Vibration Measurement Suite also has scaling functions for displacement (engineering units of mils, micron, etc.) that may be useful.  The order analysis tools have a rich set of examples and tutorials. You may wish to review. 

I have includeed the on-line help manual for the order analysis functions, lvoat.chm, and the theory behind these functions, oatconcepts.chm.  The suite has examples for each of these functions you can use to get started.