How to interpret Bode Plot?

[jenz]

Trying to find a resonance speed during shaft run-up.

Doing that, I have used the LabVIEW ExpressVI "Bode and Polar", which is included in the Sound and Vibration Toolkit.

My Question is how do I inperpret the phase information of the bode plot? The phase value changes continuously between 0 ... 360 degrees. I don't know why. Is it a question how to configure the ExpressVI?

Thank you for your help 🙂

Unfortunately, I can't upload my testdata. It's a TDMS-File.

[jenz]

... 

[preston_johnson]

you need to insure you are providing continious data from both the tachometer channel and the vibration channel.  This should provide a more consistant phase.  Also, from your png, it looks like the speed profile goes from 4500 RPM to 6000 RPM, yet the bode plot goes above 8000 RPM. 

Just some notes. 

Preston