Vibration Analysis Of Spherical Roller Bearing

[panneer.s@ssautomation.in]

Hi all,

         We are trying to measure vibration of spherical roller bearing at radial direction with constant speed 700 rpm. Our system has NI-9232 module, 352c33 Accelerometer, LabVIEW 2021 with Sound and Vibration Toolkit. We want acceleration data to be converted to velocity(microns/s) and check whether the velocity is within limits in three bands(Low band(20-120Hz),Medium band(120-700Hz),High(700-4000Hz).For that we are applying band pass filters to acceleration then integrating it to velocity then applying FFT to the velocity.

      We are facing the following problems:

            1) High Band amplitudes are much less than expected.(This was verified using Emerson Equipment)

            2) When we try to convert g values to velocity, the integration block is acting as a low pass filter and we are not getting any high frequency signals.

          I have attached VI, image of VI and settings of my DAQ. 

          I will be grateful for any suggestions

Thanks in advance.

Panneer Selvam

[Bob_Schor]

I'm unfamiliar with the Sound and Vibration Toolkit, but as the chapter in the manual on Integration makes clear, Integration always acts to decrease the amplitude of waveforms (the integral of sin (ωt) is (cos (ωt))/ω, which decreases linearly as the frequency ω increases).  Your VI says you band-pass filter first (which affects the gain and phase outside of the filter range), then integrate once (which gets rid of the acceleration signal, transforming it to a velocity signal with the 1/ω gain dependency "built-in", then plot it.  I'll let you study the manual to understand what changing from "Linear" (for the Low Band) to "Exponential" (for the Medium and High Band) spectra does.

Bob Schor

[panneer.s@ssautomation.in]

Thanks a lot for your support. I have read the manual on integration, now I understand why the amplitude decreases as frequency increases. As I have mentioned in my query before, can you help with why high band amplitudes were not picked by accelerometer?