Page 11 - Vibrations 3
P. 11
The cepstrum shows the periodicity of the spectrum – it’s
a spectrum of a spectrum.
A roller element bearing is composed of an outer ring, an
inner ring, and several roller element balls.
When a failure develops in the outer or inner ring, the
measured vibration signal will exhibit larger frequency
energy around the fault frequency of the inner or outer
race.
These characteristic frequencies are related to the
geometries of the bearing including the number of balls,
size of races, and the rotational speed of the machine.
It is not always possible to differentiate between good
bearings and faulty bearings with a power spectrum
alone.
A cepstrum is a good way to detect harmonics in the
spectrum.
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