VIBRATION COMPOSED

Composite vibration is the sum of several simple vibration. A machine vibration is a vibration composed of a series of simple vibration associated moving internal components. With this in mind, it follows that the vibration waveform of a machine is not a sinusoidal signal but can get quite complex.

Sum of simple vibrations in the time domain.

... The vast majority of the vibration signals are much more complex than this and can become extremely difficult to interpret ....

OTHER TYPES OF VIBRATION:

Besides mere vibrations, there are also other types of vibrations such as random vibration, flashing patters and modulation.

The random vibration meets no special patterns that are repeated constantly or too difficult to detect where a cycle begins and where it ends. These vibrations are usually associated turbulence blowers and pumps, lubrication problems and metal-to-metal rolling elements or cavitation. This type of pattern is better interpret the spectrum rather than in the time waveform.

The intermittent rattles are associated with continuous strokes that create a repetitive signal. These are most commonly found in gears, in the passage of the blades of an impeller or fan. These signs tend to disappear due to the damping of the medium.