vibration fundamental frequency

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Vibration Analysis
PREPARED BY: ABDULLAH ELSAWY 2016

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• Introduction to maintenance and vibration
• Types of maintenance
• The vibration waveform and spectrum
• A quick review of :
Unbalance
Misalignment
Looseness
Detecting rolling element bearing defects
• Spectrum analysis
• High frequency detection techniques
• Using vibration analysis to improve reliability
Topic

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Introduction
Your machines are talking to you

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Type Of Maintenance
What are its different types?

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Type Of Maintenance
1- Reactive maintenance
break down maintenance also know as run ti failure .hysterical
fix it whenit break
2-Preventive maintenance
know as schedule maintenance .planned maintenance historical maintenance
perform regular so that machin will not fail

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3-Redective Maintenance
Also know as condition based maintenance
If it aint broke don’t fix it
Machin warn you when they about to fail
4-Proactive Maintenance
Precision .reliability centered machine
Type Of Maintenance

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What is vibration?
Vibrations are oscillations of a system about an
equilbrium position.

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Vibration…
It is also an everyday
phenomenon we meet on
everyday life

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Vibration
Noise
Destruction
Compressor
Ultrasonic cleaning
Testing
Wear
Fatigue
• Useful Vibration Harmful vibration

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Vibration parameters
All mechanical systems
can be modeled by
containing three basic
components:
spring, damper, mass
When these components are subjected to constant force,
they react with a constant
displacement, velocity and acceleration

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How can we utilize vibration ?
• Amplitude
An indication of the severity
(amplitude is important ,but change in amplitude is more
important )
• Frequency
An indication of the nature of the fault
(many tools are available to interpret the pattern)
• Motion
An indication of the structural response
(use phase to learn more about the fault and check for
resonance )

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Vibration frequency
• Different components within the machine
generate different frequencies :shaft.vanes
and blades
• Vibration at those frequencies tells us what
part of the machine maybe damaged
• Its hard to look at waveform and relate the
vibration to the machine

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The origin of the spectrum
and waveform
• Here we will see the waveforms and spectrum

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Spectrum analysis basics
• Multiple sources of vibration
Motor and fan frequencies

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A litile more complicated
(belt drive haves the speed )

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Even more complicated
•Gearbox frequencies

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Introducing “harmonics a” and “sidebands”
• Harmonics : what happens when the vibration is not smooth
• Nice,smooth,simple vibration: simple spectrum
• Single ,dominate source of vibration.
• One main peak in the spectrum

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Complicated vibration: complicated spectrum
• More than one source of vibration
• Vibration that is not smooth
(non-linear /distorted)

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Complicated vibration impact:harmonics
:impacts:harmonics
• Multiple peaks in the spectrum at the key
forcing frequency for exaple:
• Running speed :looseness
• Bearing frequency:wear,spall

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• Apeak at the driving frequency (gearmesh)
• Peaks on either side of that .separated by the modulation
frequency (runnig speed)
Sidebands:what happens when the amplitude is not
consistent
complicated vibration :modulation :sidebands

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complicated vibration :modulation :sidebands
Sidebands can take allsorts forms
Lots of fault comdition generate sidebands
Bearing gearbox motor pump

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complicated vibration :modulation :sidebands

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complicated vibration :modulation :sidebands
• Harmonics(becouse becouse the impacts)
• Sidebands(becouse the amplitude rise and falls
as the balls go throughload zone)

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Time waveform analysis
• The time wave form is used to generated the
pectrum – you don’t have to collect extra data
• The wave form showsyou what happened from
one moment to the next –the
spectrumsummarizes everything that
happened the data was recorded

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Examples
lets look at few example where the
time waveform has helped in the
diagnostic process

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Damaged inner race of bearing

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Rotating loosness

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cavitation

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Gear box tooth damage

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Gear box tooth no damage