Vibration Analysis Flashcards
______________ is the movement of a body about its reference position. For rotating equipment the centerline of the rotating shaft is the reference.
Vibration
imbalance in the fan could be caused by wear or build up on the blades. looseness could be present within the machine. The effects of the fluidized air stream passing the blades as the blades pass the dischange ducting could cause a vibration. A bad bearing ing the motor or final drive shaft could be vibrating. this is an example of
vibration
a ________ is a graphical depiction of vibration
signature
temperature analysis is also known as ?
infrared thermography (IRT)
____________ requires no physical contact with any device to the equipment therefore, the system may be monitored without disrupting normal operations.
Temperation analysis
the scale of emissivity ranges from?
0.00 (where there is no emission) to 1.00 (where the object is completely emitting energy)
________ measures the heat beingemitted and allows comparison with a bae-line. Increassed temperatures indicate a fault that could precede failure.
Infrared thermography
_______ is a symptom of a machine that can lead to machine damage or failure.
Vibration
_________ refers to detecting, measuring and analysis the vibration and determining whether it is within normal machine parameters.
Vibration analysis
Because all mateerails have different characteristics, each displays a different signature when reacting to a forcing frequency. By changing either the mass or the stiffness of an object, you change the vibratory signature of the object. this stand for _________?
machine characteristics/material characteristics
_______ is how often an event happens in a unit of time or in one cycle.
Frequency
what are 3 terms used to describe vibration?
Frequency
amplitude
phase
the _________ is the lowest or first frequency normally associated with a particular problem.
Fundamental Frequency
a misaligned coupling can generate _____________orders. which would be a example of fundamental frequency?
1x, 2x or even 3x rpm
_______ indicates how much a machine is vibrating.
Amplitude
This total distance travelled is called the __________ and may be measured in either imperial or metric
peak-to-peak displacement
_______ readings are most consistent between 600 cpm and 60,000 cpm
Velocity
the _______ is used above 60 thousand
G’s force (Acceleration)
The breakdown of lubrication and resultant surface failure of a bearing is an example of ________
acceleration damage
the relationship between displacement, velocity and acceleration is referred to as _______
phase
when taking phase readings, keep the _______
accelerometers facing the same direction
___________ is the frequency at which an object or system naturally vibrates when a forcing function has been introduced.
natural frequency
at ___________ the system amplifies the energy from the forcing function frequency causing large amplitude.
Resonant frequency
__________ occurs in any system if the forcing function frequencies are not kept at least 20% outside the natural frequency’s range.
Resonance
the _______ of a shaft or rotor occurs when the rotor rotates at or near its natural frequency
critical speed
machines should not be operated at or near the ________ of the shaft or rotor: they should operate 20% to 30% outside of a rotor’s ______.
Critical speed
if a shaft has a natural frequency of 2300 cpm, the shaft is in _______ (shake violently) when the shaft is rotated at 2300 rpm
resonance
_________ are developed by the international organization for standardization (ISO)
Severity standards
_____ are multiples of the operating speed. For example how often the event occurs with each revolution.
Orders
If the period for one cycle is 1 second, then the frequency in cycles per minute = 60 cpm. Frequency can also be measured in ______?
orders
what is the rate of change of displacement and is measured as the maximum _____ the vibrating part achieves.
Velocity
when placed on a sine wave, the maximum velocity takesplace on ______
the neutral axis
________ is the rate of change in velocity and is measured in g’s force.
Acceleration
at _______, the system amplifies the energy from the forcing frequency causing large amplitude.
Resonant frequency
Resonance occurs in any system if the function frequencies are not kept at least _____ outside the natural freqency
20%
______ is the time required to complete one cycle of a periodic signal
period
__________ are frequencies that are not whole multiples of the rotating speed of the machine.
Non-synchronous Vibration
A ________ is normal standard for the vibration of a particular machine
Baseline
the process of vibration analysis involves converting a vibration into an electrical signal with the use of transducers, this is ______?
measuring vibration
Non-contact eddy current ______________ measure the relative distance between a bearing housing and a bearing journal
displacement transducers
_________ are used for gerenal vibration measurement and balancing
velocity transducers
A velocity transducer is primarily used to measure velocity, but the analyzer can differentiate or integrate the signal making it capable of measuring _______ and _________ through the machine.
displacement and acceleration
___________ are the most common transducers used with vibration analysis equipment. this generate their own power, but often use an amplifier to increase signal strength.
Acceleration transduceers (accelerometers)
For repeat readings, use the same method of _____________ each tim. Follow the recommendations the manufacturer suggests.
Mounting transducers
A ________ is permanently installed in the machine bearing housing so it can accurately monitor the absolute shaft vibration
shaft rider accessory
the transducer is only capable of picking up a vibration that is in line with the transducer. The transducer does not pick up vibrations that are 90 degree to the transducer this is?
pickup mounting positions
you must collect information from several directions and at several points on the machine before you can perform any analysis. These positions are usually in the horizontal, vertical and axial (HVA) positions at each bearing location and are commonly referred to as _______
HVA measurements
__________ means that the vibration analyzer changes the signal received at the vibration pickup from amplitude versus time to amplitude versus frequency.
Fast Fourier Transform (FFT)
When a vibration is complex, sophisticated vibration analyzers are used to _________ so that each can be measured and inspected independently.
separate frequencies
Another common use of _________ is to measure the phase angle of the vibration when balancing rotating parts
Strobe lights
most basic analysis procedures follow two overall steps which are ___________ and ___________
data acquisition and data interpretation
the probe must be located a specific distance from the shaft. The gap setting can be approximately ______ to ______ and is set by the manufacturer’s specifications
0.020 to 0.060
____________ does not only involve taking vibration readings, but starts with a basic investigation of the machine and its surrounding.
data acquisition
once a machine is taken out of service for a complete overhaul or a new machine is installed, you should take new ________
baseline readings
This frequency spectrum, a plot of vibration amplitude against frequency is known as the _______
vibration signature
_______ is one of the most common cause of vibration
imbalance
imbalance can be identified by a vibration frequency that is ________
1x rpm
Most of the vibration from imbalance is in the ___________
Radial direction
Frequency is usually 1x rpm, but if the ____________is severe there can be frequencies at 2 or 3x rpm
Misalignment
The axial vibration component is usually high (about 1/2 or more of the radial amplitude) which is caused by _______________
angular misalignment
an axial vibration reading of 50% or more of the radial is a good indicator of __________
misalignment
____________ cause vibration problems under several conditions. If the bearing clearance are to loose, the shaft can move around and pound on the bearing
Friction bearing
________ usually occurs at frequencies of about 45% to 50% of the shaft rotation.
oil whirl
the horizontal/radial position is probably the most commonly used for ___________
transducer measurements
_________ which can show ecactvibration waveforms, to identifying certain distinct vibration problems
oscilloscopes
