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Quizzes > Science

CAT 1 Vibration Exam Questions to Build Your Analysis Skills

Quick, free CAT 1 vibration practice test. Instant results.

Editorial: Review CompletedCreated By: Shila NorrisUpdated Aug 24, 2025
Difficulty: Moderate
Questions: 20
Learning OutcomesStudy Material
Colorful paper art depicting questions and answers for Vibration Analysis Certification Quiz

This CAT 1 vibration analysis quiz helps you diagnose machinery faults, interpret spectra, and pick the right sensors. Tackle clear, exam-style questions to spot gaps and build speed before certification. For broader practice, try the mechanical engineering quiz, strengthen core measurement skills with the metrology quiz, or review controls and devices in the instrumentation quiz.

Which sensor type is most commonly used for measuring industrial vibration?
Eddy current proximity probe
Strain gauge accelerometer
Piezoelectric accelerometer
Capacitive displacement sensor
Piezoelectric accelerometers offer a wide frequency range, high sensitivity, and robust construction, making them the most common choice for industrial vibration measurement.
In vibration analysis, velocity amplitude is typically expressed in which unit?
g
Hz
m/s²
mm/s
Vibration velocity is often measured in millimeters per second (mm/s) according to industry standards, whereas acceleration uses m/s² and frequency is measured in Hz.
A dominant peak at twice the running speed (2X) in a vibration spectrum most likely indicates which fault?
Resonance
Misalignment
Looseness
Unbalance
Misalignment, whether angular or parallel, typically generates a strong vibration component at twice the shaft running speed, seen as a 2X peak in the spectrum.
Which signal processing method is used to convert time-domain vibration data into frequency-domain information?
Envelope Analysis
Time-Domain Averaging
Fast Fourier Transform
Discrete Wavelet Transform
The Fast Fourier Transform (FFT) is the standard method for transforming vibration data from the time domain into its frequency-domain representation, revealing spectral peaks.
Elevated vibration at 1X running speed is most indicative of which machinery issue?
Unbalance
Misalignment
Bearing defect
Gear mesh error
An increase in vibration amplitude at the shaft's rotational frequency (1X) is the classic symptom of rotor unbalance.
Which factor affects rolling element bearing characteristic fault frequencies?
Ball diameter
All of the above
Contact angle
Number of rolling elements
Bearing characteristic frequencies are determined by geometric parameters such as contact angle, number of rolling elements, ball diameter, and pitch diameter, so all listed factors apply.
Which spectral feature indicates amplitude modulation often associated with mechanical looseness?
Sidebands around a fundamental frequency
Broadband random noise
Harmonics at gear mesh frequency
Single peak at running speed
Mechanical looseness causes the vibration amplitude to be modulated by impacts or movement, which appears as sidebands around the fundamental frequencies.
According to the Nyquist criterion, what is the minimum sampling rate to accurately capture a 5 kHz vibration signal?
15 kHz
2.5 kHz
5 kHz
10 kHz
Nyquist's theorem requires a sampling rate at least twice the highest signal frequency, so a 5 kHz vibration requires at least 10 kHz sampling.
Envelope detection in vibration analysis is primarily used to identify which type of fault?
Gear mesh errors
Misalignment
Rolling element bearing defects
Electrical issues
Envelope detection demodulates high-frequency resonance excited by bearing impacts, making it effective for detecting rolling element bearing defects.
Which international standard provides guidelines for evaluating vibration severity in rotating machinery?
API 670
ISO 7919
ANSI/NCSL Z540
ISO 10816
ISO 10816 defines vibration severity classes and guidelines for evaluating vibration levels in rotating machinery across different power and size ranges.
To isolate bearing fault signals, which type of filter is most appropriate?
Bandpass filter
High-pass filter
Low-pass filter
Notch filter
A bandpass filter centered on the bearing's resonant frequency range isolates the impact-induced vibrations while attenuating unrelated frequencies.
A vibration spectrum showing a broad range of harmonics and random noise without distinct peaks most likely indicates which issue?
Unbalance
Gear mesh fault
Structural looseness
Bearing defect
Structural looseness creates unpredictable movement and impacts that generate broadband noise and many harmonics rather than clear spectral peaks.
What is the main benefit of using time synchronous averaging (TSA) in gearbox analysis?
Enhances random noise
Measures residual unbalance
Isolates periodic gear meshing signals
Removes gear mesh components
TSA uses tachometer synchronization to average out non-synchronous noise, highlighting the periodic signals from gear meshing.
In order to detect a vibration signal component at 2,500 Hz, what is the minimal sampling frequency you should select?
1,250 Hz
10,000 Hz
5,000 Hz
2,500 Hz
To capture a 2,500 Hz component without aliasing, the sampling rate must be at least twice that frequency, which is 5,000 Hz.
When selecting an accelerometer for high-frequency vibration analysis, which sensor specification is most critical?
Mounting stud material
Frequency response
Sensitivity
Thermal drift
A flat and adequate frequency response beyond the highest frequency of interest ensures the sensor can accurately capture high-frequency vibration without attenuation.
Why is a bandpass filter applied before envelope demodulation in bearing fault detection?
To increase the sampling rate
To convert data into the time domain
To remove bearing defect frequencies
To isolate the resonance band excited by impacts
The bandpass filter selects the high-frequency resonance band excited by bearing defect impacts, improving the signal-to-noise ratio for envelope demodulation.
Which tool is essential for performing modal impact testing on machinery structures?
Eddy current probe
Instrumented impact hammer
Laser Doppler tachometer
Laser vibrometer
An instrumented impact hammer provides a known force input at specific points, and the response is measured with accelerometers to derive modal parameters.
In phase analysis, what does a 180° phase difference at the running speed between two measurement points typically indicate?
Points moving in phase
Anti-phase motion
No vibration
Structural resonance
A 180° phase shift shows that the two points are moving in opposite directions, commonly indicating bending modes or certain misalignment conditions.
For two-plane balancing of a rotor, how many balancing planes are required?
Four
Two
Three
One
Two-plane balancing corrects both static and couple unbalance by placing correction weights in two separate axial planes on the rotor.
According to vibration analysis reporting standards, which element is NOT typically required in the formal report?
Measurement direction
Mounting method
Operator's personal opinion
Sensor sensitivity
Formal vibration reports must document technical metadata like sensor specs, mounting, and measurement direction, but they do not include subjective personal opinions.
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Learning Outcomes

  1. Analyse vibration signatures to detect machinery faults.
  2. Identify common vibration patterns in rotating equipment.
  3. Apply diagnostic techniques for bearing and alignment issues.
  4. Evaluate vibration data using frequency and time-domain methods.
  5. Demonstrate proficiency in selecting appropriate sensors and tools.
  6. Master reporting standards for vibration analysis certification.

Cheat Sheet

  1. Understand the fundamental principles of vibration - Vibration analysis starts with grasping how vibratory motion works, including how many ways a component can move (degrees of freedom). You'll explore the tag-team of displacement, velocity, and acceleration that drives every machine's rhythm.
  2. Identify common machinery faults - Every wobble tells a story: unbalance, misalignment, bearing defects or loose parts all have unique vibration fingerprints. Learn to decode these signatures so you can find and fix issues before they become dramatic breakdowns.
  3. Master Fast Fourier Transform (FFT) - Transform time-domain data into the frequency domain to spot the exact "notes" machines hum at when healthy or hurting. FFT is like a musical score for vibrations, revealing the secret frequencies of each fault.
  4. Select and apply vibration sensors - Choosing between accelerometers, velocity sensors, or displacement probes is like picking the right tool for a recipe. We'll show you when and why each sensor shines so your measurements hit the mark.
  5. Develop time waveform analysis skills - Time waveforms capture transient events and machine behavior under real-world conditions, giving you the full story. Become adept at spotting spikes, impacts, or anomalies before they escalate.
  6. Explore signal processing techniques - Cut through noise with windowing functions like the Hanning window to minimize spectral leakage and sharpen your frequency peaks. These tricks make your analysis cleaner, clearer, and more reliable.
  7. Leverage phase analysis - By comparing vibration phases, you can pinpoint relative motion and catch misalignment or unbalance. Think of phase data as the choreography guide that aligns every dancer in the machine.
  8. Learn balancing procedures - Master single-plane and multi-plane balancing methods to smooth out rotations and extend equipment life. Perfect balance keeps vibrations low and morale high.
  9. Get certified with ISO 18436 - Familiarize yourself with the global standards for vibration analysis to boost your credibility and ensure industry best practices. Certification is your passport to top-tier maintenance roles.
  10. Practice interpreting vibration data - Hone your skills by diagnosing spectra and time-domain plots, then craft clear, actionable reports. Strong communication of your findings can be as vital as technical expertise.
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