Reference Guide
Comprehensive definitions of vibration analysis terms and technical terminology.
The rate of change of velocity with time, typically measured in units of g or m/s².
A sensor that measures acceleration forces, commonly used in vibration monitoring.
The magnitude of vibration displacement, velocity, or acceleration.
The process of adjusting the mass distribution of a rotor to reduce vibration.
A machine element that allows constrained relative motion between two parts.
The periodic variation resulting from two signals of slightly different frequencies.
The inverse Fourier transform of the logarithm of the power spectrum.
A measure of the correlation between two signals as a function of frequency.
The rotational speed at which a rotating shaft becomes dynamically unstable.
The dissipation of energy in a vibrating system.
The change in position of a vibrating body, measured in mils or micrometers.
The ratio between the largest and smallest signal a system can measure.
The distance between the center of rotation and the geometric center.
A signal processing technique used to extract modulation from a signal.
Fast Fourier Transform - an algorithm to compute the discrete Fourier transform.
A device or process that removes unwanted components from a signal.
The number of cycles per unit time, measured in Hertz (Hz).
A representation of a signal with respect to frequency rather than time.
A measurement of acceleration relative to Earth's gravity.
A frequency component at an integer multiple of the fundamental frequency.
The unit of frequency, equal to one cycle per second.
An unequal distribution of mass causing a rotating element to vibrate.
Mathematical process to convert acceleration to velocity or velocity to displacement.
A statistical measure of the 'peakedness' of a probability distribution.
A system where output is directly proportional to input.
A condition where rotating centerlines are not collinear.
The study of dynamic properties of structures under vibration excitation.
The frequency at which a system oscillates when not subjected to external forces.
Half the sampling frequency, the highest frequency that can be accurately measured.
The path traced by the centerline of a rotating shaft.
A frequency that is a multiple or fraction of rotational speed.
The total vibration amplitude within a specified frequency range.
The maximum absolute value of a waveform.
The timing relationship between two signals of the same frequency.
Materials that generate electric charge in response to mechanical stress.
A plot of power versus frequency for a signal.
A non-contact sensor that measures relative displacement.
Quality factor - a measure of the sharpness of resonance.
The tendency of a system to oscillate at maximum amplitude at certain frequencies.
Root Mean Square - a statistical measure of the magnitude of a varying quantity.
The rotating part of a machine.
The number of samples per second taken from a continuous signal.
A plot of amplitude versus frequency.
The stationary part of a rotating machine.
A representation of a signal with respect to time.
A device that converts one form of energy to another.
See Imbalance.
The rate of change of displacement, typically measured in in/s or mm/s.
Mechanical oscillation about an equilibrium point.
A graphical representation of a signal as it varies with time.
The motion of a rotating shaft centerline.
Typically the horizontal axis in a graph or the axial direction in machinery.
Typically the vertical axis in a graph or the vertical direction in machinery.
The amplitude from zero to the maximum positive or negative peak.
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