Vibration Test Basic Knowledge – The Terms of Vibration Test

Displacement – The distance that a vibrating mass moves.

Peak displacement, center-to-peak
Peak-to-Peak is the distance between the two farthest points of motion.
Units:  Inches or Millimeters

Velocity – The speed at which the vibrating mass moves.

Units: Inches per second or Meters per Second

Acceleration – The rate at which the vibrating mass changes speed.
Units: “g” peak for Sine and Shock “Grms” for Random, Sine-on-Random, and Random-on-Ran

Frequency – The number of times an oscillation occurs in a period of time.
Units: Hertz (Hz) or Cycles per Second

Mass – The amount of matter contained in a body or product

Force – The applied energy causing motion or a change in motion
Units: Force Pounds (lbf) or Newtons(N)

Power Spectral Density(PSD) – Is a measurement of amplitude and frequency in a Random Vibration spectrum.
Units: Amplitude: (y axis) g2/Hz or (m/S2)2/Hz

Frequency – (x axis) Hertz (Hz)