Glossary

The vibration monitoring industry has specialized jargon that is commonly used when talking about vibration sensors, accelerometers and associated applications. It's important that you understand common terminology to communicate effectively with vibration monitoring, reliability, condition monitoring and process automation professionals. We hope you find our glossary useful to find specialized terms and definitions used across vibration, condition monitoring and predictive maintenance.

 






NATURAL FREQUENCY (Damped)

The frequency of free vibration of a damped linear system. fd=½π x √(k/m-c/4m2)

NATURAL FREQUENCY (Undamped)

The frequency of free vibration resulting from only elastic and inertial forces of the system. fn=½π x √k/m. Regardless of damping present, the frequency of sinusoidal excitation of a single-degree-of-freedom accelerometer at which the output signal lags behind the motion of the case (housing) by a phase angle of 90°.

NEAR FIELD

Describes locations within a few inches to a few feet from the explosive event. The area is subjected to a very fast rise time, high amplitude, high frequency energy.

NODE

A point, line, or surface in a standing wave where some characteristic of the wave field has essentially zero amplitude.

NOISE

Any disagreeable or undesired acoustical or electrical oscillations.

NONLINEARITY

Used interchangeably with “linearity.”

NONREPEATABILITY

Used interchangeably with “repeatability.”