Glossary of Terms

Vibration:
An oscillation of force, displacement or acceleration in a mechanical system about some reference point. Expressed in terms of frequency and amplitude.

Shock:
A transient event defined by a sudden change in motion, force, or velocity.

Frequency:
The number of oscillation in a given time period. Usually expressed in terms of cycles or vibrations per second (Hertz).

Amplitude:
The magnification of force, displacement, or acceleration from a known reference point.

Natural Frequency:
The frequency at which a system will oscillate if moved from its free position and allowed to vibrate without external forces.

Resonance:
A condition occurring when the forcing or operating frequency of a system coincides with the natural frequency.

Spring Rate:
The value defined by the ratio of force (load) to deflection. Usually expressed as pounds per inch. Also referred to as stiffness.

Transmissibility:
The ratio of dynamic output to dynamic input. This can also be expressed as a percentage of isolation.

Damping:
The dissipation of energy. Two types of damping are: Coulomb (friction) Damping and Hysteritic (inherent) Damping.

Structural Damping:
Damping which reduces the vibration of resonating surfaces that radiate noise. Damping is accomplished by affixing a material directly to the vibrating surface. This material converts the mechanical vibration to a minimal amount of heat energy.