damping


Also found in: Dictionary, Thesaurus, Medical, Legal, Idioms, Wikipedia.

Damping

A term broadly used to denote either the dissipation of energy in, and the consequent decay of, oscillations of all types or the extent of the dissipation and decay. The energy losses arise from frictional (or analogous) forces which are unavoidable in any system or from the radiation of energy to space or to other systems. For sufficiently small oscillations, the analogous forces are proportional to the velocity of the vibrating member and oppositely directed thereto; the ratio of force to velocity is -R, the mechanical resistance. For the role of damping in the case of forced oscillations, where it is decisive for the frequency response, See Forced oscillation, Resonance (acoustics and mechanics), Harmonic motion, Oscillation, Vibration

An undamped system of mass m and stiffness s oscillates at an angular frequency &ogr;0 = (s/m)1/2. The effect of a mechanical resistance R is twofold: It produces a change in the frequency of oscillation, and it causes the oscillations to decay with time. If u is one of the oscillating quantities (displacement, velocity, acceleration) of amplitude A, then Eq. (1) holds in the damped case, whereas in the undamped case Eq. (2)

(1) 
(2) 
holds. The reciprocal time 1/α in Eq. (1) may be called the damping constant.

The damped angular frequency ωd in Eq. (1) is always less than ω0. According to Eq. (1), the amplitude of the oscillation decays exponentially; the time required for the amplitude to decrease to the fraction 1/e of its initial value is equal to 1/α.

A common measure of the damping is the logarithmic decrement δ, defined as the natural logarithm of the ratio of two successive maxima of the decaying sinusoid. If T is the period of the oscillation, then Eq. (3) holds. Then 1/δ is the number

(3) 
of cycles required for the amplitude to decrease by the factor 1/e in the same way that 1/α is the time required.

The Q of a system is a measure of damping usually defined from energy considerations. The Q is π times the ratio of peak energy stored to energy dissipated per cycle and is equal to π/δ.

If α in Eq. (1) exceeds ω0, then the system is not oscillatory and is said to be overdamped. If the mass is displaced, it returns to its equilibrium position without overshoot, and the return is slower as the ratio α/ω0 increases. If α = ω0 (that is, Q = 1/2), the oscillator is critically damped. In this case, the motion is again nonoscillatory, but the return to equilibrium is faster than for any overdamped case.

damping

[′dam·piŋ]
(engineering)
Reducing or eliminating reverberation in a room by placing sound-absorbing materials on the walls and ceiling. Also known as soundproofing.
(physics)
The dissipation of energy in motion of any type, especially oscillatory motion and the consequent reduction or decay of the motion.
The extent of such dissipation and decay.

damping

The dissipation of energy with time, e.g., the dissipation of energy in a mechanical system whose free oscillations decrease with time, resulting in a decrease in its amplitude of vibration.

damping

A technique for stabilizing an electronic or mechanical device by eliminating unwanted or excessive oscillations.
References in periodicals archive ?
Each natural frequency has a corresponding damping ratio.
It outputs the damping force that is produced in the semi active damper when the control current i is conducted through the linear solenoid and stroke velocity v.
4) Finally, stability maps of shear deformable and damped Beck columns are newly constructed using the analytical solution, which is compared with the FE solution in the practical range of damping coefficients and shear parameters.
Equivalent Viscous Damping: The most common method of defining equivalent viscous damping is to equate the energy dissipated in a vibration cycle of the actual structure and an equivalent viscous system.
Both loops can be configured with damping controllers independently.
It could be seen that damping factor is less about 30% in the case of riveted joints.
Comfort can be achieved by adding damping, but a pendulum TMD would require a costly 60-foot tall space that also increases wind load.
Thus, the higher the damping in a structure, the less noise will radiate from it when it is struck by an object.
In this paper, based on the review of the main impact models and the Hertz theory, a new approximate formula of the damping constant of Hertz-damp model is derived.
Thanks to the preload, there is sufficient damping force available, even at low piston speeds.
2007; Thompson & Hunt,1973), damping remains unknown.
Key statement: A rubber material A which has a low degree of dynamic spring stiffness, a rubber material B which has a high vibration damping effect, and a vulcanizing agent which is capable of vulcanizing only an unvulcanized mass of the rubber material B are evenly mixed together and heated to vulcanize the rubber so that the formed vibration damping rubber member has an island-sea structure in which fine particles of the vulcanized rubber material B are dispersed as a dispersed phase in a matrix phase of the vulcanized rubber material A.