damping

(redirected from Dampening effect)
Also found in: Dictionary, Medical.

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 ?
It also said the Mortgage Market Review (MMR) and additional high loan-to-income and stress-testing guidance, along with suggestions of earlier than expected interest rate rises have had a dampening effect.
Nevertheless, notes the report, the expansion of Medicaid patients over the next two years resulting from the enactment of the ACA, which is anticipated to prop up demand for prescription pharmaceuticals, along with "the bolus of baby boomers that hit retirement in 2011, will backstop the dampening effect to overall prescription pharmaceutical demand" from what Fitch forecast will be "stubbornly high" unemployment.
Whether this happens, will really come down to how robust any economic recovery is by the end of the year as an increase in borrowing rates is likely to have a dampening effect on economic output.
Ironically, while organized labor is among the most vocal advocates of such a tax, the tax would have a dampening effect on the investing practices of union pension funds.
6 September 2011 - Swedish medical technology developer Sectra AB (STO:SECT B) sees that the uncertainty around the budgetary savings in the USA has had a dampening effect on the market, the company said in its first-quarter financial report, published today.
Directly or indirectly, public sector cuts affect almost everybody - partly because many firms who supply publicly-funded bodies are losing contracts, and partly because redundancies in the public sector create uncertainty which has a dampening effect on overall consumer confidence.
I fully concur with this statement and his contention that the new translation of the Mass will have a dampening effect on such "active" participation.
17 million cases, hitting a record low for the sixth consecutive year, as the dampening effect of the aging population and weak demand among young consumers more than offset the sales bump during the scorching summer, industry observers said.
The leftist government of Rafael Correa will hail the two-year-long negotiations as a victory for its resource nationalism policy, though some analysts say the saga could have a dampening effect on much-needed foreign investment.
In addition, the current property catastrophe pricing environment is competitive, which could have a dampening effect on the company's profitability if prices continue to deteriorate, AM Best elaborated.
This period is too long and would have a dampening effect on certain businesses like textile shops and restaurants," The Star quoted him as having told reporters after meeting 14 Indian trade associations late on Monday.
The absence of Wall Street recruiters has had its dampening effect on salaries.

Site: Follow: Share:
Open / Close