Parametric resonance

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Parametric resonance is the parametrical resonance phenomenon of mechanical excitation and oscillation at certain frequencies (and the associated harmonics). This effect is different from regular resonance because it exhibits the instability phenomenon.

Parametric resonance occurs in a mechanical system when a system is parametrically excited and oscillates at one of its resonant frequencies. Parametric excitation differs from forcing since the action appears as a time varying modification on a system parameter. The classical example of parametric resonance is that of the vertically forced pendulum.

For small amplitudes and by linearising, the stability of the periodic solution is given by :

where u is some perturbation from the periodic solution. Here the Bcost term acts as an ‘energy’ source and is said to parametrically excite the system. The Mathieu equation describes many other physical systems to a sinusoidal parametric excitation such as an LC Circuit where the capacitor plates move sinusoidally

[edit] See also

• Mathieu equation

[edit] External articles

• Elmer, Franz-Josef, "Parametric Resonance". unibas.ch, July 20, 1998.

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• Cooper, Jeffery, "Parametric Resonance in Wave Equations with a Time-Periodic Potential". SIAM Journal on Mathematical Analysis, Volume 31, Number 4, pp. 821-835. Society for Industrial and Applied Mathematics, 2000 .
• "Driven Pendulum: Parametric Resonance". phys.cmu.edu (Demonstration of physical mechanics or classical mechanics. Resonance oscillations set up in a simple pendulum via periodically varying pendulum length.)