Generating a Resonance Curve for a System: A Puzzling Problem

[abcdmichelle]

Homework Statement

if i know the natural frequency of a system, how can I generate a resonance curve for the system in terms of frequency vs amplitude.

The Attempt at a Solution

I know it will have one peak, like a bell curve and the max will be the natural frequency, but i don't know how to graph a theoretical fft.
i think i should generate a random number of frequencies, or something along those lines!?

please help!

 

[gneill]

Presumably you have a system transfer function. What form is it in?

 

[abcdmichelle]

i don't! :(

All I have is the natural frequency in rad/sec.

 

[gneill]

Well, do you know anything else about the system? Is it a second order system with damping ratios and so forth? Without the actual transfer function you can only speak in generalities. http://en.wikipedia.org/wiki/RLC_circuit" for an RLC circuit.

 

[marcusl]

Many simple resonant systems in nature have a Lorentzian line shape or response function. The function is complex; the real part represents energy absorption, the imaginary part is dispersive or reactive (potential energy). If you just plot the magnitude or the magnitude squared, they are, indeed, bell shaped--but they are not Gaussian. Look up "resonance" on Wikipedia for an introduction. You'll find the magnitude squared expression under the "Theory" heading.