what is harmonic resonance?

Question

structural faliure

Answer 1

All shapes have a resonant frequency, for example a guitar string, if you build a building out of guitar strings, and then plucked it, it would resonate.

Harmonic resonance is booste experienced when a stucuture is vibrated at a key frequency. that key frequecy can be though of as a weight hanging form a rubber band, it oscilates at the same speed reguardless of displatement, that is resonance.

resonance occurs in stucutures, eletrical systems, fluid systems, and in fact the principal for the operation of the microwave, to heat your food, has to do with the resonance of a water molucule in the food your eating, when excited at resonant frequency, is oscialtes out of control causing a build up of heat.

In stuctural systems, the elasticiy of steel is a property which also allows a steel member, or system of members (a structure), to be thought of as a spring, when that spring is oscialled, or excited at its resonant frequency, then its amplitude will increase until it is equalled by friction, or damping.

The formula for the natural frequency of a stucture is given by:

Fn = SQRT(K/M)

applying some units to this equation, the natural frequency of a structure of equivalent stiffness 'k' in lb's per inch will have a natural frequency 'Fn', in Rotation Per Minute (RPM)
Fn(rpm) = 187.7*sqrt(k/m)
where k is in lbs / inch, and M is in pounds.

Answer 2

Think about when you were a kid and played on a swing. There was a certain frequency that you pumped your legs at which caused you to go higher and higher. You were pumping your legs in resonance with your mass on the swing, there was maximum energy transfer from your legs to your body moving on the swing. This was harmonic resonance.

Answer 3

The induction of a catastrophic vibration in an object by an outside source, at a frequency which is a multiple of the object' natural vibration.
I'm sure you've seen the video clip of the bridge in California being destroyed by swaying motion induced by automobile traffic.
The microwave oven induces vibration of the 0--H bond, thus heating substances containing water, fat, alcohol.