TwinTurbo.NET: Nissan 300ZX forum - It is possible to move the resonant frequency out of range?
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Subject It is possible to move the resonant frequency out of range?
     
Posted by Marshall on February 25, 2003 at 12:55 PM
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In Reply To Shorter crank only means the resonant frequency is higher posted by AshsZ (FABio) on February 25, 2003 at 12:33 PM
     
Message If the resonant frequency of the crank coincided with the frequency of the pistons firing at a certain RPM, I could see those forces quickly building up and causing damage.

But is it possible to increase the resonant frequency of the crankshaft to the point that the firing of the pistons is happening at too low of a frequency to add to each wave? For instance, if the crank is stiff enough, its natural frequency might not coincide with the firing of the pistons (causing resonation) until 15,000 rpm or something, way out of the rpm range that the engine will experience. (this was just an example)

I know they do this with bridges, when they design them they make sure they stiffen them up enough to move the resonant frequency to a point that the wind's effect on the bridge won't amplify the waves. If they didn't do this, and the bridge's resonant frequency was low enough for the wind's effect on the span to add intensity to each oscillation, you get what you had with the Tacoma Narrows bridge.
     
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