Quote:
Originally Posted by babydriver
Sometimes it's helpful to me to simplify the problem somewhat.
Imagine that we have a coil spring connecting two weights, one small one on the bottom (the unsprung weight) and one very large one above the coil spring (the sprung weight). Any change in the sprung weight will either compress the coil spring more (if heavier) or less (if lighter). For the purpose of this thought experiment, we will ignore any side to side motion that may be possible; only up and down motion is "allowed".
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True but the typical 1/4 vehicle model also takes into account tire spring rate between the unsprung mass and the road surface (input signal). It gets complicated fast. We can't simplify this problem any more that that standard model because any further simplification would result in junk answers, ie. Garbage-in-garbage-out.
Quote:
Originally Posted by babydriver
What complicates matters further is that the lower "unsprung" weight also moves. As force is applied to it in an upward direction, the spring compresses and rebounds. A downward direction will cause stretching and then rebounding. At some critical combination of rate and weight, the unsprung weight will come into resonance with the spring's rate, allowing the greatest motion with the least effort. However, this is also the point at which the entire assembly wants to continue to oscillate at the same speed as long as there is additional energy put into the system. The shock absorber (on the car) is there to reduce this resonance (i.e. bouncing).
The question is: If the damped resonance is something that is desirable or undesirable?
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The system is already tuned way lower than what you're describing, somewhere between 1-2 Hz, I think. At most 8 Hz for super racecar.
Resonance is good for musical instruments but way bad in this case.