# Damped oscillation

1. May 15, 2005

### alnywk

i am going to write a report about damped oscillation .
as i planned , i will discuss the amplitude decays exponentially with time , application .
but that are too little to talk to
then what things need to be further discuss????
and one question if i use one small card and bid card to damp the oscillation , then wt the result will i get ?

2. May 15, 2005

I'm struggling to understand exactly what you are asking, but if you want an example where damping is used, think about car and motorcycle shock absorbers. I race motorcycles, and getting the damping right is essential!

I'm not sure what you mean about the card, but if you use a big piece of card as an 'air damper' it will stop the oscillations quicker than a small piece.

For an interesting example of damping in engineering - look up the 'Millenium Bridge' project in London. This public walkway crossing the Thames was closed soon after opening as when people walked across it, they set up resonant frequencies and the whole thing started to move quite alarmingly. To fix the problem, enormous dampers were applied to the bridge to damp out the oscillations.

Hope this helps......

3. May 15, 2005

### Claude Bile

Damped oscillations fall under three categories;

- Light damping - In this case the solution is oscillatory with an exponentially decaying amplitude.
- Critical damping - The solution in this case is an exponential decay. Critical damping is the amount of damping that eliminates the vibration in the shortest possible time.
- Heavy damping - The solution here is the sum of two exponentials.

If you are talking about damped oscillations, I think you ought to discuss all three types of damping, not just the lightly damped case.

'Physics of Vibrations and Waves' by Pain has an in-depth analysis of damped simple harmonic motion and could provide further insight for your talk.

Claude.