Measuring shock and vibrations

Factual Questions
1

If I were to measure the shock and vibrations of an archery bow durring and after the shot what kind of tool would be needed to do that? I would like to see it expressed just as a seisemograph would express it. Even better if I could build one myself. The actual strength could be expressed on a scale say of 1 to 100, I would not need any real measure of energy.

 If it is something unsofisticated that I could buld myself even better. The first thought that comes to mind for a more dramatic expression would be to clamp the bow down to a specific length metal pole that would vibrate and then record the vibrations. 

 Any thoughts appreciated.
2

You need an accelerometer. Small ones are now built into things like iPhones and Nintendo Wii controllers. For example, you could buy accelerometers that can be used with the Arduino, a popular microcontroller used by hobbyists.

3

You can buy 3-axis accelerometer chips for a few dollars that will give you all the data you need. Fasten it to the bow, connect it to a computer, and write some code to show you the output however you want. I’m sure with a little googling you’ll be able to find more detailed instructions on how to accomplish that, along with some appropriate code.

ETA: Scooped by JWT

4

There are apps for both Android and iOS that do this. I use an Android one to double check for vibrations after I’ve balanced the props on my quadcopter.

5

This is all encouraging news. Thank you.

6

If an event took say 1/200 th of a second, would I be able to graph that out 4" long or so?

7

How about this for a start?

8

You can do something as simple as getting an oscilloscope app for your PC that takes input from the sound input port or microphone, and then attach a piezoelectric tweeter to the bow. Connect them up, and the tweeter will cheerfully act as an accelerometer, and with appropriate tweaking of the trigger options the oscilloscope app should be able to get you your display. Actually calibrated numbers are harder, and a MEMS accelerometer a good start. But this you can lash up for about $5.

9

This is really cool, I think that it would also track the acceleration. I will be reading up on it. Not sure why I have never seen it before.

10

This is the correct answer.

For shock and vibration, you need to use an accelerometer, either one-axis or three-axis. You’ll also need a data acquisition system and software to acquire and reduce the data. And smarts to interpret the data, which is the most challenging task.

11

The common ADXL335 chip is limited to +/-3 g on each axis. I think a bow will have much more acceleration than this. As a swag, I’d guess a range of +/-20 g would be needed.

12

Reviving an old thread.

Anything ever come of this discussion. If I had a good 3-axis accelerometer, the next questions would be

  1. what frequencies would I be looking for (would there be a way to discern which frequencies are due to which part of the bow?

  2. which signals/oscillations, as determined by when they occurred in the cycle are due the different parts of the release cycle (think separate the vibration from the string to the arrow rest, to the nock releasing from the string)

  3. what would be the best placement for measurement (or would it be best to place the accelerometer in different locations)?

Thanks