Picture a plate of steel say 2'x2'. If I smacked it with a hammer and wanted it to send a signal (rf maybe) to a receiver that turned a 12v light on for a few seconds.
Now that would be a different sensor altogether xD
If that steel plate was hit hard enough, the sensors I mentioned earlier would work... although the car air-bag sensor would only trigger once and would need to be reset.
If the plates 'move' a lot, stick with the spring type sensor I mentioned. If the plates don't 'move' that much, but vibrate a lot, you should look into piezo elements. They generate a voltage when exposed to vibration that you can use to trigger your light. The circuit used to monitor this will need to condition the signal though... because the piezo element can generate a high voltage if struck hard enough... (They are used in some BBQ lighters... a hammer strikes an element and it makes a high enough voltage to make a spark...) Of course, your application will not (or should not) create a spark xD