Sometimes your keyboard is faster than your mind in your eagerness to help, that's all
:rofl:If you knew how long it takes me write a post then my mind must be slower than a snail on national go slow day

I certainly dont know everything (but I'm keen to fill in the gaps) I just try to look at things from a practical point of veiw as well as pages of theory and calcs.

My logic was that vibration can only be transmited through a stiff material. If you take a steel bar and tap one end then vibration is transmited to the other end, but if you took a similar bar of say rubber or wood then much less vibration will be transmitted.

Therefore only a stiff structure can vibrate, No?

Anyway its getting late, Any good books you can recommed for me brush up on this subject?