Rion VM-83, Instruction Manual, Page: 85 / 106

75
Technical Information
* Contact resonance frequency
Contact resonance occurs when the area where the mounted accelerometer
contacts the measurement object becomes temporarily deformed, causing
it to act like a spring. This spring and the accelerometer mass then form a
system that vibrates at a certain resonance frequency.
The resonance frequency, which varies considerably depending on the mounting
method of the accelerometer, limits the upper range of vibration frequencies
that can be measured.
The diagram below shows the relationship between mounting method and
high range characteristics. This demonstrates that, besides selecting an ap-
propriate mounting method, it is important to set the measurement range so
that the infl uence of the contact resonance phenomenon is excluded.
Sample chart showing the infl uence of accelerometer mounting method on
high-range frequency characteristics
30
20
10
0
50 100 200 500 1000 2000 5000 10 k 20 k
Rod attachment mounting
Magnet attachment mounting
Adhesive
(instant glue)
Screw mounting
Frequency (Hz)
Response (dB)