Vibration exciter input power vs output from a piezo

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beagles
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Homework Statement


Hello, I did the following measurement:

A piezo element (mass approx. 50 gram) is fixed onto a vibration shaker
The force exert on the piezo, 0,124 N (rms) is measured with an impedance head
The vibration frequency (sinusoidal signal) is 142,4 Hz
The acceleration is measered as 0,35 m/s² rms.
The electrical output power of the piezo is measured as 1,42 mW

Homework Equations



The Attempt at a Solution


Calculated input power: 0,35*1/(2*pi*142,4)*0,124=0,04mW (=speed * force)
with the speed = integral of the acceleration and 2*pi*142 the angular frequency

So the input power is much smaller than the output electrical power, which is impossible, it seems to be a factor 1000 wrong? Does anyone see my error, or measured value that is abnormal? Thanks already!
 

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Hi

I did my best describing the problem as accurately as possible. Is the problem i stated not clear, should it be reformulated? Could anyone give a hint on what could be wrong?

Thank you already!
 
Hi,

Isn't there anyone who can give me some feedback on this?

Thanks,