Vibration exciter input power vs output from a piezo

AI Thread Summary
The discussion centers on a measurement involving a piezo element fixed to a vibration shaker, where the input power calculated is significantly lower than the output electrical power, raising concerns about the accuracy of the measurements or calculations. The measured force on the piezo is 0.124 N (rms) at a frequency of 142.4 Hz, resulting in an output power of 1.42 mW, while the calculated input power is only 0.04 mW. This discrepancy suggests a possible error in the calculations or measurement values, prompting the author to seek feedback or clarification from others. The author expresses uncertainty about the clarity of the problem statement and requests assistance in identifying potential errors. The discussion highlights the challenges in accurately measuring and calculating input and output power in piezoelectric systems.
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,
 
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