Vibration exciter input power vs output from a piezo

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SUMMARY

The discussion revolves around the measurement of input power versus output power in a piezo element fixed onto a vibration shaker. The user measured an input power of 0.04 mW and an output electrical power of 1.42 mW, leading to a discrepancy of approximately 1000 times, which is deemed impossible. The measurements included a force of 0.124 N (rms), a vibration frequency of 142.4 Hz, and an acceleration of 0.35 m/s² (rms). The user seeks clarification on potential errors in their calculations or measurements.

PREREQUISITES
  • Understanding of piezoelectric materials and their properties
  • Familiarity with vibration measurement techniques and equipment
  • Knowledge of basic physics equations related to force, acceleration, and power
  • Proficiency in using impedance heads for force measurement
NEXT STEPS
  • Review the principles of piezoelectricity and energy conversion efficiency
  • Learn about the calibration and accuracy of impedance heads in force measurement
  • Investigate the relationship between acceleration, force, and power in vibrational systems
  • Explore advanced techniques for measuring input and output power in piezo systems
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Engineers, researchers, and students working with piezoelectric devices, vibration analysis, and energy conversion systems will benefit from this discussion.

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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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