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
Messages
3
Reaction score
0

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!
 
Physics news on Phys.org
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,
 
Thread 'Collision of a bullet on a rod-string system: query'

Thread 'Collision of a bullet on a rod-string system: query'

In this question, I have a question. I am NOT trying to solve it, but it is just a conceptual question. Consider the point on the rod, which connects the string and the rod. My question: just before and after the collision, is ANGULAR momentum CONSERVED about this point? Lets call the point which connects the string and rod as P. Why am I asking this? : it is clear from the scenario that the point of concern, which connects the string and the rod, moves in a circular path due to the string...
View full post »
Thread 'A cylinder connected to a hanged mass'

Thread 'A cylinder connected to a hanged mass'

Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
View full post »

Similar threads

Maximum theoretical power from piezoelectric harvesting
Replies
12
Views
2K
Input Power against time graph - Flywheel from rest to 300rpm
Replies
18
Views
4K

Hot Threads

Recent Insights

Back
Top