Piezo Element Energy
Piezo Element Energy
(OP)
Please help out a mechanical engineer interpret this electrical verbiage.
I have an assembly that uses a Piezo element in it to excite a component upon impact. The specification requires that it
What is that in terms of Voltage, Amps, or Watts?
The disc is .7 inch diameter by .1 inch thick per MIL-P-12815 if that helps.
I'm trying to test the component that gets energized by the piezo without destroying a bunch of piezo elements in the process. Thus, I need to know how much energy the piezo actually gives off so I can reproduce it using another supply source.
I have an assembly that uses a Piezo element in it to excite a component upon impact. The specification requires that it
Quote:
shall supply electrical energy equivalent to that discharged by a 0.005 microfarad capacitor that has been charged to 9 volts, minimum, when impacted by a 1.94 ounce steel ball dropped from a height of no greater than two inches (2")
What is that in terms of Voltage, Amps, or Watts?
The disc is .7 inch diameter by .1 inch thick per MIL-P-12815 if that helps.
I'm trying to test the component that gets energized by the piezo without destroying a bunch of piezo elements in the process. Thus, I need to know how much energy the piezo actually gives off so I can reproduce it using another supply source.
--Scott
http://wertel.eng.pro





RE: Piezo Element Energy
A piezo under flexing may produce a voltage greater than 9 volts. A 1.94 oz steel ball hitting a piezo from 2" will produce a transient voltage of very short duration. Normally a piezo being struck will produce a voltage of one polarity as it is struck, and reverse polarity as it relaxes back to it's original position, but in this case the piezo will produce a voltage until it fractures.
If I was to non-destructively duplicate the condition, I would first verify the spec by setting-up the piezo with the circuit and an oscilloscope, perform the steel ball drop and record the waveform, look at the voltage/time given the circuit impedance - just to make sure I'm duplicating reasonably the 0.405 micro-couloumb value. -THEN- I would use the waveform I recorded, and play it back through a arbitrary waveform generator (taking into account possible differences in source impedance of a piezo vs the generator) to duplicate the conditions to check the operation of the circuits.
RE: Piezo Element Energy
Glenn
RE: Piezo Element Energy
I also get 202.5 nJ of energy.
One might hope that the specification has a more direct meaning; that the discharge of a 9V impression on a 5 nF capacitor actually behaves like the piezo element:
http://www.piezo.com/prodbg7qm.html
Based on that webpage, one might just try to see if a 5 nF cap with 9 V behaves like the piezo element.
TTFN
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RE: Piezo Element Energy
Your right geekEE. That's what I get for replying at the end of the work day when my brain is half fried.
RE: Piezo Element Energy
--Scott
http://wertel.eng.pro