How do piezoelectric actuators work?

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Discussion Overview

The discussion revolves around the functionality and characteristics of piezoelectric actuators, including their displacement capabilities, resonant frequencies, and potential applications in various projects. Participants explore both theoretical and practical aspects of piezoelectric materials and their use in vibration control and rapid actuation.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Homework-related

Main Points Raised

  • One participant inquires about the meaning of maximum displacement and resonant frequency, questioning if the actuator can sustain such frequencies over time.
  • Another participant clarifies that the resonant frequency indicates the vibration frequency of the actuator, suggesting that the actuator's movement speed is not specified in the data sheet.
  • A participant proposes a concept for a device that rapidly changes dimensions and oscillates at high frequencies, questioning if piezoelectric actuators can meet these requirements.
  • Some participants suggest that a raw piezoelectric element combined with a fast-switching power source may be more suitable for rapid switching than standard piezoelectric actuators.
  • One participant expresses concern about the feasibility of oscillating a significant mass rapidly, citing inertia as a potential issue.
  • Another participant speculates on the relationship between the thickness of quartz and its piezoelectric properties, noting a lack of available data on voltage-to-distortion relationships.
  • A participant mentions their project involving active vibration control using piezoelectric patches and seeks assistance with analysis in ANSYS.

Areas of Agreement / Disagreement

Participants express various viewpoints on the capabilities and limitations of piezoelectric actuators and elements, with no consensus reached on the best approach for high-frequency applications or the specific characteristics of materials like quartz.

Contextual Notes

Participants note limitations in available data regarding the voltage-to-distortion relationship for quartz and the challenges of oscillating heavier masses at high frequencies, indicating potential dependencies on material properties and design considerations.

ktoz
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Hi

I have a question about piezoelectric actuators. I'm not an engineer and have no experience with actuators, but in looking over the first item in the data sheet http://motion-controls.globalspec.com/SpecSearch/ProductSpecs?Comp=3083&VID=96478" , I see that the maximum displacement is 5 µm with a resonant frequency of 17 khz. Does that mean the surface of the actuator is able to move 5 µm every 1/17,000 of a second?

Is the above linked actuator capable of sustaining 17 khz for extended periods? Or does it require rest.

Thanks for any help
 
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No, the resonant frequency is the frequency the actuator vibrates at to move. So anything the actuator is moving should not have a natural mode close to that resonant frequency. The data sheet does not say how fast the actuator is able to move from one limit to another, but 5um isn't much...
 
Mech_Engineer said:
No, the resonant frequency is the frequency the actuator vibrates at to move. So anything the actuator is moving should not have a natural mode close to that resonant frequency. The data sheet does not say how fast the actuator is able to move from one limit to another, but 5um isn't much...

Well I have an idea kicking around for something which can rapidly change dimension (anywhere between 5um and 500um is fine) in response to an electric impulse and can oscillate between rest and expanded states 1000s or 10K, 20K 30K times per second. It needs do so for long periods without any adverse effects. Can actuators do that? Or should I be looking at some other kind of component?
 
I think what you're looking for is a raw piezoelectric element, and a fast-switching power source. Piezoelectric actuators are made to move things, not necessarily switch very quickly.
 
Mech_Engineer said:
I think what you're looking for is a raw piezoelectric element, and a fast-switching power source. Piezoelectric actuators are made to move things, not necessarily switch very quickly.

Thanks Mech_Engineer.

Can a raw piezoelectric element also move things? I haven't worked out exactly how much weight I'd need, but as a rough estimate, say 1 to 3 pounds, 5um to 50um per cycle at 10K+ cycles per second. The linear motion doesn't need to be much, just a lot of them per second.
 
Well I Googled for several hours and found that Quartz is probably a good material to look into, but one thing I couldn't find was any information about how much Quartz deforms for various thicknesses and voltages. Does anyone know of a chart that shows this voltage -to-distortion relationship?
 
This isn't a field that I know a lot about, but that seems to be an awful lot of mass to oscillate that rapidly, regardless of how small the movement is. There's a lot of inertia involved.
 
Danger said:
This isn't a field that I know a lot about

Me either

but that seems to be an awful lot of mass to oscillate that rapidly, regardless of how small the movement is. There's a lot of inertia involved.

After more thought, I think the mass could be dropped a lot, probably down to about 6 ounces or less.

I don't know if this is even possible, but if the interface between the piezoelectric material and the secondary material was stiff enough, the bond between the two materials strong enough, a second material would be essentially an extension of the piezoelectric material.

It may be that as the size of a quartz crystal increases, the frequency of its piezoelectric distortion decreases but I can't find any hard numbers on the voltage/thickness/distortion/frequency relationships for quartz

Just at an observational level, as a piece of metal gets thicker, the sound it makes when you hit it gets higher so, my gut instinct would be that quartz might behave the same.
 
Hi, mech_engineer,
I'm working on project of active vibration control using piezoelectric patches .
I'm using ANSYS for analysis part for optimal placement of smart structures on plate and also applying voltages to piezo actuators to suppress vibration.
But I'm finding difficulty in analysis part in ANSYS ,can u help me ?
 
  • #10
No it is not necessary i guess...
 

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