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Phase angle for piezoelectric

Posted Jun 3, 2013, 4:09 p.m. EDT MEMS & Nanotechnology, MEMS & Piezoelectric Devices, Materials, Modeling Tools & Definitions, Parameters, Variables, & Functions, Structural Mechanics Version 5.2a 6 Replies

Phil Garland
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Hi All,
I'm trying to find the impedance phase angle for a PZT-5H piezoelectric frequency domain simulation, but can only find the magnitude. I'm assuming that you need to enter in the tan (delta) and Qm values, but can't find where these should be included. Any pointers would be greatly appreciated.

PG
6 Replies Last Post Nov 22, 2016, 11:14 a.m. EST
Edgar J. Kaiser Certified Consultant
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Posted: 1 decade ago Jun 3, 2013, 5:39 p.m. EDT

Hi,

all quantities in COMSOL can be complex numbers. Use the real() and imag() operators to obtain the complex components and calculate the phase.

Cheers
Edgar

--
Edgar J. Kaiser
www.emphys.com
Hi, all quantities in COMSOL can be complex numbers. Use the real() and imag() operators to obtain the complex components and calculate the phase. Cheers Edgar -- Edgar J. Kaiser http://www.emphys.com
Thibaut Meurisse
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Posted: 8 years ago Nov 21, 2016, 8:13 a.m. EST
Hello,

I have the same problem, and I do not understand where to use the operators.

This is how I proceed. I modeled a piezoelectric bar made of PZT-5H. On one side I apply a ground, and on the other a potential. To calculate the impedance, I use a boundary probe which measures the current density on the same side I apply a potential.

Problem is that the probe only gives me real value. I tried to find a way to have the phase with the probe but do not find how...

Thibaut
Hello, I have the same problem, and I do not understand where to use the operators. This is how I proceed. I modeled a piezoelectric bar made of PZT-5H. On one side I apply a ground, and on the other a potential. To calculate the impedance, I use a boundary probe which measures the current density on the same side I apply a potential. Problem is that the probe only gives me real value. I tried to find a way to have the phase with the probe but do not find how... Thibaut
Dave Greve
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Posted: 8 years ago Nov 21, 2016, 6:06 p.m. EST
If you integrate the normal component of the electric displacement vector on the electrode surface you will get the charge on the electrode. Then the (complex) current is j*omega*charge.

D.W. Greve
DWGreve Consulting
If you integrate the normal component of the electric displacement vector on the electrode surface you will get the charge on the electrode. Then the (complex) current is j*omega*charge. D.W. Greve DWGreve Consulting
Thibaut Meurisse
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Posted: 8 years ago Nov 22, 2016, 4:39 a.m. EST
Hi,

I tried this, but this gives me a constant phase of pi/2 over all my frequency range. There are resonances so it should not stay constant.

Just to be sure I do it correctly. I perform a sweep over the frequency range of interest, in a Frequency Domain study. Then, after getting the charge, I multiply every point of my charge vector by the corresponding j*w. Is this right ?

I attach my model, to make sure there is no mistake.

Thibaut
Hi, I tried this, but this gives me a constant phase of pi/2 over all my frequency range. There are resonances so it should not stay constant. Just to be sure I do it correctly. I perform a sweep over the frequency range of interest, in a Frequency Domain study. Then, after getting the charge, I multiply every point of my charge vector by the corresponding j*w. Is this right ? I attach my model, to make sure there is no mistake. Thibaut

Attachments:

Dave Greve
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Posted: 8 years ago Nov 22, 2016, 10:18 a.m. EST
This does not open properly for me, perhaps because I do not have the CAD import installed right now.

But. Under "derived values" you should calculate a surface average of the normal electric displacement vector. Forget the boundary probe.

And there is an important difference between the norm (or magnitude) of the electric displacement vector (which, by definition, is purely real) and the normal component of the electric displacement on a surface (which will indeed be complex).
This does not open properly for me, perhaps because I do not have the CAD import installed right now. But. Under "derived values" you should calculate a surface average of the normal electric displacement vector. Forget the boundary probe. And there is an important difference between the norm (or magnitude) of the electric displacement vector (which, by definition, is purely real) and the normal component of the electric displacement on a surface (which will indeed be complex).
Thibaut Meurisse
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Posted: 8 years ago Nov 22, 2016, 11:14 a.m. EST
Hi D,

Ok, it seems to work now (either with a probe or with a Surface Average), thank you !
I now have a constant phase shift between the simulation and my measurements, but it may come from the measurement.

Anyway, thank you a lot !

Thibaut
Hi D, Ok, it seems to work now (either with a probe or with a Surface Average), thank you ! I now have a constant phase shift between the simulation and my measurements, but it may come from the measurement. Anyway, thank you a lot ! Thibaut

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