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About conductive electrodes of piezoceramics layers

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Hello everyone,

I am working on a piezoelectric energy harvester(substructure and a piezoceramic layer). I am applying a point force on the substructure and measuring the voltage from the surface of the piezoceramic to obtain voltage FRF (voltage/point force).

I want my model to account for the conductive electrodes bracketing the piezoceramic layer so that I can obtain uniform potential distribution throughout the surface of the piezoceramic. However, I couldnt find the appropriate boundary condition for this purpose.

I appreciate any help,
Bugra Bayik.

3 Replies Last Post 27 feb 2013, 04:49 GMT-5
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 20 feb 2013, 02:51 GMT-5
Hi

have you tried to use the terminal in "terminated" mode, or linked to a RC circuit ?,
Indeed I cannot find any perfect electric conductive layer (in the plane direction to mimic a conductor deposited on a boundary) in PZD
But I wonder if this BC (was there before) has not been replaced with the "floating potential" BC

--
Good luck
Ivar
Hi have you tried to use the terminal in "terminated" mode, or linked to a RC circuit ?, Indeed I cannot find any perfect electric conductive layer (in the plane direction to mimic a conductor deposited on a boundary) in PZD But I wonder if this BC (was there before) has not been replaced with the "floating potential" BC -- Good luck Ivar

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Posted: 1 decade ago 20 feb 2013, 07:44 GMT-5
If what you want to know is the open circuit voltage of your harvester, I would suggest using a grounded boundary condition for one of the electrodes and a floating potential for the second.
If what you want to know is the open circuit voltage of your harvester, I would suggest using a grounded boundary condition for one of the electrodes and a floating potential for the second.

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Posted: 1 decade ago 27 feb 2013, 04:49 GMT-5
Thanks a lot for the comments.

I tried floating potential and terminated boundary conditions. I am plotting electric potential amplitudes of arbitrary points on upper surface of the PZT. My FRF is between 0-200Hz and there are 6 modes in this range (they all can be observed in my measurement point). I attached the plots for:

case 1) Zero charge: It is resulting peaks at every natural frequency and arbitrary points on PZT have different amplitudes at each mode as expected.

case 2) Floating potential case: Arbitrary points on PZT have same amplitude so the uniform potential distribution is obtained. However, there is only one peak on the FRF. I lost the information for the other modes

case 3) Terminated case: In this BC i am getting an error as follows
Undefined value found.
- Detail: Undefined value found in the stiffness matrix.
.There are 1 equations giving NaN/Inf in the matrix rows for the variable mod1.pzd.V0_1
. at coordinates: (0,0,0), ...
and similarly for the degrees of freedom, NaN/Inf in the matrix columns.

I see that floating potential should be working. My question is why is it eleminating the peaks at other modes and resulting in only one peak?
Thanks a lot for the comments. I tried floating potential and terminated boundary conditions. I am plotting electric potential amplitudes of arbitrary points on upper surface of the PZT. My FRF is between 0-200Hz and there are 6 modes in this range (they all can be observed in my measurement point). I attached the plots for: case 1) Zero charge: It is resulting peaks at every natural frequency and arbitrary points on PZT have different amplitudes at each mode as expected. case 2) Floating potential case: Arbitrary points on PZT have same amplitude so the uniform potential distribution is obtained. However, there is only one peak on the FRF. I lost the information for the other modes case 3) Terminated case: In this BC i am getting an error as follows Undefined value found. - Detail: Undefined value found in the stiffness matrix. .There are 1 equations giving NaN/Inf in the matrix rows for the variable mod1.pzd.V0_1 . at coordinates: (0,0,0), ... and similarly for the degrees of freedom, NaN/Inf in the matrix columns. I see that floating potential should be working. My question is why is it eleminating the peaks at other modes and resulting in only one peak?

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