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How to assign a value to the electric field in a piezoelectric material
Posted Jan 2, 2011, 6:42 a.m. EST Low-Frequency Electromagnetics, Structural Mechanics Version 4.0 5 Replies
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Hello,
I'm using the version 4.0 and I would like to assign a value to the electric field in a piezoelectric material (namely PZT-5H) through the "Model Inputs", but unlike the "Model Outputs", it is not possible to directly attribute a value/function to the electric field.
I tried to solve this by creating "Variables" in the "Definitions" item, or adding "analytical functions" in the "Basic" section of the material, but it doesn't work.
Could someone tell me how to achieve this?
Thank you!
I'm using the version 4.0 and I would like to assign a value to the electric field in a piezoelectric material (namely PZT-5H) through the "Model Inputs", but unlike the "Model Outputs", it is not possible to directly attribute a value/function to the electric field.
I tried to solve this by creating "Variables" in the "Definitions" item, or adding "analytical functions" in the "Basic" section of the material, but it doesn't work.
Could someone tell me how to achieve this?
Thank you!
5 Replies Last Post Jan 8, 2011, 4:32 p.m. EST
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Posted:
1 decade ago
Actually the objective aimed is to observe the deformation of a unimorph bender when a voltage is applied to the piezoelectric layer...
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Posted:
1 decade ago
Hi
I do not really follow you here, if you have a structure of PZT material and you want to see it bend under an electric field, you must resolve the electric field with a ACDC physics i.e. ES electrostatic so that you have the electric field distribution across your domain and then couple this field and the structure and solve for all elementary elements of your mesh, do we agree ?
In 4.1 this is linked with the structural PZD physics, where you have the ST+ES combined: you define your PZT materials, perhaps also standard linear materials, and you set up BOTH the ST structural and the ES electrical BCs. Then the solver will combine these or you control the segregation yourself
--
Good luck
Ivar
I do not really follow you here, if you have a structure of PZT material and you want to see it bend under an electric field, you must resolve the electric field with a ACDC physics i.e. ES electrostatic so that you have the electric field distribution across your domain and then couple this field and the structure and solve for all elementary elements of your mesh, do we agree ?
In 4.1 this is linked with the structural PZD physics, where you have the ST+ES combined: you define your PZT materials, perhaps also standard linear materials, and you set up BOTH the ST structural and the ES electrical BCs. Then the solver will combine these or you control the segregation yourself
--
Good luck
Ivar
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Posted:
1 decade ago
Thank you very much Ivar,
sorry for my confusing question, I'm not used to utilize COMSOL.
I've added the ES physics to the model and determined the BC's (100V across the PZT), but the bender does not experience any deformation... Moreover I cannot set the correct constitutive relation for charge conservation in ES between E and D for PZT (it should be D = eps_0*eps_r*E + d*T)...
I also tried to add the PZD physics but unfortunately I cannot access it with the licence of my university.
Thanks a lot!
sorry for my confusing question, I'm not used to utilize COMSOL.
I've added the ES physics to the model and determined the BC's (100V across the PZT), but the bender does not experience any deformation... Moreover I cannot set the correct constitutive relation for charge conservation in ES between E and D for PZT (it should be D = eps_0*eps_r*E + d*T)...
I also tried to add the PZD physics but unfortunately I cannot access it with the licence of my university.
Thanks a lot!
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Posted:
1 decade ago
It is maybe better with a file attached!
Attachments:
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Posted:
1 decade ago
Hi
come on, there are no stupid questions, only stupid replies, I have heard ;)
We all have to start once, even with COMSOL.
Now if you licence is not including PZT it not really easy, as the PZT module contains all the specific physics and links beteween the structural ST and ACDC ES electrostatics included. Ideally you should perform the exercice of the PZT bending stack of the Model Builder to learn. Explaining all to set up ful pZT will be more than what I can manage to put one even several pages here.
Furthermore you should really get the 4.1 update, because the early4.0 is really too "early" there are many things not yet iron out in that one. Checkwith your sysadmin. THe documentation of 4.1 is also far better, I would almost recommend to use the theory of v3.5 instead of the little that weas in v4.0. Buit the methodology of the model set-up isvery different (and I find far easier and logic) in v4
The basic steps are in ES apply a gnd and a voltage to two boundaries (edges in 2D) to have Comsol reslve the potential V across the electrode gap. Then in the structural one need to link in the equtions of the PZT material, hence linking the stress tensor and the voltage (the physics missing if you do not have the PZT module), and then have this stress field to deform the structural part that is standard work for the ST physics.
To begin with you could even forget the ES module, and say V=V(y) and only start with structual and fidde the stress tensor as a function of V(y) (y being the vertical height. This is correct for a parallel plate electrode.
For your bender you have one material in standard ST (no voltage relation) and one PZT sensitive to te voltage.
Hope this helps
--
Good luck
Ivar
come on, there are no stupid questions, only stupid replies, I have heard ;)
We all have to start once, even with COMSOL.
Now if you licence is not including PZT it not really easy, as the PZT module contains all the specific physics and links beteween the structural ST and ACDC ES electrostatics included. Ideally you should perform the exercice of the PZT bending stack of the Model Builder to learn. Explaining all to set up ful pZT will be more than what I can manage to put one even several pages here.
Furthermore you should really get the 4.1 update, because the early4.0 is really too "early" there are many things not yet iron out in that one. Checkwith your sysadmin. THe documentation of 4.1 is also far better, I would almost recommend to use the theory of v3.5 instead of the little that weas in v4.0. Buit the methodology of the model set-up isvery different (and I find far easier and logic) in v4
The basic steps are in ES apply a gnd and a voltage to two boundaries (edges in 2D) to have Comsol reslve the potential V across the electrode gap. Then in the structural one need to link in the equtions of the PZT material, hence linking the stress tensor and the voltage (the physics missing if you do not have the PZT module), and then have this stress field to deform the structural part that is standard work for the ST physics.
To begin with you could even forget the ES module, and say V=V(y) and only start with structual and fidde the stress tensor as a function of V(y) (y being the vertical height. This is correct for a parallel plate electrode.
For your bender you have one material in standard ST (no voltage relation) and one PZT sensitive to te voltage.
Hope this helps
--
Good luck
Ivar