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Soft Source for SAW resonator
Posted Feb 22, 2011, 8:38 a.m. EST MEMS & Nanotechnology, MEMS & Piezoelectric Devices, Parameters, Variables, & Functions, Results & Visualization, Structural Mechanics Version 4.3b 4 Replies
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Im doing a SAW resonator, and Im interested in seeing the wave response thanks to a voltage excitation but also seeing the voltage response thanks to a reflected surface wave.
I manage to generate the wave with a gaussian pulse modulated in the resonator central frequency, and I define all electrode faces with the same potential representing it as a metal electrode and not just as an elastic electrode. The problem is that when I fix the voltage with Terminal or with Electric Potential I cant see the voltage generated by the surface wave reflections.
Is there a way to define an Electrical Potential that responds to the equations from a piezoelectric model and applies the voltage neeeded for the wave, or simply a way of deactivating the source after the pulse has been applied so the electrodes can react to the voltage from the wave?
I manage to generate the wave with a gaussian pulse modulated in the resonator central frequency, and I define all electrode faces with the same potential representing it as a metal electrode and not just as an elastic electrode. The problem is that when I fix the voltage with Terminal or with Electric Potential I cant see the voltage generated by the surface wave reflections.
Is there a way to define an Electrical Potential that responds to the equations from a piezoelectric model and applies the voltage neeeded for the wave, or simply a way of deactivating the source after the pulse has been applied so the electrodes can react to the voltage from the wave?
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4 Replies Last Post Jul 29, 2014, 9:45 a.m. EDT
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Posted:
1 decade ago
Hi
first of all your model loads but flags a few errors related to the materials, and I see that several domains have no default material defined. Normally with the material nodes, you define first the most common material =air that is applied to all domains, then you add new materials and define their specific domains. The materials are automatically deselected (overridden) in the first "air" node. In this way you will not forget any material definitions
Then to get occrect PML behaviour you should surround fully your part by two sphere/circular shells, both with "air" and define the PML on the outer shell. Currently you have partial PML's with the infinite points shared with finite points on the model this cannot converge correctly, you can only share a "infinite" point / boundary with another "infinite" item
In PZT you should define structural and electrical domains, if you do not include all domains your V voltage and electric field variables will not be correct. You need to think about both physics as independent, are all BC and domains coherent for EM fields, and then are they for the structural point of view
--
Good luck
Ivar
first of all your model loads but flags a few errors related to the materials, and I see that several domains have no default material defined. Normally with the material nodes, you define first the most common material =air that is applied to all domains, then you add new materials and define their specific domains. The materials are automatically deselected (overridden) in the first "air" node. In this way you will not forget any material definitions
Then to get occrect PML behaviour you should surround fully your part by two sphere/circular shells, both with "air" and define the PML on the outer shell. Currently you have partial PML's with the infinite points shared with finite points on the model this cannot converge correctly, you can only share a "infinite" point / boundary with another "infinite" item
In PZT you should define structural and electrical domains, if you do not include all domains your V voltage and electric field variables will not be correct. You need to think about both physics as independent, are all BC and domains coherent for EM fields, and then are they for the structural point of view
--
Good luck
Ivar
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Posted:
1 decade ago
Hi Ivar,
Thank you for your comments. I´ve rechecked materials and they´re correct now, all of the domains have a materials expect for the PML, that has user defined parameters. I'll take into account what you comment about this boundary, but still my doubt is how can I get to deactivate a voltage after a while without fixing it to zero.
The idea of the electrodes is to define the voltage for the structure. I've already defined all the EM boundaries I need and all of the structural ones. The behaviour of the structure is coherent, but because of the fixed voltage definition electrodes don´t respond to the piezoelectric effect. Is there a possibility of fixing the voltage for a certain period of time and then turn it off as if it was in a high impedance state?
Thank you for your comments. I´ve rechecked materials and they´re correct now, all of the domains have a materials expect for the PML, that has user defined parameters. I'll take into account what you comment about this boundary, but still my doubt is how can I get to deactivate a voltage after a while without fixing it to zero.
The idea of the electrodes is to define the voltage for the structure. I've already defined all the EM boundaries I need and all of the structural ones. The behaviour of the structure is coherent, but because of the fixed voltage definition electrodes don´t respond to the piezoelectric effect. Is there a possibility of fixing the voltage for a certain period of time and then turn it off as if it was in a high impedance state?
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Posted:
1 decade ago
Hi ,
I am trying to simulate a SAW device in 128 deg YX lithium niobate material using comsol. Could you please let me know if its the same material orientation that you have used for the simulation. Basically, I have tried to calculate the rotated matrices (stiffness etc) and tried to confirm this with your material properties. So I have found that it doesnt match, so just wanted to confirm if you use the same material orientation 128YX.
Waiting for your response.
Thanks,
Rahul Kishor
I am trying to simulate a SAW device in 128 deg YX lithium niobate material using comsol. Could you please let me know if its the same material orientation that you have used for the simulation. Basically, I have tried to calculate the rotated matrices (stiffness etc) and tried to confirm this with your material properties. So I have found that it doesnt match, so just wanted to confirm if you use the same material orientation 128YX.
Waiting for your response.
Thanks,
Rahul Kishor
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Posted:
1 decade ago
Hi Ivar,
I'm doing a SAW sensor, and I'm interested in seeing a RF signal fed into IDT1 on the left side of the Piezoelectric Devices ,then a SAW propagate along the surface of the Piezoelectric Devices ,IDT2 on the right of the Piezoelectric Devices received it ,I want to see the voltage response of IDT2.(model in attach file below)
I manage to generate the SAW with a gaussian pulse modulated in the resonator central frequency, and I define all electrode faces with the same potential , The problem is that I cant see the surface wave generated by the IDT1.
Could you tell me where did the problems come from?
Thank you very much,
Best wishes to you.
Yunshan.
I'm doing a SAW sensor, and I'm interested in seeing a RF signal fed into IDT1 on the left side of the Piezoelectric Devices ,then a SAW propagate along the surface of the Piezoelectric Devices ,IDT2 on the right of the Piezoelectric Devices received it ,I want to see the voltage response of IDT2.(model in attach file below)
I manage to generate the SAW with a gaussian pulse modulated in the resonator central frequency, and I define all electrode faces with the same potential , The problem is that I cant see the surface wave generated by the IDT1.
Could you tell me where did the problems come from?
Thank you very much,
Best wishes to you.
Yunshan.