electrostatic force cause displacement in parallel plate capacitor in COMSOL

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Suzan Miah

Suzan Miah

January 23, 2013 3:50pm UTC

electrostatic force cause displacement in parallel plate capacitor in COMSOL

Hi,

I have been designed a parallel-plate capacitor in COMSOL. Where one plate is connect to voltage of 10V and other one is connected to GND. and a air box is around the parallel plate capacitor.

As I know, if I applied a voltage in plate 1 then there will displace in plate one. I want to know how can I measure and plot this displacement of the plate. I have been stooped here for couple of week.

Would any one please help me in this regard.

Thank in Advance.

-Suzan

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Luke Gritter

Luke Gritter
Certified Consultant
AltaSim Technologies

January 23, 2013 4:39pm UTC in response to Suzan Miah

Re: electrostatic force cause displacement in parallel plate capacitor in COMSOL

Suzan,

You can model the deflection by coupling Electrostatics, Solid Mechanics, and Moving Mesh interfaces. Use the Maxwell surface stress tensor for the boundary load on an electrically conducting material. I've attached an example model showing the implementation. If the deflection is very small compared to the gap, the Moving Mesh interface would not be required, as the electrostatic force would not vary significantly with the displacement.

Luke Gritter
AltaSim Technologies

Attachments:   2D Diaphragm Deflection.mph  

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Suzan Miah

Suzan Miah

January 23, 2013 4:45pm UTC in response to Luke Gritter

Re: electrostatic force cause displacement in parallel plate capacitor in COMSOL

Thank you very much for your kind response..:)
Hope it will help me

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Suzan Miah

Suzan Miah

January 27, 2013 12:38pm UTC in response to Suzan Miah

Re: electrostatic force cause displacement in parallel plate capacitor in COMSOL

Hi

I used Electromechanic physic..but there is some error . they need young's modulus and poission ratio of air.
As we know that air has no Young's modulus and poission ratio.

How can I overcome from this problem. Would anyone tell me.

Thanks in advance

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Suzan Miah

Suzan Miah

January 27, 2013 12:45pm UTC in response to Suzan Miah

Re: electrostatic force cause displacement in parallel plate capacitor in COMSOL

I also need use vacuum...would any one tell me from where I can get vacuum ?

Thanks

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Ivar Kjelberg

Ivar Kjelberg

January 28, 2013 12:34pm UTC in response to Suzan Miah

Re: electrostatic force cause displacement in parallel plate capacitor in COMSOL

Hi

EMI is ES (static) and Solid together, you must add Domain nodes to distinguis "Linear Elastic Material" (without voltage solving) and "Linear Elastic Dielectric" (for solving with V i.e,.) by defining correctly the domains of solid as Linear Elastic material, you will not be asked for the Young modulus of air = linear electric material.

Note this physics module does not solve for conduction, so you need to define your GND and Terminal at the interface between solid (Linear Elastic Material), Linear Electric and/or Linear Ealstic Dielectric materials. Check carefully your doc

by the way this applies in my 4.3a version might be less rich in the previous ones

--
Good luck
Ivar

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Dolu Rex

Dolu Rex

March 3, 2013 9:39pm UTC in response to Luke Gritter

Re: electrostatic force cause displacement in parallel plate capacitor in COMSOL


Suzan,

You can model the deflection by coupling Electrostatics, Solid Mechanics, and Moving Mesh interfaces. Use the Maxwell surface stress tensor for the boundary load on an electrically conducting material. I've attached an example model showing the implementation. If the deflection is very small compared to the gap, the Moving Mesh interface would not be required, as the electrostatic force would not vary significantly with the displacement.

Luke Gritter
AltaSim Technologies


Hello,

I'm working on COMSOL 4.0a and I'm trying to compute a piece of PDMS which is compressed between two gold plates electrostatically actuated. I add two phisics Electrostatic and Solid. The electric field is correct but I don't get any displacement. Can someone help me please. I tryed to chek on Luke's code but I can not open it. I add mine to this message.

Thanks for the help!

Dolu

EDIT:

I add the moving mesh

Attachments:   test1.mph  

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Mohamed Hadj Said

Mohamed Hadj Said

March 20, 2013 5:39pm UTC in response to Dolu Rex

Re: electrostatic force cause displacement in parallel plate capacitor in COMSOL

Hello dolu rex,

me too i have the same probleme

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Mohamed Hadj Said

Mohamed Hadj Said

March 20, 2013 5:45pm UTC in response to Dolu Rex

Re: electrostatic force cause displacement in parallel plate capacitor in COMSOL

did you find the displacement ????? can someone help me to find the displacement due to th electrostatic force between the 2 paralelle plate capacitor (the file is attached) thank you for ur help.

Attachments:   electro.mph  

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Ivar Kjelberg

Ivar Kjelberg

March 20, 2013 8:16pm UTC in response to Mohamed Hadj Said

Re: electrostatic force cause displacement in parallel plate capacitor in COMSOL

Hi

order is important, also for the physics nodes !

ALE and solid interact: you should put the ALE BEFORE=ABOVE Solid physics node in the node list, as "solid" has it's own frame representation that is equivalent to ALE and disables the ALE physics for the "solid" domain.

If you put ALE after solid you double lock the solid mesh, no good ;)

Then you calculate the forces in the ES but you have no boundary load force input in your solid. You must couple manually i.e. define the output of one and the input nodes to the other physics, and ensure the variables point to each other


--
Good luck
Ivar

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Dolu Rex

Dolu Rex

March 21, 2013 10:58am UTC in response to Ivar Kjelberg

Re: electrostatic force cause displacement in parallel plate capacitor in COMSOL

Hello,

I reordered the nodes but now the program tells me that there is duplicate variable names. I thought it was because I deleted physics and add other so I made a new file but it still doesn't work.

Also is the order right now? -> electrostatics with the calculus of the force -> Moving mesh with free deformation and then -> the solid node with a boundary load with the ES force computed before to applie on the solid.

Thanks for the help.

Dolu

Attachments:   test2.mph  

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Mohamed Hadj Said

Mohamed Hadj Said

March 21, 2013 1:33pm UTC in response to Dolu Rex

Re: electrostatic force cause displacement in parallel plate capacitor in COMSOL

thank you ivar, i find the displacement now i want to find the eign frequency when DC bias applied between the beam and the ground, to see the influence of the electric field. please if someone have idea tell me what can i do

thank you for your help

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Mohammad Kamal

Mohammad Kamal

March 21, 2013 4:00pm UTC in response to Mohamed Hadj Said

Re: electrostatic force cause displacement in parallel plate capacitor in COMSOL

Could you please share your updated model

Thanks

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Ivar Kjelberg

Ivar Kjelberg

March 22, 2013 9:29am UTC in response to Mohamed Hadj Said

Re: electrostatic force cause displacement in parallel plate capacitor in COMSOL

Hi

the eigenfrequency analysis is not influenced by forces, at best by some initial stress in your material. In your case you have a non-linear force applying on the plates so the eigenfrequency will be influenced in a non linear way, but this is not caught by a linear eigenfrequency analysis, and I believe the frequency you look for depends on the amplitude.

That is far trickier, one way is to run a time series with enough resolution (long time to wait, and let the system damp down from an oscillatory starting point, and do an running FFT on that result)

--
Good luck
Ivar

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Mohamed Hadj Said

Mohamed Hadj Said

March 22, 2013 11:10am UTC in response to Mohammad Kamal

Re: electrostatic force cause displacement in parallel plate capacitor in COMSOL

Hi Mohamed Kamel,

the samples is attached just delete the step2 of analysis eigenfrquency then doying the study, then you get the deformation rapidshare.com/#!download|982p...antileverBeam_mod.mph|6079|0|0

Unfortunately I couldn't upload the file in the forum because of the size limitation.

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Mohamed Hadj Said

Mohamed Hadj Said

March 22, 2013 11:17am UTC in response to Ivar Kjelberg

Re: electrostatic force cause displacement in parallel plate capacitor in COMSOL

Hi ivar

thank you for your help so i changed my study to : step1:stationary, step2: time dependant modal and next the study???

thank you for ur help

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Mohammad Kamal

Mohammad Kamal

March 22, 2013 4:26pm UTC in response to Mohamed Hadj Said

Re: electrostatic force cause displacement in parallel plate capacitor in COMSOL


Thanks
You can upload larger file. see the following link:


www.comsol.com/support/knowledgebase/1098/

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Tatek Muschol

Tatek Muschol

December 2, 2013 3:22pm UTC in response to Mohammad Kamal

Re: electrostatic force cause displacement in parallel plate capacitor in COMSOL

Hallo,
i'm designing a resonator with a parallel Terminal, the Gnd is elastic metal part in the middle. The idea is to move the grd up n down b/n the two electrodes/terminals (top and bottom electrode), a voltage will be applied simultaneously to the top and bottom electrode so that the Gnd in the middle deforms towards the terminal with applied voltage.
How ? Which model would you recommend me? i m working with the comsol 43b version. How can i realize the switching b/n the two terminals?
See the attachment file!
i would be very thankful for any help
Tatek

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