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How can I insert a Piezoelectric Device in a model that was created only with Pressure Acoustics and Solid Mechanics

Posted 15.12.2011, 12:22 GMT-5 Acoustics & Vibrations Version 4.1 3 Replies

Fabian Rojas
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Hello,

I have a model that was created with Pressure Acoustics and Solid Mechanics. I use Solid Mechanics on some membranes so they can interact with pressure and I wanted to use Piezoelectric on this ones so I can see the relation between Voltage and Displacement.

When I put: 'Add Physics-->Piezoelectric Devices' my model stop working. Even if I disable Piezoelectric Devices and I try to make it work like at the beginning with Solid Works it doesn't want to solve the system. The first error that appears is: ' There is no feature tagged: 'mod1_V''.

I would appreciate if anybody can help me solving this problem so I don't have to restart the model.

Thanks in advance.

Fabian Rojas
3 Replies Last Post 20.12.2011, 03:15 GMT-5
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 15.12.2011, 15:52 GMT-5
Hi

mixing in physics is not always that simple (works better in the newer versions) particularly as PZT physics include solid (again) so you end up with 2 "solid" physics. Normally COMSOL accepts this as the depedent variables receive new names i.e. u2,v2,w2, etc but then as user you will have some work to get the continuity to match as you need to make these formulations by hand. then when you remove a physics COMSOL tries at best to correct and set back tthe dangling equations, sometimes with unexpected and strange results.

In conclusion, my way: is always to reconstruct a model from scratch, you can have two models open, and copy the entry field formulas from one to the next, anyhow often this makes me clean up an old model already quite tampereed with, in this way I have very few issues, and far less similar variables to look after

--
Good luck
Ivar
Hi mixing in physics is not always that simple (works better in the newer versions) particularly as PZT physics include solid (again) so you end up with 2 "solid" physics. Normally COMSOL accepts this as the depedent variables receive new names i.e. u2,v2,w2, etc but then as user you will have some work to get the continuity to match as you need to make these formulations by hand. then when you remove a physics COMSOL tries at best to correct and set back tthe dangling equations, sometimes with unexpected and strange results. In conclusion, my way: is always to reconstruct a model from scratch, you can have two models open, and copy the entry field formulas from one to the next, anyhow often this makes me clean up an old model already quite tampereed with, in this way I have very few issues, and far less similar variables to look after -- Good luck Ivar
Fabian Rojas
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Posted: 1 decade ago 19.12.2011, 08:19 GMT-5
Thank you very much Ivar, you were very with the explanations.

Now, I have one more problem, maybe you can help me.

I have a model where I want to verify that a piezoelectric membrane will have her displacement proportional than the Electric voltage. My model send a acoustic planar wave that reacts with the membrane and I first try to find the resonance frequency of the membrane.

All the system work but when I get near the resonance frequency Comsol doesn't solve the problem and exceeds the number of itinerations and doesn't converge.

So is there any way to make it converge to have at least some approximative result?

Thank you in advance

Fabian Rojas
Thank you very much Ivar, you were very with the explanations. Now, I have one more problem, maybe you can help me. I have a model where I want to verify that a piezoelectric membrane will have her displacement proportional than the Electric voltage. My model send a acoustic planar wave that reacts with the membrane and I first try to find the resonance frequency of the membrane. All the system work but when I get near the resonance frequency Comsol doesn't solve the problem and exceeds the number of itinerations and doesn't converge. So is there any way to make it converge to have at least some approximative result? Thank you in advance Fabian Rojas
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 20.12.2011, 03:15 GMT-5
Hi

most probably you do not have defined any damping in your model. without damping a resonance has its amplitude tending to INF which crashes the solver, try to add a few % viscous damping, or whatever you have as info on the actual damping (from the material and from the assembly) you can expect

--
Good luck
Ivar
Hi most probably you do not have defined any damping in your model. without damping a resonance has its amplitude tending to INF which crashes the solver, try to add a few % viscous damping, or whatever you have as info on the actual damping (from the material and from the assembly) you can expect -- Good luck Ivar

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