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Piezoelectric bimoph cantilever simulation---polarization?

Posted Oct 3, 2011, 8:07 p.m. EDT MEMS & Nanotechnology, MEMS & Piezoelectric Devices Version 3.5a 5 Replies

Fei Xie
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Dear All,

This is my first time to post a question here.

I am trying to simulate a two-layer (Bimorph) PVDF cantilever: to see the deflection of the beam if voltage is applied. However, I find there is a problem if I want to realize an opposite polarizations of these two PVDF layer. Can anyone tell me how?

I am using version 3.5a.

Thank you in advance.

Fei

5 Replies Last Post Oct 20, 2011, 4:55 a.m. EDT
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Oct 4, 2011, 1:19 a.m. EDT
Hi

V3.5 is getting "old" and vague in my reminding, but I expect that you may get around by defining two coordinate systems and then apply the physics via each coordinate system

--
Good luck
Ivar
Hi V3.5 is getting "old" and vague in my reminding, but I expect that you may get around by defining two coordinate systems and then apply the physics via each coordinate system -- Good luck Ivar
Fei Xie
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Posted: 1 decade ago Oct 4, 2011, 8:27 p.m. EDT

Dear Ivar Kjelberg,

Is there any way I can do 3D rather than 2D?

I can get access to 4.0, but will that be helpful for 3D?

Thank you!
Dear Ivar Kjelberg, Is there any way I can do 3D rather than 2D? I can get access to 4.0, but will that be helpful for 3D? Thank you!
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Oct 5, 2011, 8:18 a.m. EDT
Hi

3D needs a lot of RAm, 3.5 can handle both, in anycase I cannot advise 4.0 today, use a more recent version if so

--
Good luck
Ivar
Hi 3D needs a lot of RAm, 3.5 can handle both, in anycase I cannot advise 4.0 today, use a more recent version if so -- Good luck Ivar
Fabio Carta
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Posted: 1 decade ago Oct 19, 2011, 3:52 p.m. EDT
Hi all,

so, I have more or less the same problem. I want to simulate a bimorph cantilever made out of two layer of PVDF. I am mainly interested in mimicking the bending of the cantilever due to the application of the strain in one of the two layer. Now, the material should have a strain of 2% when a 100V/um electric field is applied across it. My structure is 2cm long, 1cm wide and 10 um thick (5um each layer, joint together through identity pair condition). I have tried to apply directly the strain in the top layer in the subdomain setting (as initial strain) or stress, and I have also tried to apply the stress in the lateral (end) surface of the top layer of the cantilever (while the other side is clamped). In both cases I get a weird number for the z displacement 0.6m (that makes no sense in a structure only 2 cm long). I'm pretty sure that I'm missing something, so I would appreciate anyone help!

Thanks,
Fabio

p.s. I'm using the structural mechanics module
Hi all, so, I have more or less the same problem. I want to simulate a bimorph cantilever made out of two layer of PVDF. I am mainly interested in mimicking the bending of the cantilever due to the application of the strain in one of the two layer. Now, the material should have a strain of 2% when a 100V/um electric field is applied across it. My structure is 2cm long, 1cm wide and 10 um thick (5um each layer, joint together through identity pair condition). I have tried to apply directly the strain in the top layer in the subdomain setting (as initial strain) or stress, and I have also tried to apply the stress in the lateral (end) surface of the top layer of the cantilever (while the other side is clamped). In both cases I get a weird number for the z displacement 0.6m (that makes no sense in a structure only 2 cm long). I'm pretty sure that I'm missing something, so I would appreciate anyone help! Thanks, Fabio p.s. I'm using the structural mechanics module
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Oct 20, 2011, 4:55 a.m. EDT
Hi

the cleanest is probably to use the thermal stress example in the model library to build up your stress correctly, then to see how the part behaves in structural. If you do eigenfrequency models, do not forget that these are linear analysis, and you need to stabilise the stress via a stationary case then linearise around this point, see the buckling examples in the doc and model library (in 3.5 you need matlab for this)

--
Good luck
Ivar
Hi the cleanest is probably to use the thermal stress example in the model library to build up your stress correctly, then to see how the part behaves in structural. If you do eigenfrequency models, do not forget that these are linear analysis, and you need to stabilise the stress via a stationary case then linearise around this point, see the buckling examples in the doc and model library (in 3.5 you need matlab for this) -- Good luck Ivar

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