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Time Dependent Study Piezoelectric Element

Posted 22 sept. 2017, 18:48 UTC−4 1 Reply

Katie Gandomi
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Hello,

Im a new user to COMSOL and as a result I think I am stuck on a pretty basic part of the program.

I want to create a time dependent study for a piezoelectric element where the electric potential of each sector changes with time, see attached image. However, when I run the study, my electric fields seems not to change. Any ideas why this might be happening? Could it be because I have defined an initial voltage instead of one that varies with time ?

1 Reply Last Post 23 sept. 2017, 02:39 UTC−4
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 8 years ago 23 sept. 2017, 02:39 UTC−4

Hi

I believe your confusion comes from the way Electromagnetism is modelled in all generality. The EM Maxwell equations are quite complex (and only in full 3D) and COMSOL has several appraoches adapted for different simplifications.

In particular the ES stands for electro-static hence is NOT adapted for time dependent studies, since a time dependent and varying electric field implies current flow, hence also electric and magnetic couplings and you are back in a full 3D EM model with all Maxwell equations.

It's true that most PZT studies are done with static fields hence ignoring the current flow (something giving headaches to the electronicians having to make the electroics drivers, as inrush currents in PZT devices can be very large). Most simple way out is to state that the current flows instantanously compared to the PZT effects, and you replace your time dependent study by a parametrised steady state study with a parameter "time" that you apply as for a time dependent default "t" variable.

Thnk over it, it's worth to get well aquinted with all the different types of EM studies and their hypothesis of simplifications that COMSOL proposes.

-------------------
Have fun COMSOLing,
Sincerely,
Ivar
Hi I believe your confusion comes from the way Electromagnetism is modelled in all generality. The EM Maxwell equations are quite complex (and only in full 3D) and COMSOL has several appraoches adapted for different simplifications. In particular the ***ES*** stands for *electro*-**static** hence is **NOT** adapted for time dependent studies, since a time dependent and varying electric field implies current flow, hence also electric and magnetic couplings and you are back in a full 3D EM model with all Maxwell equations. It's true that most PZT studies are done with static fields hence ignoring the current flow (something giving headaches to the electronicians having to make the electroics drivers, as inrush currents in PZT devices can be very large). Most simple way out is to state that the current flows instantanously compared to the PZT effects, and you replace your time dependent study by a parametrised steady state study with a parameter "***time***" that you apply as for a time dependent default "***t***" variable. Thnk over it, it's worth to get well aquinted with all the different types of EM studies and their hypothesis of simplifications that COMSOL proposes.

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