Discussion Forum

Hi

I believe these should be run coupled (fully or segregated to see) but the EC cannot understand what voltage to use like that you must link them via domain or boundary conditions using the results from the other physics.

If you are sure the physics do not interact, then you might run one and the other separately, using the results of the first phsics as initial conditions for the second, but often the physics couple so you need both.

Now how did you get the voltage for the PZT from the stress, are you nt already using a coupledphysics that solves for V the voltage ? in whic case you do not need the extra EC, as it would already be included into the first complex hysics node (always check all dependent variables of previous physics BEFORE adding in any new one ;)

To get capacity and inductances these are easier extracted via the build in port/terminal BCs of COMOSL that already integrates the local ressults and combine the equations for you, or you can write then out, the capacity is mostly obtained by integrating the energy and using the equation energy = 1/2 C"U^2 (not forgetting these are fields so appropriate integration is required

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Good luck
Ivar

Hi Ivar,

I used the piezoelectric devices physics study to run the piezoelectric simulation. Does that already include the electrostatic calculations? Also I'm not sure what is the purpose of adding the "terminal". When I labelled the top metal as the terminal and ran the simulation, the voltage generated is different from the simulation without adding the terminal. Previously I only labelled the bottom metal as ground and left the top metal alone. I included the linear elastic model and included the domains of the two metals for them. Lastly, there is an option to extract the stored energy and dissipated energy in the results menu. However, everytime I ran the simulations, these two results give an error in calculating them. Am I missing some boundary conditions needed to calculate them? Thanks.

Regards,
Lionel

Hi

check your Dependent variables carefully:

PZD solves for u and for V, while SOLID only u, and EC only V,

so if you have PZD you should have the essential of both SOLID and EC to solve common models,
if you add an EC to a PZD COMSOL will propose a dependent variable V2 for the EC, then you would have to add many equations to get V and V2 to coincide if you mix both.

What PZD does in addition to SOLID and EC, is to add the piezo specific stress/strain tensor equations that you will not find in EC alone and it adds some features of the ES (read the doc/help it's all there ;)

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Good luck
Ivar

Hello Wong,

Have you been able to solve this problem? I am also trying to solve similar problem. I do not know how to obtain charge, capacitance of Piezo resonator. I do not understand the meaning of terminal! If possible, please share your model or some simple model to help us with this.

Thanks,
Sankha

Hi Mr. Wong,

Even I am facing similar problems when I combine the different Physics, could you please share your views if you solved your problem.

Thank you.

Vittal.