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Hi

do not forget that you ahve different behaviour if your electrodes are shortened or open as the mechanical stress induces charges that might accumulate and influence the PZT material properties. therefore you might have damping too and your eigenfrequency might become complex.

For a frequency scan you can define the amplitude (if force driven) by an amplitude function a(freq) and you scan freq. The frequency scan is a harmonic (or sinus type ) scan see the doc

hope this helps
Ivar

Hi Ivar!

Thanks for your reply!

I want to excite a plate with a piezo. The input signal for the piezo is harmonic sinus: wv1(freq), the amplitude should stay constant. If i perform a parametric sweep for the freq, i got the following error:

Failed to evaluate expression.
- Expression: mod1.V-mod1.pzd.V0
Failed to evaluate variable.
- Variable: mod1.pzd.V0
- Defined as: wv1
Failed to evaluate variable.
- Variable: wv1
- Geometry: 1
- Boundary: 9

So, if i perform a frequency domain analysis, does the program automaticly assume there is a harmonic input at the piezo. This assumption makes parameter sweep for the frequency unnessesary?!

Thanks,
Steve

Hi

I would say normally yes, but I'm also often getting these kind of errors from V4, probably because I still have not fully understood the naming logic. in your case the poblems seem to stem from

mod1.V-mod1.pzd.V0

as mod1.V is normally the depedent variable so it must be something with the BC mod1.pzd.V0 ?

Normally, if you define a constant/parameter V0=1[V]and define it correctly as input on the right BC then this becomes the amplitude excitation for the harmonic sweep. Its written in the doc which variable is the harmonic sweep one, but as there are different for different cases/pysics I always have to look up (I'm using daily too many physics to remember that all, I have suggested to COMSOL to better highligh THE variable that is used for the harmonic sweep in EACH physics. Hope they manage for V4.1

Good luck
Ivar

Thanks a lot!!!