Learning Forum

[brunozanelli]

Hey everyone, I want to do a Harmonic Analysis using a Piezoelectric material to work as a sensor to detect the vibrations e ressonance. My first question is: Should I use 'Coupled Field Harmonic' to do it and can I just use 'Harmonic Analysis'?
Also, I want to use Shell elements and 'Coupled Field Harmonic' does not allow this type of element, how can I overcome it?
And last, I want the analysis to be damped, but I want to set the damping ratio by frequency. I tried the command 'MDAMP' and it worked in MSUP. Is there a way to set the damping like this in Full Method?

[Erik Kostson]

 

 

Hi

Let me answer:

My first question is: Should I use ‘Coupled Field Harmonic’ to do it and can I just use ‘Harmonic Analysis’?

Ans: Coupled Field Harmonic

Also, I want to use Shell elements and ‘Coupled Field Harmonic’ does not allow this type of element, how can I overcome it?

Ans: PZT use solid226 3D elements, so they (geometry/surface) can not be shells (there is no pzt shell available ) – structural regions can be shells (meshed with 181 elements under the hood).

And last, I want the analysis to be damped, but I want to set the damping ratio by frequency. I tried the command ‘MDAMP’ and it worked in MSUP. Is there a way to set the damping like this in Full Method?

Ans: MDAMP is for MSUP only – pzt and coupled field analysis can not do MSUP (only full method) – see help manual what type of damping can be use (e.g., material damping etc. with full method)

All the best

Erik

 

 

[brunozanelli]

Hi Erik, thank you for you reply. How can I set the mesh to be either solid226 or shell181? Do I need to set with an APDL command?

[Erik Kostson]

Hi

Perhaps I confused you when explaining - I was trying to give some insight what happens under the hood in mecahnical (so what elements are used for the different physics regions).

So you do not need anything (APDL) - you just set your pzt to piezoelectric physics region (So yes on structure and electric charge) and the surface body to pure structural physics region.

Erik

[brunozanelli]

I am trying now in a simple geometry. I made a beam surface and it does not work. I keep getting this warning. I set the shell elements to be only structural analysis and still it doesn't work.

[Erik Kostson]

 

Hi

Well it is coupled physics so we can not just have one part with single physics only (that would be like doing a pure static or harmonic analysis, and the coupled system is not for that of course)  – so you must also have the pzt in the same model.

Erik