Piezoelectric harmonic analysis 1

[usker]

Drej and cloche thank you very much for your help.
Let me in more detail explain what I want to do with piezoelectric harmonic analysis.
I have 10 piezoelectric discs stack, each disc has a hole at the center and these discs inserted on vertical stainless steel cylindric bar above each other. Totally I specified 12 material properties 10 for piezoelectric elements and 2 for stainless steel cylindric bar and bolt.
If we apply voltage between top and bottom electrodes on piezoelectric disc this piezoelectric material will shrink with some magnitude of displacement. So, when each piezoelectric disc of stack, fastened from both sides, shrinks, the stack will vibrate (Actuator working principle). If I join this model with the spring, then while shrinking by each piezoelement, the stack itself starts to vibrate, because piezoelements pretty well fastened from both sides.
Doing harmonic analysis I want to determine vibration amplitude (stainless steel bar tip UY-displacement) over frequency.
I selected as an element type PLANE223(Structural+ Electrical)which takes into account piezoelectric phenomenon, and also COMBIN14 which takes into account spring phenomenon.
DOF for PLANE223 is UX,UY,VOLT. DOF for COMBIN14 is UX,UY,UZ. For one end of the spring, for the displacement, I applied ALL DOF and specified value of zero. On the other end of the spring (connected with the assembly of piezoelement stack)I selected UX and UZ in order to constrain the node in these directions, and also I unselected ALL DOF.
As a load, I apply voltage at the interface of each piezoelement, and interface of piezoelement and stainless steel.
When I ran this analysis I thought I could get the plot of amplitude over frequency, and could determine the vertical displacement (amplitude) of the whole model. But in Time History Variables Viewer when I select: Add->Nodal Solution->DOF Solution->Y component of displacement->I select node on the tip of my model, it does not show any value for amplitude (Minimun, Maximum).
Does all I explained make sense to you?
May be this time, after I explained in more detail my problem, you will be able to help me.

Thanks a lot guys

 

[cloche]

The only possibility I see at the moment, due to the fact that you find the results you expect in the /POST1, is that you didn't ask the program to save the results at every timestep of your analysis: with the default setting, it saves only the last substep, so the /POST26 have only one point to display and so it returns no curve for any data. Seems to me a bit of a too simplicistic explanation, but...

 

[Drej]

Have you tried a simple static analysis i.e. same model, same load, only antype,static, to see if you see the displacements you're looking for?


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[Drej]

By the way, in the future you don't need to start a new thread to extend a question.


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[usker]

Hi,
When I run harmonic analysis for Piezoelectric material I get this error message from TimeHistPostpro:

can't read "p26WinArr(LAYERP26)": no such element in array
can't read "p26WinArr(LAYERP26)": no such element in array
while executing
"{::namespace inscope ::euidl::results::timeHist addDataDlg_CB1} 0"
("after" script)

Does anybody know what it is, and what shall I do?

Regards

 

[Drej]

Try the static analysis first as per my previous post. This is the only way to establish what's happening in your model. Then, once you've grasped the fundamentals of your model, try to be more clever and do the harmonic analysis.


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[usker]

I specify material properties in ANSYS and then mesh my model. But If I want to change material properties of already meshed model would it be correct? Or, I need to insert new material properties and mesh my model again with new material properties?

Regards

 

[Drej]

1/ Create the new material, let's say it's material 2 (for example MP,EX,2,205E9)
2/ select the elements that you want to change the materials properties for (ESEL,...)
3/ Issue the following: EMODIF,ALL,MAT,2 (modify all elements to have material 2 properties)


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