resonant frequency

[tthao]

Hi,

I'm new in ANSYS.
I performed a piezoelectric resonator (with solid 5), I do a static, modal and harmonic analyse. I plot the current versus frequency and I read the resonant frequency by using "ZOOM"(frequency range).
I would like ANSYS give me this resonant frequency automatically. I found a similar program that giving resonant frequency automatically (it uses solid 226), and I include it in my program (using solid 5). But it doesn't work correctly.
Can you help me?

Thao.

 

[Drej]

> I performed a piezoelectric resonator (with solid 5), I do a static, modal and harmonic analyse. I plot the current versus frequency and I read the resonant frequency by using "ZOOM"(frequency range).

Don't understand what you're doing here (ZOOM?). After you've done the modal analysis, you need to save the db, then go into /post1, read the results file, then issue the command:

set,list

This will list the natural frequencies [used in your harmonic analysis, assuming you're using modal superposition].

> I would like ANSYS give me this resonant frequency automatically. I found a similar program that giving resonant frequency automatically (it uses solid 226), and I include it in my program (using solid 5). But it doesn't work correctly.
Can you help me?

Don't understand any of this. Perhaps you could expand some more.

 

[tthao]

Thank u Drej you helped me a lot!

Finally, I would like to get the resonant frequency (in a table) on my curve "current versus frequency" in harmonic analysis. Do you think it's possible?

 

[Drej]

Just go into /post26 and read in your harmonic results, open up "Variable Viewer" and "Add data". Choose the node and the currente and then use the Plot function. Don't know why you want to put this data into a Table, it's much easier to *get the results and *vwrite out.


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[tthao]

My program (piezoelectric resonator) is:
...
...
/COM, **** APPLY THE LOADS AND OBTAIN A FULL HARMONIC SOLUTION ****
/SOLU
ANTYPE,HARM ! Harmonic analysis
HROPT,full ! Full method
D,N1,VOLT,10.0 ! Assigns excitation voltage at beam interface
D,N2,VOLT,0.0 ! Assigns zero voltage at outer surface
OUTRES,,1
KBC,1
HARFRQ,1e6,2e6
NSUBST,50
SOLVE
FINISH

/COM, **** REVIEW THE RESULTS ****
/POST26
RFORCE,2,N1,AMPS ! Defines total reaction force data for storage
/PLOPTS,INFO,OFF
/PLOPTS,TITLE,OFF ! Removes title
/AXLAB,X,FREQUENCY
/AXLAB,Y,AMPERES
/VIEW
/VUP,,Y
PLVAR,2 ! Displays amperes as a function of frequency
PRVAR,2 ! Lists amperes as a function of frequency
FINISH

This curve (current vs frequency) indicates that the resonant frequency=1.475MHz and anti-resonant frequency=1.48MHz. To get this accurate values I have to vary a lot my frequency ranging.
My question is: does ansys can give me the resonant frequency (current peak) and the antiresonant frequency(current null)automatically?

P.S.1: for your last response: where is "variable viewer" and "add data"?