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Hallo all,

In order to make coupled electromechanical analysis, I meshed two thin
parallel blocks with solid226 and solid227, and then connect them to a
resistor(circu94) and an independent voltage source(circu94)at constant volts in series. I managed to carry out static and transient analysis as an effort to determine the prestress for the following harmonic anaylsis. However it always failed.

Does it mean that there is no need to make such a kind of analysis
beforehand for harmonic analysis will automatically take into consideration of the voltage bias imposed by the circu94?

Due to the unseccessful attempt with static/transient analysis, I directly jumped to the harmonic analysis. New error shows up, saying:

Input/Output error on unit=9. Possible full disk.

According to task manager the occupied memory reaches 1.14 GB, which
overrides my 1.0 GB memory a little bit.
On that note, I'm wondering whether there exist any method to minimize the computational requirement?

Any suggestion is definitely appreciated.

Jun Ni
University of Bremen
Germany 

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given the elements cited (namely CIRCU94 and SOLID226/227)
this should be a Piezoelectric-Circuit Simulation, please advice.

If so intended, please check the following
info in help manuals, then get back for evtl. questions:

Coupled-Field Analysis Guide
Chapter 8.3. Piezoelectric-Circuit Simulation
Chap. 8.5. Sample Piezoelectric-Circuit Analysis

------------------
Gruesse,
Frank Exius

IFE Deutschland
Mo-Fr 9:00-18:00 Uhr durchgaengig
Dienstleistung in ANSYS www.ife-ansys.de
Simulation Berechnung FEM Digital Prototyping

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Hallo Franke,

Thanks a lot for your response.

My simulation is not of piezoelectric/piezoresistive type. In ANSYS8.1 only Circu94 seems to be possible to be coupled with Solid226/Solid227, which possess UX~UZ, and VOLT DOF. The blocks involved in my model are made of Nikel. I intends to determine the potential difference/voltage between the two blocks/electrodes when one of the two blocks is subject to some pressure.

I tried to conduct harmonic analysis with reduced matrix, but the error message showed me that it was not allowed to caculate the VOLT DOF with the reduced method. 

If you have any advice, please let me know.

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Hello jun_ni,

if you try getting a voltage,
you get that actually for piezoelectric material, physical effect -
otherwise, w/o piezoelectric material specification, you'll not obtain a voltage
as a result of a mechanical load.

------------------
Gruesse,
Frank Exius

IFE Deutschland
Mo-Fr 9:00-18:00 Uhr durchgaengig
Dienstleistung in ANSYS www.ife-ansys.de
Simulation Berechnung FEM Digital Prototyping

Identifikation bei Fragen im ANSYS Forum erwuenscht - Name, Firma/Bildungsstaette. Identifikation im Beitrag oder im persoenlichen Profil, oder in eMail an Moderator IFE - in letzterem Fall bitte Thema Beitrag als Referenzpunkt angeben. Danke.

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I think that in AMSYS the piezoelectric effect results from the specifications/definitions of mechanical-electrical coupled coefficients in material property. I only concern whether the DOFs of an element include both structural displacements and voltage/current. In terms of specifying of the MP, I only define its mechanical characterics, e.g. E, Possion, etc. Otherwise, there is no way to conduct any electrical-mechanical analysis with help of ANSYS except piezoelectric/piezoresistive analysis.

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[Updated 18:59 Uhr 25.11.'05]

in regard to CIRCU94 Element with VOLT and U DOF's
Element Reference (CIRCU94 Element Description) states:
'CIRCU94 is a circuit element for use in piezoelectric-circuit analyses'

You might want the tranducer TRANS126, which has coupled electromechanical effects incorporated in a (reduced order ROM) line element, or the 2D TRANS109. Of which at least the 126 allows for bi-directional effect, i.e. electric loading may introduce mechanical actuation and mechanical actuation may introduce change in electrical quantities.

This said with the precursor, that the 126 capacitive characteristics C=f(gap size) are to be extracted previously from a series of electrostatic analysis using CMATRIX, or by other means. Applicable only if, quite naturally, suitable for what you try to simulate, which isn't clearly apparent to me yet.

------------------
Gruesse,
Frank Exius

IFE Deutschland
Mo-Fr 9:00-18:00 Uhr durchgaengig
Dienstleistung in ANSYS www.ife-ansys.de
Simulation Berechnung FEM Digital Prototyping

Identifikation bei Fragen im ANSYS Forum erwuenscht - Name, Firma/Bildungsstaette. Identifikation im Beitrag oder im persoenlichen Profil, oder in eMail an Moderator IFE - in letzterem Fall bitte Thema Beitrag als Referenzpunkt angeben. Danke.

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Hi Frank

Grateful for your suggestion.

I'll read through the related documents.

Gruss, 

Jun

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Hallo Frank,

I have added Trans126 between the two electrodes, meanwhile connecting the capacitive blocks in series with a resistor and a voltage source, both of which are from Circu124.

When harmonic analysis (i.e. one block is subject to pressure) was initiated, an Error indicated that:

TRANS126 allows only small signal modal or harmonic analysis after a  large signal nonlinear analysis with prestress option. Apply
PSTRESS,ON in both the nonlinear and the subsequent harmonic/modal steps before issuing SOLVE.

However after I issued PSTRESS,ON, error still popped up. According to the err file, it seems due to the Warning:

Stress stiffening effects(e.g.  SSTIF,ON command) are not included for element CIRCU124.

1. Does it mean that it is not feasible to carry out such a kind of harmonic analysis with shunted circuits?

2. What kind of method I can adopt to get round this bug?

Thanx in advance.

Jun Ni

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