CAE Software【Femtet】Murata Software Co., Ltd.
Example26 Floating electrode
General
-
We will examine how the floating electrode works.
-
The piezoelectric material is deformed by force. The voltage generated by the deformation is analyzed.
-
The result is compared with the piezoelectric constant.
Show Results
|
Item |
Setting |
|
Solver |
Piezoelectric analysis [Rayleigh] |
|
Analysis Space |
3D |
|
Analysis Type |
Static analysis |
|
Unit |
mm |
|
Options |
N/A |
Model
The model is a rectangular solid body. The boundary condition is set on each of the faces.
Body Attributes and Materials
|
Body Number/Type |
Body Attribute Name |
Material Name |
|
0/Solid |
piezo |
000_P-4 * |
* Available from the material DB
|
Body Attribute Name |
Tab |
Setting |
|
piezo |
Direction |
Specified by: Vector Vector: X=Y=0.0, Z=1.0 |
Boundary Condition
|
Boundary Condition Name/Topology |
Tab |
Boundary Condition Type |
Setting |
|
UX0/Face |
Electric |
Magnetic wall |
|
|
Mechanical |
Displacement |
Select UX and enter 0.0 |
|
|
UY0/Face |
Electric |
Magnetic wall |
|
|
Mechanical |
Displacement |
Select UY and enter 0.0 |
|
|
UZ0/Face |
Electric |
Electric Wall |
Voltage specified: Voltage 0[V] |
|
Mechanical |
Displacement |
Select UZ and enter 0.0 |
|
|
FLOAT/Face |
Electric |
Electric Wall |
Floating electrode |
|
Mechanical |
Free |
|
|
|
PULL/Face |
Electric |
Magnetic wall |
|
|
Mechanical |
Distributed Face Load |
1[Pa] |
Results
Fig (a) below shows the stress distribution. The stress of 1 [Pa] is exhibited in the X direction. It is generated by applying the face load of 1 [Pa].
We will study the electric field generated by the mechanical stress using the d-type piezoelectric equation.
D = dT+εE (1)
Only Tx of the X component of the stress exists. Of the D constants relating to the X component of the stress, the constant having the value other than 0 is d31. It means there is a possibility that DZ component exists. From the floating electrode with the charge of 0, DZ is 0.
０ = d31*Tx+εz*Ez is derived from the equation (1). The electric field Ez is obtained by inserting the stress (Tx) in this equation. The material used for this analysis is 000P-4 having d31=-0.7e-11[C/N] and εz=200ε0.
Ez = -d31*Tx/εz = -(-0.7e-11)*1.0/(200*8.854e-12) = 3.953e-3 [V/m] (2)
Fig (b) shows the calculation result of electric field. It matches with the result obtained by the equation (2). As the electric field in the piezoelectric material is constant, the potential is obtained from Ez and the thickness.
Fig (c) below shows the voltage distribution.
