Home / Examples / Piezoelectric Analysis [Rayleigh] / Example 15: External Resister

Example 15: External Resistor

General

• A piezoelectric device consists of two parts having different polarized directions.
   

• An external resistor is connected to the piezoelectric device. The voltage generated across the resistor is solved.
   

• Unless specified in the list below, the default conditions will be applied.
   

• Obtain this session's project file. (Right-click and choose 'Save link as')
  
  

• Results will vary depending on Femtet version and the PC environment.

The project contains a model for harmonic analysis and a model for resonant analysis. The harmonic analysis only is explained here.

 

Analysis Space

Item	Settings
Analysis Space	3D
Model Unit	mm

 

Analysis Conditions

The analysis type is resonant analysis.

Item	Setting
Solver	Piezoelectric Analysis [Rayleigh]
Analysis Type	Harmonic Analysis
Options	N/A

 

The harmonic analysis tab is set up as follows.

Tab	Setting Item	Settings
Harmonic Analysis	Sweep Values	Minimum: 200×103 [Hz] Maximum: 230x103 [Hz]
	Sweep Type	Number of Divisions: 120

Graphical Objects

vol1 is polarized in +Z direction, while vol2 is polarized in +X direction.

The top and bottom faces of vol1 are set with electrodes. The electric potential is output at an end of vol2.

Body Attributes and Materials

Body Number/Type	Body Attribute Name	Material Name
0/Solid	vol1	000_P-4 *
1/Solid	vol2	000_P-4 *

(*) Available from the material DB

 

vol1 and vol2 are polarized as follows.

The body attribute directions are set up as follows:

Body Attribute Name	Direction
vol1	Vector Specified: Vector: X=0.0, Y=0.0, Z=1.0
vol2	Vector Specified: Vector: X=1.0, Y=0.0, Z=0.0

Boundary Condition

Boundary Condition Name/Topology	Tab	Boundary Condition Type	Setting
earth/Face	Electric	Electric Wall	Electric Potential Specified: Electric Potential 0 [V]
in/Face	Electric	Electric Wall	Electric Potential Specified: Electric Potential 1 [V]
out/Face	Electric	Electric Wall	Floating electrode Select [Add a resistor across to ground]. The resistances are 1, 5, and 10 [Mohm]

Results

The frequency response of the floating electrode's voltage is shown below.

The voltage peaking is less with lower resistance value.

 

Comparison with Resonant Analysis Model

The impedance frequency responses are compared between the harmonic analysis model and the resonant analysis model.

In the resonant analysis, resistor cannot be set to the floating electrode. In this sense, the model is different from the harmonic analysis model.

The impedance characteristic of the harmonic analysis model is not steep due to the resistor. Except for this, similar impedance characteristics are acquired for the resonant analysis and harmonic analysis.

Reference:

See Impedance for drawing a graph.

See Drag-and-drop on the graph window for the graph data superposition.