Home / Examples / Coupled Analysis / Piezoelectric-Acoustic Analysis [Rayleigh/Mach] / Example 3: Fully Coupled Analysis (Sound Wave Drive)

Example 3: Fully-Coupled Analysis (Sound Wave Drive)

General

• The sound wave is driven in the acoustic domain. The sound pressure is solved as the voltage of the floating electrode on the piezoelectric material.
  

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

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

 

 

Analysis Space

Item	Settings
Analysis Space	3D
Model unit	m

 

Analysis Conditions

Item	Settings
Solver	Piezoelectric Analysis [Rayleigh] Acoustic Analysis [Mach]
Analysis Type	Harmonic Analysis
Options	Select [Fully-coupled Analysis]

 

The harmonic analysis tab is set up as follows.

The sound waves propagate outside the analysis domain. Therefore the default open boundary condition below is applied.

Tab	Setting Item	Settings
Harmonic Analysis	Frequency	10X103 [Hz]
	Sweep Type	Single Frequency
Open Boundary Tab	Type	Absorbing Boundary
	Order of Absorbing Boundary	1st-order
	Coordinates of Origin	x = y = z = 0

 

Graphical Objects

Five semicircle piezoelectric materials are placed around the respiratory sphere used in the example 4. The sound pressure is measured. As shown below, one piezoelectric material has ground and floating electrode. The pressure is detected by the electric potential of the floating electrode.

 

Body Attributes and Materials

Body Number/Type	Body Attribute Name	Material Name
4/Solid	Air	000_Air(*)
5/Solid	Piezoelectric material_000	000_P-4 *
6/Solid	Piezoelectric material_045	000_P-4 *
7/Solid	Piezoelectric material_090	000_P-4 *
8/Solid	Piezoelectric material_135	000_P-4 *
9/Soid	Piezoelectric material_180	000_P-4 *

* Available from the material DB

 

 

Body Attribute Name	Tab	Analysis Domain (Solver)
Piezoelectric material_000	Analysis Domain	Piezoelectric Analysis (Rayleigh)
	Direction	(x, y, z)=(0, 0, 1)
Piezoelectric material_045	Analysis Domain	Piezoelectric Analysis (Rayleigh)
	Direction	(x, y, z)=(1, 0, 1)
Piezoelectric material_090	Analysis Domain	Piezoelectric Analysis (Rayleigh)
	Direction	(x, y, z)=(1, 0, 0)
Piezoelectric material_135	Analysis Domain	Piezoelectric Analysis (Rayleigh)
	Direction	(x, y, z)=(1, 0, -1)
Piezoelectric material_180	Analysis Domain	Piezoelectric Analysis (Rayleigh)
	Direction	(x, y, z)=(0, 0, -1)
AIR		Acoustic Analysis (Mach)

 

• Cautions: In the piezoelectric-acoustic coupled analysis, it is necessary to specify the analysis domain. Specify either piezoelectric analysis or acoustic analysis on the analysis domain tab.

 

 

Boundary Conditions

Boundary Condition Name/Topology	Tab	Boundary Condition Type	Settings
VEL/Face	Acoustic	Speed	1 [m/s]
Open/Face	Acoustic	Open Boundary
FIX	Mechanical	Displacement	UX=0, UY=0, UZ=0
UY0	Mechanical	Displacement	UY=0
V0	Electric	Electric Potential	0 [V]
FLOAT_000～FLOAT_180	Electric	Floating Electrode

 

Results

The sound pressure distribution is shown as follows. For comparison purposes, the model with piezoelectric materials removed is shown.

 

Result 1 (a) The sound pressure distribution of the model with piezoelectric materials removed Result 1 (b) The sound pressure distribution of the model including piezoelectric materials (for reference)

The electric potential of the floating electrodes is shown on the right side of the figure.

 

 

 

 

We can observe that the sound waves are obstructed by the piezoelectric materials.

The figure below is the view in the + X direction of the figure above with piezoelectric materials only shown. The colors of the semicircles indicate the electric potential of the floating electrode. The numbers on the right side of the piezoelectric materials are the electric potential of the floating electrode.

The respiratory sphere has a large sound pressure and a large voltage in its front. The voltage corresponding to the sound pressure is obtained.