Example3 Fully Coupled Analysis (Sound Wave Drive)

General

The drive from the sound wave domain is analyzed. The sound pressure is solved as the floating electrode voltage of the piezoelectric material.

Analysis Space

Item	Settings
Analysis Space	3D
Model unit	m

Analysis Conditions

Item	Settings
Solvers	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 “open boundary” condition below is applied initially.

Tab	Setting Item	Setting
Harmonic Analysis	Frequency	10×10^3[Hz]
Harmonic Analysis	Sweep Type	Single frequency
Open Boundary Tab	Type	Absorbing boundary
	Order of Absorbing Boundary	1st degree
	Coordinates of Origin	x = y = z = 0

Graphical Objects

Piezoelectric materials are placed around the respiratory sphere used in the Exercise 4. The sound pressure is measured. 5 semicircle piezoelectric materials are placed around the respiratory sphere for measurement. As shown below, one piezoelectric material has ground and floating electrode. The pressure is detected by the voltage 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

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	Voltage	0[V]
FLOAT_000～FLOAT_180	Electric	Floating electrode

Results

The sound pressure distribution is shown as follows. For comparison purpose, 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 voltage of the floating electrodes are 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 shown. The colors of the semicircles indicate the floating electrode voltages. The numbers on the right side of the piezoelectric materials are the floating electrode voltages.

The respiratory sphere has large sound pressure and the voltage is large in its front. We can consider that the voltage is obtained corresponding to the sound pressure.