microsonics - nondestructive testing · periodic half-space fem-bem coupling for surface acoustic...

Microsonics 39, rue des Granges Galand, 37550 Saint Avertin, France – Phone : +(33) (0)2 47 28 22 34

MICROSONICS

The finite element method (FEM) is very suitable for structural simulation, specially when the structure is vibrating in vacuum. When the vibrating structure is submerge in an unbounded (fluid, elastic or piezoelectric solids) medium, the radiating conditions have to be taken in to account. The boundary element method (BEM) is very suitable for unbounded medium, because the radiating conditions are exact. It is often use to complete of the finite element method.

Microsonics is FEM-BEM coupling tool, which is fully compatible to Ansys (FEM software package), and is accessible in ANSYS environment. It is a BEM solver which cover a wide physics area:

Radiation and propagation in fluid medium (acoustic), Radiation and propagation in isotropic / anisotropic solid medium, Radiation and propagation in piezoelectric medium.

Moreover, the user can define is own Green function.

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MICROSONICS39, rue des Granges Galand37550 Saint Avertin – France

Phone : +(33) (0)2 47 28 22 34 or +(33) (0)3 20 30 40 37e-mail : [email protected]


Operating principle

Microsonics is fully integrated into Ansys. Because, Microsonics input data are automatically extracted from finite elements data, using macros. Thus, Microsonics can be run in Ansys user inteface. The computation will create a impedance matrix, and write it in a Ansysbinary file (*.sub file format). The *.sub files were introduced by Ansys in order to alloy the user to interface with Ansyscalulation. Thus, there is no interference between Ansys source code and Microsonics. Note that, new Ansysversion will read previous Ansys *.sub file.

ANSYS

Binary file

BEM moduleScript command(Call system)

BEM data fileScript command

Read binary file

Thus, for Ansys user Microsonics can be easily used. It requires only the training to learn how to used a couple of additional APDL command. Several coupling FEM-BEM can be activated in the same calculation, this is very suitable for medical probe simulation.


Competition advantages

Microsonics is add-on module fully integrated into Ansys. In consequence, there is no waste of time and no risk of data error during the transfer. An external BEM code, which will need his own pre and post processing is not necessary. Microsonics use ANSYS pre and post processing thus the global cost of the FEM-BEM solution is reduced.

Microsonics FEM-BEM coupling in ANSYS covers a great number application.

User Green function can be integrate and use in Ansys.

Ansys-Microsonics coupling is the only tool which alloy FEM-BEM multicoupling. Multicoupling is very suitable for medical probe device (one coupling for the backing or substrate and one for the fluid) and for RF-filter (one coupling on each resonator).

Microsonics is pioneer in modeling of acoustic MEMS devices (Bulk Acoustic Wave, RF-MEMS) radiating in the substrate. Thus is enable to estimate correctly the quality factor.


Applications areas

Microsonics is suitable for most dynamic problems of structure

surrounded by an unbounded domain, in particular:

Vibroacoustic (noise cancellation),

Underwater acoustic,

Ultrasound imaging,

Sensor,

RF filter (BAW and SAW devices),

MEMS Resonator (anchor losses),

Building and industrial equipment (soil-structure coupling),

Seismic.


Two FEM-BEM coupling, one for the solid medium (backing) and one in fluid medium.

Radiated pressure by a Medical probe

Acoustic FEM-BEM coupling for ultrasound imaging

Receiving sensitivity

Electrical admittance

FEM-BEM piezocomposite probe modelling

Key parameters: Coupling factors, radiated pressure (or power) and bandwidth

2D or 3D simulation tool accounting for ultrasound probe radiating in water

Solution proposed: FEM-BEM coupling

FEM for ultrasound probe & BEM backing and water


Radiated pressure by a cMUT

Acoustic FEM-BEM coupling for ultrasound imaging(Capacitive Micromachined Ultrasonic Transducers)

Key parameters: Coupling factors, collapse voltage bandwidth and cross-talk

2D or 3D simulation tool accounting for cMUT radiating in water


FEM for cMUT & BEM backing and water

Pressure on the cMUT top face

Resonance frequency : 15 MHz Collapse voltage : 31.50 voltsBandwidth @ -6.0 dB : >100%

D. EKEOM, IEEE-UFFC Symposium 2006


Acoustic FEM-BEM coupling for ultrasound imaging(Capacitive Micromachined Ultrasonic Transducers)

D. EKEOM, MUT Workshop 2007

Key parameters: Coupling factors, collapse voltage bandwidth and cross-talk

2D or 3D simulation tool accounting for cMUT radiating in water


FEM for cMUT & BEM backing and water

Elastodynamic BEM

Acoustic BEM


Elastic half-space FEM-BEM coupling for Solidly Mounted resonator(Bulk Acoustic Waves - RF filter devices)

Quality factors and coupling coefficientsQs Qp k2

1D Mason’s model : 10500 10500 6.46%2D FEM-BEM model : 4260 1360 6.10%(Loss less materials )

Electrical impedance of a Solidly Mounted Resonator radiating in silicon substrate

Red: FEM-BEM couplingBlue: Mason Model

1,E+01

1,E+02

1,E+03

1,E+04

1,E+05

1,E+06

1,E+07

2050 2070 2090 2110 2130 2150 2170 2190 2210 2230 2250

f (MHz)

mod

(Z) a

.u.

-2

-1,5

-1

-0,5

0

0,5

1

1,5

2

2050 2070 2090 2110 2130 2150 2170 2190 2210 2230 2250

f (MHz)

arg

(Z)

D. EKEOM, B. DUBUS and A. VOLATIER, IEEE-UFFC Symposium 2007

resonator

Bragg reflector

substrate

p

s

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x

y

resonator

Bragg reflector

substrate

p

s

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resonator

Bragg reflector

substrate

resonator

Bragg reflector

substrate

p

s

()

x

y

resonator

Bragg reflector

substrate

p

s

()

x

y

resonator

Bragg reflector

substrate

p

s

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resonator

Bragg reflector

substrate

resonator

Bragg reflector

substrate

p

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x

y BEM silicon substrate modelling

Key parameters: Quality and coupling factors and purity of resonance

2D or 3D simulation tool accounting for resonator-substrate coupling


FEM for resonator+Bragg reflector & BEM for substrate


Periodic half-space FEM-BEM coupling for Surface Acoustic Waves(RF filter devices)

Quality factors and coupling coefficientsQs Qp k2

3D FEM-BEM model : 1300 7300 10.%

Key parameters: Quality and coupling factors and purity of resonance

2D or 3D simulation tool accounting for resonator-substrate coupling

Solution proposed: periodic FEM-BEM couplingFEM for resonator & BEM for piezoelectric substrateUser piezoelectric Green function Programmable Features


Elastic half-space FEM-BEM coupling for MEMS resonator(Anchor acoustic losses)

Key parameters: Quality factor, radiated power and purity of resonance

2D or 3D simulation tool accounting for beam-substrate coupling

Solution proposed: FEM-BEM coupling, FEM for beam & BEM for substrate

Quality factorQs Qp k2

2D FEM Only : 65.4%3D FEM-BEM model : 180 9000 65.7%(Loss less materials)

Displacement @ parallel resonance frequencyreal & imaginary


Elastic half-space FEM-BEM coupling for MEMS resonator(Anchor acoustic losses)

Key parameters: Quality factor and purity of resonance

2D or 3D simulation tool accounting for beam-substrate coupling

Solution proposed: FEM-BEM coupling, FEM for beam & BEM for substrate

Displacement module and phase

Zoom at resonance frequency


Microsonics Users

Bulk Acoustic Wave resonator

CEA-Léti (France), EPCOS (Germany), EPFL (Switzerland), IEMN (France), STMicroelectronics (France)

Surface Acoustic Wave resonator

EPCOS (Germany)

RF-MEMS

ENSIAME (France), IEMN (France)

Ultrasound Imaging

Fraunhofer-IBMT (Germany)

microsonics - nondestructive testing · periodic half-space fem-bem coupling for surface acoustic...

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