How TMM/FTMM simulations help you understand the vibro-acoustic response of multi-layer systems

How TMM/FTMM simulations help you understandthe vibro-acoustic response of multi-layer systems

François-Xavier BécotFabien Chevillotte, Luc Jaouen

Booth 11

Altair Technology Conference

Munich, Germany – 26.Jun.2014

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Acknowledgements to my colleagues Fabien Chevillotte and Luc Jaouen . . .

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Matelys TMM & Porous Materials Automotive Aeronautics Multi-physics Conclusions

A few words about

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Matelys is an independent research laboratorydedicated to the study of porous materialsin acoustics, thermics, elastics and flow

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Acoustic description of porous materials

Industrial applications : automotive

Industrial applications : aeronautics

Industrial applications : multi-physics

Conclusions

F.-X. Bécot – www.matelys.com EATC – 26.Jun.2014


Acoustic description of porous materials• TMM : Transfer Matrix Method• principles of modeling

Industrial applications : automotiveIndustrial applications : aeronauticsIndustrial applications : multi-physicsConclusions



FEM compared to TMMCell



Acoustic description of porous materials• TMM : Transfer Matrix Method• principles of modeling

Industrial applications : automotiveIndustrial applications : aeronauticsIndustrial applications : multi-physicsConclusions





Air saturated pores

Solid frames

Em

men

tal

Mel

amin

e fo

am



Poro-visco-elastic medium ⇔ Two phases’ medium



Poro-visco-elastic medium ⇔ Two phases’ medium



Two phases’ medium ⇔ homogenisation



Two phases’ medium ⇔ homogenisation

λ� charac. dim◦



Homogenisation ⇔ semi-phenomenological models






Three types of dissipations

in the fluid phase

• viscous flow• thermal exchanges with skeleton





Three types of dissipations

in the fluid phase

• viscous flow• thermal exchanges with skeleton

in the solid phase

• structural (skeleton deformation)



Rigid & motionlessbehaviour

Road pavement

Limp behavior:Youngʹs modulus

close to 0

Rigid body behavior:Low mass density to stiffness ratio

Cotton candy

Flower foam

Visco-Elastic skeleton

Soft-touch mattress

Biot model

Acoustical and elastical parameters required.

Acoustical parameters required only.

Equivalent fluid model

2 phases coupled

2 phases NOT coupled



Acoustic description of porous materials

Industrial applications : automotive• multi-scale optimisation study

Industrial applications : aeronauticsIndustrial applications : multi-physicsConclusions



Sound insulation performance of a multi-layer sound package

⇒ coupling Micro-Macro & Multi-layer modellingScalingCell Cell



Acoustic description of porous materialsIndustrial applications : automotive

Industrial applications : aeronautics• sound paths in studded partition

Industrial applications : multi-physicsConclusions



Identifying the sound paths in studded partitions

102

103

104

Frequency64Hz)

Diffuse6field6sound6transmission6loss64dB)

Solid6borneGW6airborneGW6total6:6364−5;−12)MEL6airborneMEL6total6:6354−5;−12)

20 dB

⇒ little impact of filling material



Acoustic description of porous materialsIndustrial applications : automotiveIndustrial applications : aeronautics

Industrial applications : multi-physics• material scale• component scale

Conclusions



Cubic centered cell with pore closing membranes

fluid phase solid phase withoutmembranes

solid phase withmembranes



Tuning the size of the “windows”

“natural” opening “forced” opening



Influence of the pore window sizeThermal conductivity (% of max value)

M1 calc.

M2 calc.

M3 calc.

M4 calc.

M4 > M3 > M2 > M1

RiRi

RiRi

Rw6(micrometres)

Th

erm

al6c

on

du

ctiv

ity

6(%

6max

6val

ue)

100

50

0

75

25

0 100 200 300 400 500 600



Influence of the pore window sizeSound absorption coefficient in diffuse field (ISO 354)

0 1000 2000 3000 4000 50000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

MA

TE

LYS−

AcV

/ Ju

l13

SoundRabsorptionRcoef.RdiffuseRfieldR(ISOR354)

FrequencyR(Hz)

56RRRRpR=R0.45R(H)106RRpR=R0.30R(H)206RRpR=R0.25R(H)306RRpR=R0.20R(H)406RRpR=R0.20R(H)506RRpR=R0.15R(H)606RRpR=R0.15R



Acoustic description of porous materialsIndustrial applications : automotiveIndustrial applications : aeronautics

Industrial applications : multi-physics• material scale• component scale

Conclusions



Acousto-thermal behaviour Vs. volumic mass

80%

85%

90%

95%

100%

80%

85%

90%

95%

100%

Volumic mass (kg/m3)

Rw+C (% max value)Thermal resistance (% max value)



Acousto-thermal behaviour Vs. convection in air gaps

70%

75%

80%

85%

90%

95%

100%

70%

75%

80%

85%

90%

95%

100%

Configuration of air gaps (mm)

Rw+C (% max value)Thermal resistance (% max value)



Acoustic description of porous materialsIndustrial applications : automotiveIndustrial applications : aeronauticsIndustrial applications : multi-physics

Conclusions



Future materials

• heterogeneous materials

• graded materials

• hybrid passive / active materials / energy harvester

Stakes

• morphing technologies

• 3D printing / structured materials

• multi-physics development

• multi-functional materials

• manufacturing capacities

• technological know-how


Thank you for your attention !

SAPEM 2014 in KTH (Stockholm-Sweden) 16-17-18 December 2014

http://sapem2014.matelys.com/

Acoustical Porous Material Recipes TMM/FTMM Micro-Macro model Porous charac.

Cell ScalingCell CellCellRoKF.-X. Bécot – www.matelys.com EATC – 26.Jun.2014

Engineering

How TMM/FTMM simulations help you understand the vibro-acoustic response of multi-layer systems