a patch transfer function approach for vibro-acoustic analysis … · 2018. 12. 19. · spatial...

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VIRTUAL VEHICLE Research Center is funded within the COMET – Competence Centers for Excellent Technologies – programme by the Austrian Federal Ministry for Transport, Innovation and

Technology (BMVIT), the Federal Ministry for Digital and Economic Affairs (BMDW), the Austrian Research Promotion Agency (FFG), the province of Styria and the Styrian Business Promotion

Agency (SFG). The COMET programme is administrated by FFG.

A patch transfer function approach for vibro-acoustic

analysis with poroelastic materials

PBNv2 – First Public Technical Course

INSA Lyon, November 28-29, 2018

Jan Rejlek, Eugène Nijman, Markus Polanz, Nicola Contartese

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Agenda

November 29, 2018 | Rejlek et al. PBNv2 – First Public Technical Course 2

▪ Motivation for automotive NVH

▪ NVH complexity & challenges

▪ Automotive poroelastic materials (PEM)

▪ State-of-the-art in numerical modelling of PEM

▪ Patch transfer function (PTF) approach

▪ PTF trim characterisation

▪ Application examples

▪ Conclusions and outlook

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Noise is a societal challenge


…noise

▪ fastest growing pollutant in Europe

▪ traffic-related noise accounts for over 1 million healthy years of life lost in EU annually1

▪ European Parliament has approved a law to reduce the limit pass-by noise levels via a

three-phase plan, which will apply from 20162

1 WHO-JRC, 2011; Report on “Burden of disease from environmental noise”, ISBN: 978 92 890 0229 5; http://www.who.int/quantifying_ehimpacts/publications/e94888/en/2 EU Press Release IP/14/363, http://europa.eu/rapid/press-release_IP-14-363_en.htm, April 2nd, 2014

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http://www.who.int/quantifying_ehimpacts/publications/e94888/en/

http://europa.eu/rapid/press-release_IP-14-363_en.htm

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Motivation for automotive NVH


“noise policies”

▪ tightening of legal noise regulations

“competitive nature of market”

▪ growing customers` expectations

▪ short “development-product to market” phase

▪ NVH is becomes a brand differentiator

“novel challenges”

▪ conflicting design criteria

• lightweight design

• alternative propulsion

• downsizing/ downspeeding

▪ NVH complexity

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The NVH complexity


▪ common platforms/modules

▪ vehicle derivates

▪ “strong backbone”

Image courtesy of Renault/Nissan

Image courtesy of Volkswagen AG

PhD track of

Nicola Contartese

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Current trends in automotive industry


https://en.wikipedia.org/wiki/List_of_BMW_vehicles

→ increased number of car series and/or derivates

→ shortening of product development phase

→ new propulsion architectures (BEV, HEV, PHEV)

“1996”

7 product lines

~6 yrs development time

“2016”

26 product lines

excl. Mini marque (9)

~3 yrs development time

Images courtesy wikipedia.org

BMW AG

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Role of NVH in vehicle development process


▪ inherent parallel nature

▪ multitude of functional attributes for different components

▪ highly competitive environment (cost, weight, package constraints)

▪ outsourcing/ sub-contracting

▪ target setting/achieving procedure

▪ iterative process (mule, prototype, pre-series)

▪ NVH driven by details

▪ application of (reliable) NVH CAE tolls still limited

▪ key role of NVH testing

→ hybrid methods could enhance

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Automotive sound packages


▪ Sound packages: are made up from a combination of materials, notably

▪ porous materials (foams, fibers, felts, carpets, porous films, fabrics)

▪ damping materials

▪ limp and elastic (solid) layers

▪ The goal: to control noise (interior/exterior)

▪ Drawback

▪ added mass (sound package on average passenger car ~80 kg)

▪ packaging problems

▪ costs

sound insulation

absorption

structural damping (baseline drawing courtesy of BMW AG)

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Physics behind


image courtesy of BWF Envirotec

image courtesy of Université de Sherbrooke

▪ Porous materials

▪ Two phases: solid and fluid

▪ Elastic coupling

▪ Visco-inertial coupling

▪ What do they do ?

→ Transform acoustic energy into heat

▪ How do they dissipate energy?

▪ viscous effect

▪ thermal effect

▪ structural damping

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State-of-the-art in modelling of poroelastic

materials


1. Equivalent mechanical models

2. Empirical models (Delaney-Bazley)

3. Transfer-Matrix-Method (semi-analytical, locally-reacting)

4. Microstructural models (homogenisation, Biot theory)

▪ State-of-the-art in vibro-acoustic modelling of poroelastic materials

→ full FE Biot-based approach

▪ detailed description, but

▪ computationally expensive

▪ need for Biot parameters

→ state-of-the-use (?)

Accuracy

Assumptions

Monet-Descombey Julien, Zhang Charles, Hamdi Mohamed-Ali, A Partition Finite Element Method Allowing

the Calculation of the Vibro-Acoustic Response of Fully Trimmed Vehicles in Medium Frequency Range, In

proceedings of INTERNOISE 2008, 26-29 October, Shanghai, China.

image courtesy of BASF

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Novel approach to PEM characterisation


Development of a novel methodology to describe vibro-

acoustic behaviour of sound insulation materials

▪ dynamics described in terms of surface impedance rather than material micro-

models

▪ non-contact measurement of surface impedance

▪ methodology implemented in a sub-structuring coupling scheme to account

for interaction with structure and fluid

Objective

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Patch Transfer Function (PTF) approach


▪ sub-structuring into separate physical domains

▪ determination of surface impedance

▪ coupling at common interfaces

Key advantage: the trim is characterised on a macroscopic level

image courtesy of AUDI AG

image courtesy of BASF and Autoneum

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Patch Transfer Function (PTF) approach


Limitation: wavelength > double the patch dimension

Poroelastic

domain

Acoustic cavity

StructurePTF

PTF

Ouisse M., Maxit L., Cacciolati C., and Guyader J., “Patch transfer functions as a tool to couple linear acoustic problems”.

Journal of Vibration and Acoustics, 127:458-466, October 2005, doi:10.1115/1.2013302.

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Spatial averaging of field variables


▪ Fields variables (p,v) phase averaged over each patch

▪ Blocked impedance (for low-impedance “soft” materials (air or foam))

is the pressure on patch i when patch j is excited by uniform velocity and all

other patches k are blocked (v=0).

▪ Free mobility (for high-impedance “hard” materials (plate))

is the velocity on patch i when patch j is excited by uniform pressure and all

other patches k are free (p=0).

0=

=

jkpj

iij

p

vY

0=

=

jkvj

iij

v

pZ

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Validation example


Cavity-backed plate with liner

Practical implementation

▪ 1.7 x 0.8 x 1 m

▪ rigid cavity (5 faces)

▪ 2 mm steel plate (clamped)

▪ Basotect® TG melamine foam t = 42 mm

Melamine foam sample

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Validation example


cavity SPL prediction

▪ Interfaces discretisation: 40cm patches → N=8

▪ Assessment of the impedance/mobility matrices:

▪ Structure characterisation → experimental / numerical

▪ TRIM characterisation → experimental / numerical

▪ Cavity charcterisation → analytical

F

TZ12

TZ2

CZ2

𝑧𝐶

Cp

TZ1SY𝑦𝐹

Cavity

TrimPlate

22 ,vp

11,vp

=

+−

−

−

0

0

0

0

2

1

1

2212

121

Fy

v

v

p

ZZZ

IY

ZZIF

CTT

S

TT

2)( vzp TCC =

2

1

Goal

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Sub-domain characterisation


• Steel plate characterisation:

− Uniform pressure patch excitation approximated by superposition of point forces

− Fluid loading negligible

• Cavity characterisation:

− Rectangular volume with rigid walls → analytical model (modal summation)

[Air-borne Sound Source Characterisation by Patch Impedance Approach, G. Pavic, Journal of Sound and Vibration, 2010]

• Trim characterisation?

− direct measurement of p at interfaces provided that v=0

− measurement of both p,u and assessment of Z by

inverse technique (no blocked conditions required)

0=

=

jkpj

iij

p

vY

x

0=

=

jkvj

iij

v

pZ

0=

=

jkvj

iij

v

pZ

0=

=

jkvj

iij

v

pZ

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PTF trim - direct approach


▪ Skeleton and fluid motion blocked at the interface

▪ Imposed v, direct measurement of p

▪ Pressure microphones → fluid pressure, skeleton motion neglected

▪ Similar setup as Dynamic stiffness (ISO9052-1)

surface input Z - surface transfer Z

22 ,vp11,vp

patch 1 patch 2

0=

=

jkvj

iij

v

pZ

Assessment of the blocked impedance of a melamine sample

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PTF trim - direct approach



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PTF trim - indirect approach


▪ Skeleton and fluid motion blocked at the bottom interface

▪ Skeleton and fluid motion free at the top interface

▪ Imposed v, direct measurement of both p,v → p-u probes

▪ Assessment of blocked impedance by inversion

▪ Efficient fluid excitation, weak skeleton excitation

A B

1 2

TRIM specimenspeaker positionarray position

rigid ground (v=0)

=

2

1

2

1

2221

1211

p

p

v

v

ZZ

ZZ

surface input Z

surface transfer Z

22 ,vp11,vp

patch 1 patch 2

0=

=

jkvj

iij

v

pZ

Assessment of the blocked impedance of a melamine sample

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PTF trim - indirect approach



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▪ Continuity conditions at interfaces

▪ Eliminate v2, determination of Zm

▪ Applicable to any surface impedance measurement

1

3

2

Airgap correction


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Correction for the impedance of the air layer between the specimen surface and the

actual measurement plane

Low freq. → mass governed side walls radiation

High freq. → stiffness of the airgap

• Assumption: p does not change along the air layer

thickness

• Air slit impedance

1−= vpZa

d

0 100 200 300 400 500 600 700 800 900 100040

50

60

70

80

90

L [

dB

]

0 100 200 300 400 500 600 700 800 900 1000-180

-90

0

90

180

f [Hz]

[

o]

PBNv2 – First Public Technical Course 23

Airgap calibration

rigid dummy specimen

November 29, 2018 | Rejlek et al.

- input Z

- transfer Z

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Test case: rigid cavity-backed plate


SPL [dB] @ receiver

Experimental plate and analytical cavity characterisation – NO Trim

• 40cm patch → 30Hz structure – 430Hz fluid

• Adequate prediction at freq. higher than theoretical limit

• Analytical cavity model updating → equivalent damping coefficient

100 200 300 400 500 600 700 800 900

60

80

100

120L [dB

]

100 200 300 400 500 600 700 800 900-180

-90

0

90

180

f [Hz]

[

o]

Reference - PTF prediction

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Test case: sub-systems mobility analysis


Input mobility Y

Experimental plate and trim, analytical cavity characterisation

• Strong interaction trim-cavity

• Weak interaction trim-structure (added structural damping negligible)

• Trim mainly increases cavity absorption

Structure – Trim - Cavity

0 100 200 300 400 500 600 700 800 900

-100

-80

-60

-40

-20L [dB

]

0 100 200 300 400 500 600 700 800 900

-100

0

100

[dB

]

f [Hz]

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100 200 300 400 500 600 700 800 900

60

80

100

120L [dB

]

100 200 300 400 500 600 700 800 900-180

-90

0

90

180

f [Hz]

[

o]

Test case: cavity-backed plate with liner


SPL [dB] @ receiver

Experimental plate and trim, analytical cavity characterisation

• 40cm patch → 30Hz structure – 430Hz fluid

• Adequate prediction up to half fluid wavelength

• Trend is captured at higher freq.

Reference- PTF prediction

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Conclusions

pros

▪ fast material characterisation

▪ (quasi) non-local effects included

▪ no need for material microscopic parameters

▪ high degree of versatility (test/simulation) and scalability

▪ suitable for target setting procedure (OEM-trim supplier)

▪ might become a new standard for material description

cons

▪ sampling criterion

▪ flat trim specimens

▪ Equivalent mechanical models

▪ Empirical models

▪ Transfer-Matrix-Method

▪ PTF

▪ Microstructural models

Accuracy

Assumptions

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PBNv2 – First Public Technical Course 27November 29, 2018 | Rejlek et al.

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Outlook & ongoing research

▪ Sound proof of validity range, modelling guidelines

▪ Generalisation of the methodology

▪ thickness variation

▪ non-planar geometries

▪ finite size of trim specimen

▪ Integration into existing OEM / supplier

product development processes

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PBNv2 – First Public Technical Course 28November 29, 2018 | Rejlek et al.

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Publications


Polanz, M. et al. (2018), The Patch-Transfer-Function (PTF) Method Applied to Numerical Models of Trim Materials

Including Poro-Elastic Layers, SAE International, DOI:10.4271/2018-01-1569.

Veronesi G. and Nijman E.J.M. (2016), On the sampling criterion for structural radiation in fluid. The Journal of the

Acoustical Society of America, 139, 2982-2991, DOI: http://dx.doi.org/10.1121/1.4950989.

Albert, C. G. et al. (2016), Prediction of the vibro-acoustic response of a structure-liner-fluid system based on a patch

transfer function approach and direct experimental subsystem characterisation, Applied Acoustics, 112, 14 – 24, ISSN

0003-682X, DOI: http://dx.doi.org/10.1016/j.apacoust.2016.05.006.

Veronesi G. (2015), A Novel PTF-Based Experimental Characterisation fo Poro-elastic Materials: Method and Sampling

Criterion. PhD Thesis, Università degli Studi di Ferrara, Facoltà di Ingegneria.

Veronesi G., Albert C., Rejlek J., Nijman E., Bocquillet A. (2014), “Patch Transfer Function Approach for Vibro-Acoustic

Analysis of Fluid-Porous- Structural Problems”, In proceedings of the 8th International Styrian Noise, Vibration &

Harshness Congress (ISNVH 2014), July 2-4, Graz, Austria, SAE Technical Paper 2014-01-2092, doi:10.4271/2014-01-

2092.

Rejlek J., Veronesi G., Albert C., Nijman E., Bocquillet A. (2013), “A combined Computational-Experimental Approach for

Modelling of Coupled Vibro-Acoustic Problems”, SAE Technical Paper 2013-01-1997, DOI:10.4271/2013-01-1997.

Albert C. (2012) Vibro-acoustic coupling of structural, porous and fluid domains based on simulation and experiment,

M.Sc. thesis, Institute of Theoretical and Computational Physics, Graz University of Technology.

http://dx.doi.org/10.1121/1.4950989

http://dx.doi.org/10.1016/j.apacoust.2016.05.006

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Acknowledments


PBNv2 H2020-MSCA-ITN-ETN project (GA 721615)

VIRTUAL VEHICLE Research Center is funded within the COMET – Competence Centers for Excellent

Technologies – programme by the Austrian Federal Ministry for Transport, Innovation and Technology

(BMVIT), the Federal Ministry for Digital and Economic Affairs (BMDW), the Austrian Research Promotion

Agency (FFG), the province of Styria and the Styrian Business Promotion Agency (SFG). The COMET

programme is administrated by FFG.

Industrial & scientific partners involved

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Thank you for your attention!


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~ Trim ~

Dr. Jan Rejlek

Department NVH & Information systems

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Inffeldgasse 21A

A-8010 Graz

[email protected]

www.v2c2.at

mailto:[email protected]

http://www.v2c2.at/

a patch transfer function approach for vibro-acoustic analysis … · 2018. 12. 19. · spatial...

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