Materials and Systems for Noise Control: Categorization and Challenges

Transcription

1 Purdue University Purdue e-pubs Publications of the Ray W. Herrick Laboratories School of Mechanical Engineering Materials and Systems for Noise Control: Categorization and Challenges J Stuart Bolton Purdue University, bolton@purdue.edu Follow this and additional works at: Bolton, J Stuart, "Materials and Systems for Noise Control: Categorization and Challenges" (2010). Publications of the Ray W. Herrick Laboratories. Paper This document has been made available through Purdue e-pubs, a service of the Purdue University Libraries. Please contact epubs@purdue.edu for additional information.

2 Materials and Systems for Noise Control : 4 Categorization and Challenges J. Stuart Bolton Ray W. Herrick Labs Purdue University KSNVE Spring Meeting May 13, 2010

3 General Categories 1. Dissipative Materials Fibrous materials Foams Microperforated Panels 2. Barriers Steel/aluminum panels Sheet rock Metamaterials Materials for Noise Control 3. Barriers/Absorbers Automotive carpet treatments Double panel systems 4. Sound Field Modification Acoustical cloaking 2

4 Dissipative Materials Dissipation mechanisms Viscous Thermal Structural Examples of porous materials Glass fiber Mineral wool Open or partially open cell foams Applications Automotive, Aircraft, 3

5 SEM Glass Fiber 4

6 SEM Partially Reticulated Foam 5

7 Microperforated Material 6

8 Sound Propagation in Porous Media Poroelastic Materials Two phases: Solid (frame) and gas (air) Allow two longitudinal wave types which appear in both phases Allow transverse wave motion if frame possesses shear stiffness Display large sensitivity to boundary conditions if frame is relatively stiff (modulus near that of air) Special cases: limp and rigid 7

9 Absorption Treatments Bonded/Bonded Bonded/Unbonded Membrane Foam Backing Airspace Unbonded/Bonded Unbonded/Unbonded 8

10 Normal Incidence Absorption Effects of Airspace at front and rear (Foam 25 mm, 30kg/m 3, Membrane kg/m 2, Airspaces 1 mm) Film/Foam/Backing Film/Space/Foam/Backing Film/Foam/Space/Backing Film/Space/Foam/Space/Backing 9

11 Modeling of Porous Media Objective It should be possible to close this loop and specify acoustical materials in terms of microstructure rather than acoustical properties 10

12 Automotive Automotive Carpet Treatment Underhood Absorber Headliner From : Huntsman International LLC 11

13 Topological Optimization From : Two-dimensional poroelastic acoustical foam shape design for absorption coefficient maximization by topology optimization method, by J. S. Lee, Y. Y. Kim, J. S. Kim and Y. J. Kang, Journal of Acoustical Society of America, 123 (2008) 12

14 Microperforated Materials Random incidence id absorption measurement 13

15 Microperforated Materials Performance similar to glass fiber or foam in the speech interference range : 6 x 6 x 2 : 3 x 3 x 2 : 6 x 6 x 1 : 3 x 3 x 1 : 2 unsegmented + : 1 unsegmented Frequency [Hz] Performance can be modeled successfully using Maa model and recent modifications by Sakagami, Yoo and Bolton, and others 14

16 Equations of Motion and Velocity Conditions Volume velocity continuity at x=0 1 p I j o x x 0 d (1 ) t s d t f 1 j o p x II x 0 0 d (1 ) t s d f t Force equilibrium at x=0 Solid Fluid p p I I p p II II 2 ( d f ds ) 4 2 d Rt D ds T ds s 1 t t ( d R t f d t s ) d f j oh' t 2 s 2 p I : Pressure at source side p II : Pressure behind the panel d s : Displacement of solid part d f : Displacement of fluid part ρ s: Membrane mass per unit area R f : Flow resistance D: Flexural stiffness T: Tension h : Effective thickness Ω: Porosity 15

17 Comparison between Predictions and Measurements n prediction B.D.=1 cm measurement e e B.D.=1 cm 0.2 prediction B.D.=2 cm measurement B.D.=2 cm 0.1 prediction B.D.=4 cm measurement B.D.=4 cm Freq [Hz] 1 n prediction B.D.=1 cm measurement B.D.=1 cm 0.2 prediction B.D.=2 cm measurement B.D.=2 cm 0.1 prediction B.D.=4 cm measurement B.D.=4 cm Freq [Hz] Good agreement is shown between measurements and predictions by using adjusted hole size n prediction B.D.=1 cm measurement B.D.=1 cm prediction B.D.=2 cm measurement B.D.=2 cm prediction B.D. =4 cm measurement B.D.=4 cm Freq [Hz] d (nominal) [mm] d (adjusted) [mm] t [mm] S S S D / loss factor [N m 2 ] 0.7/ / / 0.07 T [N] ρ s [kg/m 2 ] N

18 Flexural Stiffness Effect n D0=1 D0= D0=0.4 D0= D0=0.2 D0= D0=0.01 D0= Freq [Hz] Depending on the flexural stiffness, the absorption performance can be enhanced with a proper loss factor d [mm] t [mm] D [N m 2 ] 1, 0.6, 0.4, 0.3, 0.2, 0.1, 0.01, loss factor in D T [N] Mass/area [kg/m 2 ] N Size [mm] x

19 CFD Models - Fluent Microperforated Panel 1 mm mm 1 mm v in P 1 P mm.4512 mm m 1 18

20 Microperforated Panel Compare with ih Guo/Maa prediction i 19

21 Challenges Dissipative Materials Optimal tuning of fibrous materials for different frequency ranges by controlling fiber size Relation of foam microstructures to macroscopic properties such as flow resistivity, viscous, thermal characteristic lengths, and tortuosity Advanced fibers with resonant elements (additional internal degrees of freedom) 3-D topological optimization (shape and layering) Inhomogeneous materials (voids and mass concentrations and varying fiber sizes) Material anisotropy Estimation of macroscopic properties based on acoustical data Microperforated panel hole geometry Effect of flexural vibration on lightweight microperforated materials 20

22 Barrier Materials Single and double panels with dissipative lining Panels with viscoelastic cores Composite materials Honeycomb carbon fiber materials Engineered linings Metamaterials Functionalized cellular structures to create stopbands 21

23 Sound Transmission Through Double Panels Approach Substitute allowed solutions into boundary conditions 22

24 Aircraft Application Conventional ribbed-aluminum fuselage Y X Honeycomb core Different stiffness in X,Y & Z dir. solid and fluid (air) parts Replaced by Nomex honeycomb sandwich Panel Z Transversely poro-elastic modeling Y X Transversely isotropic properties 5 elastic constants : E x = E y, E z,g zx,v xy,v zx Z Porous foam with constants, porosity, bulk density, flow resistivity it and tortuosityt 23

25 TL for ½ Lined and Unlined Fuselage Example Lined model 80 Lined with 1/2 glass fiber 70 prediction 60 measurement 50 Unlined model Unlined with 1/2 air layer TL (db) prediction measurement * About 15dB improvement above 1kHz by lining with ½ fibrous material in the air space between honeycomb panel and the interior trim Frequency (Hz) 24

26 Internal Barrier Structures To create surface with low radiation efficiency From : A passive sound canceling material using lightweight embedded machines by Paul C. Lu and Gary F. Hawkins, American Institute of Aeronautics and Astronautics, April 2007, Honolulu, Hawaii 25

27 Internal Barrier Structures Kinematic mechanisms to amplify motion and allow damping effects to be increased From : Mid-frequency response of structures with integral compliant mechanisms: Verification and validation, By E.M. Dede, G.M. Hulbert, Journal of Sound and Vibration, 313(2008)

28 Metamaterials - Resonant Objective to create negative effective mass to prevent wave propagation in certain frequency ranges From : Development and Applications of Acoustic Metamaterials by H. From : Development and Applications of Acoustic Metamaterials by H. Huang, Preliminary exam proposal at Purdue University in April

29 Metamaterials - Resonant From : Development and Applications of Acoustic Metamaterials by H. From : Development and Applications of Acoustic Metamaterials by H. Huang, Preliminary exam proposal at Purdue University in April

30 Metamaterials - Resonant Works by reducing radiation efficiency effectiveness is strongly angle of incidence dependent From : Meta-Material Sound Insulation by E. Wester, X. Bremaud and B. Smith, Building Acoustics, 16 (2009) 29

31 Barrier Materials Challenges Effective attributes of barrier linings - Dissipation or barrier? Multi-functional linings - Airborne noise control and structural damping Enhance damping of composite panel systems Weight efficiency of advanced solutions - Kinematic amplification - Metamaterials Relation between metamaterials and fuzzy structures Manufacturing of metamaterials 30

32 Barriers/Absorbers Semi-permeable mass layers built into carpet systems Lining for double panel systems 31

33 Barriers/Absorbers Approach 1 : Barrier * Noise source Steel panel Interior space Poor absorption Barrier layer Absorbing material - Heavy barrier layer prevents sound from entering interior - Good barrier, poor absorption Approach 2 : Absorptive treatment only * Good absorption - Eliminate heavy barrier layer but increase interior absorption - Poor barrier, good absorption - Lighter weight 32

34 Barriers/Absorbers High flow resistance * Sound source Panel Resistive layer Impermeable barrier Reduced flow resistance Absorptive surface treatment Absorptive layer Useful for automotive carpet systems and dash panel treatments Resistive layer compressed fiber or microperforated polymer Adjust mass and flow resistance to minimize interior sound level (i.e., do not optimize either transmission loss or absorption) 33

35 Aircraft Fuselage Double Panel Treatment Dissipation Barrier Lining material contribution to transmission loss At low frequencies - energy dissipation in lining increases TL At high frequencies barrier performance of lining increases TL 34

36 Barriers/Absorbers Challenges Development of metric that combines barrier and absorptive behavior Lining materials identification of key factors contributing to transmission loss 35

37 Sound Field Modification Acoustic Cloaking Material around scattering object has anisotropic and spatially-varying density and stiffness Object is made invisible Object is shielded from sound field From : Scattering theory derivation of a 3D acoustic cloaking shell by S.A. Cummer, B. Popa, D. Schuring, D.R. Smith, J. Pendry, M. Rahm and A. Starr, Physical Preview Letters, 100, (2008) 36

38 Acoustic Cloaking-resonant From : Analysis of Cummer-Schuring acoustic cloaking by L. Cai and J. Sanchez-Dehesa, New Journal of Physics, 9 (2007) 37

39 Acoustic Cloaking Challenges Proposed implementations based on metamaterials are resonant - Can cloaking be made broadband in principle? Analysis based on rigid scatterer Anisotropic density and spatially varying stiffness Manufacturing of necessary materials Weight and volume comparisons with existing solutions (Physics vs. Engineering) 38

40 General Acoustical Materials Further Challenges Cost Weight efficiency Volume efficiency Robustness durability and installation Thermal barrier performance Functional attributes - Sustainability and recyclability - Antibacterial 39

41 Important Emerging Applications Hospital and medical Safety at work, patient t recovery, and speech privacy Green buildings Positive contribution to LEED certification Windows and ventilation systems Lightweight vehicles Electric and hybrid vehicle 40

42 Locally Resonant Structure We show that by using multiple weights per cell plus simple stacking of the membrane reflectors operative in different frequency regimes, a light-weight, relatively thin acoustic attenuation panel can be implemented that demonstrates effectiveness over a broad frequency range of Hz, with an average STL of >40 db 41

43 Locally Resonant Structure From : Measurement of sound transmission through panels of locally resonant material between impedance tube by K. M. Ho, Z. Yang, X. X. Zhang, P. Sheng, Applied Acoustics 66 (2005),

44 Locally Resonant Structure Problems 1. Most of the transmission performance comes from edge constraint effect without regard to the mass required to provide a rigid support 2. This material is proposed to be a double panel lining, but it works by reflection and not dissipation, and we know that double panel linings at low frequencies encies must be dissipative to enhance the TL of a double panel 43