Weight Minimization of Noise Treatments by Balancing Absorption and Transmission Performance

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1 Purdue University Purdue e-pubs Publications of the Ray W. Herrick Laboratories School of Mechanical Engineering Weight Minimization of Noise Treatments by Balancing Absorption and Transmission Performance Hyunjun Shin Purdue University, J Stuart Bolton Purdue University, Follow this and additional works at: Shin, Hyunjun and Bolton, J Stuart, "Weight Minimization of Noise Treatments by Balancing Absorption and Transmission Performance" (2017). 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 1 Automotive Noise Weight minimization of noise treatments by balancing absorption and transmission Performance Hyunjun Shin and J. Stuart Bolton Ray W. Herrick Laboratories Purdue University

3 OBJECTIVE 2 Minimize the weight of a sound package by balancing between absorption and transmission performance Engine Noise Sound Package Transmitted Noise Reflected Noise Trade-off between transmission and absorption Transmission Absorption

(A) Noise spectrum of automobile engine (B) Engine running at 5000 RPM Engine running at various RPMs References: (A) Direct Sound Radiation Testing

4 ENGINE NOISE SPECTRUM 3 Optimizing the weight of the sound package in the range of 500 Hz to 4000 Hz à allows passengers to communicate without interference Engine noise is mainly distributed in the range of Hz àoverlaps with a human speech range Noise spectrum of automobile engine (A) Noise spectrum of automobile engine (B) Engine running at 5000 RPM Engine running at various RPMs References: (A) Direct Sound Radiation Testing on a Mounted Car Engine, SAE-technical paper, 2088 (2014) (B) Noise Test and Analysis of Automobile Engine, Mechanics and Material, Vol. 307, pp (2013)

5 HOW TO OBTAIN THE SOLUTIONS 4 MODELING CALCULATION OPTIMIZATION Acoustic Model 11.25ρc Transfer Matrix Method P 1 U 1 = Aluminum Panel Limp Porous Flexible MPP Air Space P t U t Genetic Algorithm function Solutions yielding the same SAP magnitude Noise Treatment Aluminum Limp Porous Flexible MPP Aluminum Panel (1 mm) Limp Porous (30 mm) Flexible MPP (0.2 mm) Space-averaged Pressure Magnitude Pool of Solutions SAP = D KLM Re (P D) F + Im (P D ) F n PICK THE LOWEST SURFACE DENSITY COMBINATION

6 ACOUSTIC MODEL 5 Incidence Interior Space L=50 cm Termination Impedance ρc Termination Impedance: ρc (absorption coefficient of 0.3 ) Sound Absorption Average [ ASTM C423] Interior Space Averaged Coefficient α QRSTQUS = 1 12 YLFZ[[ \] X YLF[[ \] α Y α^_`styat = YLc YLM α Y S Y S`a`Qd For Seats, Windows, and Roof Design and Optimization of Vehicle Interior Sound Package,Shuming CHEN, Dengfeng WANG, Ankang ZUO, Zhen CHEN State Key Laboratory of Automotive Dynamic Simulation Sound Intensity Measurements in Vehicle Interiors, Jakob Mørkholt, Jørgen Hald and Svend Gade, Bruël & Kjær, Nærum, Denmark Predicting Vehicle Interior Sound with Statistical Energy Analysis Chadwyck T. Musser and Jerome E. Manning, Cambridge Collaborative, Concord, Massachusetts George Chaoying Peng, Jaguar Land Rover, Coventry, United Kingdom

7 MODELING OF SOUND PACKAGES 6 Sound Package layout ALUMINUM PANEL LIMP POROUS LAYER FLEXIBLE MPP Aluminum panel Limp Porous Flexible MPP Density: 2700 kg/m^3 Thickness: 1 mm Young s Modulus: 69e9 Poisson s Ratio: 0.33 RIGID POROUS (EQUIVALENT FLUID MODEL) (JCA-model) RIGID POROUS (EQUIVALENT FLUID MODEL) (JCA-model) LIMP POROUS FLEXIBLE MPP (Parallel addition with Mass/Area) Limp Porous Flexible MPP Density(solid part): 1 to 15 kg/m^3 Flow resistivity: 3300 to MKS Rayls/m Surface Density: 0.1 to 3 kg/m^2 Flow resistance: 100 to 1500 MKS Rayls Adjusting the acoustic properties (Density and Flow Resistance) of both Limp Porous and Flexible MPP to minimize the weight while maintaining its acoustic performance Johnson D. L., Koplik J. and Dashen R., Theory of dynamic permeability and tortuosity in fluid-saturated porous media, J. Fluid Mech. 176, 1987, pp NOISE-CON 2017 Champoux Y. and Allard J.-F., Dynamic tortuosity and bulk modulus in air-saturated porous media, J. Appl. Phys. 70, 1991, pp June 12-14, 2017

8 MATERIAL PROPERTIES 7 Material Surface Density (kg/m2) Thickness (mm) Young s Modulus (Pa) Poisson s Ratio Aluminum Plate x Limp Porous 30 Flexible MPP 0.2 Material Porosity Thermal characteristic Length (m) Limp Porous x10 h6 Material Hole diameter (m) Thermal characteristic Length (m) Viscous characteristic Length (m) Viscous characteristic Length (m) Flexible MPP 100x10 h6 100x10 h6 100x10 h6 Tortuosity The values are taken out of X. Olny, R. Panneton, and J. Tran Van, Experimental Determination of the Acoustical Parameters of Rigid and Limp Materials using Direct Measurements and Analytical Solutions, Proc. Forum Acusticum 2002, Sevilla, Spain (2002).

9 FLEXIBLE MPP MODEL 8 Complex density of the rigid porous using JCA model ρj Sk = l mn o p [1 + rp stl m n o u1 + vswn x otl m ) ] r x y x p x Complex bulk modulus of the rigid porous K Sk (ω) = γ (γ 1) 1 j γ P [ φ 8k Λ F C ρ [ ω 1 + j Λ F C ρ [ ω 16k hm

10 FLEXIBLE MPP MODEL 9 Characteristic impedance and Complex Wavenumber Z Sk_ ŽŽ = ρj Sk K Sk k Sk_ ŽŽ = ρj Sk K Sk Transfer impedance of the rigid MPP Z`_ YUY = ρ a c 1 + R Q 1 R Q ρ a c = 2ρ acr Q 1 R Q R Q : Reflection coefficient of the rigid porous with an anechoic backing Transfer impedance and Transfer matrix of a flexible MPP v Add the impedance of an impermeable barrier in parallel Z`_ ds Y ds = jωm ŽŽ Z`_ YUY 1 Z`_ ds Y ds Z`_ YUY + jωm ŽŽ 0 1

11 BUILDING TRANSFER MATRICES 10 Incidence 1 Pa [94dB] P M U M P F U F L=50 cm P œ U œ P M U M = N MM N MF N FM N FF L MM L MF L FM L FF P œ U œ Transfer matrix of Noise Treatment Transfer matrix of Air space Transfer matrix of Noise Treatment Transfer Matrix of Noise Treatment = Transfer Matrix of Aluminum Panel Transfer Matrix of Limp Porous Transfer Matrix of Flexible MPP N 11 N 11 = 1 jωm alum N 21 N cos k eq_limp h jsin(k eq_limp h¼/z eq_limp jz eq_limp sin»k eq_limp h¼ cos k eq_limp h 1 0 Z t_flexible 1

12 BUILDING TRANSFER MATRICES 11 Transfer matrix of an Interior Air Space Transfer Matrix of Interior Air Space = Transfer Matrix of An Air L 11 L 11 L 21 L 22 = cos k air (x 3 x t ) jz air sin(k air (x 3 x t )) jsin(k air (x 3 x t )¼/Z air cos k air (x 3 x t ) Pressure and Velocity Calculation using TMM Termination Condition P M U M = N MM N MF N FM N FF P F U F P F U F = L MM L MF L FM L FF P œ U œ Z`= P œ /U œ Therefore, P F = (L MM + L MF )P œ P œ = Z` 2 ρcl MM N FM + L MM N MM + L MF N FM ρc Z` + L MF N MM 1 Z` + ρcl FM N FF + L FM N MF + L FF N FF ρc Z` + L MF N MF 1 Z`

13 PRESSURE IN THE INTERIOR SPACE 12 Incidence P F U F A B P œ U œ Termination Impedance ρc x [ x` L=50 cm x Ç Pressures at location 2 & 3 P F = Ae hyã Ä + Be YÃ Ä P œ = Ae hyã È + Be YÃ È Since P 2 and P 3 were calculated in the previous step, A = P œ P F e hyã Ä e hyã B = P F(e hyã( ÄÊ É¼ e hyã œ ÄÊ É + e hfyã È) P œ e hyã Ä É e hfyã Äe hyã É e hyã É e hfyã Äe hyã É Thus, sound pressure at any location between x` and x Ç is P = Ae hikx + Be ikx x` x x Ç

14 SPACE-AVERAGED PRESSURE MAGNITUDE 13 To quantify the interior space acoustic pressure between the noise treatment and the termination, space-averaged pressure magnitude is calculated. SAP = n il1 Re (P n ) 2 + Im (P n ) 2 n n=1, 2, k, n P 1 U 1 P 2 U 2 P 3 U ρc P M =Re(P M ) + jim(p M ) P Ã =Re(P Ã ) + jim(p Ã ) Space-averaged pressure magnitudes then averaged over frequency between 500 and 4000 Hz (resolution of 4 Hz) Space Averaged Pressure [Pa] 500 Hz Frequency [Hz] 4000 Hz Target Frequency Range is between 500 Hz 4000 Hz. (Speech Interference Range) Average pressure

15 OPTIMIZATION PROCESS 14 Equivalent fluid model Pressure in the air space calculation Set the target pressure Aluminum panel Limp Porous Flexible MPP TMM Space Averaged Pressure [Pa] Current pressure Space Averaged Pressure [Pa] Target pressure 500 Hz Frequency [Hz] 4000 Hz Space-averaged pressure magnitude (frequency range 500 Hz to 4000 Hz) 500 Hz Frequency [Hz] 4000 Hz Updated σ MPP, m MPP, σ porous, m porous Flexible MPP σ daø σ ŽŽ σ Ù m daø m ŽŽ m Ù Limp porous Layer σ daø σ ataùç σ Ù m daø m ataùç m Ù Surface Densities and Flow resistances for both limp porous and flexible MPP are subjects to change in the boundary limits E = 1 SAP Current SAP Target Error Function Optimization starts with randomly selected surface densities, and flow resistances for both limp porous and flexible MPP

16 INPUTS FOR OPTIMIZATION 15 Randomly assigned starting points for optimization Lower and Upper Boundaries Material Limp Porous Flexible MPP Surface Density 0.03 to 0.45 (kg/m2) 0.1 to 3 (kg/m2) Flow Resistance 100 to 1500 (Mks Rayls) 100 to 1500 (Mks Rayls)

17 OPTIMIZATION RESULTS I 16 Target pressure close to 0.02 Pa [ 60 db ] case All combinations which yields averaged pressure of 0.02 Pa Heaviest Weight Combination Material Lightest Combination Properties of Lightest and Heaviest materials Flexible MPP Flow Resistance [MKS Rayls] Surface Density [kg/m 2 ] Limp Porous Layer Flow Resistance [MKS Rayls] Surface Density [kg/m 2 ] Total [kg/m 2 ] Flow Resistance Flow Resistance [MKS Rayls] [MKS Rayls] Lightest Weight Combination Heaviest Combination Surface Density [kg/m 2 ] Surface Density [kg/m 2 ] [kg/m 2 ]

18 OPTIMIZATION RESULTS II 17 Surface densities under 0.8 kg/m 2 (Termination Impedance: 11.25ρc) Flow Resistance (MKS Rayls) MPP Limp Porous Total Surface Density (kg/m 2 ) Flow Resistance (MKS Rayls) Surface Density (kg/m 2 ) Surface Density (kg/m 2 ) All combinations shown above yielded averaged pressure magnitude close to 0.02 Pa

19 OPTIMIZATION RESULTS III 18 Total surface densities for various space-averaged pressures Space-averaged pressures for Two different surface densities 60 db 60 db Space Averaged Pressure [db] As the space average pressure decreases, i.e., performance increases, the range of possible surface densities reduction decreases. Incidence: 94 db 34 db drop Noise Treatment : 60 db

20 ACOUSTIC PERFORMANCE COMPARISONS 19 Absorption Transmission Absorption Coefficient Transmission Loss Tradeoff between absorption and transmission performance to reach the certain level of averaged pressure in the interior space.

21 EFFECTS OF THE TERMINATION IMPEDANCE 20 Termination impedance is doubled to see its effects Acoustic performances of the noise treatment which yields the average pressure of 0.03 Pa 22.50ρc (α=0.16) Absorption Coefficient Transmission Loss

22 CONCLUSIONS 21 Noise treatment was successfully modeled using JCA equivalent fluid model Space-averaged pressure in the interior space was calculated using TMM Surface density of a noise treatment was minimized for various averaged pressures in the interior space while maintaining its acoustic performances It is verified that there is a tradeoff between absorption and transmission performance of the noise treatment In this research, the procedure for the optimization of the weight of the sound package was demonstrated. In the future, more complicated acoustic model and the sound package will be studied

23 REFERENCES Arnaud Duval, Jean-Francois Rondeau, Guillaume Deshayes and Benoit Teyssandier, Generalized Light-Weight Concept: A Comprehensive Acoustic Package Weight Reduction Strategy, Proc. Automobile Comfort Conference, Le Mans, France (2006). 2. Arnaud Duval, Jean-Francois Rondeau, Lars Bischoff, Guillaume Deshayes and Ludovic Dejaeger, Generalized Light-Weight Concept: Improving the Acoustic Performance of Less than 2500g/m F insulators, SAE Technical Paper,2136 (2009). 3. Arnaud Duval, Jean-Francois Rondeau, Ludovic Dejaeger, Francis Lhuillier and Julien Monet-Descombey, Generalized Light-Weight Concepts: A New Insulator 3D Optimization Procedure, SAE Technical Paper, 1947 (2013). 4. A. Parrett, C.Wang, X. Zeng, D. Nieulubowciz, M. Snowden, J.H. Alexander, R.W. Gerdes, B. Leeder and C. Zupan, Application of Micro-Perforated Composite Acoustic Material to a Vehicle Dash Mat, SAE Technical Paper,1623 (2011). 5. Jun Zhang, Guanni Zhu, Xiaoxuan Zhang, Hogyu Liu, Congguang Liu, The Vehicle NVH Development and Engineering Application of the Lightweight Sound Package, V. Proc. SAE-China Congress: Selected Papers, (2014). 6. Xian Wu, Xiaokang Tang, Jianwang Shao, Optimization of acoustic performance of a vehicle dash sound package, Proc. Inter-Noise 2016, Hamburg, Germany (2016) 7. Yuksel Gur, Jian Pan, Wanlu Li, David A. Wagner, Development of Vehicle Dash and Floor Subsystem Sound Package for Lightweight Vehicl, Proc. Noise-Con 2016, Providence, Rhode Island, US (2016). 8. Chadwyck T.Musser, Jerome E. Manning, and George Chaoying Peng, Predicting Vehicle Interior Sound with Statistical Energy Analysis, Sound & Vibration. 46(12), 8-14 (2012). 9. Jacob Morkholt, Jorgen Hald and Svend Gade, Sound Intensity Measurements in Vehicle Interiors, Journal of the Acoustical Society of America. 132, 1984 (2012). 10. S.K. Jain, M.P. Joshi, P.G. Shravage, P.S. Yadav and N.V. Karanth, Evaluation of Acoustic Performance of Automotive Seats by Experimental and Simulation Techniques, SAE Technical Paper, 0105 (2013). 11. Yvan Champoux and Jean-F. Allard, Dynamic Tortuosity and Bulk Modulus in Air-Saturated Porous Media, Journal of Applied Physics. 70(4), (1991). 12. Hyunjun Shin and J. Stuart Bolton, Barrier Mass and Flow Resistance Optimization for Interior Noise Reduction, Proc. Noise-Con 2016, Providence, Rhode Island, US (2016). 13. Noureddine Atalla and Franck Sgard, Modeling of Perforated Plates and Screens using Rigid Frame Porous Models, Journal of Sound and Vibration. 303, (2007). 14. X. Olny, R. Panneton, and J. Tran Van, Experimental Determination of the Acoustical Parameters of Rigid and Limp Materials using Direct Measurements and Analytical Solutions, Proc. Forum Acusticum 2002, Sevilla, Spain (2002). 15. T. Herdtle and J. Stuart Bolton, Effect of Thermal Losses and Fluid-Structure Interaction on the Transfer Impedance of Microperforated Films, Proc. Noise-Con 2014, Fort Lauderdale, Florida, US (2014).

24 THANK YOU

25 APPENDIX A. LIMP POROUS MODEL Complex density of the limp porous Complex density of the rigid porous was calculated using JCA model dyã = Aρj TYUY Sk + B TYUY + C ρj Sk ρj Sk A = ρ ãq`, B = ρ a F, C = ρ ãq` 2ρ a ρ ãq` = 1 φ ρ Ç + φρ a, Complex bulk modulus of the limp porous K Sk (ω) = γ (γ 1) 1 j γ P [ φ 8k Λ F C ρ [ ω 1 + j Λ F C ρ [ ω 16k hm

26 APPENDIX A. LIMP POROUS MODEL Characteristic impedance of the rigid MPP Z Sk_dYã = ρj dyã Sk K Sk Complex wavenumber of the rigid MPP k Sk_dYã = ρj dyã Sk ä K Sk Transfer matrix for a limp porous cos k Sk_dYã h jsin(k Sk_dYã h¼ Z Sk_dYã (jz Sk_dYã sin(k Sk_dYã h¼ cos k Sk_dYã h

27 APPENDIX C. FLEXIBLE MPP MODEL α ê = ɛ h ξ = 2 Φ π ɛ = (1 1.13ξ 0.09ξ F ξ œ ) 8r 3π σ = 8η Φr F α ê : Tortuosity e : Corrected length η : Kinetic viscosity f : Open porosity ρ a : Ambient air density k: Thermal conductivity s : Static air flow resistivity g : Ratio of specific heats C : Specific heat at constant pressure L : Viscous characteristic length Λ : Thermal characteristic length

28 APPENDIX B. CAR INTERIOR SPACE ABSORPTION Ceiling reflects the noise (α 0.25) Dash panel blocks the engine noise and absorb the interior noise Windows reflect the noise (α 0.1) Carpets absorb noise in midfrequency range Leather Seats absorb the noise (α 0.5)

29 APPENDIX C. EFFECTS OF THE TERMINATION IMPEDANCE Material properties for two different termination impedances both of which yielded the average pressure of 0.03Pa in the interior space. Termination Impedance Flexible MPP Limp Porous Layer Total Flow Resistance [Mks Rayls] Flow Resistance [Mks Rayls] 11.25*ρc Surface Density [kg/m 2 ] Surface Density [kg/m 2 ] Surface Density [kg/m 2 ] Flow Resistance [Mks Rayls] Flow Resistance [Mks Rayls] 22.50*ρc Surface Density [kg/m 2 ] Surface Density [kg/m 2 ] Surface Density [kg/m 2 ] Surface density for higher termination impedance case came out to be lower than that of lower termination impedance case.

The Effect of Flexibility on the Acoustical Performance of Microperforated Materials

Purdue University Purdue e-pubs Publications of the Ray W. Herrick Laboratories School of Mechanical Engineering -- The Effect of Flexibility on the Acoustical Performance of Microperforated Materials