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Passive/Active Acoustic metamaterials

Dr. Hervé Lissek EPFL - Laboratoire d’ ElectroMagnétisme et d’Acoustique. Passive/Active Acoustic metamaterials. Introduction. Acoustic Metamaterials increasing research topic in the Physical Acoustics community

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Passive/Active Acoustic metamaterials

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  1. Dr. Hervé Lissek EPFL - Laboratoire d’ElectroMagnétisme et d’Acoustique Passive/Active Acousticmetamaterials

  2. Introduction • AcousticMetamaterials • increasingresearchtopic in the PhysicalAcousticscommunity • design accessible throughstraightforward concepts (electroacoustic analogies) • Ongoingresearchat LEMA-EPFL • Dual Transmission-Line basedacoustic/mechanicalmetamaterials • Theoretical/Experimental validation of 1D prototype • Theoreticalassessement of 2D configurations • Electroacousticabsorbers: • Shunt a loudspeakerwith active electric networks = active control of acousticimpedance Bongard F., Lissek H., Mosig J.R., Acoustic transmission line metamaterial with negative/zero/positive refractive index, PRB 82(9), september 2010 Gouraud B., Métamatériauxacoustiques type ligne de transmission, Rapport de stage long de recherche FIP-M1, ENS, juillet 2010 Lissek H., Boulandet R., Fleury R., Electroacoustic absorbers: bridging the gap between shunt loudspeakers and active sound absorption, JASA 129(5), 2011 Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  3. Introduction K : Bulk modulus r : Mass density g : Propagation constant Fields variation in exp(-gz) Acoustic metamaterials Negative refraction Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  4. Introduction - Applications • Lowfrequency noise absorption Yang Z., Dai H. M., Chan N. H., Ma G. C., Sheng P., Acoustic metamaterial panels for sound attenuation in the 50–1000 Hz regime, APL 96, January 2010 Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  5. Introduction - Applications • Lowfrequency noise absorption • Superlenses, subwavelengthimaging Zhu J., Christensen J., Jung J., Martin-Moreno L., Yin X., Fok L., ZhangX.,.Garcia-VidalF. J, A holey-structured metamaterial for acoustic deep-subwavelength imaging, NPL 7, January 2011 Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  6. Introduction - Applications • Lowfrequency noise absorption • Superlenses, subwavelengthimaging • Acousticcloaking Zhang S., Xia C., Fang N., Broadband Acoustic Cloak for Ultrasound Waves, PRL 106, January 2011 Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  7. Dual TL-basedAcousticmetamaterials • Dual Transmission Line • Analogies withElectromagnetics • Transmission-Line approach • Waveguides periodically loaded with “inclusions” Only K < 0 Side holes [Lee, JPCM 21, 2009] Only K < 0 Helmholtz resonators [Fang, NM 51, 2006] Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  8. Dual TL-basedAcousticmetamaterials • Implementation of a “double negative acoustic medium” based on a transmission line approach •  Dual Transmission Line! Generally:Composite Right/Left-Handed (CRLH) medium Conventional medium Negative refraction medium In practice:  Implementation of series acoustic compliances + shunt masses … Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  9. Dual TL-basedAcousticmetamaterialsseriescompliances • How to implementsuchelements? E : Young’s modulus  : Poisson’s ratio rm : mass density h : thickness mass-compliance approximation Clamped thin plate Equivalent acoustic circuit Thin plates theory: Exact mechanical impedance Acoustic impedance Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  10. Dual TL-basedAcousticmetamaterialsseriescompliances • Validation • Kapton® FPC membrane, h = 125 m, a = 9.06 mm • simulations with COMSOL MULTIPHYSICS (Application mode: “Stress-Strain with Acoustic Interaction”) • Computing reflection and transmission coefficients under plane waves  series equivalent impedance Zam: Dominated by mam (Imaginary part) Dominated by Cam Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  11. Dual TL-basedAcousticmetamaterialsShunt masses • How to implementsuchelements? • Shunt masses can be achieved with small open ducts (“stubs”).  p = 0  small “shunt” duct   shunt acoustic mass mat (+ parasitic Cat) matcan be approx. by Equivalent acoustic circuit Open radial stub Radial duct theory  exact expression of Yat mass-compliance approximation (mat, Cat)… Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  12. Dual TL-basedAcousticmetamaterialsShunt masses • Validation • Open radial duct with b = 1 mm and a = 9.06 mm • Simulations with COMSOL MULTIPHYSICS • Computing reflection and transmission coefficients under plane waves  extraction of shunt impedance Zat = 1/Yat: Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  13. Symmetric unit-cell Dual TL – Model and Design • Structure proposée: “detailed model” “lumped-elements model” d = 34 mm = /10 @ 1 kHz subwavelength unit-cell effective medium characteristics Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  14. duAL TL – Performances (1/2) dispersion diagram bB(refraction index: n = bB/k) Bloch impedance ZB n < 0 band (backward waves)  1 octave !! n > 0 band (forward waves) Bloch parameters = scattering parameters of a TL equivalent to the periodic structure Bongard F., Contribution to characterization techniques for practical metamaterials and microwave applications., PhD Dissertation n° 4407 , EPFL, 2009 Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  15. duAL TL – Performances (1/2) dispersion diagram bB(refraction index: n = bB/k) Bloch impedance ZB n < 0 band (backward waves)  1 octave !! n > 0 band (forward waves) Smooth impedance wideband matching = n = 0 @ f0= 1 kHz : transition frequency No band gap  “matched conditions” !It is possible to match the resonance frequencies of the series and shunt branches Bongard F., Contribution to characterization techniques for practical metamaterials and microwave applications., PhD Dissertation n° 4407 , EPFL, 2009 Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  16. duAL TL – Performances (1/2) dispersion diagram bB(refraction index: n = bB/k) n < 0 band (backward waves)  1 octave !! n > 0 band (forward waves) Bongard F., Contribution to characterization techniques for practical metamaterials and microwave applications., PhD Dissertation n° 4407 , EPFL, 2009 Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  17. Example of mismatchedresonators Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  18. duAL TL – Performances (2/2) • 10 cells structure :scattering parameters r : Reflection coeff. t : Transmission coeff. wideband -10 dB matching 0° transmission phase Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  19. Dual TL – Radiation properties (1/2) • Radiation of open stubs fast-wave radiation band “Efficiency” :( = 1 for lossless structure) fast-wave radiation band Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  20. Dual TL – Radiation properties (2/2) fast-wave radiation band 1030 Hz fast-wave radiation band 930 Hz Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  21. expErimentalstudy • 1D dual TL prototype • Rectangularwaveguide: section 23mm x 23mm • Membranes = 50mm Bronze-Beryllium plates clampedbetweentwo adjacent cells • Stubs = cylindricalducts (radius 4mm, length 20mm) Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  22. expErimentalstudy • Characterization (series + shunt impedances) • Plates vibratoryvelocityvi: • PVDF film (9mm) glued on one face • Acoustic pressure pi in eachconnectingcavity v1 p1 p2 Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  23. expErimentalstudy • Characterization (series + shunt impedances) Stub admittance + Im(Yap) . Re(Yap) withCap=41.10-8 Pa-1 and map=0.13 kg.m-2 Plate seriesimpedance + Im(Zas) . Re(Zas) withmas=0.4 kg.m-2 and Cas=6.6.10-8m.Pa-1 Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  24. expErimentalstudy • Characterization: dispersion diagram Dispersion diagramprocessedaccording to Zas and Yap Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  25. expErimentalstudy (Lee et al) • Characterization: phase velocity Phase velocity as a function of frequency. Visualization of the three typical waves (t2 =t1+Dt). At 350 Hz the wave propagates backwards, At 650 Hz the wave is evanescent, At 950 Hz the wave travels forward. Lee S.H., Park C.M., Seo Y.M. et al, Composite Acoustic Medium with Simultaneously Negative Density and Modulus, PRL 104, 2010 Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  26. Experimentalstudy • Experimental issues: • Design discrepancies: building the structure induces heterogeneous tension on the plates • Resonance frequencies hardly tuneable in practice! • Only local measurements for now • Experimental assessment to be optimized: • measurement of coefficients a and b in TL-impedance tube Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  27. Active acousticmetamaterialsActive Control of acousticimpedance Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  28. Rationale for turninginto active • Possibility to tune acousticpropertieshardlyachievablewith passive structures • In 2010, Akl et al proposed a configuration with active HRs • piezo-transducerat the back of the cavities • direct pressure feedback  Programmable bulkmodulus • Variable mass densityalso achievablewith active membranes Akl W., Baz A..,Configurations of Active Acoustic Metamaterialwith Programmable BulkModulus, Proc. SPIE, 2010 Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  29. Active control of acousticimpedance • An electroacoustictransducercanbeused as a variable acousticimpedance • Concept of "electroacoustic absorber"  • Applied in FP7-OPENAIR • Mechanicalresonator • - mech. resistanceRms • mass Mms • mech. complianceCms bn(s) Vn(s) P(s) Lissek H., Boulandet R., Fleury R., Electroacoustic absorbers: bridging the gap between shunt loudspeakers and active sound absorption, JASA 129(5), 2011 Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  30. Active control of acousticimpedance • In the case of an electrodynamicloudspeaker + shunt R//L//C electricresonator • Variable R modifies RmEA • Variable L modifies CmEA • Variable C modifies MmEA bn(s) Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  31. Active control of acousticimpedance Natural resonator Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  32. Active control of acousticimpedance Positive shunt resistance Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  33. Active control of acousticimpedance Negative shunt resistance Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  34. Active control of acousticimpedance Positive R and negativeL and C Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  35. Active control of acousticimpedance NegativeC Positive C Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  36. Active control of acousticimpedance NegativeL Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  37. Active control of acousticimpedance • Theoretically, an electroacousticresonatorparameterscanbemodified to a large extent • Reduction of mass // compliance (negative inductance // capacitance) • increasesresonancefrequency of membranes • possible alignement of plates in a multi-cellmetamaterial • Reduction of resistance (negativeresistance) • reduceslosses in the metamaterial Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  38. Experimentalassessment Active electricload Absorption coefficient Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  39. CONCLUSIONS Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  40. Conclusions – perspectives • 1D dual TL concept validated • Seriescomplianceachievedwith membranes • Shunt masses achievedwith open derivationducts • Effective propertiesassessednumerically • Local propertiesassessedexperimentally • In parallel, several applications assessed: • Sound absorption in the LF range • Subwavelengthimaging • Acousticcloaking Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  41. Conclusions – perspectives • Active control of acousticimpedance • Variable acousticresonatorparameters • reducelosses in the resonator • stiffen the resonator • lighten the resonator • No need to use sensor for fedbacks • But pressure feedback (combinedwith active electricload) canimprove the stability Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  42. Conclusions – perspectives • Active acousticmetamaterials • Couldtakeadvantages of actuated membranes • Varynegative mass • Varynegativebulkmodulus • Set, by electric control, the bandwidths of work • possibility to overcomepractical issues • Losslessmechanicalsystems • Alignement of membranes Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

  43. Collaborators: Dr. Frédéric Bongard, Baptiste Gouraud Romain Boulandet, Romain Fleury, Anne-Sophie Moreau Thankyou for your attentiontime for questions… Dr. Hervé Lissek - EPFL - Passive and Active Acoustic metamaterials

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