The Acoustics and Mechanics of Porous Materials Research Group
The Acoustics and Mechanics of Porous Materials Research Group
The Acoustics and Mechanics of Porous Materials Research Group
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<strong>The</strong> <strong>Acoustics</strong> <strong>and</strong> <strong>Mechanics</strong> <strong>of</strong> <strong>Porous</strong> <strong>Materials</strong><strong>Research</strong> <strong>Group</strong>– p.1/8
<strong>The</strong> <strong>Research</strong> <strong>Group</strong>11 Pr<strong>of</strong>., Ass. pr<strong>of</strong>. <strong>and</strong> full time researchers1 PhD students (+1 cotutelle with KTH)1 Technical staffActivity initiated by J.-F. Allard in the 80s(Biot medal 2008, Decibel d’Or special price 2011)Mainly focused on air saturated porous materialInternational Collaborations: KTH, Univ. <strong>of</strong> Sheffield, Univ. <strong>of</strong> Salford, KULeuven...National Collaborations: Supméca, Univ. Bourgogne, ENTPE, LMA...– p.2/8
Characterization -Acoustic parameters-An example <strong>of</strong> sucessfull technology transfer LAUM - CTTMDedicated to the Johnson-Allard modelFlowmeter, PorosimeterImpedance tube <strong>of</strong> various φ⇒Impedance tube with moving microphone⇒Square cross-section tubeUltrasonic characterizationCollab. CTTM <strong>and</strong> KULeuven⇒Analytic reconstructionIn situ characterizationParameteric antenna...– p.4/8
CharacterizationAcoustic parametersImpedance sensor (Pride-Lafarge)Collab. CTTMGraded porous materialsCollab. Sheffield, LMSSaturated by viscous fluidLMAc Project (2014-2018)Mechanical parametersMechanical bench (“Rigidimeter”)Collab. CTTMSurface Acoustic WaveCollab. KULeuven & Univ. Bourgogne– p.5/8
Modeling<strong>The</strong>oretical modelJ.-F. Allard: Biot-Johnson-Allardmodel (widely used)Numerical modelingTransfer Matrix MethodCTTM: Maine3A⇒TMM avoiding divergenceContinously graded porous materialsCollab. KULeuven, Univ. <strong>of</strong> BradfordIn-house Finite-Elements codesD. Lafarge: Biot-Pride-Lafarge modelGeneral macroscopic model involvingspatial <strong>and</strong> time dispersionx 2(mm)100-10-20-30201004.543.532.521.5Heuristic homogenizationDazel et al. formulationScattering (HF)-Limp model-10-20-300 10 20 30 40 50 60 70 80x 1(mm)Multiple scattering method <strong>and</strong> modematching techniqueModel reductionCollab. KTHDiscontinuous Galerkin MethodCollab. ISVRTime domain methods10.5– p.6/8
Design <strong>of</strong> acoustic metamaterials1.2mean d|p(x,w)| (a.u.)10.80.60.40.2Experimental resultsModified MSM0500 1000 1500 2000 2500 3000 3500 4000Frequency (Hz)Coupling <strong>of</strong> b<strong>and</strong>gap <strong>and</strong> resonancesTunability (shape <strong>of</strong> scatterers)Wave guidesNegative refractionHeuristic homogenization <strong>of</strong> sonic crystalSustainability– p.7/8
Design <strong>of</strong> metaporous materials10.90.8A > 0.9 for λ air ≈ 8×LAbsorption coefficient0.70.60.50.40.30.20.10ExperimentalFEMhomogeneous layer500 1000 1500 2000 2500 3000 3500 4000Frequency (Hz)Absorption associated with the use porous materials (HF)+Absorption associated with mode excitations (BF) due to irregularities or inclusions3D configurations, i.e., spheres, Helmholtz resonators...Structured microstructure, i.e., subwavelength resonators...Collab. Supméca, ENTPE, Univ. <strong>of</strong> Salford (ANR-Metaudible project, 2013-2017)Spin-<strong>of</strong>f compagny Metcoustic (funded by SATT, French Gov., <strong>and</strong> Local Ententities)– p.8/8
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