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Projeto Tratamentos Isolantes Acusticos (11)98950-3543

Jul 09, 2015

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Diversas pesquisas e profundos estudos nos têm permitido oferecer aos nossos clientes uma extensa gama de produtos para tratamentos e condicionamentos acústicos. A atuação da Refrasol na área da acústica vai desde o fornecimento e aplicação de materiais de proteção acústica e termo-acústica em coberturas, forros e telhados através de processos de projeção pneumática de fibras minerais incombustíveis e de aplicações de pinturas cerâmicas isolantes, até projetos completos e de execução de sistemas de enclausuramento e isolamentos acústicos de áreas críticas.

Com a utilização dos mais modernos produtos existentes no mercado, a temos condições de oferecer a mais ampla gama de soluções em tratamentos isolantes e fono-absorventes, para quaisquer condições de trabalho.

  • Purdue UniversityPurdue e-Pubs

    Publications of the Ray W. Herrick Laboratories School of Mechanical Engineering

    7-1-2013

    The Influence of Boundary Conditions andConstraints on the Performance of Noise ControlTreatments: Foams to MetamaterialsJ Stuart BoltonPurdue University, [email protected]

    Follow this and additional works at: http://docs.lib.purdue.edu/herrick

    This document has been made available through Purdue e-Pubs, a service of the Purdue University Libraries. Please contact [email protected] foradditional information.

    Bolton, J Stuart, "The Influence of Boundary Conditions and Constraints on the Performance of Noise Control Treatments: Foams toMetamaterials" (2013). Publications of the Ray W. Herrick Laboratories. Paper 82.http://docs.lib.purdue.edu/herrick/82

  • J. Stuart BoltonRay. W. Herrick LaboratoriesSchool of Mechanical EngineeringPurdue University

    RASD 2013, Pisa, Italy, July, 2013

  • Effect of front and rear surface boundary conditions on foam sound absorption

    Influence of edge constraints on transmission loss of poroelastic materials including effect of finite mass supportssupports

    Metamaterial Barrier

    2

  • 3

  • Normal Incidence Measurement Normal Incidence Measurement f flf flof Reflectionof Reflection

    4

  • FilmFilm--faced Polyurethane Foamfaced Polyurethane Foam

    Scanning electron micrographs of the foam sample

    25mmlayeroffoam onesidecoveredwithflamebondedfilm,theotheropen.

    Many intact membranesManyintactmembranes

    5

  • Reflection Impulse ResponseReflection Impulse Response

    (Film-faced surface up) (Foam-open surface up)

    6

  • OneOne--Dimensional Dimensional PoroelasticPoroelasticM i l ThM i l ThMaterial TheoryMaterial Theory

    Equationsofmotion:Fluid:

    Solid:

    Based on Zwikker and Kosten, plus Rosin with complex density and air ff k f b hstiffness taken from Attenborough.

    7

  • Boundary ConditionsBoundary Conditions

    Open foam surface Foam surface sealed with an i i b

    Foam fixed to a hard backingimperious membrane

    8

  • Reflection Impulse Response Reflection Impulse Response --p pp pPredictedPredicted

    Film-faced FoamOpen Surface Foam

    Reflectionfromrearsurface Disaster!

    9

  • FilmFilm--faced Foam / Thin Air Gapfaced Foam / Thin Air Gap/ p/ p

    Impedance:

    10

  • FilmFilm--forced Foam / Thin Air Gapforced Foam / Thin Air GapFilmFilm forced Foam / Thin Air Gapforced Foam / Thin Air Gap

    1600 Hz350 Hz

    1600 Hz

    Inverted reflection from rear surface

    11

  • Rear Surface Boundary ConditionsRear Surface Boundary Conditions25mm foam layer with bonded membrane

    1. No Airspace:

    2. Airspace:p

    12

  • membranefoamo Bonded/Bondedbacking

    /

    o Bonded/Unbondedairspace

    o Bonded/Unbonded

    b d d d do Unbonded/Bonded

    o Unbonded/Unbonded

    13

  • Normal Incidence AbsorptionNormal Incidence Absorptionpp

    o Foam 25mm,30kg/m3o Membrane 0.045kg/m2o Airspaces 1mm

    Effects of Airspace at front and rear

    1.Film/Foam/Backing

    2.Film/Space/Foam/Backing

    3.Film/Foam/Space/Backing

    EffectsofAirspaceatfrontandrear

    / / p / g

    4.Film/Space/Foam/Space/Backing

    14

  • Impedance Tube TestingImpedance Tube TestingMelamineFoam(8.6kg/m3)

    100 mm diameter

    p gp g

    100mmdiameter 25mmthick

    Eachsamplefitexactlybytrimmingthediameter&checkingthep y y g gfitwithaTLmeasurement

    TwoFacing&TwoRearSurfaceBoundaryConditions Multipletrials Multiplesamples

    15

  • Sample Fit: TL QualificationSample Fit: TL Qualificationp Qp Q

    N Z TL S l

    Transmission Loss NonZeroTL=SampleConstrained AsCut

    1st Trim

    2nd Trim

    3rd Trim

    ZeroTL=SampleFreetoMove 4

    th Trim

    NoLeakage

    16

  • Surface ConfigurationsSurface ConfigurationsFront Surface: Rear Surface:

    gg

    1 2 1 2

    Loose Glued Gap Fixed

    1) Plastic film near, but not adhered to foam

    1) Small gap between foam & rigid wall

    ) dh d d2) Plastic film glued to foam

    2) Foam adhered to rigid wall

    17

  • Absorption vs. Configuration Absorption vs. Configuration -- TestTest

    AbsorptionCoefficient Loose - Gap

    -- TestTest

    Loose - Fixed

    Gl d GGlued - Gap

    Glued-Fixed

    18

  • Helmholtz Resonator EffectHelmholtz Resonator Effect

    ??

    M h i l I dMechanical Impedance

    Mass

    StiffStiffness

    Total Acoustic Impedance

    19

  • Helmholtz Resonator EffectHelmholtz Resonator Effect

    ??

    Combined Foam + Helmholtz Resonator System is Similar to

    Measured System

    20

  • Helmholtz Resonator EffectHelmholtz Resonator Effect

    ??But is it really due to edge gaps?

    Measured GluedF i Fi dFacing + Fixed

    with Edge Sealed

    21

  • 22

  • RestingonFloor BondedtoBacking

    23

  • Tensioned Tensioned MembranesMembranesModelModel VerificationVerification Velocity MeasurementVelocity MeasurementModel Model Verification Verification Velocity MeasurementVelocity Measurement

    25

  • Model Verification Model Verification Vibrational Vibrational ModesModesModesModes

    Theory ExperimentAbsolute velocity of membrane - Experiment

    1st 0.5

    1

    p

    |

    /

    |

    v

    /

    p

    |

    m

    a

    x

    -0.050

    0.05

    -0.050

    0.050

    xy

    |

    v

    /

    2nd

    26

  • Model Verification Model Verification Experiment Experiment SetSet--upupSetSet--upup

    27

  • Model Verification Model Verification Model Model OptimizationOptimizationOptimizationOptimizationo Given experimental results as

    input Find appropriate materialinput, Find appropriate material properties (To , s , )

    Why this behavior? Finite size, held at edge, finite stiffness.

    28

  • Glass Fiber Material Inside of Glass Fiber Material Inside of Sample HolderSample HolderSample HolderSample Holder

    29

  • Anechoic Transmission Loss Anechoic Transmission Loss (Green)(Green)(Green)(Green)

    35

    40Experiment FE Prediction (Edge constrained)Prediction (Unconstrained case)

    25

    30

    15

    20

    T

    L

    (

    d

    B

    )

    5

    10

    15

    Increase in TL due to edge constraint

    102 103 1040

    5

    F (H )

    (10dB)Shearing mode

    Frequency (Hz)

    30

  • PoroelasticPoroelastic Material Properties Material Properties Used in CalculationsUsed in CalculationsUsed in Calculations Used in Calculations

    MaterialBulk

    density

    (Kg/m3)

    Porosity TortuosityEstimated flow

    resistivity

    (MKS Rayls/m)

    Shear modulus

    (Pa)

    Loss factor

    Yellow

    Green

    6.7

    9.6

    0.99

    0.99

    1.1

    1.1

    21000

    31000

    1200

    2800

    0.350

    0.275

    31

  • Variation of Shear ModulusVariation of Shear Moduluso As shear modulus increases, the minimum location of TL moves to

    higher frequencies

    30

    35

    40Shear M odulus = 1000 PaShear M odulus = 2000 PaShear M odulus = 3000 PaShear M odulus = 4000 Pa

    20

    25

    30

    L

    (

    d

    B

    )

    10

    15

    T

    L

    102 103 1040

    5

    Frequency (Hz)Frequency (Hz)

    32

  • Variation of Flow ResistivityVariation of Flow Resistivity

    40

    FlowresistivitycontrolsTLatlowandhighfrequencylimit

    30

    35

    F low res is t ivity = 10000 M K S R ay ls /mF low res is t ivity = 20000 M K S R ay ls /mF low res is t ivity = 30000 M K S R ay ls /mF low res is t ivity = 40000 M K S R ay ls /m

    20

    25

    T

    L

    (

    d

    B

    )

    1 0

    15

    10 2 10 3 10 40

    5

    F requenc y (H z )

    33

  • Investigation of Vibrational Investigation of Vibrational Modes of Glass Fiber MaterialsModes of Glass Fiber MaterialsModes of Glass Fiber MaterialsModes of Glass Fiber Materials

    34

  • Vibrational Modes of Fiber Glass Vibrational Modes of Fiber Glass Materials (1st and 2nd Modes Green)Materials (1st and 2nd Modes Green)Materials (1st and 2nd Modes, Green)Materials (1st and 2nd Modes, Green)

    ExperimentFEM

    0

    0.5

    1

    (a)

    |

    v

    f

    /

    p

    |

    /

    |

    v

    f

    /

    p

    |

    m

    a

    x

    0

    0.5

    1

    (b)

    |

    v

    f

    /

    p

    |

    /

    |

    v

    f

    /

    p

    |

    m

    a

    x

    1st

    -0.05

    0

    0.05

    -0.05

    0

    0.050

    xy -0.05

    0

    0.05

    -0.05

    0

    0.050

    xy

    (133Hz)

    0.5

    1

    (c)

    |

    /

    |

    v

    f

    /

    p

    |

    m

    a

    x

    0.5

    1

    (d)|

    /

    |

    v

    f

    /

    p

    |

    m

    a

    x

    2nd

    -0.05

    0

    0.05

    -0.05

    0

    0.050

    xy

    |

    v

    f

    /

    p

    |

    -0.05

    0

    0.05

    -0.05

    0

    0.050

    xy

    |

    v

    f

    /

    p

    |2nd

    (422Hz)

    35

  • Internal Constraint to Enhance Internal Constraint to Enhance the Sound Transmission Lossthe Sound Transmission Lossthe Sound Transmission Loss the Sound Transmission Loss

    36

  • Sound Tra