A Dielectric Elastomer Acoustic Liner

Dodge, Chelsea; Zhang, Yang; Cattafesta, Louis N.; Howerton, Brian M.; Kreitzman, Jordan R.

doi:10.2514/6.2021-2244

Cited by 4 publications

(9 citation statements)

References 9 publications

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“…Active Helmholtz resonators 9 have produced large resonance shifts but at frequencies above the range of interest here. A membrane, on the other hand, can have lower absorptive properties relative to a plate and when embedded into an acoustic liner, resonance shifts of 32 Hz 14 and 100 Hz 15 were observed. The results here showed low frequency resonance shifts of 213 Hz in the range of 700–1000 Hz, a comparatively larger variation.…”

Section: Discussionmentioning

confidence: 99%

“…By actuating the DE, a 32 Hz shift in the resonant frequency was observed below 500 Hz, a relatively low frequency for attenuation that is difficult to achieve in practice. A preliminary version of the present work 15 split the cavity of an acoustic liner with a DE and saw a shift in the resonance frequency due to the DE activation of approximately 100 Hz.…”

Section: Introductionmentioning

confidence: 99%

“…Researchers have also split the cavity depth or replaced side walls with compliant membranes and plates [10][11][12][13] that resulted in low frequency attenuation, albeit without actuation. A compliant active material that has been incorporated into liners is a dielectric elastomer (DE), 14,15 a smart material capable of changing shape and stiffness when subjected to an electric field. [16][17][18][19] Abbad et al 14 replaced the rigid top sheet surrounding the hole of a Helmholtz resonator with a DE.…”

Section: Introductionmentioning

confidence: 99%

“…The need to predict the acoustic impedance of an embedded DE membrane to better choose a design became apparent in earlier work. 15 Solano et al 20 developed and validated an electroacoustic model of a square DE membrane subjected to pressure and voltage loading. The solution was used to derive the acoustic impedance of the membrane, which included the active component of a DE membranethe variable in-plane stress when subjected to an electric field.…”

Section: Introductionmentioning

confidence: 99%

“…The work presented here is thus an extension of Dodge et al, 15 in which the optimum liner dimensions and DE material properties are explored using the electroacoustic membrane model developed in Solano et al 20 The LEM of the DE membrane is coupled with the acoustics of the liner to evaluate the effective lumped acoustic impedance of the dielectric elastomer acoustic liner, or DEAL for short. Using the MATLAB optimization toolbox, an optimization scheme is formulated to determine the optimal dimensions and membrane parameters to maximize acoustic absorption over a specified frequency range and also to maximize the resonance frequency tuning of the liner due to application of voltage to the DE.…”

Section: Introductionmentioning

confidence: 99%

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Modeling, design, and optimization of a dielectric elastomer acoustic liner

Solano,

Cattafesta

2023

International Journal of Aeroacoustics

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The modeling, design, and optimization of an embedded dielectric elastomer (DE) membrane acoustic liner is considered. The acoustic impedance of the liner is modified when the DE is subjected to voltage, resulting in a reduction of the in-plane stress. A lumped element model of an embedded dielectric elastomer acoustic liner is derived and validated in a normal incidence impedance tube and is subsequently used to optimize its performance. The optimization cost functions include (1) maximization of the average absorption coefficient over a targeted frequency range, 400 – 1600 Hz and (2) maximization of the change in the liner fundamental resonance frequency when the membrane is activated. Good agreement between measured and predicted absorption is observed. Tuning of the resonant frequency requires a numerical solution for resonance using the imaginary part of the impedance, since a simple analytical expression for resonance cannot be derived due to the complex coupling between the acoustics of the liner and the electro-mechanics of the DE membrane. Nonetheless, resonant frequency shifts predicted with the lumped element model compare favorably to those measured with the activated liner sample, with a shift of 213 Hz.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Modeling, design, and optimization of a dielectric elastomer acoustic liner

Solano,

Cattafesta

2023

International Journal of Aeroacoustics

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Modeling of Advanced Helmholtz Resonator Liners with a Flexible Wall

et al. 2023

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Acoustic liners are an effective way to dampen aircraft noise. Conventional single-degree-of-freedom liners consist of a perforated facesheet backed with a honeycomb structure and a rigid end plate. Their damping excels near their resonance frequency, which is antiproportional to the cavity depth ([Formula: see text]-resonator) or the cavity volume (Helmholtz resonator). However, this is a challenge for low-frequency noise with long wavelengths due to the limited installation space. We therefore propose a resonator in which the back cavity is divided into two cavities by a flexible plate. The aim is to combine the damping mechanisms of the Helmholtz resonator with the material damping of the flexible plate. With carefully chosen parameters, this flexible plate resonates well below the Helmholtz frequency. We derived an analytic model based on waveguide theory to predict the impedance of the resonator concept. The Helmholtz equation was solved to (numerically) determine the scattering coefficients of a channel section in which one wall is lined with the predicted resonator impedance. The predicted dissipation agreed well with experimental data from measurements at the aeroacoustic wind tunnel DUCT-R.

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