Transmission loss of honeycomb sandwich structures with attached gas layers

Naify, Christina J.; Huang, Chi‐Hsiang; Sneddon, Matthew; Nutt, Steve

doi:10.1016/j.apacoust.2010.09.005

Cited by 22 publications

(8 citation statements)

References 14 publications

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“…Tension was measured by adding mass to the center of the structure and measuring the out-of-plane displacement of the membrane as a function of mass magnitude (for further details, see Ref. 7).…”

Section: A Sample Fabricationmentioning

confidence: 99%

“…5 Several approaches have been considered to improve acoustic insulation without increased weight penalty. These have included addition of mass inclusions to foam materials, 6 impedance mismatch of gas layers, 7 and the use of microperforated panels. 8 These approaches have shown varying degrees of improvement in sound insulation, although they have provided minimal increase in transmission loss (TL) (<20 dB) at low frequencies (<1000 Hz).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Scaling of membrane-type locally resonant acoustic metamaterial arrays

Naify

Chang²,

McKnight³

et al. 2012

The Journal of the Acoustical Society of America

Self Cite

120

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Metamaterials have emerged as promising solutions for manipulation of sound waves in a variety of applications. Locally resonant acoustic materials (LRAM) decrease sound transmission by 500% over acoustic mass law predictions at peak transmission loss (TL) frequencies with minimal added mass, making them appealing for weight-critical applications such as aerospace structures. In this study, potential issues associated with scale-up of the structure are addressed. TL of single-celled and multi-celled LRAM was measured using an impedance tube setup with systematic variation in geometric parameters to understand the effects of each parameter on acoustic response. Finite element analysis was performed to predict TL as a function of frequency for structures with varying complexity, including stacked structures and multi-celled arrays. Dynamic response of the array structures under discrete frequency excitation was investigated using laser vibrometry to verify negative dynamic mass behavior.

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Section: A Sample Fabricationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Scaling of membrane-type locally resonant acoustic metamaterial arrays

Naify

Chang²,

McKnight³

et al. 2012

The Journal of the Acoustical Society of America

Self Cite

120

View full text Add to dashboard Cite

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“…Pores allow for the easy entrance of sound waves, and the sound waves are then debilitated by the fibers due to the boundary layer losses. Therefore, the sound absorption is high [8]. Moreover, the application of hot pressing is also conducive for sound absorption.…”

Section: Limited Oxygen Index (Loi) Testmentioning

confidence: 99%

Mechanical, Acoustic and Flame-Retarding Properties of Sound Absorbent/Flame Retardant Composite Nonwoven Fabrics: Effects of Needle Punching and Hot Pressing

Huang¹,

Hsing²,

Ou³

et al. 2017

dtetr

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Regular nonwoven sound absorbing materials are short of flame retardant properties, and this study aims to produce nonwoven fabrics with sound absorption and flame resistance. Flame retardant polyester (PET) fibers are made into matrices. These matrices are combined with low melting point polyester (LPET) fibers via needle punching in order to form sound-absorbing/flame-retarding composite nonwoven fabrics. The tensile strength, bursting strength, sound absorption, and limited oxygen index (LOI) measurements are then used to evaluate the composite nonwoven fabrics, thereby examining the optimal parameters. Using an LPET matrix as the interlay and being hot pressed, the composite nonwoven fabrics have the maximum sound absorption due to the interior pore structure is improved. *

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“…The application of metamaterials-concepts to realize unprecedented physical responses has met with considerable success. Analytical, numerical and experimental investigations on negative effective mass [16][17][18], double negativity [19], tunable absorption in and transmission through membrane-type acoustic metamaterials [20][21][22][23][24][25][26][27][28], broadband noise mitigation using metamaterial panels with stacked membranes [29], impedance mismatch-driven reduction in transmitted sound energy for structures with attached gas layers [30], acoustic barriers utilizing cellular [31] and flexible [32,33] sub-structures, coupled membranes displaying monopolar and dipolar resonances [34], absorption using degenerate resonators [35], and targeted energy transfer from an acoustic medium to a nonlinear membrane [36] as well as for seismic mitigation [37] have been reported. There have been several studies ranging from tunable structural-scale AM [38,39] to active AM designs [40] that have clearly demonstrated their unique advantages.…”

Section: Introductionmentioning

confidence: 99%

On the Frequency Up-Conversion Mechanism in Metamaterials-Inspired Vibro-Impact Structures

2019

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Conventional acoustic absorbers like foams, fiberglass or liners are used commonly in structures for industrial, infrastructural, automotive and aerospace applications to mitigate noise. However, these have limited effectiveness for low-frequencies (LF, <~500 Hz) due to impractically large mass or volume requirements. LF content being less evanescent is a major contributor to environmental noise pollution and induces undesirable structural responses causing diminished efficiency, comfort, payload integrity and mission capabilities. There is, therefore a need to develop lightweight, compact, structurally-integrated solutions to mitigate LF noise in several applications. Inspired by metamaterials, tuned mass-loaded membranes as vibro-impact attachments on a baseline structure are considered to investigate their performance as an LF acoustic barrier. LF incident waves are up-converted via impact to higher modes in the baseline structure which may then be effectively mitigated using conventional means. Such Metamaterials-Inspired Vibro-Impact Structures (MIVIS) could be tuned to match the dominant frequency content of LF acoustic sources. Prototype MIVIS unit cells were designed and tested to study energy transfer mechanism via impact-induced frequency up-conversion and sound transmission loss. Structural acoustic simulations were done to predict responses using models based on normal incidence transmission loss tests. Simulations were validated using experiments and utilized to optimize the energy up-conversion mechanism using parametric studies. Up to 36 dB of sound transmission loss increase is observed at the anti-resonance frequency (326 Hz) within a tunable LF bandwidth of about 300 Hz for the MIVS under white noise excitation. Whereas, it is found that under monotonic excitations, the impact-induced up-conversion redistributes the incident LF monotone to the back plate’s first mode in the transmitted spectrum. This up-conversion could enable further broadband transmission loss via subsequent dissipation in conventional absorbers. Moreover, this approach while minimizing parasitic mass addition retains or could conceivably augment primary functionalities of the baseline structure. Successful transition to applications could enable new mission capabilities for aerospace and military vehicles and help create quieter built environments.

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Transmission loss of honeycomb sandwich structures with attached gas layers

Cited by 22 publications

References 14 publications

Scaling of membrane-type locally resonant acoustic metamaterial arrays

Scaling of membrane-type locally resonant acoustic metamaterial arrays

Mechanical, Acoustic and Flame-Retarding Properties of Sound Absorbent/Flame Retardant Composite Nonwoven Fabrics: Effects of Needle Punching and Hot Pressing

On the Frequency Up-Conversion Mechanism in Metamaterials-Inspired Vibro-Impact Structures

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