Design and experimental investigation of V-folded beams with acoustic black hole indentations

Gao, Nansha; Wei, Zihan; Hu, Hong; Krushynska, Anastasiia O.

doi:10.1121/1.5088027

Cited by 143 publications

(38 citation statements)

References 13 publications

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“…The concept of metamaterials has been expanded to the elastoacoustic field in recent years. Such metamaterials are now widely applied in the fields of vibration and noise control [6][7][8][9][10], acoustic cloaking [11][12][13], seismic shields [14,15], acoustic wave lensing [16,17], wave trapping [18,19] and acoustic black holes [20,21] among other fields. Effective negative constants can be observed from elastic/acoustic metamaterials as well as electromagnetic metamaterials, including negative mass and dynamic stiffness [22][23][24], negative bulk modulus [25] and double negative characteristic [26,27].…”

Section: Introductionmentioning

confidence: 99%

Rainbow metamaterials for broadband multi-frequency vibration attenuation: Numerical analysis and experimental validation

Meng

Chronopoulos

Fabro

et al. 2020

Journal of Sound and Vibration

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In this study, we propose a 'rainbow' metamaterial to achieve broadband multifrequency vibration attenuation. The rainbow metamaterial is constituted of a Π-shaped beam partitioned into substructures by parallel plates insertions with two attached cantilever-mass acting as local resonators. Both resonators inside each substructure can be non-symmetric such that the metamaterial can have multi-frequency bandgaps. Furthermore, these cantilever-mass resonators have a progressively variant design along the beam, namely rainbow-shaped, for the purpose of achieving broader energy stop bands. Π-shaped beams partitioned by parallel plate insertions can be extended to honeycomb sandwich composites, hence the proposed rainbow metamaterial can serve as a precursor for future honeycomb composites with superior vibration attenuation for more industrial applications. A mathematical model is first developed to estimate the frequency response functions of the metamaterial. Interaction forces between resonators and the backbone structure are calculated by solving the displacement of the cantilever-mass resonators. The plate insertions are modeled as attached masses with both their translational and rotational motion considered. Subsequently, the mathematical model is verified by comparison with experimental results. Metamaterials fabricated through an additive manufacturing technique are tested with a laser doppler receptance measuring system. After the validation of the mathematical model, a numerical study is conducted to explore the influences of the resonator spatial

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Section: Introductionmentioning

confidence: 99%

Rainbow metamaterials for broadband multi-frequency vibration attenuation: Numerical analysis and experimental validation

Meng

Chronopoulos

Fabro

et al. 2020

Journal of Sound and Vibration

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“…Moreover, AP increased, meaning that allicin makes the biofilm sparser and the pore and gap between the colonies increase, which could increase the antibiotics penetration [24] . TE also changed from before to after the allicin action, further indicating that the biomembrane heterogeneity decreased and the structure tended to be simple after the action of allicin, which led to the mature biomembrane returning to the active state of metabolism, also weakening its resistance [25] . Moreover, allicin (10 μg/mL) thinned of the biofilm thickness and structure, although the effect was not obvious at high dose [26] .…”

Section: Resultsmentioning

confidence: 98%

Study on Biofilm Formation Process Based on Image Structure Analyzer Software Analysis

Li¹

2021

ijps

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In order to better study the biofilm formation process, image structure analyzer software was used to quantitatively analyze the biofilm formation process of Pseudomonas aeruginosa under different concentrations of glucose and allicin. Glucose solution (5.6, 7.0, 11.1, 16.7, 20 and 30 mmol/L) was added to the culture medium of non repetitive Pseudomonas aeruginosa and 6 groups were formed. Minimum inhibitory concentration of allicin to Pseudomonas aeruginosa PAO1 was determined by Tryptic Soy Broth micro dilution method. Single colony was inoculated into Tryptic Soy Broth according to garlic concentration (10; 128 μg/mL). Concomitantly, 3 groups were divided into 1, 3 and 7 d study. The groups of experimental materials were placed in confocal laser scanning microscope for observation and the obtained pictures were imported into the image structure analyzer software, through which the quantitative analysis of the biofilm structure was performed. As main findings we found that as glucose concentration increases, the thickness of Pseudomonas aeruginosa biofilm gradually increased. After glucose (30 mmol/L) treatment for 3 d, areal porosity decreased from 0.93±0.10 to 0.62±0.02 and the biofilm became thicker; textural entropy changed from 6.67±0.99 to 7.88±0.21, meaning an increase in biofilm heterogeneity and thickness; the average diffusion distance decreased from 2.44±0.28 to 1.72±0.36, the biofilm became thicker and the average diffusion distance between colonies also decreased. Under the intervention of allicin 10 μg/mL, the thickness of biomembrane was significantly reduced, the structure of biomembrane was sparse and the numbers of dead and living bacteria were significantly reduced. Under the action of allicin 128 μg/mL, the thickness of biomembrane was further reduced and the dead bacteria were clustered. After the action of allicin 128 μg/mL for 7 d, areal porosity increased from 0.68±0.10 to 0.92±0.02, the biomembrane became sparser; textural entropy increased from 6.67±0.93 changed to 5.52±0.548, the membrane heterogeneity decreased. Image structure analyzer software showed to be suitable for quantitative analysis of biofilm formation process. It is concluded that with the increase of glucose concentration, the maturation speed of Pseudomonas aeruginosa biofilm is accelerated, and the thickness of biofilm is gradually increased; allicin can destroy the self structure of Pseudomonas aeruginosa biofilm.

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“…been proved to be effective by vibration test [28]. On the other hand, acoustic black holes are generally believed to act only on flexural waves, but V-folded acoustical black hole metastructure could attenuate longitudinal and flexural vibration [29]. It is worth noting here that theory and simulation calculation are often not consistent with the experimental results in some frequencies, out-of-plane modes and torsional modes [30] exist in vibration test, and are neglected in twodimensional models.…”

Section: Introductionmentioning

confidence: 92%

Elastic Wave Modulation in Hollow Metamaterial Beam With Acoustic Black Hole

et al. 2019

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We propose and discuss the elastic wave attenuation of hollow metamaterial beam embedded acoustic black hole. More abundant physical phenomena are given by modal analysis, shows that the band gap of three-dimensional acoustic black hole metamaterial is different from two-dimensional one. Lateral flexural vibrations occurs and make the original first two-dimensional band gap be compressed, and the opening of first three-dimensional band gap are caused by coupling effect between the longitudinal and lateral flexural vibrations. Below 1200Hz, only two band gaps exist, the geometric parameter m1 and angle γ could affect the band structure a lot, while the effect of geometric parameter m0 is a little less. Mutual validation of transmission spectra of vibration test and finite element analysis calculation and band gaps, illustrating its validity of the structure design, corresponding results could stimulate the realizations of three-dimensional acoustic black hole structure, particularly paves the way for the bridge from the corresponding theory of low frequency vibration and noise reduction to the practical application.INDEX TERMS Acoustic black hole, band gap, metamaterial beam, vibration test.

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Design and experimental investigation of V-folded beams with acoustic black hole indentations

Cited by 143 publications

References 13 publications

Rainbow metamaterials for broadband multi-frequency vibration attenuation: Numerical analysis and experimental validation

Rainbow metamaterials for broadband multi-frequency vibration attenuation: Numerical analysis and experimental validation

Study on Biofilm Formation Process Based on Image Structure Analyzer Software Analysis

Elastic Wave Modulation in Hollow Metamaterial Beam With Acoustic Black Hole

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