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Keywords = phononic cavity

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15 pages, 4555 KiB  
Article
Seismic Isolation via I-Shaped and T-Shaped Large-Scale Phononic Metamaterials
by Nikos Aravantinos-Zafiris, Mihail M. Sigalas and Eleftherios N. Economou
Appl. Sci. 2024, 14(19), 8967; https://doi.org/10.3390/app14198967 - 5 Oct 2024
Cited by 1 | Viewed by 1371
Abstract
In this work, the attenuation of surface seismic waves from large-scale phononic metamaterials is numerically studied. The proposed metamaterials consist of rectangular trenches that form either I-shaped or T-shaped cavities embedded at the ground surface. The numerical investigation includes the study of the [...] Read more.
In this work, the attenuation of surface seismic waves from large-scale phononic metamaterials is numerically studied. The proposed metamaterials consist of rectangular trenches that form either I-shaped or T-shaped cavities embedded at the ground surface. The numerical investigation includes the study of the response of the proposed structures for different values of their geometric parameters. In addition, modifications of the proposed structures where heavy cores coated with a soft material were considered in the cavities were also numerically studied. For a more realistic numerical approach, the transmission spectrum of a selected large-scale phononic metamaterial was also investigated in a suitable half-space numerical scheme. The results of the present research showed that the studied large-scale metastructures could be a very promising potential candidate for seismic shielding applications for the protection of existing urban or countryside structures. The proposed metamaterials are low in cost and easy to construct for the protection of existing buildings, critical infrastructures, or even entire urban areas without need for any kind of intervention at them, therefore providing an effective solution in the field of seismic isolation. Full article
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16 pages, 8286 KiB  
Article
A DFT Computational Study of Type-I Clathrates A8Sn46−x (A = Cs or NH4, x = 0 or 2)
by Nikolaos Kelaidis, Emmanuel Klontzas and Andreas Kaltzoglou
Materials 2024, 17(18), 4595; https://doi.org/10.3390/ma17184595 - 19 Sep 2024
Viewed by 1559
Abstract
Semiconducting clathrates have attracted considerable interest in the field of thermoelectric materials. We report here a computational study on the crystal structure, the enthalpy of formation, and the physical properties of the following type-I clathrates: (a) experimentally studied Cs8Sn44 and [...] Read more.
Semiconducting clathrates have attracted considerable interest in the field of thermoelectric materials. We report here a computational study on the crystal structure, the enthalpy of formation, and the physical properties of the following type-I clathrates: (a) experimentally studied Cs8Sn44 and hypothetical Cs8Sn46 and (b) hypothetical (NH4)8Sn46−x (x = 0 or 2). The ab initio VASP calculations for the nominal stoichiometries include the geometry optimization of the initial structural models, enthalpies of formation, and the electronic and phonon density of states. Comparison of the chemical bonding of the structural models is performed via the electron localization function. The results show that the presence and distribution of defects in the Sn framework for both Cs8Sn46−x and (NH4)8Sn46−x systems significantly alters the formation energy and its electrical properties, ranging from metallic to semiconducting behavior. In particular, one defect per six-membered Sn ring in a 3D spiro-network is the thermodynamically preferred configuration that results in the Cs8Sn44 and (NH4)8Sn44 stoichiometries with narrow-band gap semiconducting behavior. Moreover, the rotation of the ammonium cation in the polyhedral cavities is an interesting feature that may promote the use of ammonium or other small molecular cations as guests in clathrates for thermoelectric applications; this is due to the decrease in the lattice thermal conductivity. Full article
(This article belongs to the Special Issue Feature Papers in Materials Physics (2nd Edition))
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12 pages, 4690 KiB  
Article
Understanding the Effect of Carbon Nanotube Core Designs on Controlling Bandgaps and Wave Directionality in Cement
by Nanziri Esther Kayondo and Shreya Vemuganti
Eng 2024, 5(3), 1811-1822; https://doi.org/10.3390/eng5030096 - 7 Aug 2024
Viewed by 1045
Abstract
Phononic or acoustic bandgap materials have often been made using a polymer matrix with metal inclusions such as tin and steel, which have high densities compared to the matrix material. Acoustic bandgaps are observed when waves are not transmitted at certain frequencies. These [...] Read more.
Phononic or acoustic bandgap materials have often been made using a polymer matrix with metal inclusions such as tin and steel, which have high densities compared to the matrix material. Acoustic bandgaps are observed when waves are not transmitted at certain frequencies. These have been applied in cavity resonators, acoustic waveguides, and more. This paper introduces a concept of using cement as the surrounding matrix and carbon nanotubes as the core inclusions to develop phononic materials. The exhibition of a bandgap makes it possible for the cementitious phononic material to be used as a sensor for cement cracking and defects in oil well bores. This paper discusses ways to optimize the characteristics of the carbon nanotube core to develop gaps in transmission spectra. It shows the behavior of the cementitious material with changing filling fraction, location of core cells, and surrounding defects, creating a pathway for paradigm-shifting non-destructive sensing technologies. Full article
(This article belongs to the Special Issue Women in Engineering)
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19 pages, 2260 KiB  
Article
Quantum Dynamics of Cavity–Bose–Einstein Condensates in a Gravitational Field
by Zhen Li, Wang-Jun Lu and Ya-Feng Jiao
Photonics 2024, 11(3), 205; https://doi.org/10.3390/photonics11030205 - 24 Feb 2024
Viewed by 1991
Abstract
We theoretically studied the quantum dynamics of a cavity–Bose–Einstein condensate (BEC) system in a gravitational field, which is composed of a Fabry–Pérot cavity and a BEC. We also show how to deterministically generate the transient macroscopic quantum superposition states (MQSSs) of the cavity [...] Read more.
We theoretically studied the quantum dynamics of a cavity–Bose–Einstein condensate (BEC) system in a gravitational field, which is composed of a Fabry–Pérot cavity and a BEC. We also show how to deterministically generate the transient macroscopic quantum superposition states (MQSSs) of the cavity by the use of optomechanical coupling between the cavity field and the BEC. The quantum dynamics of the cavity–BEC system specifically include phase space trajectory dynamics, system excitation number dynamics, quantum entanglement dynamics, and quantum coherence dynamics. We found that the system performs increasingly complex trajectories for larger values of the Newtonian gravity parameter. Moreover, the number of phonon excitations of the system can be increased by coupling the cavity–BEC system to Newtonian gravity, which is analogous to an external direct current drive. The scattering of atoms inside the BEC affects the periodicity of the quantum dynamics of the system. We demonstrate a curious complementarity relation between the quantum entanglement and quantum coherence of cavity–BEC systems and found that the complementarity property can be sustained to some extent, despite being in the presence of the cavity decay. This phenomenon also goes some way to show that quantum entanglement and quantum coherence can be referred to together as quantum resources. Full article
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13 pages, 4584 KiB  
Article
Feedback Control of Quantum Correlations in a Cavity Magnomechanical System with Magnon Squeezing
by Mohamed Amazioug, Shailendra Singh, Berihu Teklu and Muhammad Asjad
Entropy 2023, 25(10), 1462; https://doi.org/10.3390/e25101462 - 18 Oct 2023
Cited by 32 | Viewed by 2061
Abstract
We suggest a method to improve quantum correlations in cavity magnomechanics, through the use of a coherent feedback loop and magnon squeezing. The entanglement of three bipartition subsystems: photon-phonon, photon-magnon, and phonon-magnon, is significantly improved by the coherent feedback-control method that has been [...] Read more.
We suggest a method to improve quantum correlations in cavity magnomechanics, through the use of a coherent feedback loop and magnon squeezing. The entanglement of three bipartition subsystems: photon-phonon, photon-magnon, and phonon-magnon, is significantly improved by the coherent feedback-control method that has been proposed. In addition, we investigate Einstein-Podolsky-Rosen steering under thermal effects in each of the subsystems. We also evaluate the scheme’s performance and sensitivity to magnon squeezing. Furthermore, we study the comparison between entanglement and Gaussian quantum discord in both steady and dynamical states. Full article
(This article belongs to the Special Issue Advances in Quantum Communication)
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12 pages, 5683 KiB  
Article
Measurement-Based Control of Quantum Entanglement and Steering in a Distant Magnomechanical System
by Huatang Tan
Photonics 2023, 10(10), 1081; https://doi.org/10.3390/photonics10101081 - 26 Sep 2023
Cited by 3 | Viewed by 1361
Abstract
In this paper, we propose a scheme for measurement-based control of hybrid Einstein–Podolsky–Rosen (EPR) entanglement and steering between distant macroscopic mechanical oscillator and yttrium iron garnet (YIG) sphere in a system of an electromechanical cavity unidirectionally coupled to an electromagnonical cavity. We reveal [...] Read more.
In this paper, we propose a scheme for measurement-based control of hybrid Einstein–Podolsky–Rosen (EPR) entanglement and steering between distant macroscopic mechanical oscillator and yttrium iron garnet (YIG) sphere in a system of an electromechanical cavity unidirectionally coupled to an electromagnonical cavity. We reveal that when the output of the electromagnonical cavity is continuously monitored by homodyne detection, not only the phonon–magnon entanglement and steering but also the purities of the phononic, magnonic and phonon–magnon states are considerably enhanced. We also find that the measurement can effectively retrieve the magnon-to-phonon steering, which is not yet obtained in the absence of the measurement. We show that unconditional phonon–magnon entanglement and steering can be achieved by introducing indirect feedback to drive the magnon and mechanical subsystems. The long-distance macroscopic hybrid entanglement and steering can be useful for, e.g., fundamental tests for quantum mechanics and quantum networks. Full article
(This article belongs to the Special Issue Hybrid Quantum Magnonics)
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16 pages, 9058 KiB  
Article
Analysis of Vibration-Damping Characteristics and Parameter Optimization of Cylindrical Cavity Double-Plate Phononic Crystal
by Chunsheng Song, Qi Yang, Xuechun Xiong, Rui Yin, Bo Jia, Yaru Liang and Haining Fang
Materials 2023, 16(13), 4605; https://doi.org/10.3390/ma16134605 - 26 Jun 2023
Cited by 3 | Viewed by 1854
Abstract
For the application of low-frequency vibration damping in industry, a cylindrical cavity double-layer plate-type local resonance phononic crystal structure is proposed to solve low-frequency vibration in mechanical equipment. Initially, using COMSOL 5.4 software, the bending wave band gap is calculated in conjunction with [...] Read more.
For the application of low-frequency vibration damping in industry, a cylindrical cavity double-layer plate-type local resonance phononic crystal structure is proposed to solve low-frequency vibration in mechanical equipment. Initially, using COMSOL 5.4 software, the bending wave band gap is calculated in conjunction with elastic dynamics theory and the BOLOCH theorem to be 127–384 Hz. Then the mechanism of bending wave gap is analyzed by combining element mode shape and an equivalent model. Subsequently, the bending vibration transmission characteristics of the crystal plate are explained, and the vibration-damping characteristics are illustrated in combination with the time–frequency domain. An experimental system is constructed to verify the vibration-damping properties of crystal plates; the experimental results and simulation results are verified with each other. Finally, the element structural parameters are optimized using the RSM. Fifty-four sets of experiments are designed based on six structural factors and three levels, and the expressions between the bending wave band gap and six structural factors are obtained. Combining the particle swarm algorithm, the optimization is performed with the band gap width as the target. This method is shown to be more accurate than the commonly used interior point method. The structure of cylindrical-cavity-type phononic crystal and the parameter optimization method proposed in this paper provide a certain reference for the design of local-resonance-type phononic crystal. Full article
(This article belongs to the Special Issue Recent Progress in Functional Materials and Their Applications)
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16 pages, 4090 KiB  
Article
Phononic Crystal Made of Silicon Ridges on a Membrane for Liquid Sensing
by Abdellatif Gueddida, Victor Zhang, Laurent Carpentier, Jérémy Bonhomme, Bernard Bonello, Yan Pennec and Bahram Djafari-Rouhani
Sensors 2023, 23(4), 2080; https://doi.org/10.3390/s23042080 - 13 Feb 2023
Cited by 12 | Viewed by 2636
Abstract
We propose the design of a phononic crystal to sense the acoustic properties of a liquid that is constituted by an array of silicon ridges on a membrane. In contrast to other concepts, the ridges are immersed in the liquid. The introduction of [...] Read more.
We propose the design of a phononic crystal to sense the acoustic properties of a liquid that is constituted by an array of silicon ridges on a membrane. In contrast to other concepts, the ridges are immersed in the liquid. The introduction of a suitable cavity in the periodic array gives rise to a confined defect mode with high localization in the cavity region and strong solid–liquid interaction, which make it sensitive to the acoustic properties of the liquid. By using a finite element method simulation, we theoretically study the transmission and cavity excitation of an incident flexural wave of the membrane. The observation of the vibrations of this mode can be achieved either outside the area of the phononic crystal or just above the cavity. We discuss the existence of the resonant modes, as well as its quality factor and sensitivity to liquid properties as a function of the geometrical parameters. The performance of the proposed sensor has then been tested to detect the variation in NaI concentration in a NaI–water mixture. Full article
(This article belongs to the Section Physical Sensors)
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13 pages, 560 KiB  
Article
Phonon Blockade in Parametrically Pumped Acoustic Cavity at Finite Temperature
by Zhenglu Duan, Yongkang Shao, Yi Ren and Biao Huang
Symmetry 2023, 15(1), 245; https://doi.org/10.3390/sym15010245 - 16 Jan 2023
Cited by 2 | Viewed by 1839
Abstract
In this study, we investigated the phonon blockade effect in a parametrically driven and dissipative acoustic cavity at finite temperature. With the approximated analytical results based on the steady-state density-matrix master equation, we found that a quantum-interference-induced phonon blockade exists at finite temperature. [...] Read more.
In this study, we investigated the phonon blockade effect in a parametrically driven and dissipative acoustic cavity at finite temperature. With the approximated analytical results based on the steady-state density-matrix master equation, we found that a quantum-interference-induced phonon blockade exists at finite temperature. We found a crossover between the quantum and thermal regimes on the curve of the second-order correlation function of the acoustic mode as the temperature increases. This phenomenon implies an asymmetry about the quantum and classic regimes. We also numerically simulated the single-phonon emission using the Monte Carlo wave function method. The results showed that a wide and deep dip around the zero time delay exists on the curve of the time-delayed second-order correlation function, which implies the possibility of observing a strong phonon blockade with pulse driving. Our study outlines a potential candidate for a efficient single-phonon source and applications in quantum information and phononic quantum networks. Full article
(This article belongs to the Special Issue Advances in Quantum Information)
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11 pages, 2163 KiB  
Article
High-Q Slow Sound Mode in a Phononic Fishbone Nanobeam Using an Acoustic Potential Well Cavity
by Ying-Pin Tsai, Bor-Shyh Lin and Fu-Li Hsiao
Crystals 2023, 13(1), 95; https://doi.org/10.3390/cryst13010095 - 4 Jan 2023
Cited by 2 | Viewed by 2006
Abstract
Phononic crystals and phononic metamaterials are popular structures for manipulating acoustic waves with artificially arranged units that have different elastic constants. These structures are also used in acousto-optic coupling and optomechanical structures. In such research, a 1-D nanobeam containing a cavity region sandwiched [...] Read more.
Phononic crystals and phononic metamaterials are popular structures for manipulating acoustic waves with artificially arranged units that have different elastic constants. These structures are also used in acousto-optic coupling and optomechanical structures. In such research, a 1-D nanobeam containing a cavity region sandwiched by two mirror regions is one of the most common designs. However, searching bandgaps for suitable operation modes and the need for the mirror region are limitations in the device design. Therefore, we introduce the slow sound mode as the operating acoustic mode and use an acoustic potential well to further trap the phonons in the cavity. Three types of structures are introduced to investigate the effect of the potential well. The products of the mode frequencies and the quality factors of the modes are used to demonstrate the performance of the structures. The displacement field and the strain field show the concentrated slow sound modes of the potential wells and produce high quality factors. Full article
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19 pages, 2943 KiB  
Article
Tunable Topological Acoustic Tamm States in Comblike Structures Based on Band Inversion around Flat Bands
by Soufyane Khattou, Yamina Rezzouk, Madiha Amrani, Mohamed El Ghafiani, El Houssaine El Boudouti, Abdelkrim Talbi and Bahram Djafari-Rouhani
Crystals 2022, 12(12), 1685; https://doi.org/10.3390/cryst12121685 - 22 Nov 2022
Cited by 5 | Viewed by 2015
Abstract
We investigate the existence of acoustic Tamm states at the interface between two one-dimensional (1D) comblike phononic crystals (PnCs) based on slender tubes and discuss their topological or trivial character. The PnCs consist of stubs grafted periodically along a waveguide and the two [...] Read more.
We investigate the existence of acoustic Tamm states at the interface between two one-dimensional (1D) comblike phononic crystals (PnCs) based on slender tubes and discuss their topological or trivial character. The PnCs consist of stubs grafted periodically along a waveguide and the two crystals differ by their geometrical parameters (period and length of the stubs). We use several approaches to discuss the existence of Tamm states and their topology when connecting two half-crystals. First, we derive a necessary and sufficient condition on the existence of interface states based on the analysis of the bulk band structure and the symmetry of the band edge states. This approach is equivalent to an analysis of the Zak phases of the bulk bands in the two crystals. Indeed, a topological interface state should necessarily exist in any common bandgap of the two PnCs for which the lower (upper) band edges have opposite symmetries. A novelty of our structure consists in the fact that the symmetry inversion results from a band closure (flat band) rather than from a gap closure, in contrast to previous works. Then, such interface states are revealed through different physical quantities, namely: (i) the local density of states (LDOS), which exhibits a high localization around the interface; (ii) sharp peaks in the transmission spectra in the common bandgap when two finite crystals are connected together; (iii) the phases of the reflection coefficients at the boundary of each PnC with a waveguide, which have a direct relationship with the Zak phases. In addition, we show that the interface states can transform to bound states in the continuum (BICs). These BICs are induced by the cavity separating both PnCs and they remain robust to any geometrical disorder induced by the stubs and segments around this cavity. Finally, we show the impossibility of interface states between two connected PnCs with different stub lengths and similar periods. The sensitivity of these states to interface perturbations can find many practical applications in PnC sensors. Full article
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14 pages, 6574 KiB  
Article
Unidirectional Coherent Phonon Emission in an Optomechanic Nanobeam Containing Coupled Cavities
by Alexander V. Korovin, Yan Pennec and Bahram Djafari-Rouhani
Photonics 2022, 9(9), 610; https://doi.org/10.3390/photonics9090610 - 28 Aug 2022
Cited by 2 | Viewed by 1856
Abstract
Nonreciprocal phonon emission is predicted theoretically from the coherent excitation of two coupled optomechanical cavities arranged along a phoxonic crystal nanobeam. The latter consists of a periodic array of holes and stubs and exhibits simultaneous photonic and phononic bandgaps. It is shown that [...] Read more.
Nonreciprocal phonon emission is predicted theoretically from the coherent excitation of two coupled optomechanical cavities arranged along a phoxonic crystal nanobeam. The latter consists of a periodic array of holes and stubs and exhibits simultaneous photonic and phononic bandgaps. It is shown that nonreciprocal phonon emission arises from a combined effect of the spatial symmetry of the cavities and their underlying coupled phononic modes and the temporal phase shift between the excitation sources. This demonstration paves the way for the development of advanced integrated phonon networks and circuits, in which mechanical waves connect different elements in phononic and optomechanical structures. Full article
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12 pages, 4216 KiB  
Article
Photo-Elastic Enhanced Optomechanic One Dimensional Phoxonic Fishbone Nanobeam
by Fu-Li Hsiao, Ying-Pin Tsai, Wei-Shan Chang, Chien-Chang Chiu, Bor-Shyh Lin and Chi-Tsung Chiang
Crystals 2022, 12(7), 890; https://doi.org/10.3390/cryst12070890 - 23 Jun 2022
Cited by 3 | Viewed by 2135
Abstract
We investigated the strength of acousto-optical (AO) interaction in one-dimensional fishbone silicon nanobeam computationally. The structure can generate phononic and photonic band gaps simultaneously. We use defect cavity optical mode and slow light mode to interact with acoustic defect modes. The AO coupling [...] Read more.
We investigated the strength of acousto-optical (AO) interaction in one-dimensional fishbone silicon nanobeam computationally. The structure can generate phononic and photonic band gaps simultaneously. We use defect cavity optical mode and slow light mode to interact with acoustic defect modes. The AO coupling rates are obtained by adding the optical frequency shifts, which result from photo-elastic effect and moving-boundary effect disturbances. The AO coupling rates are strongly dependent on the overlap of acoustic and optical mode distribution. The strength of AO interaction can be enhanced by choosing certain acoustic defect modes that are formed by the stretching of wings and that overlap significantly with optical fields. Full article
(This article belongs to the Special Issue Advances in Phononic Crystals and Elastic Metamaterials)
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10 pages, 4581 KiB  
Article
Selective Properties of Mid-Infrared Tamm Phonon-Polaritons Emitter with Silicon Carbide-Based Structures
by Chengxuan Gong and Gaige Zheng
Micromachines 2022, 13(6), 920; https://doi.org/10.3390/mi13060920 - 10 Jun 2022
Cited by 9 | Viewed by 2452
Abstract
Electromagnetic (EM) absorbers and emitters have attracted much interest because of their versatile applications. A photonic heterostructure composed of silicon carbide (SiC) layer/germanium (Ge) cavity/distributed Bragg reflector (DBR) has been proposed. Selective emission properties have been investigated through rigorous coupled wave analysis (RCWA) [...] Read more.
Electromagnetic (EM) absorbers and emitters have attracted much interest because of their versatile applications. A photonic heterostructure composed of silicon carbide (SiC) layer/germanium (Ge) cavity/distributed Bragg reflector (DBR) has been proposed. Selective emission properties have been investigated through rigorous coupled wave analysis (RCWA) method. The results illustrate that Tamm phonon-polaritons can be excited, and the magnetic field is partially centralized at the junction of Ge cavity and SiC film, aimed to improve the interactions of photon–phonon. The absorptivity/emissivity of the structure can be better optimized by controlling the coupling of surface modes with the incident wave. Near-unity absorption can be achieved through optimizing the SiC grating/Ge cavity/distributed Bragg reflector (DBR) multilayer structure with geometrical parameters of ds = 0.75 μm, dg = 0.7 μm, d1 = 1.25 μm and d2 = 0.75 μm, respectively. Physical mechanism of selective emission characteristics is deliberated. In addition, the simulation results demonstrate that the emitter desensitizes to the incidence angle and polarization state in the mid-infrared (MIR) range. This research ameliorates the function of the selective emitters, which provides more efficient design for SiC-based systems. Full article
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18 pages, 12256 KiB  
Article
Research on Low-Frequency Noise Control of Automobiles Based on Acoustic Metamaterial
by Yi Liao, Haibo Huang, Guangbao Chang, Deyang Luo, Chuanlai Xu, Yudong Wu and Jiyou Tang
Materials 2022, 15(9), 3261; https://doi.org/10.3390/ma15093261 - 1 May 2022
Cited by 20 | Viewed by 4491
Abstract
With the transformation of the trend of vehicle electrification, the overall noise level in the vehicle is gradually reduced. The problem of low-frequency noise in the vehicle, which was previously ignored, is becoming more and more prominent. To solve the vehicle low-frequency noise [...] Read more.
With the transformation of the trend of vehicle electrification, the overall noise level in the vehicle is gradually reduced. The problem of low-frequency noise in the vehicle, which was previously ignored, is becoming more and more prominent. To solve the vehicle low-frequency noise problem, a combination of real-vehicle tests and simulation analysis is carried out. During the test, the driver and passengers feel that there is a relatively obvious low-frequency roar noise in the car, which results from the structural radiation noise of the trunk door vibration. Therefore, to solve this problem, we design an acoustic metamaterial with lightweight and miniaturized features based on the local resonance principle of phononic crystals. Firstly, the selection of the resonant unit configuration and the design of the band gap are implemented. Then, the layout planning of the whole vehicle, the layout of the resonance unit and the design of the base frame are implemented. The actual vehicle test results show that: after attaching the designed acoustic metamaterial, the low-frequency noise sound pressure levels in the front and rear of the vehicle were reduced by 2.0 dB (A) and 2.3 dB (A), respectively, meanwhile, the interior noise sound quality was improved. The sound pressure level at the driver’s right ear in the car has an abnormal peak of around 35Hz. In addition, the driver and passengers feel that there is a relatively obvious low-frequency roar noise in the car, and through low-pass filtering of the collected signals, it is confirmed that the peak frequency is the main cause of the low-frequency roar in the car. The low-frequency steady-state noise of the car is generally considered to be the low-frequency vibration of the body panel and the radiation occurs. Through the finite element simulation analysis (Grid Participation Analysis) of the abnormal peak frequency, the results show that the low-frequency roar is caused by the low-frequency vibration of the tailgate sheet metal, and the problem peak frequency is not coupled with the acoustic cavity mode. Facing the problem of the low-frequency roar radiated into the car by the vibration of the tailgate sheet metal parts, based on the local resonance band gap theory, we developed a design to suppress the 35 Hz vibration of the tailgate sheet metal parts and meet the characteristics of lightweight and miniaturization. By attaching the acoustic metamaterial to the tailgate and performing CAE simulation of the whole vehicle, it is determined that the structure can indeed reduce the 35 Hz noise in the car and the peak value of the tailgate sheet metal vibration. Full article
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