Showing papers by "Yue-Sheng Wang published in 2019"
TL;DR: In this paper, a helical acoustic metasurface, capable of providing a modulated wavefront of reflected sound with continuously tunable broadband operation, is demonstrated, and the matched screw-and-nut mechanism can lead to pragmatic applications of metamaterials for three-dimensional control of sound.
Abstract: In advancing the performance of metamaterials, key features nowadays are tunability and a wide range of operating frequencies. Here a helical acoustic metasurface, capable of providing a modulated wavefront of reflected sound with continuously tunable broadband operation, is demonstrated. The authors' matched screw-and-nut mechanism can lead to pragmatic applications of metasurfaces for three-dimensional control of sound. This concept for continuous tuning is an important step for achieving broadband, multifunctional acoustic metasurfaces, and may inspire designs featuring curved tunable, active programmable, or randomly coding metasurfaces.
90 citations
TL;DR: In this paper, a unified topology optimization framework was developed for broadband double-negative acoustic metamaterials with different microstructure symmetries, minimal structural feature sizes and dispersion extents of effective parameters.
64 citations
54 citations
TL;DR: In this article, the effects of hard inclusions on the buckling modes, post-buckling deformations, and band structures in soft porous periodic structures were investigated. And the authors provided a useful reference for the design of tunable phononic switches and acoustic filters.
53 citations
TL;DR: In this article, the elastic wave problem is converted into a linear eigenvalue system from which the extended displacements and stresses are expressed in terms of the eigenvalues and eigenvectors.
Abstract: Devices based on piezoelectric semiconductors (PSCs) have recently received particular attention due to their wide bandgap where strain energy band engineering under both static and time-harmonic deformations is the key. In this paper, we investigate and characterize the elastic waves propagating in an anisotropic n-type PSC plate. To achieve our goals, we first introduce the new notations for the extended displacements, stresses, strains, and modulus to arrive at a mathematically elegant extended Stroh formalism. Then, the elastic wave problem is converted into a linear eigenvalue system from which the extended displacements and stresses are expressed in terms of the eigenvalues and eigenvectors. Finally, making use of the boundary conditions on the top and bottom surfaces of the plate, wave dispersion and attenuation are derived analytically. Numerical examples are presented to systematically study the effect of the surface boundary condition, steady-state carrier density, plate thickness, and biasing electric field on the wave speed and attenuation of both shear horizontal and Lamb waves in the transversely isotropic ZnO PSC plate. Some interesting characteristics of the elastic waves observed in this paper could be helpful as theoretical guidance when designing PSC-based devices.
51 citations
TL;DR: In this article, the authors proposed a new class of active elastic metamaterials and a cloaking design consisting of double Helmholtz cavities, which shows a controllable effective bulk modulus in which a negative value appears over a wide frequency range.
46 citations
TL;DR: In this article, the authors proposed a new damage index for the crack identification of beams made of functionally graded materials (FGMs) by using the wavelet analysis, which is defined based on the position of wavelet coefficient modulus maxima in the scale space.
42 citations
TL;DR: In this article, the non-reciprocal transmission of elastic waves is realized by the enlightenment of an acoustic diode, which consists of a linear phononic crystal attached by a nonlinear elastic medium.
34 citations
TL;DR: In this paper, the authors derived the equations of wave motion including the magneto-electro-mechanical coupling effect and solved them by taking the size effect into account and based on the nonlocal theory.
31 citations
28 citations
TL;DR: In this paper, the phase velocity and attenuation of two longitudinal elastic waves depend nonlinearly on porosity and viscosity of the fluid, and when two fluid-saturated porous metamaterials are arranged to form a periodic composite, different band gaps are opened for the two longitudinal waves and these couple to form anticrossings in the dispersion relation.
Abstract: Fluid-saturated porous metamaterials described following Biot’s theory support two longitudinal elastic waves. The phase velocity and attenuation of these waves depend nonlinearly on porosity and viscosity of the fluid. Furthermore, when two fluid-saturated porous metamaterials are arranged to form a periodic composite, different band gaps are opened for the two longitudinal waves and these couple to form anticrossings in the dispersion relation. The complex band structure of one-dimensional composites is derived and compared with
numerical transmission through a finite sample obtained by the finite element method. It is found that the anticrossings disappear rapidly as viscosity increases, while attenuation band gaps become dominated by the fastest of the two longitudinal waves. Increasing porosity further leads to wider and lower-frequency band gaps. These results are relevant to practical applications of fluid-saturated porous metamaterials, e.g., to engineered soils.
TL;DR: The design of an elastic wave metamaterial with electrically switchable properties, which is studied in this work, contains a T-shaped waveguide in a plate with the 3D printing technology and the active control system is used to tune the propagation direction of the flexural wave.
Abstract: Propagation of elastic waves along a direction has special interests in practical applications. These concerns generate the design of an elastic wave metamaterial with electrically switchable properties, which is studied in this work. The structure contains a T-shaped waveguide in a plate with the 3D printing technology; and the active control system is used to tune the propagation direction of the flexural wave. The piezoelectric patches which are connected by the negative capacitance circuits are applied to behave as the active control system. The finite element simulation is performed to give the theoretical prediction of the switchable waveguide and the tunable equivalent parameters are achieved by the electrical circuits. The active control experiments are finally carried out to support the numerical design.
TL;DR: The numerical results show that the wavefront of the reflected wave can be manipulated over a wide frequency range; and the gradient design of the unit cells can suppress the parasitic reflection.
Abstract: In this paper, modulation of reflected wavefront out of the incident plane by a tunable acoustic metasurface is investigated based on the fully generalized Snell’s law in the three-dimensional space. The metasurface is constructed by a square lattice of circular holes with gradient annular bumps. The phase shift is tuned by changing the volume of water filled in the holes. The acoustic wave steering out of the incident plane and the out-of-plane acoustic focusing with the oblique incidence at the subwavelength scale are demonstrated numerically by selecting suitable distributions of water depth. The numerical results show that the wavefront of the reflected wave can be manipulated over a wide frequency range; and the gradient design of the unit cells can suppress the parasitic reflection. The present work is relevant to the practical design of novel acoustic devices.
TL;DR: In this paper, the effects of active feedback control on elastic wave metamaterials were studied and the effective mass density and sound radiation by a point force excitation was investigated.
Abstract: To show the effects of active feedback control on elastic wave metamaterials, this research is focused on effective mass density and sound radiation by a point force excitation. The expressions of ...
TL;DR: In this article, a technique based on the metal magnetic memory (MMM) was developed to evaluate the contact damage of ferromagnetic materials under nonferromagnetic and iridium indenters by measuring the magnetic flux leakage (MFL) signals.
Abstract: A technique based on the metal magnetic memory (MMM) is developed to evaluate the contact damage of ferromagnetic materials under nonferromagnetic and ferromagnetic indenters by measuring the magnetic flux leakage (MFL) signals. Great difference between the MFL signals for the ferromagnetic indenter and non-ferromagnetic indenter is experimentally observed. The normal signal shows a dip in the contact region for the ferromagnetic indenter but an increase for the non-ferromagnetic indenter; the tangential signal experiences a peak-peak change through zero in the contact region for the ferromagnetic indenter but a peak for the non-ferromagnetic indenter. Furthermore, the amplitude of MFL signals for the ferromagnetic indenter is considerably larger than that for the non-ferromagnetic indenter. The mechanism of the signal variation is analyzed by considering the magnetic-stress coupling effect. Criteria of the early contact damage are developed based on the variations of the MFL signals and their gradients; and the evaluation parameters are extracted.
TL;DR: In this article, the surface effect on the static bending behavior of functionally graded porous (FGP) nanobeams subjected to a concentrated transverse load is studied by using Reddy's higher-order b...
Abstract: In this paper, the surface effect on the static bending behavior of functionally graded porous (FGP) nanobeams subjected to a concentrated transverse load is studied by using Reddy’s higher-order b...
TL;DR: In this paper, a new microstatistical model is developed to explain the magnetization and magnetostriction mechanisms for isotropic materials, where the probability of angular distribution between magnetic moment and magnetic field is expressed by a modified Boltzmann distribution.
Abstract: Magnetization and magnetostriction are of critical importance to understand the magnetic behavior of ferromagnetic materials under stress and magnetic fields. The micromechanism of magnetization (or magnetostriction) is determined by the probability of angular distribution of magnetic moments and saturation magnetization (or saturation deformation). Thus, the probability of angular distribution of magnetic moments is important to construct the relationship between the magnetization (or magnetostriction) and magnetic moments. In this letter, a new microstatistical model is developed to explain the magnetization and magnetostriction mechanisms for isotropic materials. The probability of angular distribution between magnetic moment and magnetic field is expressed by a modified Boltzmann distribution. The results calculated by the present model are compared with the experimental results. The values of the determination coefficient R 2 indicate that the present model can accurately describe the relationship between magnetization and magnetostriction under both stress and magnetic fields.
TL;DR: The results show that the single dark solitary wave solution is stable, and the multiple dark solitary waves are unstable.
Abstract: A granular chain of elastic spheres via Hertzian contact incorporates a classical nonlinear force model describing dynamical elastic solitary wave propagation. In this paper, the multiple solitary waves and their dynamic behaviors and stability in such a system are considered. An approximate KdV equation with the standard form is derived under the long-wavelength approximation and small deformation. The closed-form analytical single- and multiple-soliton solutions are obtained. The construction of the multiple-soliton solutions is analyzed by using the functional analysis. It is found that the multiple-soliton solution can be excited by the single-soliton solutions. This result is confirmed by the numerical analysis. Based on the soliton solutions of the KdV equation, the analytic solutions of multiple dark solitary waves are obtained from the original dynamic equation of the granular chain in the long-wavelength approximation. The stability of the single and multiple dark solitary wave solutions are numerically analyzed by using both split-step Fourier transform method and Runge-Kutta method. The results show that the single dark solitary wave solution is stable, and the multiple dark solitary waves are unstable.
TL;DR: In this paper, the authors proposed a new technique to obtain phononic band structures with complex eigenfrequencies but real wavevectors, whenever elastic losses are proportional to frequency.
Abstract: The consideration of material losses in phononic crystals leads naturally to the introduction of complex valued eigenwavevectors or eigenfrequencies representing the attenuation of elastic waves in space or in time, respectively. Here, we propose a new technique to obtain phononic band structures with complex eigenfrequencies but real wavevectors, in the case of viscoelastic materials, whenever elastic losses are proportional to frequency. Complex-eigenfrequency band structures are obtained for a sonic crystal in air, and steel/epoxy and silicon/void phononic crystals, with realistic viscous losses taken into account. It is further found that the imaginary part of eigenfrequencies are well predicted by perturbation theory and are mostly independent of periodicity, i.e., they do not account for propagation losses but for temporal damping of Bloch waves.
TL;DR: In this paper, the perturbation method is applied to investigate the frictionally excited thermoelastic dynamic instability (TEDI) of a functionally graded material (FGM) coating in half-plane sliding against a homogeneous halfplane, and the results show that use of FGM coatings can improve the TEDI of this sliding system and reduce the possibility of interfacial failure by controlling the interfacial tensile stress.
Abstract: The perturbation method is applied to investigate the frictionally excited thermoelastic dynamic instability (TEDI) of a functionally graded material (FGM) coating in half-plane sliding against a homogeneous half-plane. We assume that the thermoelastic properties of the FGM vary exponentially with thickness. We also examine the effects of the gradient index, sliding speed, and friction coefficient on the TEDI for various material combinations. The transverse normal stress for two different coating structures is calculated. Furthermore, the frictional sliding stability of two different coating structures is analyzed. The obtained results show that use of FGM coatings can improve the TEDI of this sliding system and reduce the possibility of interfacial failure by controlling the interfacial tensile stress.
TL;DR: In this paper, the elastohydrodynamic lubrication (EHL) line contact between a rigid cylindrical punch and a transversely isotropic piezoelectric halfplane was investigated.
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TL;DR: In this article, the authors investigated the thermal wave crystals based on the dual-phase lag model to control the non-Fourier heat conduction process, and they showed that the larger the difference in thermal wave impedances is, the wider the thermal band gaps will be.
Abstract: Thermal wave crystals based on the dual-phase-lag model are investigated in this paper by both theoretical analysis and numerical simulation to control the non-Fourier heat conduction process. The transfer matrix method is used to calculate the complex dispersion curves. The temperature field is calculated by the finite difference time domain method. The results show that thermal band-gaps exist due to the Bragg-scattering. The key parameters characterizing the band-gaps are analyzed. The thermal wave impedance and mid-gap frequencies are introduced to predict band-gaps theoretically. Our results show that the larger the difference in the thermal wave impedances is, the wider of the thermal band-gaps will be. This study demonstrates a type of the thermal metamaterials which have potential innovative applications such as thermal imagining, thermal diodes and thermal waveguides for energy transmission.
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TL;DR: In this article, a zero-frequency seismic metamaterial (ZFSM) consisting of a three-component seismic plate and a half space is proposed to attenuate ultra-low frequency seismic surface waves.
Abstract: A zero-frequency seismic metamaterial (ZFSM) consisting of a three-component seismic metamaterial plate and a half space is proposed to attenuate ultra-low frequency seismic surface waves The design concept and models are verified firstly by lab-scale experiments on the seismic metamaterial consisting of a two-component seismic metamaterial plate and a half space Then we calculate the band structures of the one-dimensional and two-dimensional ZFSMs, and evaluate their attenuation ability to Rayleigh waves A wide band gap and a zero-frequency band gap (ZFBG) can be found as the band structure of the seismic metamaterial is almost equal to the band structure of the seismic metamaterial plate plus the sound cone It is found that the Rayleigh waves in the ZFSM are deflected and converted into bulk waves When the number of the unit cells of the ZFSM is sufficient, the transmission distance and deflection angle of the Rayleigh waves in the ZFSM are constant at the same frequency This discovery is expected to open up the possibility of seismic protection for large nuclear power plants, ancient buildings and metropolitan areas