Showing papers by "Yue-Sheng Wang published in 2008"
TL;DR: In this paper, the elastic wave propagation in phononic crystals with piezoelectric and piezomagnetic inclusions is investigated taking the magneto-electro-elastic coupling into account.
122 citations
TL;DR: In this paper, a nonlinear Rayleigh surface wave was generated without having to drive the transmitting piezoelectric transducer at high voltages; driving at low voltages limits the excitation of the intrinsic nonlinearity of the transducerer element, and enables an efficient measurement procedure to isolate inherent material non-linearity.
Abstract: This note presents a procedure to generate nonlinear Rayleigh surface waves without having to drive the transmitting piezoelectric transducer at high voltages; driving at low voltages limits the excitation of the intrinsic nonlinearity of the piezoelectric transducer element, and enables an efficient measurement procedure to isolate inherent material nonlinearity. The capabilities of this proposed technique are demonstrated by measuring the material nonlinearity of aluminum alloy 2024 and 6061 plates with Rayleigh surface waves.
90 citations
TL;DR: In this article, the frictionless contact problem of a functionally graded piezoelectric layered half-plane in-plane strain state under the action of a rigid flat or cylindrical punch is investigated.
85 citations
TL;DR: In this paper, the axisymmetric frictionless contact problem of a functionally graded coated half-space is investigated by using the transfer matrix method and Hankel integral transform technique, the problem is reduced to a Cauchy singular integral equation.
Abstract: The main interest of this study is a new method to solve the axisymmetric frictionless contact problem of functionally graded materials (FGMs). Based on the fact that an arbitrary curve can be approached by a series of continuous but piecewise linear curves, the FGM is divided into a series of sub-layers with shear modulus varying linearly in each sub-layer and continuous at the sub-interfaces. With this model, the axisymmetric frictionless contact problem of a functionally graded coated half-space is investigated. By using the transfer matrix method and Hankel integral transform technique, the problem is reduced to a Cauchy singular integral equation. The contact pressure, contact region and indentation are calculated for various indenters by solving the equations numerically.
83 citations
TL;DR: In this article, the propagation and localization of Rayleigh waves in disordered piezoelectric phononic crystals with material 6mm are studied taking the electromechanical coupling into account.
Abstract: In this paper, the propagation and localization of Rayleigh waves in disordered piezoelectric phononic crystals with material 6 mm are studied taking the electromechanical coupling into account. The electric field is approximated as quasi-static. The analytical solutions of Rayleigh waves are obtained. The 6×6 transfer matrix between two consecutive unit cells is obtained by means of the mechanical and electrical continuity conditions. The expression of the localization factor in disordered periodic structures is presented by regarding the variables of the mechanical and electrical fields as the elements of the state vector. The numerical results for a piezoelectric phononic crystal—PVDF-PZT-2 piezocomposite—are presented and analyzed. From the results we can see that the localization is strengthened with the increase of the disorder degree. The characteristics of the passbands and stopbands are influenced by different ratios of the thickness of the polymers to that of the piezoelectric ceramics. Disorder in elastic constant c11 of PZT-2 can also result in the localization phenomenon. The propagation and localization of Rayleigh waves in piezoelectric phononic crystals may be controlled by properly designing some structural parameters.
69 citations
TL;DR: In this paper, the reflection and refraction of a plane wave incidence obliquely at the interface between piezoelectric and piezomagnetic media is analyzed, and the authors show that the most amount of the incident energy goes with the waves that are the same type as the incident wave, while the energy arising from wave mode conversion occupies a less part of the energy.
62 citations
TL;DR: In this paper, the problem of a functionally graded coated half-space indented by an axisymmetric smooth rigid punch is considered and the shear modulus of the graded coating is assumed to be an exponential function and the Poisson's ratio is a constant.
Abstract: This paper is concerned with the problem of a functionally graded coated half-space indented by an axisymmetric smooth rigid punch. The shear modulus of the graded coating is assumed to be an exponential function and the Poisson’s ratio is a constant. With the use of Hankel integral transform technique, the axisymmetric frictionless contact problem is reduced to a Cauchy singular integral equation. The contact pressure, contact radius and penetration depth are calculated for various indenters by solving the equations numerically. The results show that these quantities are greatly affected by the gradient of the coating.
60 citations
TL;DR: In this article, the band structures of a two-component Fibonacci phononic quasicrystal with symmetries were studied and the results showed the merits of using the localization factors.
57 citations
TL;DR: In this paper, the phase velocities of Rayleigh-type surface waves in a piezoelectric-piezomagnetic layered half-space are derived and the dispersion relations have been numerically derived and computed by considering the coupling of piezolectric and piezOMagnetic behaviors.
Abstract: Propagation of Rayleigh-type surface waves in a piezoelectric-piezomagnetic layered half-space is investigated. The materials are assumed to be transversely isotropic crystals. The dispersion relations have been numerically derived and computed by considering the coupling piezoelectric and piezomagnetic behaviors. The phase velocities are obtained for four kinds of electric-magnetic boundary conditions at the free surface. The variations of mechanical displacements, electric and magnetic potentials along the thickness direction of the layer are obtained. The effects of different electric-magnetic boundary conditions on the phase velocity and mode shapes of displacements, electric and magnetic potentials have been discussed. The results show that the lowest mode is Rayleigh mode and that the phase velocities of the higher modes tend to the shear wave velocity of the piezoelectric layer as the frequency increases. The electric boundary conditions dominate the phase velocity. The magnetic boundary conditions have a significant effect on the mode shapes of the displacements, electric and magnetic potentials of the first mode. It is also found that piezoelectric material properties have an important effect on wave propagation. The result is relevant to the analysis and design of various acoustic surface wave devices constructed from piezoelectric and piezomagnetic materials.
57 citations
TL;DR: In this paper, an analytical methodology is presented to study the active vibration control of beams treated with active constrained layer damping (ACLD), which is based on the conventional theory of structural dynamics.
Abstract: An analytical methodology is presented to study the active vibration control of beams treated with active constrained layer damping (ACLD). This analytical method is based on the conventional theory of structural dynamics. The process of deriving equations is precise and easy to understand. Hamilton's principle with the Rayleigh–Ritz method is used to derive the equation of motion of the beam/ACLD system. By applying an appropriate external control voltage to activate the piezoelectric constraining layer, a negative velocity feedback control strategy is employed to obtain the active damping and effective vibration control. From the numerical results it is seen that the damping performances of the beam can be significantly improved by the ACLD treatment. With the increase of the control gain, the active damping characteristics are also increased. By equally dividing one ACLD patch into two and properly distributing them on the beam, one can obtain better active vibration control results than for the beam with one ACLD patch. The analytical method presented in this paper can be effectively extended to other kinds of structures.
50 citations
TL;DR: Based on the variational theory, a wavelet-based numerical method was developed to calculate the defect states of acoustic waves in two-dimensional phononic crystals with point and line defects as discussed by the authors.
TL;DR: In this paper, the authors investigated the frictionless contact problem of a layered half-plane made of functionally graded piezoelectric material (FGPM) in the plane strain state under the action of a rigid punch whose shape may be flat, triangular or cylindrical.
Abstract: This paper investigates the frictionless contact problem of a layered half-plane made of functionally graded piezoelectric material (FGPM) in the plane strain state under the action of a rigid punch whose shape may be flat, triangular or cylindrical. It is assumed that the punch is a perfect electrical insulator with zero electric charge distribution. The electroelastic properties of the FGPM layer vary exponentially along the thickness direction. By using the Fourier integral transform technique, the problem is reduced to a Cauchy singular integral equation which is then numerically solved to determine the contact pressure, contact region, maximum indentation depth, normal stress, electrical potential and electric displacement fields. The stress intensity factor is also given to quantitatively characterize the singularity behavior of the contact pressure at the ends of a flat and triangular punch. Numerical results show that both the material property gradient of the FGPM layer and the punch geometry have a significant influence on the contact performance of the FGPM layered half-plane.
TL;DR: In this article, the dispersion curves and displacement fields are calculated with different piezoelectric volume fractions for layered periodic composites consisting of piezolectric and piezomagnetic phases.
TL;DR: In this paper, a wavelet-based method is developed to calculate the band structures of surface modes in two-dimensional phononic crystals including mixed fluid/solid systems and systems with small or large acoustic mismatch.
Abstract: A wavelet-based method is developed to calculate the band structures of surface modes in two-dimensional phononic crystals including mixed fluid/solid systems and solid/solid systems with small or large acoustic mismatch. The defect modes of the surface waves are also calculated by using the supercell technique. The method is validated by recomputing the samples already studied in literatures. The results show some merits of the present method. In addition, the present method is applied to some new samples to show more properties of the surface modes. The influences of various factors, especially the acoustic mismatch, on the surface modes are discussed in detail. The present method may serve as an alternative method for studying the surface waves in general phononic lattices.
TL;DR: In this article, the elastic wave localization in disordered periodic piezoelectric rods with initial stress was studied using the transfer matrix and Lyapunov exponent method, where the electric field was approximated as quasi-static.
TL;DR: In this paper, the localization of wave propagation due to random disorder is discussed by introducing the concept of the localization factor that is calculated by the plane-wave-based transfer-matrix method, and two kinds of quasi phononic crystals that have quasi-periodicity (Fibonacci sequence) in one direction and translational symmetry in the other direction are considered and the band structures are characterized by using localization factors.
TL;DR: In this paper, the hybrid time-domain boundary element method (BEM) together with the multi-region technique is applied to simulate the dynamic process of crack deflection/ penetration at an interface in a bi-material.
Abstract: The hybrid time-domain boundary element method (BEM), together with the multi-region technique, is applied to simulate the dynamic process of crack deflection/ penetration at an interface in a bi-material. The whole bi-material is divided into two regions along the interface. The traditional displacement boundary integral equations (BIEs) are employed with respect to the exterior boundaries; meanwhile, the non-hypersingular traction BIEs are used with respect to the part of the crack in the matrix. Crack propagation along the interface is numerically modelled by releasing the nodes in the front of the moving crack tip and crack propagation in the matrix is modeled by adding new elements of constant length to the moving crack tip. The dynamic behaviours of the crack deflection/penetration at an interface, propagation in the matrix or along the interface and kinking out off the interface, are controlled by criteria developed from the quasi-static ones. The numerical results of the crack growth trajectory for different inclined interface and bonded strength are computed and compared with the corresponding experimental results. Agreement between numerical and experimental results implies that the present time-domain BEM can provide a simulation for the dynamic propagation and deflection of a crack in a bi-material.
TL;DR: In this article, the von Mises stress, elastic strain energy density and hydrostatic pressure in different matrix channels are calculated when the external stress is applied along the [0, 0, 1], [1, 1, 0] and [1, 1, 1] directions, respectively.
TL;DR: In this paper, the authors investigated the influence of disorder on the band gap in two-dimensional disordered piezoelectric phononic crystals using the finite-difference time-domain (FDTD) method.
01 Nov 2008
TL;DR: In this paper, a computational method based on finite element method is presented to evaluate the propagation of acoustic waves through three-dimensional phononic crystals consisting of simple cubic (SC), body-centered cubic (BCC), or face centered cubic array spheres embedded in a host complete and accurate band structure information is obtained to identify the band gaps and eigenmodes.
Abstract: In this paper, a computational method based on finite element method is presented to evaluate the propagation of acoustic waves through three-dimensional phononic crystals consisting of simple cubic (SC), body-centered cubic (BCC) or face-centered cubic (FCC) array spheres embedded in a host Complete and accurate band structure information is obtained to identify the band gaps and eigenmodes The results indicate that the finite element method is precise for the band structure computation of the phononic crystals and can reduce computing time to a certain extent
01 Nov 2008
TL;DR: In this article, a boundary element method is developed to calculate the band gaps of out-of-plane elastic waves propagating in two-dimensional phononic crystals, and the convergence of the sums in this Green's function is accelerated by Ewald representations.
Abstract: A boundary element method is developed to calculate the band gaps of out-of-plane elastic waves propagating in two-dimensional phononic crystals. The Green's function satisfying Bloch's theorem is chosen as the fundamental solution of this problem. The convergence of the sums in this Green's function is accelerated by Ewald representations. Based on the fundamental solutions, the boundary integral equations in a unit cell of the periodic structure are given, which involve integrals over the boundary between the scatterer and the matrix. Constant boundary elements are adopted to discretize the boundary. As an example, the band gaps of solid-solid binary systems are calculated and analyzed. The results show that the boundary element method is an effective numerical analysis tool.
01 Dec 2008
TL;DR: In this paper, the authors explored the band structures of bending wave propagating in the phononic crystal thin plates with point defect and found that the defect modes exist in the first band gap, the frequencies and the numbers of defect modes are strongly dependent on the defect filling fraction and the filling fraction, and the defect bands disappear at very low or very high filling fractions.
Abstract: The band structures of bending waves propagating in the phononic crystal thin plates with point defect are explored based on the supercell technique combined with the improved plane wave expansion method. The plate is composed of a periodic array of circular crystalline Al2O3 cylinders embedded in the epoxy matrix for square lattice. The point defect is introduced by changing one of the cylinders' radii. The results show that the defect modes exist in the first band gap, the frequencies and the numbers of the defect modes are strongly dependent on the defect filling fraction and the filling fraction. All the flat defect bands appearing in the first band gap are nondegenerate. For a given defect filling fraction, there are up to five nondegenerate defect bands emerging inside the first band gap, and the frequencies of defect bands increase with the filling fraction increases. The defect bands disappear at very low or very high filling fractions. For a given filling fraction, three nondegenerate defect bands appearing near the upper edge of the gap move to the middle as the defect filling fraction is reduced, and the edges of the first band gap remain hardly changed. The study of the displacement distributions associated with the three defect modes shows that the flat bands correspond to the special localized frequencies of the waves. For the two lower defect modes, the displacement amplitudes around the defect are much bigger than that at or far away from the defect. However, for the higher defect mode, the displacement amplitude reaches the maximum at the location of the defect and decays rapidly with the distance away from that. Obviously, the bending waves correspond to such three modes are so localized at or near the defect that they can not escape into the surrounding phononic crystals. That is, the point defect behaves like a resonant vacant.
01 Nov 2008
TL;DR: In this paper, the authors prove that the material parameters determining directly phononic band gaps of the z-mode are the mass density ratio and the shear modulus ratio, and that the maximum band gap appears at both large mass densities and shear densities, and becomes wider with these two parameters increasing.
Abstract: In this paper, starting with wave equation, we prove that material parameters determining directly phononic band gaps of the z-mode are the mass density ratio and the shear modulus ratio Plane wave expansion method is used for calculating band gaps The influences of these parameters on phononic band gaps are analyzed for different lattices: square and hexagonal The results show that the maximum band gap appears at both large mass density ratio and shear modulus ratio, and becomes wider with these two parameters increasing Compared with the shear modulus ratio, the mass density ratio is more important to the appearance of the band gap, but not to the width of the band gap Only acoustic impedance ratio or wave velocity ratio cannot control band gaps The results could be helpful in tuning band gaps
01 Dec 2008
TL;DR: In this paper, the displacement transfer coefficients of all the scattered waves are calculated by the transfer matrix and the stiffness matrix methods, and it is shown that the most energy is carried by the transmitted waves which are of the same mode as the incident wave when the frequencies are at the passbands.
Abstract: This paper has studied the frequency band characteristics of the piezoelectric/piezomagnetic layered periodic composites. Both piezoelectric and piezomagnetic materials are assumed to be transversely isotropic. The displacement transfer coefficients of all the scattered waves are calculated by the transfer matrix and the stiffness matrix methods. Numerically calculated results show that the band structures are described consistently by the dispersion curves and the frequency responses of the transmitted waves. The most energy is carried by the transmitted waves which are of the same mode as the incident wave when the frequencies are at the passbands. However, the displacement transfer coefficients of quasi-transverse (QSV) or quasi-longitudinal (QP) waves arising from wave mode conversion may be very large at some particular frequencies in some passbands. Compared to the coupled transmitted magnetoacoustic (MA) and electroacoustic (EA) waves, the transfer coefficients of electric potential (EP) and magnetic potential (MP) waves are a little bigger.
01 Nov 2008
TL;DR: In this paper, the band structures of two-dimensional phononic crystals with one-dimensional quasi-periodicity were characterized by localization factors calculated by using the plane-wave-based transfermatrix method.
Abstract: By viewing the quasi-periodicity as the deviation from the periodicity in a particular way, the quasi phononic crystal that has quasi-periodicity (Fibonacci sequence) in one direction and translational symmetry in the other direction is considered. The band structures are characterized by localization factors which are calculated by using the plane-wave-based transfer-matrix method. The results show that the localization factor is an effective parameter in characterizing the band gaps of two-dimensional phononic crystals with one-dimensional quasi-periodicity. The quasi phononic crystals exhibit more band gaps with narrower width than the ordered and randomly disordered systems.