Wave Propagation In Piezoelectric Media Research Articles

Polynomial approach for modeling a piezoelectric disc resonator partially covered with electrodes

The frequency spectrum of a partially metallized piezoelectric disc resonator was studied using Legendre polynomials. The formulation, based on three-dimensional equations of linear elasticity, takes into account the high contrast between the electroded and non-electroded regions. The mechanical displacement components and the electrical potential were expanded in a double series of orthonormal functions and were introduced into the equations governing wave propagation in piezoelectric media. The boundary and continuity conditions were automatically incorporated into the equations of motion by assuming position-dependent physical material constants or delta-functions. The incorporation of electrical sources is illustrated. Structure symmetry was used to reduce the number of unknowns. The vibration characteristics of the piezoelectric discs were analyzed using a three-dimensional modelling approach with modal and harmonic analyses. The numerical results are presented as resonance and anti-resonance frequencies, electric input admittance, electromechanical coupling coefficient and field profiles of fully and partially metallized PIC151 and PZT5A resonator discs. In order to validate our model, the results obtained were compared with those published previously and those obtained using an analytical approach.

Ordinary Differential Equation applied to ultrasonic wave Propagation in piezoelectric material

The propagation of ultrasonic waves is still a topic of interest due to its applications in surface acoustic wave devices (SAW). Research works related to propagation in various media as multilayer, thin film and semi infinite media can be found in the recent literature. Applications of these studies include technological areas as electronic systems and sensors. Acoustic wave propagation in piezoelectric media is basically achieved by the use of the ordinary differential equations method ODE. Our purpose is to elucidate how ODE is carried out leading to a best identification of the involved electromechanical partial waves. The eigenvector equation related to ODE method has been solved in three cases depending on the symmetry of the sagittal plane. Therefore the fundamental acoustic tensor is reformulated with respect to the existing coupling between the elastic partial waves and the electrical one. The new formulation of ODE is useful during propagation studies either in elastic materials or piezoelectric ones. The obtained results are illustrated on the well known piezoelectric material ZnO, which is assumed to be hexagonal.

Simulation of piezoelectric devices by two- and three-dimensional finite elements

A method for the analysis of piezoelectric media based on finite-element calculations is presented in which the fundamental electroelastic equations governing piezoelectric media are solved numerically. The results obtained by this finite-element calculation scheme agree with theoretical and experimental data given in the literature. The method is applied to the vibrational analysis of piezoelectric sensors and actuators with arbitrary structure. Natural frequencies with related eigenmodes of those devices as well as their responses to various time-dependent mechanical or electrical excitations are computed. The theoretically calculated mode shapes of piezoelectric transducers and their electrical impedances agree quantitatively with interferometric and electric measurements. The simulations are used to optimize piezoelectric devices such as ultrasonic transducers for medical imaging. The method also provides deeper insight into the physical mechanisms of acoustic wave propagation in piezoelectric media.

A Finite Element Analysis of the Piezoelectric Waveguide Convolver

Absfmct-A variational finite element analyijs of linear and low nonlinear guided wave propagation in piezoelectric media is proposed here. The method is applied to thin metallic AI &ides on Ez LiNb03! such as employed in waveguide convolvers. First dispersion c‘urves and tield amplitude profiles for linear analysis are obtained. Then the method is applied to account for the nonlinear mixing mechanisps and to compute the,ponvolution 6gure of merit. The hear field distribution at w is used to compute the driving forces at 2w, and the forced problem is solved at 2w.

Zero-field elastic constants of uvite

The theories of Kyame [1] and Koga et al. [2] on stress wave propagation in piezoelectric media are critically studied and compared with each other. Solutions of the modified Christoffel's equations predicted by each theory for piezoelectric crystals in class 3m are derived. The velocities of ultrasonic waves propagated through a gem quality uvite specimen in particular directions were measured at 293 K using the pulse-echo overlap method. All of the independent zero-field elastic moduli were calculated from the measured wave velocities and compared with the available data in the literature. The values of the elastic constants in 10 12 dyn cm 2 were found to be C 11 = 3.016 ± 0.2% C 66 = 1.028 ± 0.3% C 33 = 1.698 ± 0.2% C 13 = 0.47 ± 3% C 44 = 0.655 ± 0.3% c 14 = −0.089 ± 6%. The calculated bulk modulus, shear modulus and Poisson's ratio, using the Voigt-Reuss-Hill (VRH) approximation, are K H = 1.226 × 10 12 dyn cm 2 , G H = 0.826 × 10 12 dyn cm 2 and σ H = 0.224. The Debye temperature is 764 K.

Wave propagation in piezoelectric medium of hexagonal symmetry

The wave propagation at large distances from a source of disturbance (isolated harmonic electric charge or body force of fixed frequency) in an infinite piezoelectric medium belonging to classes (6), (6 m m) or ceramic (α m) and (6 2 2) is discussed by means of asymptotic evaluation (at large distances) of Fourier integrals. Numerical results are given for the (6 m m) crystal class using the constants of cadmium selenide crystal.