Multilayered Piezoelectric Structures Research Articles

Parameter optimization of surface acoustic waves via multilayer structures

A method and algorithm for numerical analysis and optimization of the basic parameters of electroacoustic surface waves propagating in multilayer piezoelectric structures are described. Combinations of layer materials and piezoelectric substrates for which an electroacoustic surface wave has optimal parameters of propagation (low dispersion, high electromechanical coupling coefficient, high thermal stability, low diffraction losses, etc.) are found.

Acoustic cavity polariton in multilayer piezoelectric structures

Coupling between the transverse electromagnetic mode of the coplanar strips and transverse acoustic phonon mode in the multilayer piezoelectric structures is considered. It is shown that it leads to the formation of a coupled entity—acoustic cavity polariton, whose frequency and velocity can be adjusted within a very broad range by the proper design of the piezoelectric cavity. The acoustic cavity polaritons can be used in filters, delay lines, and solid-state traveling wave devices for frequencies of up to 100 GHz.

Mindlin's problem for an anisotropic piezoelectric half–space with general boundary conditions

This paper considers Mindlin's problem in an anisotropic and piezoelectric halfspace with general boundary conditions, including 16 different sets of surface conditions. The Green's function due to...

Adaptive lagrange finite element methods for high precision vibrations and piezoelectric acoustic wave computations in SMT structures and plates with nano interfaces

This paper discusses the validity of (adaptive) Lagrange generalized plain finite element method (FEM) and plate element method for accurate analysis of acoustic waves in multi-layered piezoelectric structures with tiny interfaces between metal electrodes and surface mounted piezoelectric substrates. We have come to conclusion that the quantitative relationships between the acoustic and electric fields in a piezoelectric structure can be accurately determined through the proposed finite element methods. The higher-order Lagrange FEM proposed for dynamic piezoelectric computation is proved to be very accurate (prescribed relative error 0.02%–0.04%) and a great improvement in convergence accuracy over the higher order Mindlin plate element method for piezoelectric structural analysis due to the assumptions and corrections in the plate theories. The converged Lagrange finite element methods are compared with the plate element methods and the computed results are in good agreement with available exact and experimental data. The adaptive Lagrange finite element methods and a new FEA computer program developed for macro- and micro-scale analyses are reviewed, and recently extended with great potential to high-precision nano-scale analysis in this paper and the similarities between piezoelectric and seismic wave propagations in layered structures and plates are stressed.

Axisymmetric deformation of piezoelectric multilayers

Abstract Multilayers are of technological importance. From the mechanical point of view they represent inhomogeneity in the elasticity. The material properties in one layer may be different from those in another although each layer may still be homogeneous. Mechanically, multilayers can be characterized by a variation in thermophysical constants with the direction normal to the layer interfaces. Few solutions of the basic equations of piezoelasticity have been found for such systems. In this paper we develop the foundations of the theory of piezoelasticity under axisymmetric deformation for heterogeneity. Integral transform techniques are used to reduce the problem to the solution of singular integral equations. The fundamental solutions for multilayered piezoelectric materials and structure are established. The model is general enough to account for any number of layers, and for any number of penny-shaped cracks. An additional advantage of the present model is that it can treat some certain inhomogeneous...

Control of Piezoelecric Smart Structures

This paper deals with the controller design for multi-layered piezoelectric structures. From the control point of view piezoelectric materials have the big advantage of making it easy to adjust the actuators and sensors to the special structural application that is to be controlled. It will be shown that an appropriate spatial shaping of the surface electrode of the piezoelectric actuator and sensor layers simplifies the control synthesis task to a great deal.

Modeling of multilayer piezoelectric structures

Based on the classical K.L.M. equivalent circuit for a piezoelectric ceramic and a matrix formulation, a method to model the electro-acoustic behavior of multilayer piezoelectric structures is described. In this iterative implementation, valid for any number of active layers, different external elements can be inserted such as electrodes and bond layers. Both types of electrical connections between successive layers (i.e. in series or in parallel) can be defined. Finally, a three layer structure is fabricated, characterized and the results are compared with theoretical predictions.

Acoustooptic modulator using the Stark effect and stress-induced bandgap changes

An analysis of the semiconductor multiple-quantum-well (MQW) acoustooptic modulator is performed. The strain and electric-field components generated by surface acoustic waves (SAW's) in a multilayered semiconductor piezoelectric structure are presented. The effects of a SAW propagation on the modulator optical parameters are studied. Two kinds of SAW effects in the modulator structure are taken into account: the variation of the excitonic energies of the MQW due to strain and the companion electric field generated by the SAW is determined. The hole's effective mass change induced by the SAW is analyzed and included in the Schrodinger equation. The optical absorption coefficient spectra of the modulator as a function of the SAW power is presented. Experimental results concerning optical absorption variations of quantum-well structures produced by various SAW powers are shown.

Unidimensional modeling of multi-layered piezoelectric transducer structures

Multi-layered transducer structures offer the potential of improved performance in terms of increased transmit sensitivity, greater bandwidth, and enhanced reception characteristics. Unfortunately, the successful design of such devices is often difficult, owing to the complex interaction between the active piezoelectric layers and passive intermediate interface layers. Furthermore, in many practical applications, the loading effects imposed by the electrical drive circuitry often limit the performance improvements that may be physically realized. This paper describes the development of a comprehensive, unidimensional modeling approach. This model may be employed to facilitate the analysis and subsequent optimization of laminated transducer assemblies. The devices currently under consideration include both piezoceramic and piezopolymer configurations, as well as alternative piezocomposite designs. The effects of varying bondline thickness and the introduction of passive interface layers are examined, as is the influence of the electrical load circuitry on overall system response. The ability to accurately predict the response of stacked piezoelectric structures is demonstrated through extensive comparison of experimental and theoretical responses. This paper concludes by highlighting the important role that modeling plays in the design, fabrication, and optimization of complex multi-layered transducer assemblies.

Resonance reflection and transmission of shear elastic waves in multilayered piezoelectric structures

Inclined incidence of a shear horizontal elastic wave on a periodic structure of piezoelectric layers with metallized interfaces is considered. The layers are supposed to be made from the identical crystal of hexagonal symmetry but have alternating widths d1,d2. Due to the condition of fixed electropotential, each interface provides the reflection proportional to the parameter of electromechanical coupling q2. The interference of the reflected waves in the periodic structure causes the existence of the Bragg resonances in the reflection-transmission spectrum so that ‖R‖max≊1 for a sufficiently large number of layers. Since q2≪1, the considered reflection spectrum exhibits some specific features such as high selectivity, modulation of the heights of the Bragg maximums depending on the value d1/(d1+d2), and the extinction effect.

Propagation of acoustoelectric waves in a layered cylinder with conducting layers

In multilayer acoustoelectric waveguides, the piezoelectric layers may be separated by metallic conducting layers. Propagation of shear waves within such structures of a regular type with planar dividing boundaries for the properties was studied. In this paper, we investigate acoustoelectric waves in multilayer piezoelectric structures containing conducting layers, with cylindrical dividing surfaces for the properties. The method for solving the boundary-value problem is a generalization of the approach outlined. We should turn our attention to the fact that the order of the dispersion determinant in these problems depends on the number of piezoelectric-conductor junctions. When the curvature of the cylindrical surface is equal to zero, the constructed solution goes to the solution of the problem for a planar waveguide.

Optimisation of MQW structures for acousto-optic absorption modulators

A systematic study is presented of a multiple-quantum-well (MQW) acousto-optic modulator. The device utilises the electro-absorptive effects in quantum wells and the electric field induced by surface acoustic waves (SAW). The propagation of SAW in multilayered piezoelectric structures is studied and the electric field is calculated. The optical absorption coefficient in a MQW is calculated as a function of the applied electric field and the MQW parameters. A systematic approach for optimising the performance of a MQW acousto-optic modulator is presented.

Five port lattice model for simulation of piezoelectric structures possessing twin, compressional modes of vibration

A method is presented for predicting the performance of multilayered piezoelectric structures which demonstrate two, loosely coupled compressional modes of vibration. A linear systems, lattice approach is developed using a matrix formulation for implementation of the transducer transfer functions in the frequency domain. The technique is computationally efficient, providing good results over a key range of transducer dimensions and is especially useful for the practical evaluation of multilayered, linear or diced array structures.