Effective Properties Of Piezoelectric Composites Research Articles

Determination of effective properties of piezoelectric composites containing short fibers

The present paper studies the effects of local field fluctuations on the effective electromechanical coupling coefficients of piezoelectric composites containing short fibers. The finite-element method (FEM) is applied to study the overall behavior of such composites. Geometric models containing spheroid inclusions of two fiber arrangements, simple cubic and body-centered cubic, are modeled with FEM to predict the effective coefficients. The results thus obtained are validated with the results obtained from the analytical method based on Eshelby’s solution to the ellipsoidal inclusion problem. The analytical solution obtained through the Eshelby method is generalized for spheroid inclusions to compare the results with those of the FEM study. All finite-element studies are carried out through the finite-element software package Ansys 18.0. A detailed analysis of results is presented to understand better the behavior of such composites and their effective property variation with change in fiber volume fraction.

Dynamic effective property of piezoelectric composites with coated piezoelectric nano-fibers

Abstract This paper addresses the size-dependent dynamic effective electro-elastic properties of piezoelectric composites embedded with coated piezoelectric nano-fibers. By using the Effective Field Method of electric–elastic coupling wave, the randomly distributed coated nano-fibers in the piezoelectric media are reduced into a typical piezoelectric coated nano-fiber. To analyze the size-dependent effect, the coupling surface/interface theory is introduced to analyze the interface effect around the coating layers. Wave function expansion method is used to express the coupling wave field in the effective coupling field. The piezoelectrically stiffened elastic modulus and effective coupling wave number are obtained. Through analysis, it is found that the coupling surface/interface effect on the piezoelectrically stiffened elastic modulus show significant variation with the material properties of coating layer and the incident wave frequency. The effect of piezoelectric property of surfaces/interfaces on the effective shear modulus is also examined. Comparison with the existing results is given to validate this dynamic electro-elastic model.

Effective moduli of ellipsoidal particle reinforced piezoelectric composites with imperfect interfaces

The effective properties of piezoelectric composites with ellipsoidal particles embedded imperfectly in the matrix are investigated. The dilute approximation method, the Mori–Tanaka method, the self-consistent method, and the differential scheme are all modified to incorporate the bonding imperfection to predict the effective elastic, dielectric, and piezoelectric moduli of the composite. The corresponding formulae are rigorously derived with the help of the modified piezoelectric Eshelby tensor. Numerical examples are considered to illustrate the effect of imperfect interfaces on the effective properties of piezoelectric composites. It is found that good agreement with the existing experiments can be achieved by properly selecting the interface parameters. This clarifies the importance of the inclusion of imperfect interfaces in the modeling. The particular size-dependent characteristic due to the interface imperfection is also investigated numerically.

Effective properties of piezoelectric composites with periodic structure

The transformation field theory is developed to investigate the effective properties of piezoelectric composites consisting of anisotropic inclusions having arbitrary geometrical shapes in unit cell. The complicated boundary problem of arbitrary geometrical shapes of anisotropic inclusions is solved by introducing the transformation strain and electric fields. Motivated by theoretical investigation of the effective properties of piezoelectric composites, as an example, the effective dielectric, elastic, and piezoelectric constants of spherical periodic piezoelectric composites are discussed, and a good agreement is obtained by comparing the calculation results with the experimental data in the dilute limit.

Shear Lag Micromechanics Model for Effective Properties of Piezoelectric Composites

Prediction of the effective properties of piezoelectric composites with the help of shear lag micromechanics model is discussed. The shear lag micromechanics model is derived by considering a representative volume of the composite that contains a piezoelectric inclusion. Both homogeneous and heterogeneous inclusion problems are considered. In the homogeneous inclusion problem, a piezoelectric inclusion is present inside a piezoelectric medium, whereas in heterogeneous inclusion either a piezoelectric inclusion is present inside a matrix medium or a matrix inclusion is present inside a piezoelectric medium. A new matrix method is followed for evaluation of effective properties of the piezoelectric composite using a shear lag model. The inclusion considered is of rectangular parallelopiped type. The effect of the geometry of the inclusion on the effective mechanical and piezoelectric properties of the composite is studied.

Influence of polarization orientation on the effective properties of piezoelectric composites

The effective properties of 0–3- and 1–3-type piezoelectric composites of lead zirconate titanate and vinylidene fluoride–trifluoroethylene with different polarization status in both phases are calculated using an effective-medium theory. The effects of volume fraction and polarization orientation on the effective behavior are presented in detail. The theory gives results in reasonable agreement with recent experimental ones. The theoretical predictions demonstrate the interesting behavior of the composites and provide a general guideline for optimizing the microstructural scale of the composites for piezoelectric transducers and pyroelectric sensors.

Effects of damage on effective properties of piezoelectric composites

The present study aims to examine the effects of microcracking damage on the effective electroelastic moduli of piezoelectric fibrous composites. First, the ten independent material constants for a two-phase transversely isotropic, fibrous piezocomposite are given in explicit forms using Mori-Tanaka mean field method. Then, considered are the damage effects in three typical cases of damage, namely the isotropic, completely anisotropic and evolutionary damage. It is found that some effective electroelastic moduli are insensitive to the microcracking damage while some others show evident dependence on the accumulation of damage.

Micromechanics determination of the effective properties of piezoelectric composites containing spatially oriented short fibers

This article presents an analytical unified method for determining the effective electroelastic properties of piezoelectric composites containing spatially oriented short fibers, which are treated as spheroidal inclusions. Both the matrix and inclusions are assumed to be linearly piezoelastic and transversely isotropic. The electroelastic tensors analogous to Eshelby tensors for elastic ellipsoidal inclusions have been obtained and also evaluated numerically for finite fiber aspect ratios. Utilizing these tensors and applying the Mori-Tanaka mean field theory to account for the interaction between inclusions and matrix, the effective electroelastic properties of the composites are expressed analytically in terms of phase properties, orientation angles, volume fraction and inhomogeneity shape. It is indicated that the proposed methods yield identical results when either a traction-electric displacement or an elastic displacement-electric field is prescribed on the compsite boundary. Finally, numerical examples are given for a BaTiO 3 PZT-5 H composite. The results show that the longitudinal and in-plane shear moduli increase with fiber length, while the other moduli, piezoelectric and dielectric constants decrease.

An analysis of piezoelectric composite materials containing ellipsoidal inhomogeneities

A set of four tensors corresponding to Eshelby’s tensor in elasticity are obtained for an ellipsoidal inclusion embedded in an infinite piezoelectric medium. These tensors, which describe the elastic, piezoelectric, and dielectric constraint of the matrix, are obtained from W. F. Deeg’s solution to inclusion and inhomogeneity problems in piezoelectric solids. These tensors are then used as the backbone in the development of a micromechanics theory to predict the effective elastic, dielectric, and piezoelectric moduli of particle and fibre reinforced composite materials. The effects of interaction among inhomogeneities at finite concentrations are approximated through the Mori-Tanaka mean field approach. This approach, although widely utilized in the study of uncoupled elastic and dielectric behaviour, has not before been applied to the study of coupled behaviour. To help ensure confidence in the theory, the analytical predictions are proven to be self-consistent, diagonally symmetric, and to exhibit the correct behaviour in the low and high concentration limits. Finally, numerical results are presented to illustrate the effects of the concentration, shape, and material properties of the reinforcement on the effective properties of piezoelectric composites and analytical predictions are shown to result in good agreement with existing experimental data.

Multiple-scattering approach to effective properties of piezoelectric composites.

We develop a general theoretical framework for predicting the effective properties of piezoelectric composites in terms of multiple-scattering theory. For transversely isotropic piezoelectric composites of aligned cylindrical fibers exhibiting transversely isotropic piezoelectricity embedded in an isotropic matrix, we give the first-order approximation of the theory and present a numerical study of the effective piezoelectric coefficients. It predicts the enhanced hydrostatic and voltage piezoelectric coefficients for the two-phase fiber-reinforced piezoelectric composites. The theoretical predictions also compare reasonably well with the experimental results.

The theory of effective properties of piezoelectric composites

The theory of effective properties of piezoelectric composites