Average electro-mechanical properties and responses of active composites (original) (raw)
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Advance In Micromechanics Analysis of Piezoelectric Composites
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Electromechanical properties of continuous fibre-reinforced piezoelectric composites
Mechanics of Composite Materials, 1997
A composite material with unidirectional cylindrical ®bers periodically distributed is considered here, where each periodic cell is a binary homogeneous piezoelectric medium with square symmetry in welded contact at the interface. This paper makes use of some results obtained for a similar elastic composite in Rodr õguez-Ramos et al. [Mech. Mater. 33 (2001) 223±235]. Relatively simple closed-form expressions for the overall properties are obtained by the asymptotic homogenization method. The local problems that arise are solved by means of potentials methods of a complex variable and Weierstrass elliptic and related functions. Benveniste and Dvorak universal type of relations for some of the overall properties are derived in a simple new way without solving any local problem. The number of local problems to get all coecients is 3. The numerical computation of the eective properties is simple. Averaged properties of these piezocomposites relevant to hydrostatic and medical imaging transducer applications are computed and compared with existing experimental results. The comparison shows quite a good agreement with experimental data. Ó
Different numerical unit cells models using ANSYS® finite element package are developed for unidirectional periodic composites made of piezoelectric (PZT) fibers embedded in a soft non-piezoelectric matrix. These finite element models are used for prediction of the effective electromechanical coefficients of the periodic transversely isotropic piezoelectric cylindrical fiber composite. Special emphasis is placed on the formulation of the boundary conditions that allows the simulation of all modes of overall deformation arising from any arbitrary combination of mechanical and electrical loading. These numerical models providing a powerful tools for fast calculation of the effective electromechanical properties of 1-3 piezocomposites with arbitrary geometrical inclusion configurations. The developed models has been applied to unidirectional piezoelectric fiber composites with periodic hexagonal arrangement of piezoelectric fibers. The effective coefficients of elastic stiffness, piezo...
Materials which exhibit piezoelectric behavior generate an electrical field in response to a mechanical deformation or alternatively undergo a mechanical deformation in response to an applied electrical field. This work presents the development of unit cell numerical models of 1-3 periodic composites, with piezoelectric fibers made of PZT embedded in a non-piezoelectric matrix. The common approach for estimating the macro-mechanical properties of 3D piezoelectric fiber composites is carried out by the unit cell approach, also called a representative volume element (RVE), which captures the major features of the underlying micro-structure. The main idea of this method consisting on evaluating a globally homogeneous medium equivalent to the original composite, where the strain energies stored in the two systems are approximately the same, with special emphasis placed on the formulation of suitable boundary conditions. The boundary conditions allow the simulation of all modes of the ov...
Constitutive modeling of piezoelectric polymer composites
Acta Materialia, 2004
A new modeling approach is proposed for predicting the bulk electromechanical properties of piezoelectric composites. The proposed model offers the same level of convenience as the well-known Mori-Tanaka method. In addition, it is shown to yield predicted properties that are, in most cases, more accurate or equally as accurate as the Mori-Tanaka scheme. In particular, the proposed method is used to determine the electromechanical properties of four piezoelectric polymer composite materials as a function of inclusion volume fraction. The predicted properties are compared to those calculated using the Mori-Tanaka and finite element methods.
Optimization of the piezoelectric response of 0–3 composites: a modeling approach
Smart Materials and Structures, 2011
Finite element modeling is used in this study to optimize the electromechanical behavior of 0-3 composites according to the material properties of their constituents. Our modeling approach considers an 'extended' 2D representative volume element (RVE) with randomly dispersed piezoelectric particles. A variable distribution of their polarization axes is also implemented because a full periodic arrangement of fillers and a unique poling orientation are unrealistic in practice. Comparisons with a simpler RVE and with an analytical model based on the Mori-Tanaka approach are performed as a function of the particle concentration for the elastic, dielectric and piezoelectric homogenized properties. An optimization of the piezoelectric response of 0-3 composites according to material considerations is then computed, allowing it to be shown that the piezoelectric strain coefficient is not the only relevant parameter and that lead-free piezoelectric fillers such as LiNbO 3 and ZnO are competitive alternatives. Finally, the piezoelectric responses of 0-3 composites with different filler arrangements are quantitatively compared to 1-3 composites and to the corresponding bulk material.
Numerical representative volume element (RVE) models using ANSYS® finite element package are developed for 1–3 periodic composites made of piezoelectric (PZT) fibers embedded in a soft non-piezoelectric matrix (polymer matrix). The RVE method is used to predict the effective electromechanical coefficients of the periodic transversely isotropic piezoelectric cylindrical fiber composite. Special emphasis is placed on the formulation of the boundary conditions that allows the simulation of all modes of overall deformation arising from any arbitrary combination of mechanical and electrical loading. This numerical approach allows the extension to composites with arbitrary geometrical inclusion configurations, providing a powerful tool for fast calculation of their effective coefficients. The effective coefficients for hexagonal arrangements of unidirectional piezoelectric cylindrical fiber composites are evaluated for different fiber volume fractions. Then, for verification the homogeniz...
Journal of Electroceramics, 2010
This paper is concerned with the study of effective piezoelectric properties of 1-3 ferroelectric ceramic / polymer composites. The aim of this paper is to show the role of a combination of the electromechanical properties of components and microgeometry of the 1-3 composite in determining its anisotropic piezoelectric response. The system of ceramic rods in the form of elliptic cylinders is an important microgeometric factor that influences the piezoelectric coefficients and their anisotropy. Examples of the piezoelectric response and anisotropy are analysed for the 1-3 composites based on either "soft" or "hard" ceramic and having either piezo-active or piezo-passive matrix. Combinations of the ceramic and polymer components are found that provide different volumefraction dependences of the piezoelectric coefficients d à 3j and g à 3j : both monotonic, both non-monotonic, monotonic d à 3j and non-monotonic g à 3j , and vice versa. Examples of volumefraction dependences of electromechanical coupling factors k à 3j are also considered. A comparison of the effective piezoelectric coefficients calculated by the effective field method and the finite element method is carried out for different compositions in wide ranges of the ratio of semiaxes of the ellipse and of volume fractions of the components. Good agreement between data calculated by means of the aforementioned methods is obtained for the 1-3 structure comprising the elliptic cylinders.
Mechanics of Advanced Materials and Structures, 2019
Presented is a development of models for predicting the effective properties of a piezocomposite reinforced with hollow piezoelectric fibers. The models are established based on micromechanics of representative volume element so-called modified concentric cylinders model. Predicted are five effective elastic constants, two effective piezoelectric coefficients, one effective dielectric permittivity, and two thermal expansion coefficients. Numerical results of a chosen material system are discussed. Comparisons with finite-element method show very good agreements. The predicted effective properties of the piezocomposite with hollow fibers provide the enhancement in several performance parameters up to three times as high as those with solid piezoelectric fibers.