Limits to the enhancement of piezoelectric transducers achievable by materials engineering

Smith, W.A.

doi:10.1109/ultsym.1992.275912

Cited by 7 publications

(16 citation statements)

References 8 publications

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“…Variations in temperature and magnetic ®eld are considered unimportant. This is compatible with the piezoelectric ceramics, polymers, and composites in current use (see Smith 1992). With these assumptions, the behavior of the piezoelectric medium is described by the following piezoelectric constitutive equations which relate the stress T ij , strain S kl , electric ®eld E k , and electric displacement D i (see IEEE 1984):…”

Section: Constitutive Equations Of Piezoelectric Materialsmentioning

confidence: 93%

“…Substituting (18) into the microscopic equation and seeking its solution, we obtain two sets of equations (see Telega 1990, and Galka et al 1992):…”

Section: Theoretical Formulationmentioning

confidence: 99%

“…This can be achieved by designing the unit cell of the piezocomposite material using a similar procedure as in the case of elastic structures. The space of achievable properties for the piezocomposite material is also dictated by thermodynamic considerations that require positive de®niteness of the tensor involving the elastic, piezoelectric, and dielectric properties, as discussed in Smith (1992). Other bounds however, are not available for piezoelectric materials in the literature.…”

Section: Introductionmentioning

confidence: 99%

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Optimal design of piezoelectric microstructures

Silva

Fonseca

Kikuchi

1997

Computational Mechanics

139

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Application of piezoelectric materials requires an improvement in their performance characteristics which can be obtained by designing new topologies of microstructures (or unit cells) for these materials. The topology of the unit cell (and the properties of its constituents) determines the effective properties of the piezocomposite. By changing the unit cell topology, better performance characteristics can be obtained in the piezocomposite. Based on this idea, we have proposed in this work an optimal design method of piezocomposite microstructures using topology optimization techniques and homogenization theory. The topology optimization method consists of ®nding the distribution of material phase and void phase in a periodic unit cell, that optimizes the performance characteristics, subject to constraints such as property symmetry and stiffness. The optimization procedure is implemented using sequential linear programming. In order to calculate the effective properties of a unit cell with complex topology, a general homogenization method applied to piezoelectricity was implemented using the ®nite element method. This method has no limitations regarding volume fraction or shape of the composite constituents. Although only two-dimensional plane strain topologies of microstructures have been considered to show the implementation of the method, this can be extended to threedimensional topologies. Microstructures obtained show a large improvement in performance characteristics compared to pure piezoelectric material or simple designs of piezocomposite unit cells. IntroductionPiezoelectric materials have the property of converting electrical energy (electric ®eld and applied electrical charge) into mechanical energy (strain and stress) and vice versa. They are widely used in electromechanical sensors and actuators such as robotics sensors, ultrasonic transducers for medical imaging and non destructive evaluation (NDE), underwater acoustics (some hydrophones and naval sonars), and other applications. The main goal in the transducer design in all these applications is to increase the response of the transducer which can be achieved, for example, by increasing the electromechanical energy conversion. The energy conversion depends on many factors, one of the most important being the properties of the piezoelectric material. In this work, we consider ultrasonic imaging and naval sonar applications. In these applications, it is well known that materials such as``1±3 piezocomposite'' (piezoceramic rods embedded in a soft polymer matrix) allow greater sensitivity, in both low and high frequency applications, than pure piezoceramic (see Auld 1991, andSmith 1993). This improvement occurs because the composite material provides effective properties (elastic, piezoelectric, and dielectric) that produce a better performance than pure piezoelectric materials. These effective (homogenized) properties can be determined by considering the topology of the composite microstructure (or unit cell, the smallest structure that is periodic ...

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Section: Constitutive Equations Of Piezoelectric Materialsmentioning

confidence: 93%

“…Substituting (18) into the microscopic equation and seeking its solution, we obtain two sets of equations (see Telega 1990, and Galka et al 1992):…”

Section: Theoretical Formulationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Optimal design of piezoelectric microstructures

Silva

Fonseca

Kikuchi

1997

Computational Mechanics

139

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“…This requirement leads to specific algebraic constraints on the material properties [8], [9], such as the Poisson's ratios, σ E 12 , σ E 13 , and σ E p , and coupling factors, k 31 , k p , k t , and k 33 , be less than one in magnitude. In isotropic materials, the Poisson's ratio has an even more restricted range-between minus 1 and plus 0.5-but in anisotropic materials the situation is somewhat more complex [8], [9]. The quantity k i3 was introduced as maximal material CEMC to an electric field along the material's polar axis (denoted as z or 3).…”

Section: Introductionmentioning

confidence: 99%

Invariants of electromechanical coupling coefficients in piezoceramics

Mezheritsky

2003

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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The relationships between coefficients of electromechanical coupling (CEMC) of various types of piezoceramic resonator (PR) vibrations are considered. Being constant for a given piezoceramic state, the range of variation of piezoceramics dielectric permittivity from a mechanically "free" condition at relatively low frequencies up to an "overall clamped" condition at high frequencies is determined by a consecutive "clamping", caused by a complex of CEMCs of various particular vibrational modes peculiar to the resonator. As the difference between "free" and "overall clamped" permittivities is always determined by the maximal piezomaterial k i3 coupling coefficient, the difference does not depend on the path that was gone through the low-high frequency range, which includes all the vibrational modes possible for a particular PR. The influence of the piezoelectric and elastic anisotropy of lead-zirconatetitanate (PZT) piezoceramic materials on relative CEMC variations was experimentally investigated.

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“…Em geral, estas combinações resultam em novos materiais compósitos que oferecem vantagens substanciais em relação a materiais piezelétricos convencionais. Assim, em transdutores de ultrassom e sonares, por exemplo, estas vantagens são alto acoplamento eletromecânico, o qual mede a conversão de energia no piezocompósito (portanto, sua sensibilidade), e baixa impedância acústica, que auxilia na transmissão das ondas acústicas para o meio, como tecidos do corpo humano ou água (SMITH, 1989;SAFARI, 1994). O projeto de materiais piezocompósitos tem sido aplicado a sensores e transdutores (AKDOGAN; ALLAHVERDI; SAFARI, 2005), transdutores bilaminares ou bimorphs (SMITS; DALKE; COONEY, 1991; SEELEY; CHATTOPADHYAY; BREI, 1996; IM; KIM; ROH, 1998), transdutores flextensionais (ABDALLA et al, 2005), transdutores ultrassônicos (LAMBERTI et al, 2000;ANDRADE et al, 2009; LI; LISSENDEN, 2011), piezocompósitos para coleta de energia (TIEN; GOO, 2010) e transdutores piezocompósitos de casca com orientação de fibra (KIYONO; SILVA; REDDY, 2012), entre outros.…”

Section: Introductionunclassified

Projeto de materiais piezocompósitos baseados no conceito de gradação funcional utilizando o método de otimização topológica.

Vatanabe¹

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Ao meu orientador, Prof. Dr. Emílio C. N. Silva, agradeço pela atenção dispensada, discussões estimuladas e sugestões dadas durante todo o período de elaboração deste trabalho. Os anos de convívio me proporcionaram enorme amadurecimento acadêmico, profissional e pessoal. Ao Prof. Dr. Glaucio H. Paulino, agradeço pela colaboração nas publicações dos artigos e principalmente pelo incentivo e motivação para o desenvolvimento desta pesquisa. À EPUSP (Escola Politécnica da Universidade de São Paulo) por disponibilizar toda a infraestrutura necessária para o desenvolvimento desta pesquisa. À FAPESP (Fundação de Amparo à Pesquisa do Estado de São Paulo) pela concessão da bolsa de doutorado, viabilizando a realização deste trabalho. Ao CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico) pelo apoio financeiro neste trabalho. Minha sincera gratidão à minha mãe Fujika, ao meu pai Luiz Carlos e à minha irmã Francina, pela educação que vocês me deram, pela formação que vocês me proporcionaram e pelo apoio incondicional em todos os meus sonhos. À Valência, agradeço pelo amor e apoio incondicional, e à sua mãe Elisa, pelo apoio ao longo deste trabalho.

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Limits to the enhancement of piezoelectric transducers achievable by materials engineering

Cited by 7 publications

References 8 publications

Optimal design of piezoelectric microstructures

Optimal design of piezoelectric microstructures

Invariants of electromechanical coupling coefficients in piezoceramics

Projeto de materiais piezocompósitos baseados no conceito de gradação funcional utilizando o método de otimização topológica.

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