Browsing by Author "Kuo, Hsin-Yi"

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Anisotropic multiferroic ellipsoidal particulate composites
(2020-02-01)
Kuo, Hsin-Yi
;
Ling, Yu-Hsiang
;
土木工程學系
;
Department of Civil Engineering
The objective of this work is to investigate the magnetoelectricity (ME) of an ellipsoidal particulate composite made of piezoelectric and piezomagnetic phases. We employ a micromechanical model, the Mori-Tanaka mean-field method, to evaluate the effects of crystallographic orientations of the constituents, and the aspect ratio, volume fraction, and orientations of the ellipsoids. We compare this micromechanical solution with those predicted by the finite element analysis, which provides the benchmark results for a periodic array of inclusions. Based on this model, we find the optimal aspect ratio and volume fractions of the inclusion when the ellipsoids are poled along the normal direction. Further, we show that, for the case of CoFe2O4\documentclass[12pt]$$\hbox {BaTiO}_{{3}}$$\end{document} ellipsoidal particulate composite, the ME voltage coefficient can be enhanced at the optimal orientation as compared to those at normal cut.
Decoupling transformation for piezoelectric-piezomagnetic fibrous composites with imperfect interfaces
(2015-02-01)
Kuo, Hsin-Yi
;
Chen, Chin-Yuan
;
土木工程學系
;
Department of Civil Engineering
We study the effective magnetoelectricity of piezoelectric-piezomagnetic fibrous composites with imperfect interfaces subjected to anti-plane shear deformation coupled to in-plane electromagnetic fields. Two kinds of imperfect interfaces, mechanically stiff and highly electromagnetic conducting interfaces, and mechanically compliant and weakly electromagnetic conducting interfaces, are considered for the phenomenon of contact resistance between the constituents. The decoupling transformation approach previously used in composite media with perfect interfaces is extended to the current configuration. The predicted macroscopic behaviors are in good agreement with the known solutions. It is observed that moduli of the composite with imperfect contacts do not fulfill the compatibility conditions L*La-1Lb - LbLa-1L* = 0, which was supposed to be microstructure independent connections for the two-phase heterogeneous media. Finally, we use the two-level recursive scheme to show the equivalence between the imperfect interfaces and an infinity thin homogeneous interface layer. (C) 2014 Elsevier Ltd. All rights reserved.
Effect of the imperfect interface on the scattering of SH wave in a piezoelectric cylinder in a piezomagnetic matrix
(2014-12-01)
Kuo, Hsin-Yi
;
Yu, Shu-Han
;
土木工程學系
;
Department of Civil Engineering
We propose an exact analysis for the scattering of an anti-plane shear wave by a piezoelectric circular cylinder in a piezomagnetic matrix with imperfect interfaces. Two typical imperfect interfaces are investigated: mechanically stiff and highly electromagnetic conducting interfaces, and mechanically compliant and weakly electromagnetic conducting interfaces. We obtain the fields of scattered wave by means of series expansion, and show that whether the interface is a perfect contact or with imperfection, it is sufficient to invert a 4 x 4 matrix and an infinite number of 6 x 6 matrices to solve the involved unknowns. Numerical examples are presented to demonstrate the effect of the imperfection on the directivity patterns, scattering cross-sections, and potential field distributions. Results show that the mechanical or highly electric conducting imperfect interface has great effect on those values. Further, we observe a large low-frequency peak of the scattering cross-section for the composite with mechanical stiff imperfection. (C) 2014 Elsevier Ltd. All rights reserved.
Effective magnetoelectric effect in multicoated circular fibrous multiferroic composites
(2011-05-15)
Kuo, Hsin-Yi
;
Pan, Ernian
;
土木工程學系
;
Department of Civil Engineering
Rayleigh's formalism is generalized for the evaluation of the effective material properties in multicoated circular fibrous multiferroic composites. The derived solution is applied to the special three-phase composite in which coated fibers are embedded in a matrix. For composites made of piezoelectric (BaTiO(3)) and piezomagnetic (CoFe(2)O(4) or Terfenol-D) phases, we find that the magnetoelectric effect in the composite made of CoFe(2)O(4) coated BaTiO(3) in matrix Terfenol-D is five times larger than that in the composite made of BaTiO(3) coated Terfenol-D in matrix CoFe(2)O(4). Furthermore, in each case, with appropriate coating to the circular fiber, the magnetoelectric effect in the coated composites can be enhanced by more than one order of magnitude as compared to the corresponding noncoating composite. (C) 2011 American Institute of Physics. [doi:10.1063/1.3583580]
Effective moduli of multiferroic fibrous composites with spring-type imperfect interfaces under generalized plane strain with transverse electromagnetic fields
(2016-02-01)
Kuo, Hsin-Yi
;
Huang, Tzu-Yu
;
土木工程學系
;
Department of Civil Engineering
This paper studies the effective behavior of multiferroic fibrous composites with imperfect interfaces subjected to generalized plane strain deformation coupled to out-of-plane electromagnetic fields. Mechanically compliant and weakly electromagnetic conducting interfaces are considered for the phenomenon of contact resistance between the constituents. The complex variable approach previously used in elastic composite media with perfect interfaces is extended to the current configuration. We obtain the closed-form formula of the effective property by adopting the dilute scheme, Mori-Tanaka method, ad hoc approximation, and the two-level recursive scheme. Numerical examples are considered to illustrate the effect of imperfect interfaces, and to compare the results among different micromechanical models. (C) 2015 Elsevier Ltd. All rights reserved.
Effective property of multiferroic fibrous composites with imperfect interfaces
(2013-10-01)
Kuo, Hsin-Yi
;
土木工程學系
;
Department of Civil Engineering
This paper studies the effective behavior of piezoelectric and piezomagnetic circular fibrous composites with imperfect interfaces under longitudinal shear with in-plane electromagnetic fields. Two kinds of imperfect contact are investigated: mechanically stiff and dielectrically/magnetically highly conducting interfaces, and mechanically compliant and dielectrically/magnetically weakly conducting interfaces. For the former case, the potential field is continuous, while the normal component of the flux undergoes a discontinuity across the interface. For the latter case, the normal component of the flux is continuous, while there is a jump of potential field at such a contact. The classic work of Rayleigh (1892 Phil. Mag. 34 481-502) in a periodic conductive perfect composite is generalized to the current coupled magnetoelectroelastic composites with imperfect interfaces. It is shown that the expression of the effective property has exactly the same form as that in the ideal coupling composite. Finally, this method is used to study BaTiO3-CoFe2O4 composites and provide insights into enhancing the effective magnetoelectric voltage coefficient by properly choosing the interface.
Electrostatic interactions of arbitrarily dispersed multicoated elliptic cylinders
(2010-03-01)
Kuo, Hsin-Yi
;
土木工程學系
;
Department of Civil Engineering
We propose a theoretical framework for evaluation of electrostatic potentials in an unbounded isotropic matrix containing a number of arbitrarily dispersed elliptic cylinders subjected to a remotely prescribed potential field. The inclusions could be homogeneous or confocally multicoated, and may have different sizes, aspect ratios and different conductivities. The approach is based on a multipole expansion formalism, together with a construction of consistency conditions and translation operators. This procedure generalizes the approach of the classic work of Rayleigh [1] for a periodic array of circular disks or spheres to an arbitrarily dispersion of elliptic cylinders. We combine the methods of complex potentials with a re-expansion formulae and the generalized Rayleigh's formualtion to obtain a complete solution of the many-inclusion problem. We show that the coefficients of field expansions can be written in the form of an infinite set of linear algebraic equations. Numerical results are presented for several configuarions. We further apply the obtained field solutions to determine the effective conductivity of the composite. (C) 2009 Elsevier Ltd. All rights reserved.
Fibrous composites of piezoelectric and piezomagnetic phases
(2013-07-01)
Kuo, Hsin-Yi
;
Bhattacharya, Kaushik
;
土木工程學系
;
Department of Civil Engineering
We propose a theoretical framework for evaluation of magnetoelectroelastic potentials in a fibrous composite with piezoelectric and piezomagnetic phases, motivated by the technological desire for materials with large magnetoelectric coupling. We show that the problem with transversely isotropic phases can be decomposed into two independent problems, plane strain with transverse electromagnetic fields and anti-plane shear with in-plane electromagnetic fields. We then consider the second problem in detail, and generalize the classic work of Lord Rayleigh (1892) to obtain the electrostatic potential in an ordered conductive composite and its extension to a disordered system by Kuo and Chen (2008) to the current coupled magnetoelectroelastic problem. We use this method to study BaTiO3-CoFe2O4 composites and provide insights into obtaining large effective magnetoelectric coefficient. (C) 2012 Elsevier Ltd. All rights reserved.
Fibrous composites of piezoelectric and piezomagnetic phases: Generalized plane strain with transverse electromagnetic fields
(2014-08-01)
Kuo, Hsin-Yi
;
土木工程學系
;
Department of Civil Engineering
This work presents a theoretical framework for solving the field distributions of a piezoelectric-piezomagnetic fibrous composite subjected to generalized plane strain with transverse electromagnetic fields. The matrix is infinite containing arbitrarily distributed circular cylinders, which may have different sizes and material properties. By introducing an eigenstrain corresponding to the electro-magneto-elastic effect, this coupling problem can be reduced to an equivalent plane elasticity problem. The classic work of Muskhelishvili to obtain the elastic potential of a composite is generalized to the current multi-field multi-inclusion media. Several numerical examples are presented to demonstrate the effectiveness of the approach. (C) 2014 Elsevier Ltd. All rights reserved.
Functionally graded piezoelectric-piezomagnetic fibrous composites
(2018-04-01)
Kuo, Hsin-Yi
;
Hsin, Kai-Chi
;
土木工程學系
;
Department of Civil Engineering
We investigate the magnetoelectric effect and potential fields of functionally graded multiferroic fibrous composites under anti-plane shear deformation coupled to in-plane electric and magnetic fields. The cylinders are exponentially graded along the radial direction. Rayleigh's formalism and composite cylinder assemblage model are generalized to account for the configuration. We find that the grading parameter has a dramatic effect on the potential field of the inclusion and the effective property of the composite. We adopt this approach to numerically study the exponentially graded composite and provide insights into developing new multiferroic fibrous media with high magnetoelectric coupling.
Magnetoelectric effect of three-phase core-shell-matrix particulate multiferroic composites
(2012-03-01)
Kuo, Hsin-Yi
;
Wu, Tzu-Sheng
;
土木工程學系
;
Department of Civil Engineering
This paper studies the magnetoelectricity of a core-shell-matrix three-phase particulate composite made of piezoelectric (PE) and piezomagnetic (PM) phases. We propose a micromechanical model, the two-level recursive scheme in conjunction with Mori-Tanaka's method, to investigate the effective magnetoelectric coupling coefficients of the composite. We compare this micromechanical solution with those predicted by finite element analysis, which provides the benchmark results for a periodic array of inclusions. Both the magnitudes and trends between them are in good agreement. Based on this micromechanical approach, we show that, for the case of PE/PM/PM (core/shell/matrix) multiferroic composite, with a coating appropriate for the inhomogeneity, the effective magnetoelectric coupling can be enhanced many-fold as compared to the noncoated counterpart. Further, useful design principles are proposed for engineering magnetoelectric composites. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3692385]
Magnetoelectricity in coated fibrous composites of piezoelectric and piezomagnetic phases
(2013-01-01)
Kuo, Hsin-Yi
;
Peng, Cheng-You
;
土木工程學系
;
Department of Civil Engineering
This paper studies the effective magnetoelectric (ME) behavior of coated fibrous composites made of piezoelectric and piezomagnetic phases. We employ a micromechancial model, the two-level recursive scheme together with the Mori-Tanaka method, to evaluate the ME effect of the composites. The magnitudes and trends of the solutions are in good agreement with the calculations by the finite element analysis. Based on this model, we find the optimal volume fractions of the inclusion, the ratio of the radii between the core and shell for maximum ME coupling. Further, we correlate the ME effect with the material parameters of the constituent phases and propose useful engineering guide to the development of new ME coated fibrous composites. (C) 2012 Elsevier Ltd. All rights reserved.
Magnetoelectricity in multiferroic particulate composites with arbitrary crystallographic orientation
(2012-10-01)
Kuo, Hsin-Yi
;
Kuo, You-Min
;
土木工程學系
;
Department of Civil Engineering
This paper studies the magnetoelectricity (ME) of a spherical particulate composite made of piezoelectric and piezomagnetic phases. The effects of crystallographic orientations and the volume fraction of inclusion are investigated by a micromechanical approach. The solutions are in good agreement with predictions by finite element analysis. Based on this micromechanical method, we show that, for the CoFe2O4-LiNbO3 particulate composite, the effective ME voltage coefficient can be enhanced at the optimal orientation as compared to those at normal cut orientation. Further, we observe that the ME coupling is sensitive to the piezoelectric constant e(15). The optimal orientation of the ME voltage coefficient is near that of the piezoelectric constant e(15).
Multicoated elliptic fibrous composites of piezoelectric and piezomagnetic phases
(2011-07-01)
Kuo, Hsin-Yi
;
土木工程學系
;
Department of Civil Engineering
A theoretical framework is developed to investigate the magnetoelectroelastic potential in a multicoated elliptic fibrous composite with piezoelectric and piezomagnetic phases. We generalize the classic work of Rayleigh (1892) to obtain the electrostatic potential in ordered conductive composites and its extension to a disordered system (Kuo, 2010; Kuo & Chen, 2008) to the current coupled magnetoelectroelastic multicoated elliptic composites. We combine the methods of complex potentials with a re-expansion formulae and the generalized Rayleigh's formulation to obtain a complete solution of the multi-field many-inclusion problem. It is shown that the coefficients of field expansions can be written in the form of an infinite set of linear algebraic equations. Numerical results are presented for several configurations. We use this method to study BaTiO(3)-CoFe(2)O(4) composites and find that, with appropriate coating, the effective magnetoelectric voltage coefficient can be enhanced with one order of magnitude compared to their non-coating counterpart. (C) 2011 Elsevier Ltd. All rights reserved.
Multilayer multiferroic composites with imperfect interfaces
(2018-07-01)
Kuo, Hsin-Yi
;
Wu, Tien-Jung
;
Pan, Ernian
;
土木工程學系
;
Department of Civil Engineering
We study the macroscopic behaviors of multilayered multiferroic composites with interface imperfections by a direct micromechanical approach. Both generalized interface stress type and generalized linear spring type imperfect interfaces are considered. Concise matrix expressions of the overall behaviors of the layered piezoelectric-piezomagnetic composite with contact imperfection are presented. The key step is to observe that the two types of imperfect interface conditions are equivalent to the perfect ones due to the laminated geometry. Numerical calculations are demonstrated for BaTiO3-CoFe2O4 multilayer media, and are shown in good agreement with the more involved interphase model. Furthermore, it is observed that the interface imperfection would reduce the magnitude of the magnetoelectric voltage coefficients as compared to the corresponding perfect interface case. This feature is opposite to that predicted and observed in the corresponding cylindrical composites.
Optimization of magnetoelectricity in multiferroic fibrous composites
(2012-07-01)
Kuo, Hsin-Yi
;
Wang, Yong-Liang
;
土木工程學系
;
Department of Civil Engineering
"We propose a method to optimize the effective magnetoelectric voltage coefficient of fibrous composites made of piezoelectric and piezomagnetic phases. The optimization of magnetoelectricity is with respect to the crystallographic orientations and the volume fraction for the two materials. We show that the effective in-plane (alpha(E.11)*) and out-of-plane (alpha(E.33)*) coupling constants can be enhanced many-fold at the optimal orientation compared to those at normal orientation. For example, we show that the constants are 101 and 5 times larger for the optimal orientation of CoFe2O4 fibers in a BaTiO3 matrix of the optimized volume fraction compared to the normal orientation, while they are 43 and 5 times larger for BaTiO3 fibers in a CoFe2O4 matrix. The predictions are in good agreement with the finite element analysis. (C) 2012 Elsevier Ltd. All rights reserved."
Optimization of magnetoelectricity in piezoelectric-magnetostrictive bilayers
(2010-12-01)
Kuo, Hsin-Yi
;
Slinger, Alex
;
Bhattacharya, Kaushik
;
土木工程學系
;
Department of Civil Engineering
Magnetoelectric coupling is of interest for a variety of applications, but is weak in monolithic materials. Strain-coupled bilayers or multilayers of piezoelectric and magnetostrictive material are an attractive way of obtaining enhanced effective magnetoelectricity. This paper studies the optimization of magnetoelectricity with respect to the crystallographic orientations and the relative thickness of the two materials. We show that the effective transverse (alpha(E,31)) and longitudinal (alpha(E,33)) coupling constants can be enhanced many-fold at the optimal orientation compared to those at normal orientation. For example, we show that the constants are 17 and 7 times larger for the optimal orientation of a lithium niobate/Terfenol-D bilayer of equal thickness compared to the normal orientation. The coupling also increases as the piezoelectric phase gets thinner.
Optimization of magnetoelectricity in piezoelectric-magnetostrictive bilayers
(2010-12-01)
Kuo, Hsin-Yi
;
Slinger, Alex
;
Bhattacharya, Kaushik
;
土木工程學系
;
Department of Civil Engineering
Magnetoelectric coupling is of interest for a variety of applications, but is weak in monolithic materials. Strain-coupled bilayers or multilayers of piezoelectric and magnetostrictive material are an attractive way of obtaining enhanced effective magnetoelectricity. This paper studies the optimization of magnetoelectricity with respect to the crystallographic orientations and the relative thickness of the two materials. We show that the effective transverse (alpha(E,31)) and longitudinal (alpha(E,33)) coupling constants can be enhanced many-fold at the optimal orientation compared to those at normal orientation. For example, we show that the constants are 17 and 7 times larger for the optimal orientation of a lithium niobate/Terfenol-D bilayer of equal thickness compared to the normal orientation. The coupling also increases as the piezoelectric phase gets thinner.
Scattering of anti-plane shear waves by arbitrarily distributed circular cylinders in a functionally graded multiferroic fibrous composite
(2018-04-01)
Kuo, Hsin-Yi
;
Huang, Yu-An
;
Sun, Chi-Hsiang
;
土木工程學系
;
Department of Civil Engineering
In this work, a theoretical framework is developed for the multiple scattering of an anti-plane shear wave by a functionally graded multiferroic fibrous composite. The composite consists of arbitrarily distributed circular cylinders and may have different sizes and material constituents. The cylinders are exponentially graded along the radial direction. We exploit the multipole expansions, transition matrix, and Graf's addition/binomial expansion theorems to obtain a complete solution of the multiple scattering problem in the scenario of functionally graded multiferroic composites. These solved magneto-electro-elastic fields are then used to obtain the directivity patterns of the scattered wave, dynamic stress (electric displacement/magnetic flux) concentration factors, and scattering cross sections. Numerical results reveal the profound influence of the functionally graded parameter, the material properties of constituent phases, the number of inclusions, as well as the frequency of a propagating SH wave on the scattered field induced by the functionally graded fibers. It is expected that the formulation and numerical results serve as useful references for the design and manufacture of functionally graded piezoelectric-piezomagnetic fibrous composites under dynamic loadings.
Size-dependent effective behaviors of multiferroic fibrous composites with interface stress
(2017-02)
Kuo, Hsin-Yi
;
Wang, Kai-Hong
;
土木工程學系
;
Department of Civil Engineering
The objective of this work is to study the size-dependent effective behaviors of multiferroic fibrous composites with interface stress subjected to generalized in-plane deformation and out-of-plane electromagnetic fields. Using the complex variable approach together with several micromechanical models, closed form expressions of the effective moduli are obtained. In contrast to the composite with perfect bonding, the effective property formulations show the dependence on the size of the fibers. The derived solutions are applied to several examples to demonstrate the effect of interface stress, and to examine the results among different micromechanical models. Numerical results show that while most of the effective moduli increase as the radius of the fiber decreases, the magnetoelectric voltage coefficient, the figure of merit of the multiferroic material, decreases. Further, when considering the effective transverse shear modulus of composite with interface stress, a higher order approximation is required for the equivalency between an interphase and an imperfect interface if the interphase is not sufficiently thin or is very stiff. (C) 2016 Elsevier Ltd. All rights reserved.