Showing papers on "Piezoelectricity published in 2000"
TL;DR: It is shown that a large piezoelectric response can be driven by polarization rotation induced by an external electric field, and the computations suggest how to design materials with better performance, and may stimulate further interest in the fundamental theory of dielectric systems in finite electric fields.
Abstract: Piezoelectric materials, which convert mechanical to electrical energy (and vice versa), are crucial in medical imaging, telecommunication and ultrasonic devices. A new generation of single-crystal materials, such as Pb(Zn1/3Nb2/3)O3-PbTiO3 (PZN-PT) and Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT), exhibit a piezoelectric effect that is ten times larger than conventional ceramics, and may revolutionize these applications. However, the mechanism underlying the ultrahigh performance of these new materials-and consequently the possibilities for further improvements-are not at present clear. Here we report a first-principles study of the ferroelectric perovskite, BaTiO3, which is similar to single-crystal PZN-PT but is a simpler system to analyse. We show that a large piezoelectric response can be driven by polarization rotation induced by an external electric field. Our computations suggest how to design materials with better performance, and may stimulate further interest in the fundamental theory of dielectric systems in finite electric fields.
1,789 citations
TL;DR: High resolution x-ray powder diffraction measurements on poled PbZr1-xTixO3 (PZT) ceramic samples have shown that for both rhombohedral and tetragonal compositions the piezoelectric elongation of the unit cell does not occur along the polar directions but along those directions associated with the monoclinic distortion.
Abstract: High resolution x-ray powder diffraction measurements on poled PbZr1-xTixO3 (PZT) ceramic samples close to the rhombohedral-tetragonal phase boundary (the so-called morphotropic phase boundary) have shown that for both rhombohedral and tetragonal compositions the piezoelectric elongation of the unit cell does not occur along the polar directions but along those directions associated with the monoclinic distortion. This work provides the first direct evidence for the origin of the very high piezoelectricity in PZT.
921 citations
TL;DR: In this article, the authors present a review of the deposition, integration, and device fabrication of ferroelectric PbZrxTi1-xO3 (PZT) films for applications in microelectromechanical systems.
Abstract: This paper reviews deposition, integration, and device fabrication of ferroelectric PbZrxTi1-xO3 (PZT) films for applications in microelectromechanical systems. As examples, a piezoelectric ultrasonic micromotor and pyroelectric infrared detector array are presented. A summary of the published data on the piezoelectric properties of PZT thin films is given. The figures of merit for various applications are discussed. Some considerations and results on operation, reliability, and depolarization of PZT thin films are presented.
846 citations
TL;DR: In this article, the behavior of piezoelectric elements as strain sensors is investigated and the performance of PZT and PVDF sensors compared with conventional foil strain gages is demonstrated.
Abstract: This paper investigates the behavior of piezoelectric elements as strain sensors. Strain is measured in terms of the charge generated by the element as a result of the direct piezoelectric ef- fect. Strain measurements from piezoceramic (PZT) and piezofilm (PVDF) sensors are compared with strains from a conventional foil strain gage and the advantages of each type of sensor are dis- cussed, along with their limitations. The sensors are surface bonded to a beam and are calibrated over a frequency range of 5-500 Hz. Correction factors to account for transverse strain and shear lag ef- fects due to the bond layer are analytically derived and experimentally validated. The effect of tem- perature on the output of PZT strain sensors is investigated. Additionally, design of signal condition- ing electronics to collect the signals from the piezoelectric sensors is addressed. The superior performance of piezoelectric sensors compared to conventional strain gages in terms of sensitivity and signal to noise ratio is demonstrated.
624 citations
TL;DR: In this article, the crystal orientation dependence of piezoelectric fields in wurtzite strained Ga0.9In0.1N/GaN heterostructures was analyzed.
Abstract: We calculated the crystal orientation dependence of piezoelectric fields in wurtzite strained Ga0.9In0.1N/GaN heterostructures. The highest longitudinal piezoelectric field of 0.7 MV/cm can be generated in (0001)-oriented biaxial-strained Ga0.9In0.1N layer coherently grown on GaN. On the contrary, no longitudinal piezoelectric field is induced in strained layers grown along orientations at an off angle of 39° or 90° from (0001). The high symmetry planes with these angles are, for instance, (1124) and (1012) for 39°, and (1120) and (1010) for 90°. We also calculated the crystal orientation dependence of the transition probability in a 3-nm strained Ga0.9In0.1N/GaN quantum well, which indicated that the transition probability with these non-(0001) orientations becomes 2.3 times larger than that with the (0001) orientation. We conclude that high-performance strained nitride-based optical devices can be obtained by control of the crystal orientation.
514 citations
TL;DR: Recent studies involve submicron films of aromatic and aliphatic polyureas prepared by vapor deposition polymerization in vacuum and the piezoelectricity of polyurethane produced by the coupling of electrostriction and bias electric fields.
Abstract: Electrets of carnauba wax and resin have exhibited good stability of trapped charges for nearly 50 years. Dipolar orientation and trapped charge are two mechanisms contributing to the pyro-, piezo-, and ferroelectricity of polymers. Since the 1950s, shear piezoelectricity was investigated in polymers of biological origin (such as cellulose and collagen) as well as synthetic optically active polymers (such as polyamides and polylactic acids). Since the discovery of piezoelectricity in poled polyvinylidene fluoride (PVDF) in 1969, the pyro-, piezo-, and ferroelectricity were widely investigated in a number of polar polymers, such as copolymers of vinylidene fluoride and trifluoroethylene, copolymers of vinylcyanide and vinylacetate, and nylons. Recent studies involve submicron films of aromatic and aliphatic polyureas prepared by vapor deposition polymerization in vacuum and the piezoelectricity of polyurethane produced by the coupling of electrostriction and bias electric fields. Gramophone pickups using a piece of bone or tendon were demonstrated in 1959. Microphones using a stretched film of polymethyl glutamate were reported in 1968. Ultrasonic transducers using elongated and poled films of PVDF were demonstrated in 1972. Headphones and tweeters using PVDF were marketed in 1975. Hydrophones and various electromechanical devices utilizing PVDP and its copolymers have been developed during the past 30 years. This paper briefly reviews the history and recent progress in piezoelectric polymers.
504 citations
27 Apr 2000
TL;DR: The Synchronized Switch Damping (SSD) as discussed by the authors is a semi-passive approach, where the piezoelectric inserts are continuously switched from open circuit to short circuit synchronously to the structure motion.
Abstract: The SSD technique proposed here addresses the problem of resonance damping on a mechanical structure. SSD stands for Synchronized Switch Damping. Apart from active techniques, passive ones consist in connecting a piezoelectric insert attached to the structure to a passive electric network in which the energy generated by the piezoelectric inserts is degraded. In the semi passive approach, the piezoelectric inserts are continuously switched from open circuit to short circuit synchronously to the structure motion. Due to this switching mechanism, a phase shift appears between the piezoelectric strain and the resulting voltage, thus creating energy dissipation. For the new technique proposed here, instead of discharging the piezoelectric inserts during a brief short circuit, they are connected on a small inductor, allowing the inversion of the voltage and then released to open circuit. In this case the voltage amplitude is optimized and is 90 degrees out of phase with the motion then enhancing the damping mechanism. The technique is applicable at any frequency without the need for a large tuned inductor, especially for low frequency applications. There is no need for external power supply unless for the low power circuitry of the switch device. The implementation of the switch drive with a very cheap micro-controller is described. Experimental results measured on cantilever beams made with different materials are proposed. Damping ability ranges from 6 dB on a very viscoelastic epoxy beam to nearly 20 dB on a steel beam. Harmonic excitation and transient results are both proposed and compared. Finally, an electromechanical model is proposed, giving an interpretation of the damping mechanism. Theoretical predictions are in good agreement with the experiments.
341 citations
TL;DR: In this article, a semi-active control law is used to switch the electrical shunt circuit of a piezoelectric actuator for energy dissipation in a simple mechanical system.
Abstract: In this paper, a semi-active control law is used to switch the electrical shunt circuit of a piezoelectric actuator for energy dissipation in a simple mechanical system. Switching is carried out between open-circuit (high stiffness) and short- or resistive-circuit (low stiffness) states. The actuator is held in its high stiffness state when the system is moving such that energy can be stored in the actuator. When the system’s motion would cause it to receive energy back from the actuator, the actuator is switched to a low stiffness state, dissipating the energy. In this paper, the concept is developed starting with the governing piezoelectric equations. Numerical simulation results are presented which show that the technique provides energy dissipation that is comparable to other piezoelectric shunt mechanisms, using optimal shunt resistance in each case. Finally, a brief analysis is presented in which the piezoelectric element is used in a flexible beam element to illustrate the effects of a parallel str...
334 citations
TL;DR: An analytical model based on structural vibration theory and theory of piezoelectricity was developed and used to predict the electromechanical (E/M) impedance response, as it would be measured at the PSS terminals as discussed by the authors.
Abstract: In the beginning, the classical one-dimensional analysis of piezoelectric active sensors is reviewed. The complete derivation for a free-free sensor is then extended to cover the cases of clamped and elastically constrained sensors. An analytical model based on structural vibration theory and theory of piezoelectricity was developed and used to predict the electromechanical (E/M) impedance response, as it would be measured at the piezoelectric active sensor’s terminals. The model considers one-dimensional structures and accounts for both axial and flexural vibrations. The numerical analysis was performed and supported by experimental results. Experiments were conducted on simple beam specimens to support the theoretical investigation, and on thin gauge aluminum plates to illustrate the method’s potential. It was shown that E/M impedance spectrum recorded by the piezoelectric active sensor accurately represents the mechanical response of a structure. It was further proved that the response of the structure...
270 citations
TL;DR: In this article, a simplified recipe for the direct finite-difference computation of the proper piezoelectric coefficients emerges naturally, from which a simplified algorithm for the proper PPI coefficients is presented.
255 citations
TL;DR: In this article, two different damage detection schemes are combined in this methodology, which involves utilizing the electromechanical coupling property of piezoelectric materials and tracking the changes in the frequency response function data, respectively.
Abstract: This paper presents an integrated methodology to detect and locate structural damage. Two different damage detection schemes are combined in this methodology, which involves utilizing the electromechanical coupling property of piezoelectric materials and tracking the changes in the frequency response function data, respectively. Physical changes in the structure cause changes in mechanical impedance. Due to the electromechanical coupling in piezoelectric materials, this change in structural mechanical impedance causes a change in the electrical impedance of the piezoelectric sensor. Hence, by monitoring the electrical impedance one can qualitatively determine when structural damage has occurred or is imminent. Based on the fact that damage produces local dynamic changes, this technique utilizes a high frequency structural excitation (typically greater than 30 kHz) through the surface-bonded piezoelectric sensor/actuators. As a second step, a newly developed model-based technique, using a wave propagation ...
TL;DR: In this article, the Luttinger-Kohn 6×6 Hamiltonians for the valence bands of the zinc-blende crystals written in the wurtzite bases for (001) and (111) crystal orientations were shown to be block diagonalized to two 3×3 Hamiltonians, which have analytical solutions for eigenvalues and eigenvectors.
Abstract: The electronic properties of (001)-, (111)-oriented zinc-blende and (0001)-oriented wurtzite crystals are investigated theoretically, where the spontaneous polarization and piezoelectric (PZ) field effects are taken into account. We show that the Luttinger–Kohn 6×6 Hamiltonians for the valence bands of the zinc-blende crystals written in the wurtzite bases for (001) and (111) crystal orientations and the Hamiltonian for the (0001)-orientation of wurtzite crystals can all be block diagonalized to two 3×3 Hamiltonians, which have analytical solutions for eigenvalues and eigenvectors. We then derive analytical expressions for the strain dependent band-edge effective masses and interband optical matrix elements of zinc-blende and wurtzite GaN crystals and compare their numerical results as well as valence band structures. Although the compressively strained zinc-blende quantum wells in materials such as GaAs- and ZnSe-based systems show reduced threshold carrier densities due to the lower in-plane effective m...
TL;DR: In this paper, the electromechanical response equations of polypropylene (pp) electrets are derived for their operation as sensors and as actuators, assuming reasonable charge distributions and charge densities, the calculated piezoelectric constants are in good agreement with measured values.
Abstract: Permanently charged films with a cellular or porous structure represent a new family of polymer electrets. These materials show piezoelectric properties with high piezoelectric constants. The electromechanical response equations of such films are derived for their operation as sensors and as actuators. Experimental results are also presented for cellular polypropylene (pp). In particular, measurements of the direct and inverse piezoelectric constants in the frequency range 0 to 10 kHz and of the variation of these constants across the surface of the films are discussed. These measurements, performed by direct application of stress or by the use of a profilometer, an accelerometer and an interferometer yield a frequency-independent piezoelectric d/sub 33/ constant of /spl lsim/ 220 pC/N. Assuming reasonable charge distributions and charge densities, the calculated piezoelectric constants are in good agreement with the measured values. The theoretical model shows the reciprocity of the piezoelectric constants.
TL;DR: In this article, the authors investigated the possibility of replacing the rotary type of fan in some noise-sensitive electronic devices by different vibrating metal plates and found that the resonant frequency of the vibrating plate decreases with the increase of its length ( l ) if the length of the piezoelectric ceramic bimorph (L ) is kept constant.
Abstract: Several types of piezoelectric fans for cooling electronic devices were constructed and tested at 60 Hz, 110 V and 220 V, respectively. The aim of the work is to investigate the possibility of replacing the rotary type of fan in some noise-sensitive electronic devices. Different vibrating metal plates were tested and analyzed theoretically. It is found that the resonant frequency of the vibrating plate decreases with the increase of its length ( l ) if the length of the piezoelectric ceramic bimorph ( L ) is kept constant. The series-type fan with l =31.8 mm, made of phosphor bronze vibrating plate (S6), shows the highest value of fan tip displacement of 35.5 mm and produced wind velocity of 3.1 m/s driven by a 220 V, 60 Hz power source.
TL;DR: In this paper, mass densities, relative dielectric constants, and piezoelectric material parameters were determined on single crystals of LGS, LGN, and LGT grown with high structural perfection by the Czochralski technique.
TL;DR: In this article, a closed-cell microporous polypropylene foams are shown to exhibit piezoelectric resonance modes in the dielectric function, coupled with a large anisotropy in the electromechanical and elastic material properties.
Abstract: Charged closed-cell microporous polypropylene foams are shown to exhibit piezoelectric resonance modes in the dielectric function, coupled with a large anisotropy in the electromechanical and elastic material properties. Strong direct and converse dynamic piezoelectricity with a piezoelectric d33 coefficient of 140 pC/N at 600 kHz is identified. The piezoelectric d33 coefficient exceeds that of the ferroelectric polymer polyvinylidene fluoride by a factor of 5 and compares favorably with ferroelectric ceramics. Applications of similar concepts should provide a broad class of easily fabricated “soft” piezoelectric materials.
TL;DR: New insight is presented into seven important considerations for the design of active piezoelectric polymer ultrasound transducer construction and packaging requirements, materials characterization and modeling, film thickness and active area design, electroding selection, backing material design, and front protection/matching layer design.
Abstract: Much work has been published on the design of ultrasound transducers using piezoelectric ceramics, but a great deal of this work does not apply when using the piezoelectric polymers because of their unique electrical and mechanical properties. The purpose of this paper is to review and present new insight into seven important considerations for the design of active piezoelectric polymer ultrasound transducers: piezoelectric polymer materials selection, transducer construction and packaging requirements, materials characterization and modeling, film thickness and active area design, electroding selection, backing material design, and front protection/matching layer design. Besides reviewing these design considerations, this paper also presents new insight into the design of active piezoelectric polymer ultrasonic transducers. The design and fabrication of an immersible ultrasonic transducer, which has no adhesive layer between the active element and backing layer, is included. The transducer features direct deposition of poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] copolymer onto an insulated aluminum backing substrate. Pulse-echo tests indicated a minimum insertion loss of 37 dB and -6 dB bandwidth of 9.8 to 22 MHz (71%). The use of polymer wear-protection/quarter-wave matching layers is also discussed. Test results on a P(VDF-TrFE) transducer showed that a Mylar/sup TM/ front layer provided a slight increase in pulse-echo amplitude of 15% (or 1.2 dB) and an increase in -6 dB pulse-echo fractional bandwidth from 86 to 95%. Theoretical derivations are reported for optimizing the active area of the piezoelectric polymer element for maximum power transfer at resonance. These derivations are extended to the special case for a low profile (i.e., thin) shielded transducer. A method for modeling the non-linear loading effects of a commercial pulser-receiver is also included.
TL;DR: In this article, a textured Nb-doped bismuth titanate ceramics (Bi4Ti32x/5NbX/5O12, where x 5 0.02) were fabricated by templated grain growth.
Abstract: Textured Nb-doped bismuth titanate ceramics (Bi4Ti32x/5Nbx/5O12, where x 5 0.02) were fabricated by templated grain growth. It was found that the use of a fine precursor powder led to enhanced densification of the ceramic, while Nb doping reduced electrical conduction and dielectric loss, which enabled poling at high temperatures and high electric fields. Sintered tapes showed anisotropic dielectric and piezoelectric properties when measured parallel and perpendicular to the casting plane (e.g., the remanent polarization differed by more than a factor of 15 in the two directions). The piezoelectric constant parallel to the casting plane of the tape was ;30 pC/N, or ;77% of the single-crystal value. Thermal depoling studies demonstrated that high-temperature piezoelectric applications are possible up to ;450°C in textured, doped bismuth titanate.
TL;DR: In this article, the authors present a basic creep model with some parameters that have hysteresis properties which make it possible to predict an open loop response of PZT actuators based on these properties.
Abstract: A major limitation of piezoelectric translator (PZT) actuators is their lack of accuracy originated from the hysteresis and creep. Nevertheless the creep phenomenon is an important factor in many applications of PZT actuators, but it has been investigated less frequently in comparison with the displacement hysteresis. In this article, we present a basic creep model with some parameters that have hysteresis properties which make it possible to predict an open loop response of PZT actuators based on these properties.
TL;DR: A new motor is presented which is judged to be capable of surpassing the characteristics of other piezoelectric motors because of its unique design which allows the piez Zoelectric drive elements to be pre-stressed in the direction of their polarization.
TL;DR: In this article, lead zirconate titanate (PZT) thin films with a Zr/Ti ratio of 52/48 were deposited on platinized silicon substrates by a sol-gel method and crystallized with preferred (111) or (100) orientation.
Abstract: Lead zirconate titanate (PZT) thin films with a Zr/Ti ratio of 52/48 were deposited on platinized silicon substrates by a sol-gel method and crystallized with preferred (111) or (100) orientation. Both the piezoelectric properties (d33) and the field-induced strains of the films with different thickness and preferred orientation were measured by a laser Doppler heterodyne interferometer. The weak-field dielectric constants and dissipation factors were also measured as a function of film thickness for comparison with other work reported in the literature. The field-forced polarization switching (P-E) behavior was examined by Sawyer–Tower measurement. Both the piezoelectric properties and the dielectric constants of the PZT thin films were found to be strongly dependent on the film thickness. An increase in the piezoelectric constants and dielectric constants with increasing film thickness was observed for both films with preferred (111) and (100) orientations. Films with (100) preferred orientation were fo...
TL;DR: In this paper, a diagnostic layer is adapted for detecting and measuring changes in the condition of the material, e.g., the site and extent of damage in the material and the curing process of a composite material.
Abstract: A diagnostic layer (10) having a network of actuators and sensors (14) may be incorporated into or on the surface of composite, metallic, and laminated materials (12) for monitoring the structural health of the material. The diagnostic layer (10) is adapted for detecting and measuring changes in the condition of the material, e.g., the site and extent of damage in the material. In a preferred embodiment, piezoelectric devices are embedded in the diagnostic layer in a network, and serve as actuators and sensors. Signals emitted from the sensors in response to physical deformation, either by an impact or as a result of stress waves generated (10) by actuators, are diagnostic of the current condition of the diagnostic layer. The diagnostic layer is also adapted to monitor the curing process of a composite material and accurately determine when curing is complete. Methods for monitoring changes in conditions of a material are also disclosed.
TL;DR: In this article, the converse piezoelectric effect using scanning force microscopy (SFM) combined with a lock-in technique was used to characterize at the nanoscale level ferroelectric SrBi2Ta2O9 and Bi4Ti3O12 thin films.
Abstract: The local polarization state and the electromechanical properties of ferroelectric thin films can be probed via the converse piezoelectric effect using scanning force microscopy (SFM) combined with a lock-in technique. This method, denominated as piezoresponse SFM, was used to characterize at the nanoscale level ferroelectric SrBi2Ta2O9 and Bi4Ti3O12 thin films, grown by pulsed laser deposition. Two types of samples were studied: polycrystalline films, with grains having random orientations, and epitaxial films, consisting of (100)orth- or (110)orth-oriented crystallites, 100 nm to 2 μm in lateral size, which are embedded into a (001)-oriented matrix. The ferroelectric domain structure was imaged and the piezoelectric response under different external conditions was locally measured for each type of sample. Different investigation procedures are described in order to study the ferroelectric properties via the electromechanical response. A distinct ferroelectric behavior was found for single grains of SrBi2Ta2O9 as small as 200 nm in lateral size, as well as for 1.2 μm×175 nm crystallites of Bi4Ti3O12. By probing separately the crystallites and the matrix the investigations have demonstrated at the nanoscale level that SrBi2Ta2O9 has no spontaneous polarization along its crystallographic c-axis, whereas Bi4Ti3O12 exhibits a piezoelectric behavior along both the a- and c-directions. The electrostriction coefficients were estimated to be 3×10-2 m4/C2 for polycrystalline SrBi2Ta2O9 and 7.7×10-3 m4/C2 for c-orientedBi4Ti3O12.
TL;DR: In this paper, the matrix and inclusions of 0-3 composites of lead titanate (PT) in polyvinylidenefluoride trifluoroethylene (P(VDF-TrFE)) have been independently poled by a special poling method.
Abstract: The matrix and inclusions of 0–3 composites of lead titanate (PT) in polyvinylidenefluoride trifluoroethylene (P(VDF–TrFE)) have been independently poled by a special poling method. The polarization states of both constituents are investigated by the measurement of the dynamic pyroelectric coefficients of the composites in the temperature range of 20–90 °C, within which the copolymer matrix undergoes a ferroelectric-paraelectric phase change. The pyroelectric coefficients of PT and P(VDF–TrFE) have the same sign, while their piezoelectric coefficients have opposite signs. This allows the preparation of composites with enhanced pyroelectric but reduced piezoelectric activity when the matrix and inclusions are polarized in the same direction, or vice versa if the constituents are oppositely polarized. For a PT volume fraction of 27% it was possible to prepare a pyroelectric composite with vanishing piezoelectric activity or a piezoelectric composite with vanishing pyroelectric activity by poling the matrix ...
TL;DR: In this article, a finite element unit cell model for investigation of arbitrary loading conditions is developed for composites with periodic arrangements of continuous aligned fibers, where special emphasis is placed on the formulation of the boundary conditions to allow for simulation of all modes of overall deformation arising from any arbitrary combination of mechanical and electrical loading.
TL;DR: In this article, a new actuation method of piezoelectric actuators for removing the hysteresis and creep effect was proposed and the actuation result was presented.
Abstract: Many researchers have studied the actuation of piezoelectric actuators using a model of the hysteresis of piezoelectric transducer (PZT). However, these hysteresis modeling methods to remove the nonlinearity in PZT did not include the consideration of PZT’s creep effect which is a very important factor in many open-loop application of piezoelectric actuator. In order to compensate for the creep effect of PZT as well as the hysteresis of displacement, the notion of “voltage creep” is proposed in this article. And, with the notion, a new actuation method of piezoelectric actuators for removing the hysteresis and creep will be proposed and the actuation result will be presented.
TL;DR: In this article, a critical energy density function prevails at the onset of crack initiation, it is possible to establish the relative size of an inner and outer damage zone around the crack tip; they correspond to the ligaments at failure caused by pure electric field and pure mechanical load.
TL;DR: In this paper, the static three-dimensional deformations of multilayered piezoelectric rectangular plates are obtained by using the Eshelby-Stroh formalism.
Abstract: Analytical solutions for the static three-dimensional deformations of multilayered piezoelectric rectangular plates are obtained by using the Eshelby-Stroh formalism. The laminated plate consists of homogeneous elastic or piezoelectric laminae of arbitrary thicknesses. The equations of static, linear, piezoelectricity are exactly satisfied at every point in the body. The analytical solution is in terms of an infinite series; the continuity conditions at the interfaces and boundary conditions at the edges are used to determine the coefficients. The formulation admits different boundary conditions at the edges and is applicable to thick and thin laminated plates. Results are presented for thick piezoelectric plates with two opposite edges simply supported and the other two subjected to various boundary conditions. @S0021-8936~00!01803-1#
TL;DR: In this paper, the authors provided a basic mechanics model for the flexural analysis of a sandwich beam coupled with a piezoelectric layer, where the Euler beam model for a long and thin beam structure was employed, together with the electric potential satisfying the surface free charge condition for free vibration analysis.
Abstract: This paper provides a basic mechanics model for the flexural analysis of a sandwich beam coupled with a piezoelectric layer. The Euler beam model for a long and thin beam structure is employed, together with the electric potential satisfying the surface free charge condition for free vibration analysis. The distribution of the piezoelectric potential is obtained by including the Maxwell equation in the formulation. Based on the results of vibration analysis, it is shown that the dynamic characteristic of the entire structure is related to the position of the piezoelectric layer. More importantly, the mode shape distribution of the electric potential in the piezoelectric layer in the longitudinal direction is related to the transverse displacement, or more accurately the curvature, of the sandwich beam, and the latter is dependent on the boundary conditions. Hence, the commonly adopted assumption of uniform electric potential in the longitudinal direction needs to be carefully re-examined. The distribution of electric potential obtained serves as a guide for selecting the trial function for the mode shapes of the electric potential required in numerical methods, such as FE modelling, for coupled piezoelectric structures.
TL;DR: In this article, 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.
Abstract: 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.