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A new paper-based microfluidic switch activated by surface acoustic wave (SAW) was presented. The switch was comprised of two folded paper microchannels and an unfolded paper microchannel. One of the folded paper microchannels was connected with the unfolded paper microchannel. Two interdigital transducers (IDTs) and two reflectors were fabricated on 128° yx-LiNbO3substrate using microelectrical technology. When an amplified RF signal was applied to the IDTs, a droplet on the piezoelectric substrate was actuated to the unfolded paper microchannel by SAW. Folded angle of a folded paper microchannel was increased and connected with the other folded paper microchannel to implement ‘on’ function of the microfluidic switch. The switch was examined using red dye solution microfluids and mixed indicating solution of 330 mmol/L Citric acidmonohydrate, 10 mmol/L N-(1-Naphthyl) ethylenediamine dihydrochloride and 50 mmol/L Sulfanilamide. The presented switch is valuable for programmable paper-based microfluidic device for multiple sample analyses. [ABSTRACT FROM AUTHOR]

In this paper, a coupled piezoelectric/semiconducting model is established and applied to study the effect of arbitrarily-located axial mechanical loadings on electric potential distribution in ZnO nanofiber, and the corresponding energy bands are computed via an eight-band k·p method. Results show that the band gap can be tuned by about 25 meV at band edges and about 200 meV away from band edges. The maximum valance band and minimum conduction band are located at band edges. The good mechano-electric effect of piezoelectric semiconductors and the simulating method presented in this paper can be used in designing novel semiconductor devices. [ABSTRACT FROM AUTHOR]

AbstractThis research paper investigates the complex dynamics of Love wave propagation on a piezoelectric plate situated atop a micropolar elastic half-space having imperfect interface. The study delves into the multifaceted effects of flexoelectricity, micro-inertia, guiding layer thickness, and interfacial imperfection on the characteristics of Love waves. The electromechanical coupling factor which is significant in analyzing SAW device performances is also studied. Variable separable method is used to solve the governing equations and desired solution is obtained analytically. The findings contribute to a deeper understanding of Love wave propagation in complex elastic structures and development of advanced sensors and communication technologies. [ABSTRACT FROM AUTHOR]

This paper introduces a tunable design for an electrically actuated vibrating ring micro-gyroscope. This mechanism contains eight piezoelectric micro-beams attached to the vibrating ring in each drive and sense directions. Employing a full geometric non-linear model for the vibrating ring and accounting for the micro-beam's mid-plane stretching; the mathematical model associated with the present system is obtained. Afterward, utilizing the Hamilton principle together with the Ritz method, the reduced equations of motion are derived. The present results are validated by those available in the literature for simpler systems. A three-dimensional (3D) finite element (FE) simulation was carried out in COMSOL Multiphysics commercial software for the case of static deformation since dynamic simulation imposes great computational costs. Next, in-depth parametric studies emphasizing the effect of piezoelectric actuation are conducted. Finally, reporting guidelines for tuning the present vibrating ring micro-gyroscope, the advantages of the proposed design are addressed. [ABSTRACT FROM AUTHOR]

Our paper deals with a mixed initial-boundary value problem in thermoelasticity of piezoelectric bodies with dipolar structure. It is considered the general case of a thermoelastic body which inhomogeneous and also anisotropic and we add the effect of piezoelectricity. We take into account the main equations and basic conditions of a temperature rate dependent theory which predict the waves propagation with a finite speed. Using some middle conditions imposed on the boundary conditions and initial data, we obtain that our mixed problem admits one solution. A generalized form of the Hamilton's principle is obtained to cover this context. [ABSTRACT FROM AUTHOR]

The principle of piezoelectricity has been used to design the micro-electro-mechanical system-based piezoelectric energy harvester for generating electrical energy from surrounding vibrations. The huge popularity of these energy harvesters (EHs) is due to their small size. This paper designs the EH for the heating, ventilation, and air conditioning system. Different cantilever structures with different shapes of the same fabricated area have been designed and investigated at an excited acceleration of 1 g (9.8 ms−2). The multi-perforated cantilever structure has the better stress distribution within the cantilever structure and generates better output voltage and power than their basic design. The proposed tapered multi-perforated cantilever structure has the least value of the resonant frequency of 98.59 Hz which is 31.13% less than the rectangular cantilever structure. The proposed structure generates the output voltage of 14 V which is 91.78% higher than the basic rectangular cantilever structure. It also generates the average output power of 7.15 µW which is 213.59% higher than basic rectangular cantilever structure. [ABSTRACT FROM AUTHOR]

This paper reviews recent studies conducted on various structural shapes coupled with piezoelectric materials for vibration energy scavenging. We focus primarily on micro and meso-sized geometrical structures designed with piezoelectric transducers to develop harvesters. A comprehensive analogy and contrasts between the reviewed works with regards to their advantages, applicability as well as their demerit are presented. We highlight issues that need to be addressed and potential future research to be conducted. It is hoped that this review will provide useful information in selecting suitable shapes of harvesters for maximum realization of energy from ambient vibration for utilization in various applications. [ABSTRACT FROM AUTHOR]

Piezoelectric quasicrystals have attracted the tremendous attention of researchers for their unique properties. In this paper, the semi-analysis solutions of the functionally graded multilayered two-dimensional decagonal piezoelectric quasicrystal plates are investigated for mixed boundary-value problems. Based on the quasicrystal linear elastic theory, the state-space method is employed to derive the state equations composed of partial differential along the thickness direction. The differential quadrature method is utilized to discretize state variables to satisfy the mixed boundary conditions in the horizontal plane. Different from the conventional propagator matrix, a new propagator relationship is proposed to study numerical instability caused by extensive discrete points. Comprehensive numerical results are shown for the sandwich quasicrystal plate with four different stacking sequences. The numerical results reveal the effect of the functional gradient index factors, and boundary conditions on the electric potential, electric displacements, stresses, and displacements under the mechanical/electric loadings. [ABSTRACT FROM AUTHOR]

This paper details several piezoelectric energy recovery interface circuits that have been widely studied at home and abroad to rectify the AC power generated by piezoelectric energy harvesting devices into DC power for direct utilization or storage, and divides the energy recovery circuits into single-stage, bipolar, and three-stage interface circuits according to the purpose and number of interfaces. According to the different interface circuits, the development history of each interface is introduced in detail, and a preliminary outlook on the piezoelectric energy harvesting circuit is provided for further improvement by related researchers. [ABSTRACT FROM AUTHOR]

This paper proposes a novel finite element model (FEM) that can completely characterize the galloping based piezoelectric energy harvester (GPEH) systems. The challenges faced by conventional analytical models in explaining the complex nonlinear dynamics of GPEHs are completely resolved. The present system consists of a cantilever beam with two piezoelectric patches and a square prism attached at the end. A FEM code, in MATLAB environment, is developed to solve the proposed model, and the solutions are compared with the experimental and analytical results from the literature. The lateral galloping force coefficient is represented by a 7th order polynomial based on the quasi-steady theory ensuring highest precision (proved in literature). The results from the present model are found to be in a good agreement with the experimental values, and the accuracy is better compared to the analytical solutions at low wind speeds (<2.5 m/s). The position of maximum efficiency lies near to the onset speed of galloping (2–3 m/s) and the magnitude decreases with further increase in the wind speed. The present work emphasizes the importance of FE (numerical) solution over the conventional analytical ones, and hence will open a door to explore new numerical models in this area. [ABSTRACT FROM AUTHOR]

Poly(vinylidene fluoride) (PVDF) has been a kind of particularly attractive piezoelectric materials for its excellent piezoelectric property. It has been proven that the piezoelectric property of PVDF can be improved by electrospinning. Recently, the technical innovations on the multiple aspects of preparing electrospun PVDF nanofibers such as collecting equipment and the pretreatment emerged in endlessly. The article introduces electrospinning briefly firstly and the second part of the paper introduces some recent research on the preparation of electrospun PVDF nanofibers. The researches about promising applications using electrospun PVDF nanofibers involve biomedicine, sensors, and energy harvesting due to its flexibility, biocompatibility, and outstanding performance. The last part of the paper reviews the typical research. [ABSTRACT FROM AUTHOR]

A piezoelectric geophone is a vibration transducer that converts mechanical vibrations into electrical signals via the piezoelectric effect. At present, the commonly used sensitive component of the conventional piezoelectric geophone is piezoelectric ceramic (PZT) material, which has low structural flexibility and high natural frequency. This paper reports a piezoelectric geophone based on polyvinylidene fluoride (PVDF) film with a sensitive unit composed of PVDF film and spiral cantilever beam, which can increase the sensitivity and reduce the low-frequency cutoff frequency. Firstly, the PVDF piezoelectric film is introduced, and the sensitive unit with PVDF piezoelectric film and spiral cantilever beam is designed. Secondly, the signal conditioning circuit and the digital module circuit are designed according to the characteristics of the detector and the test environment. Finally, the performance tests and fabrication of the geophone are carried out. The results indicate that the piezoelectric geophone has a stable sensitivity of 230 mV/m/s2 in the range of 4–90 Hz, which are superior to the existing piezoelectric geophone. [ABSTRACT FROM AUTHOR]

Energy harvesting from piezoelectric is proved to be a viable technology to source low power electronic devices. In this paper, piezoelectric energy harvester is designed such that the energy is harvested by utilizing the switching of the MOSFET in DC-DC converter, which becomes an integral part of modern industrial equipment. Energy harvesting is realized by piezoelectric and converse effect of piezoelectric material. The harvester is designed to have transmitter and receiver piezoelectric separated by metal plate, connected across the drain and source terminals of the MOSFET. The performance of the harvester is experimentally evaluated with boost converter for supercapacitor storage. [ABSTRACT FROM AUTHOR]

In this paper, we are concerned with a time-dependent transmission problem for a thermo-electric-magneto-elastic solid immersed in an inviscid and compressible fluid. It is shown that the problem can be treated by the boundary-field equation method, provided an appropriate scaling factor is employed. Based on estimates of variational solutions in the Laplace-transformed domain, we obtain the properties of corresponding solutions in the time-domain without having to perform explicit inversions of the variational solutions in the Laplace-transformed domain. [ABSTRACT FROM AUTHOR]

A multi-component measurement system centred on piezoelectric force sensor is an important mechanical measurement device, in which the piezoelectric sensor is mainly composed of force-sensitive components. The force-electric conversion performance of quartz wafer containing seed crystal and quartz crystal wafers is the main issue of the research in this paper. In the way of microscopic imaging and X-ray diffraction spectrum analysis, based on macroscopic physical properties of crystals, the theoretical basis of piezoelectric effects and the Neumann principle of elastic mechanics, both kinds of crystals have the same matrix of positive piezoelectric effects. Through static and continuous loading tests on quartz wafer containing seed crystal and ordinary quartz wafer, the maximum deviation of the electric charge, respectively, generated by X0° and Y0°cut type seed crystal wafers and ordinary quartz wafer in the static test under the same vector force loading is finally obtained, both seed-containing wafer and ordinary quartz wafer have excellent linearity. In continuous loading test, seed-containing wafer also has good continuous loading performance and can maintain a stable charge output under quasi-static input. Therefore, it is concluded that seed crystal wafers can also be used for actual testing. [ABSTRACT FROM AUTHOR]

In this paper, we analyze acoustic wave propagation in anisotropic fluids and solids. By formulating the acoustic system as an evolution equation over a Hilbert space, we obtain global in time solutions when the associated material parameters are bounded and measurable. In particular, we prove well-posedness of a Cauchy problem for wave propagation in piezoelectric crystals. We then provide a stability analysis of these solutions not assuming positive definiteness of the stress–strain tensor or the piezoelectric stress tensor. Finally we prove continuous dependence on initial data, allowing the piezoelectric tensor to depend on space and time, provided solutions belong to an appropriate function space. [ABSTRACT FROM AUTHOR]

In this paper, a size-dependent Euler–Bernoulli beam model, which takes the flexoelectricity, piezoelectricity, and dielectricity as well as the surface elasticity into consideration, is established. Theoretical solutions for the static bending deflection of thin beams under different loading (uniformly distributed and concentrated load) and boundary conditions (cantilevered, both ends simply supported, clamped–clamped), are established. Moreover, an iterative finite element algorithm is developed for the analysis of thin flexoelectric beams under any load and boundary conditions. Our numerical results show the direct bulk flexoelectricity always play the role of stiffening the beams with various boundary conditions, while the residual surface stresses behave either stiffening or softening the nanobeams dependent on boundary conditions. The present investigation also demonstrates the size-dependent effects of flexoelectricity on the bending rigidity and piezoelectricity. [ABSTRACT FROM AUTHOR]

This paper concerns laminates made of composite plies with piezoelectric actuators. The subject of the paper is the research of laminates having, in some directions, null expansion coefficients in extension or having the same expansion coefficient in each direction (isotropic behavior). The general equations for the problem are given in the theoretical framework of the so-called polar method for the representation of plane tensors. Some simple formulas are given for the case of expansion coefficients of a standard plate introduced in the paper. Some numerical examples close the paper. [ABSTRACT FROM AUTHOR]

The article introduces a series of papers on phase transition materials and piezoelectricity. In particular, these papers discuss materials having unusually strong piezoelectric character and contain experimental results on x-ray and neutron diffraction, dielectric and infrared spectroscopy, the existence of morphotropic phase boundaries, and the relaxor/ferroelectric crossover in disordered materials.

This paper investigates the thermo-electro-mechanical effects in the nonlinear response of piezoelectric laminated plates exposed to thermal and/or mechanical fields. The mechanics incorporate a) the direct piezoelectric effect through the coupling between electric-mechanical fields, b) the pyroelectric effect through the coupling between electric-thermal fields, and c) the geometric nonlinear effects due to large rotations and initial stresses. Building upon the nonlinear multifield mechanics an eight-node plate finite element is developed to discretize the generalized coupled nonlinear equations, which are subsequently linearized and iteratively solved, using the Newton-Raphson technique. Numerical evaluations demonstrate the capability of the present model to capture both of direct piezoelectric and pyroelectric effects in the nonlinear electromechanical response of piezoelectric composite plates, exposed to thermal and/or mechanical fields. The influence of direct piezoelectric and pyroelectric effects on thermal buckling and postbuckling response of various piezocomposite plates, is investigated. The possibility of pyroelectric effect to promote thermal buckling of piezocomposite plates with attached sensor patches is also quantified. The influence of thermo-electro-mechanical effects on the nonlinear response of smart composite plates, subject to either uniform or gradient temperature variations is finally illustrated. [ABSTRACT FROM AUTHOR]

C-eigenvalues and C-eigenvectors of piezoelectric-type tensors play an important role in the piezoelectric effect and the converse piezoelectric effect. In this paper, with the help of components of general C-eigenvectors, we present a new class of inclusion sets to locate all general C-eigenvalues for a given general piezoelectric-type tensor. Finally, numerical examples are reported to be tighter than some existing results. [ABSTRACT FROM AUTHOR]

The main goal of this paper is to develop a mathematical model for the piezoelectric elastic-semiconductor medium. The medium is homogeneous and isotropic that is exposed to photothermal excitation processes. Gauss's law of electrostatics is used to obtain the effect of the piezoelectric phenomenon. The governing equations with the electric potential are expressed in terms of thermoelasticity theory and photothermal theory. One-dimensional Laplace transform is used to get the solution of some physical quantities when the heat sources and body forces are absent. The mechanical forces and thermal loads are used to get the analytical solution of physical quantities under investigation. The inverse Laplace technique with a numerical method is employed to obtain the solution in the time-physical domain. A novel parameter depends on pyro-electric moduli is presented. Some numerical results are illustrated and shown graphically. [ABSTRACT FROM AUTHOR]

The paper reports on the piezoelectric performance, electromechanical coupling and related energy-harvesting figures of merit of three forms of 1–2–2 composites based on domain-engineered single crystals. The effect of the single-crystal piezoelectric properties and elastic properties of the laminar polymer matrix on the appropriate figures of merit of the composite is studied. The main active components of the studied composites are [0 0 1]-poled perovskite-type single crystals with chemical compositions: 0.92Pb(Zn1/3Nb2/3)O3–0.08PbTiO3, 0.67Pb(Mg1/3Nb2/3)O3–0.33PbTiO3 and [Lix(K1−yNay)1−x](Nb1−zTaz)O3: Mn, where x = 0.06, y = 0.1–0.3, z = 0.07–0.17, and the level of Mn doping is 0.25 mol. %. Examples of non-monotonic volume-fraction dependences of the piezoelectric properties, figures of merit and anisotropy factors are analysed. New diagrams are first built to demonstrate the volume-fraction regions where a large anisotropy of the piezoelectric coefficients d3j* and electromechanical coupling factors k3j* is achieved, and where energy-harvesting figures of merit of the composite are at least five times larger than analogous parameters of single-crystal components. The studied 1–2–2 composites are of interest as anisotropic materials with high piezoelectric sensitivity and large figures of merit which are important for sensor, energy-harvesting and related applications. [ABSTRACT FROM AUTHOR]

An adaptive energy harvesting system for high voltage piezoelectric generators is presented in this paper. Maximum power point tracking scheme is applied in the adaptive system. Low-power-consumption schemes are applied in the control system and harvesting circuit. A self-startup circuit is also applied to the system. Theoretical analysis was explored to determine optimal parameters for the harvesting system. Experiments were done to verify the theoretical analysis. The experimental results show that the harvesting system can achieve an efficiency of 17.5 ∼ 73.3% for piezoelectric generator with a peak open-circuit voltage of 6 ∼ 20 V. And the harvesting system can be self-powered from low input power as 25 μW. The average power consumption of the microcontroller can be low as 3.5 μW. [ABSTRACT FROM AUTHOR]

This paper describes the manufacture of structural composites incorporating piezoelectric fibres which are finding interest in applications such as shape-changing applications, sensors to detect mechanical strain or vibration and energy harvesting. In this paper preliminary results are presented for a simple cantilever structure consisting of piezoelectric fibres with planar electrodes that are co-cured within a carbon fibre reinforced plastic (CFRP). Processing methods to embed functional fibres are described along with characterization of the piezoelectric and mechanical properties of the resulting material. [ABSTRACT FROM AUTHOR]

In this paper, a multiobjective optimization approach for obtaining the optimal distribution of surface-bonded piezoelectric sensors and actuators for noise attenuation in sandwich panels is presented. The noise attenuation is achieved by using negative velocity feedback control with co-located sensors and actuators. The control gains are also optimized in order to obtain the most efficient noise attenuation in a given frequency band. An in-house implementation of a viscoelastic soft core sandwich plate finite element, including surface-bonded piezoelectric sensors and actuators with active control capabilities, is used for obtaining the frequency response of the panels. The sound transmission capability of the panels is evaluated using the radiated sound power, along with the Rayleigh integral approach, which is suitable for lightly coupled structural/acoustic problems. The Direct MultiSearch (DMS) optimization algorithm is used to minimize the added weight due to the piezoelectric material, minimizing also the number of required controllers and maximizing the noise attenuation. The total length of the radiated sound power curve is shown to be an effective measure of noise attenuation in a given frequency band. Trade-off Pareto fronts and the obtained optimal configurations are presented and discussed. [ABSTRACT FROM AUTHOR]

In this paper, effect of Dy3+substitution on structural, microstructural, dielectric, ferroelectric and piezoelectric properties of barium titanate has been studied. Results of density measurement indicates that substitution of Dy3+results in increase in density of BT. Grain size increases significantly with the substitution of Dy3+. Dy3+substituted BT sample possess higher dielectric constant, better ferroelectric properties but weak piezoelectric properties. [ABSTRACT FROM AUTHOR]

The use of piezoelectric ceramics as actuators and/or sensors is prevalent. This paper is aimed to explore simple but useful equivalent circuit models of piezoelectric ceramics with the consideration of energy dissipation. Based on the electrical impedance, the equivalent circuit models of piezoelectric ceramics are investigated under unloaded and loaded conditions. The characteristics and physical meanings of the circuit models are discussed by considering the frequency range of interest. The circuit models and discussions in this paper can provide a good understanding on the behaviors of the piezoelectric ceramics when designing and analyzing the piezo-based systems and structures. [ABSTRACT FROM AUTHOR]

The propagation characteristics of Love wave form an essential basis for designing highly sensitive microacoustic devices for sensing applications. In this paper, the propagation of Love wave in a micropolar-piezoelectric structure is investigated with the objective of enhancing the performance of Love wave-based devices. A study has been carried out by using two sets of a piezoelectric material, i.e. PZT-5H and BaTiO 3 material. The closed-form expression of the dispersion relations is derived analytically for electrically open and electrically short conditions. The effects of internal microstructures of the micropolar elastic half-space, the thickness of a piezoelectric layer, the piezoelectric constants, and the dielectric constants are illustrated graphically on the phase velocity for both the considered materials of the piezoelectric layer under electrically open and short conditions. [ABSTRACT FROM AUTHOR]

Among Aurivillius-phase ferroelectric ceramics, CaBi2Nb2O9 is considered as the best candidate with potential applications in ultrahigh-temperature piezoelectric devices due to the highest Tc (∼940 °C). This paper reports that BiMn co-substitution at A and B sites gives rise to dramatic enchantments in ferroelectricity, piezoelectricity, and electrical resistivity of CaBi2Nb2O9 ceramics. The optimum composition (Ca0.97Bi2.03Nb1.99Mn0.01O9) with a Tc of 953 ± 3°C shows a high ferroelectric remnant polarization (Pr), field-induced strain (S33), piezoelectric activity d33 and d 33 ∗ with values of ∼11.1 µC/cm2, 4.9 × 10−4, 20.8 and 26.1 pC/N, respectively, which are about two to three times those of CaBi2Nb2O9. Significant ferroelectric remnant polarization (Pr = 11.1 µC/cm2), field-induced strain (S33 = 4.9 × 10−4), and piezoelectric activity (d33 = 20.8 pC/N, d 33 ∗ = 26.1 pC/N) are simultaneously induced in ultrahigh Tc CaBi2Nb2O9 piezoceramics by BiMn substitution. [ABSTRACT FROM AUTHOR]

An algorithm for the layout of a piezoelectric that provides the most efficient performance within a specified range of vibration frequencies is proposed in this paper. This algorithm is based on the consideration of a special parameter within the area of a piezoelectric element's possible location. This parameter characterizes the superposition of electromechanical coupling coefficients' for all the natural vibration frequencies included in a specified frequency range. The condition for defining the best option for location of the piezoelectric element in the case of several equivalent positions is specified. The efficiency of the proposed algorithm is shown numerically. The electromechanical coupling coefficients were calculated numerically based on solution to the problem of natural vibrations for electroelastic bodies using a finite element method. The calculations were performed to define the best location for a single piezoelectric element at the surface of a thin-walled shell having a half-cylindrical shape. The results are presented for natural vibration frequencies within the frequency range from 0 up to 1100 Hz. The numerical results were obtained by solving the problem of natural vibrations with a finite element method using the ANSYS software package. [ABSTRACT FROM AUTHOR]

In this paper, we look into the fundamental mechanism to retrieve the power from physical vibrations by using microelectromechanical systems (MEMS) energy harvesters. An analytical model is presented for the velocity-damped resonant generator (VDRG) that delivers electrical power through the power enhancement mechanism using the mechanical resonance of a suspended mass. Deliverable power is also analytically discussed with respect to the theoretical limit, and a view to understand the VDRG behaviors is presented in association with the impedance matching condition and the quality factors. Mechano-electric power conversions including electrostatic induction, electromagnetic induction, and piezoelectric effect are discussed to study the scaling effect. Recent examples of MEMS VDRGs are reviewed and evaluated in terms of the power density. [ABSTRACT FROM AUTHOR]

In this paper some variational principles are revisited for the fundamental equations of a regular region of piezoelectric, thermopiezoelectric, and hygrothermopiezoelectric (but non-stochastic, non-local, and non-relativistic) materials in the elastic range. Certain oversights, and especially, those involving the so-called Hu-Washizu variational principle of piezoelectricity that was first formulated in a paper ("Variational Principles in Piezoelectricity," Lettere Al Nuovo Cimentò, vol. 7, 449-454, 1973) are clarified within the "ISI-Web of Science" publications in the open literature. Similar variational principles of piezoelectricity are cited. [ABSTRACT FROM AUTHOR]

A connecting tube between the measured object and the pressure sensing element is a common component part of pressure measurement systems. Dynamic characteristics of the resulting fluid oscillator may significantly influence the magnitudes of dynamic measurement errors. This paper presents an experimental analysis of dynamic characteristics of connecting tubes of different lengths and diameters. Inlet step pressure changes were generated by a system of two loudspeakers, and pressure responses were measured by a piezoelectric measurement system. Using the measured responses, the characteristic natural frequencies and damping of the system under discussion were determined. The results were further employed to estimate the response settling time, which is required to sufficiently reduce dynamic measurement errors. [ABSTRACT FROM AUTHOR]

Active systems have attracted a great deal of attention in the last few decades due to the potential benefits they offer over the conventional passive systems in various applications. Dealing with active systems requires the possibility of modeling and simulation of their behavior. The paper considers thin-walled active structures with laminate architecture featuring fiber reinforced composite as a passive material and utilizing piezoelectric patches as both sensor and actuator components. The objective is the development of numerically effective finite element tool for their modeling. A 9-node degenerate shell element is described in the paper and the main aspects of the application of the element are discussed through a set of numerical examples. [ABSTRACT FROM AUTHOR]

This paper presents a three-dimensional microfabrication and integration technology for MEMS smart materials that utilizes a spray coating method. Spray coating is shown to be most effective for additional deposition on non-planar surfaces. PZT films were formed both on flat and uneven surfaces at a thickness of about 1μ m. Perovskite structures were formed with suitable heat treatment and ferroelectric P-E hysteresis loop was also obtained. This paper is the first report from our group and other researchers on the deposition of smart materials for MEMS using a spray coating method. Spray coating has been proposed as an effective three-dimensional coating method which can be used to deposit piezoelectrics, pyroelectrics, magnetics, etc. for sensors and actuators. The hydrophilic and hydrophobic properties between the substrate surface and ejected liquid are most essential process factors in the spray coating method for improving the film growth conditions. [ABSTRACT FROM AUTHOR]

This paper is presented to achieve the objective of energy harvesting from vibrational sources through piezoelectric materials. In this analysis, two piezoelectric buzzers: 35 mm buzzer and 27 mm buzzer were used to carry out the experiment. The experimental set-up includes an electro-dynamic shaker, function generator and a power amplifier. Buzzer of thickness 35 mm gave maximum output at resonant frequency of 23 Hz and 57 g of mechanical stress while buzzer of thickness 27 mm gave maximum output at resonant frequency of 25 Hz and 27 g of weight. The paper also presents some important applications of piezoelectricity in day-to-day life. [ABSTRACT FROM PUBLISHER]

This paper presents a two-stage adaptive boost converter with low-voltage starter for low voltage piezoelectric energy harvester. The adaptive technique can deal with a range of input voltages from the piezoelectric generator for required output voltages. The parameters of the converter including inductance, switching frequency, duty cycles and the input/output voltage are studied for conversion efficiencies. The experiment results show that a two-stage adaptive boost converter can achieve a conversion efficiency of 84.3%∼91.3% for a piezoelectric harvester in the considered low voltage range to charge an 1.5Venergy storage device. [ABSTRACT FROM AUTHOR]

This paper focuses on the characterization and static structural analysis of piezoelectric actuator to investigate the sequential increasing effect of piezoelectric patches. The effect on the tip deflection is observed analytically, numerically and experimentally. By varying the quantity and the geometry of piezoelectric patches/beams, the actuation effect is analyzed. A mathematical model has been developed for the unequal lengths of patches and beam. The analysis is carried out numerically to examine the tip deflection under various parameters. The results are analyzed and verified experimentally. The results are found to be in accordance with the analytical and numerical results. This permits the desired configuration of an actuator in applications like hydraulic valves for actuating and controlling the flow of liquid as per need. [ABSTRACT FROM AUTHOR]

Piezoelectric actuators are widely used in many fields such as medical instruments, optics, and aerospace due to their small size and high reliability. Piezoelectric cantilever actuators are used in different configurations such as unimorph and bimorph. In this paper, a 3-D lead zirconate titanate (PZT) bimorph was modeled in COMSOL Multiphysics software for investigation of series and parallel configuration. Theoretical analysis has been developed for the measurement of deformation of a piezoelectric cantilever in inverse piezoelectric effect. The experiment was also performed to examine the deformation of piezoelectric bimorph cantilever. It is found that under a constant applied electric field of 100 V bimorph piezoelectric actuator produces maximum deformation at 100 mm length, 30 mm width, and 20 mm thickness. It is also found that piezoelectric series benders have relatively less deformation than piezoelectric parallel benders. Experimental results show good agreement with theoretical and Numerical results. [ABSTRACT FROM AUTHOR]

This paper presents an analytical method to study the effect of inclusions in piezoelectric materials on the creep rate. The driven force for the creep rate of piezoelectric materials with inclusion is from diffusional mass transport along the inclusion interface. The results show that the creep rate of piezoelectric materials containing the rigid inclusion with the shape parameter m = 0.8 appears at the minimum, and the effect of inclusion volume fraction on the creep rate of piezoelectric materials with soft inclusion becomes the smaller and smaller, as the stiffness of soft inclusion decreases. Thus, the effect of inclusion on creep characteristics can be improved by controlling the material property, the sizes, shapes, and volume ratio of inclusions. [ABSTRACT FROM AUTHOR]

The hydrokinetic energy of flowing water is plentiful, environment-friendly, renewable and can be harvested. This paper reports a new energy harvesting system using vortex-induced vibration (VIV). The proposed convertor harvests vibrations of a bluff body resulting from interaction of the alternating vortices created by the unsteady separation. These vortices are shed from the sides of the bluff body and form a pattern in the wake known as the von Kármán vortex street. The vortices create unsteady loading and induce vibrations with a predictable frequency and amplitude. Assisted by the bluff body with specific geometry and piezoelectric generators, the kinetic energy of the water flow can be converted into mechanical vibrations and electrical energy. In order to maximise the output energy of the harvester, the natural frequency of the mechanical system needs to lock into the frequency of the VIVs. Thus, the geometry of the bluff body has to be optimised to match the natural frequency of the convertor. This study examines the conceptual design of the physical model. The fluid-structure interaction model is applied to study the preliminary design. The maximum energy density that can be extracted by the proposed convertor from the water flow with velocities from 0.2 to 1 m/s is also estimated.Abbreviations: 1.CFD Computational Fluid Dynamics; 2.DC Direct Current (electricity); 3.FIM Fluid Induced Motion; 4.ODE Ordinary Differential Equation; 5.PTC Passive Turbulence Control; 6.VIV Vortex Induced Vibration; 7.VIVACE Vortex Induced Vibration Aquatic Clean Energy; 8.2D Two Dimensional [ABSTRACT FROM AUTHOR]

The paper focuses on the analysis of the multicaloric effect in solids. In particular, the presented approach is applicable to thin films as well. For the piezoelectric material, the multicaloric phenomenon includes two well-known effects: electro and elastocaloric; and two new ones - piezoelectocaloric and flexocaloric. These new effects are due to the temperature dependence of the piezoelectric and flexoelectric coefficients. The piezoelectric effect at medium fields is found to be comparable with the electrocaloric one and can be called a giant. The obtained results can be used for the design and optimization of new cooling devices and generators. [ABSTRACT FROM PUBLISHER]

Surface effect responsible for some size-dependent characteristics can become distinctly important for piezoelectric nanomaterials with inherent large surface-to-volume ratio. In this paper, we investigate the surface effect on the free vibration behavior of a spherically isotropic piezoelectric nanosphere. Instead of directly using the well-known Huang-Yu surface piezoelectricity theory (HY theory), another general framework based on a thin shell layer model is proposed. A novel approach is developed to establish the surface piezoelectricity theory or the effective boundary conditions for piezoelectric nanospheres employing the state-space formalism. Three different sources of surface effect can be identified in the first-order surface piezoelectricity, i.e. the electroelastic effect, the inertia effect, and the thickness effect. It is found that the proposed theory becomes identical to the HY theory for a spherical material boundary if the transverse stress components are discarded and the electromechanical properties are properly defined. The nonaxisymmetric free vibration of a piezoelectric nanosphere with surface effect is then studied and an exact solution is obtained. In order to investigate the surface effect on the natural frequencies of piezoelectric nanospheres, numerical calculations are finally performed. Our numerical findings demonstrate that the surface effect, especially the thickness effect, may have a particularly significant influence on the free vibration of piezoelectric nanospheres. This work provides a more accurate prediction of the dynamic characteristics of piezoelectric nanospherical devices in nano-electro-mechanical systems. [ABSTRACT FROM AUTHOR]

Because of the importance of the electromagnetic interference resistance in the modern life, the electromagnetic shielding of the piezoelectric vibration acceleration sensor is analyzed in this paper. The shell of the piezoelectric vibration acceleration sensor is taken as a three-layer rectangular cavity with apertures. The shielding effectiveness of the shell irradiated by plane electromagnetic wave is modelled using transmission line theory. In the modeling process, incident angle and polarization angle of the plane electromagnetic wave are introduced, and the scattering voltage produced on the outer aperture is taken as the radiation source. The aperture is taken as the asymmetrical coplanar stripline and the rectangular cavity is taken as a rectangular waveguide with one end completely open and another end completely closed. The shielding effectiveness of the cavity is calculated using transmission line theory. Compared to the others before, this method improves the completeness of the model, computation speed, and the shielding effectiveness which supplies good reference for engineering practice. [ABSTRACT FROM AUTHOR]

In this paper, a cylindrical piezoelectric quasi-travelling wave motor, which used only a single vibrator to generate bidirectional rotations by changing the driving signal frequencies, was presented. The stator of the proposed motor consists of a metal tube and one piece of piezo-plate bonded onto the tube. Because of the asymmetric structure design, the single piezo-plate can excite two degenerated bending modes at one resonant frequency for generating rotation; while it can also excite a torsion mode and a bending vibration at another resonant frequency for generating reverse rotation. The prototype motor, whose stator was 6 mm in diameter and 26 mm in length, can rotate anticlockwise at a driving frequency of ∼51 kHz and clockwise at a driving frequency of ∼58 kHz. The motor achieved a maximum speed of 606 rev min−1 and a stall torque of 1·08 mN m under a driving voltage of 116Vp-p. This research has provided a design way for piezo-motor miniaturisation. [ABSTRACT FROM AUTHOR]

A self-powered piezoelectric energy harvesting interface circuit (PEHIC) with wide input range and good performance is presented in this paper. The proposed PEHIC consists of a two-stage active charge pump rectifier and an ultra-low power intermittent power management unit (IPMU). Active diodes based on unbalanced-biased comparators improve the reverse leakage current problem that conventional active diodes faced. By limiting the output voltage between 1.2 and 0.8 V, the IPMU working in intermittent mode can provide an expanded input range and ensure that the interface circuit has a large transient output power. Implemented in a 65 nm standard complementary metal oxide semiconductor (CMOS) technology, the PEHIC has been simulated and verified. Simulation results show that an AC signal with amplitude ranging from 0.32 to 1.5 V and frequencies of 20 Hz-3 kHz can be rectified. The maximum output current is as large as 5 mA. The peak power conversion efficiency is up to 81% when the input voltage is 0.8 V at 200 Hz. The PEHIC can be self-powered without the need for additional power supply. [ABSTRACT FROM AUTHOR]

This study discloses the diode’s influences on the piezoelectric energy harvesting performance. The piezoelectric-based energy harvesting system plays an important role in scavenging environment vibration energy into electrical energy, which can be utilized by low-power electronic devices. With respect to the interface circuit, a full-wave bridge circuit is usually needed to rectify the alternating current (AC) signal into a direct current (DC) signal. The full-wave bridge is composed of four diodes, whose characteristics may influence the harvested power significantly. Therefore, in this paper, the diodes’ properties and influences on the energy harvesting performance are analyzed and presented via simulation and experimental studies. It is found the harvested energy has close relationship with the diode characteristics. For the high source impedance case, diode with low reverse leakage current is favorable. For the low source impedance case, diode with low forward voltage drop is favorable. The corresponding experimental study is carried out via a piezoelectric beam, which shows that the measured harvested power differences can almost be up to 800% for the same test structure. [ABSTRACT FROM AUTHOR]

The thickness vibration mode of the piezoelectric composite is the most common operation mode in transducer applications. The study on the thickness vibration characteristics plays a key role in application.In this paper, the influence of volume fraction of piezoceramic on the thickness vibration characteristics of 1-3 piezoelectric composites was investigated. Through finite element analysis and simulation, the relationship between vibration performance parameters and the ceramic volume fraction of composites was obtained. The samples with volume fraction of 0.2 ∼ 0.6 were prepared by cutting and filling and tested by Impedance Analyzer.Experimental and simulation results were matched by comparison. [ABSTRACT FROM AUTHOR]

In this paper, vibration analysis of a circular polymeric piezoelectric is presented. The microplate is modelled using Kirchhoff theory. The viscoelastic property of the polymer is introduced using Kelvin–Voigt laws. The interaction with fluid is modelled as a damping foundation beneath the plate. Moreover, anisotropic piezoelectric properties of the polymer are considered. The boundary conditions are clamped at the outer edges. Taking into account all above matters, the governing equation is derived. Free and force vibration of the problem is solved using assumed mode method and Newmark’s β method. The effect of variations in input voltage, damping coefficient, viscoelastic parameter and excitation frequency is investigated. The results are compared with developed finite element methods. Excellent agreement is observed between two methods. [ABSTRACT FROM AUTHOR]