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Piezoelectric ceramics with high electro strain are widely used in actuators, sensors, and so on. Here, this work investigates the electro strain of representative piezoelectric materials, and analyzes the influence of electrode type on the electro strain of PZT41 with significant strain anomalies. It is found that the occurrence of abnormally significant strain is not affected by the electrode but caused by intrinsic defects. Therefore, the ceramic samples with and without defects tailoring in Na 0.5 Bi 0.5 TiO 3 (NBT) based and PbZr 0.52 Ti 0.48 O 3 (PZT) based systems were prepared by the solid-state reaction method, and the results show that abnormally ultrahigh electro strains occur in excessively thin samples with diploes due to defects tailoring. Through displacement configuration experiments and comprehensive analysis of polarization switching processes, it is found that the occurrence of asymmetric abnormal significant strains is caused by reversible bending deformation in excessively thin samples. This work provides new support for the emergence of ultrahigh electro strain in piezoelectric ceramics. [ABSTRACT FROM AUTHOR]

We discovered large electric-field-induced strain in pyro-vanadate-phosphate Cu2−xZnxV1.8P0.2O7. Distinct from conventionally used piezoelectric materials including lead-zirconate-titanate, this material expands almost isotropically at room temperature when an electric field is applied. This volume change, exceeding 1000 ppm under the field of E = 3900 V/cm, is of the largest class induced by an electric field. The strain is phenomenologically interpreted as electrostriction because it is symmetric about E = 0 and because it obeys a higher term than E-linear such as E squared. The present x-ray diffraction experiments suggest that the applied electric field distorts the crystal lattice, although there is no structural phase transition. This material performs a volume-change-driven actuator function that is distinct from the strain-driven counterpart of piezoelectric materials. The discovery of actuator functionality in a material system with a non-perovskite structure, unlike the actuator materials developed to date, is a major breakthrough for future actuator engineering. [ABSTRACT FROM AUTHOR]

Purpose: This work proposes a model for assessing the dynamic behavior of a non-uniform Functionally Graded Piezoelectric Material (FGPM) tapered beam exposed to a harmonic electrical load. The FGPM structure is modeled as a unimorph cantilever beam with the top surface made of piezoelectric material and split into ten sections; each section is considered an independent actuator. Methods: Timoshenko's assumptions and Hamilton's principle are used to derive the dynamic equation of motion based on the finite element method (FEM). The damping effect was taken into account according to the well-known Raleigh formula. Results: First, a validation procedure is performed to check the proposed model's correctness. Then, a parametric analysis is carried out to predict the effect of material and geometrical characteristics on the beam's output on both frequency-domain and time-domain, such as the power law index, taper ratio, and degree polynomial function. A comparison between the vibrational energy for different parameters is investigated. Finally, the effect of piezoelectric patch locations is examined within the time-domain. Conclusions: The findings showed that the resonance frequency decreases as the power law index rises. In addition, it declines when the polynomial degree and taper ratio parameters are raised. Indeed, for the referential case N = 1 (n = 0), the vibrational energy was reduced with a fraction ranging from 7.35% to 22.35%. Meanwhile, increasing taper ratio values implies a reduction from 23.10% ( α = 0.3 ) to 55.68% ( α = 0.5 ). The obtained results show that the investigated factors including the patch location, impact the time-domain analysis considerably. [ABSTRACT FROM AUTHOR]

This report describes the actuator functionality of a ceramic composite that uses the volume change caused by the insulator–metal (I–M) transition of VO2. When an electrical field was applied at 295 K, 50 vol. %-VO2/Al2O3 ceramic composite underwent the I–M transition because the VO2 powder dispersed in the composite became metallic. Simultaneous measurement of I–V characteristics and linear strain demonstrated that this I–M transition was accompanied by a positive strain. This strain increased with increase in the limit current value, which limits excessive current flow after transition. The strain exceeded 1300 ppm at maximum. Its magnitude corresponded to the volume change obtained from thermal expansion measurements on the composite. This composite performs a volume-change-driven actuator function that is distinct from the strain-driven counterpart of piezoelectric materials. [ABSTRACT FROM AUTHOR]

This report describes the actuator functionality of a ceramic composite that uses the volume change caused by the insulator–metal (I–M) transition of VO2. When an electrical field was applied at 295 K, 50 vol. %-VO2/Al2O3 ceramic composite underwent the I–M transition because the VO2 powder dispersed in the composite became metallic. Simultaneous measurement of I–V characteristics and linear strain demonstrated that this I–M transition was accompanied by a positive strain. This strain increased with increase in the limit current value, which limits excessive current flow after transition. The strain exceeded 1300 ppm at maximum. Its magnitude corresponded to the volume change obtained from thermal expansion measurements on the composite. This composite performs a volume-change-driven actuator function that is distinct from the strain-driven counterpart of piezoelectric materials. [ABSTRACT FROM AUTHOR]

We present the modeling and analysis of electrical coupling in a hysteretic deformable mirror with 2D memory piezoactuators, which are made of a purposely designed piezomaterial sandwiched between electrodes arranged crosswise and actuated by a multiplexing approach. Using a modified Miller model to describe the memory effect which is based on the ferroelectric domain switching processes, the proposed framework is used to simulate the electric-field dependence of the strain in the piezoelectric material that exhibits asymmetric butterfly loops with remnant deformation through the finite element method. The desired butterfly memory effect in the material is obtained by modifying the saturated dipole polarization curve in the Miller model. The proposed method allows us to numerically investigate the electrical coupling between actuators in more detail and correspondingly understand their influence to the mirror facesheet. [ABSTRACT FROM AUTHOR]

In this article, analytical solutions of piezoelectric bimorph and unimorph actuator in cantilever configurations are developed using the second-order constitutive equation. Tip deflection ratio (TDR), a dimensionless parameter, is defined to analyze the effect of second-order coefficients of piezoelectric materials on the response of bimorph and unimorph actuators. Four piezoelectric unimorphs of varying geometries are fabricated and tested to verify the nonlinear response under applied electric field. Furthermore, second-order coefficients of lead zirconate titanate (PZT; APC 850) are derived by fitting the experimental data with nonlinear analytical solution. The nonlinear response of all the piezoelectric unimorphs compares well with the experimental results. [ABSTRACT FROM AUTHOR]

The endeavour of this research is to locate the position of small-depth cracks in beam type structural element and to restore the dynamic response of the cracked beam through steady-state vibration analysis with the help of piezoelectric material. An open crack induces a discontinuity in rotational displacement curve of a vibrating element, though this discontinuity is an efficient parameter to detect the crack, but at the same time, there is no proper conventional method to check the discontinuity in a vibrating beam. The present study reveals that a bending piezoelectric sensor can efficiently detect the discontinuity due to the fact that the voltage output from the piezoelectric sensor depends on the difference in rotational displacement at its two ends. Subsequently, it is observed that by applying external time-varying voltage on a piezoelectric patch, the dynamic response of a cracked beam can be restored. Since the applied external voltage on the patch produces a local moment near the crack which diminish the effect of crack. Mathematical and finite element model are developedto obtain the results. An experimental set-up is made to validate few of the theoretically obtained results. [ABSTRACT FROM AUTHOR]

0.96(Na 0.5 K 0.5)(Nb 0.93 Sb 0.07)O 3 −(0.04−x)BaZrO 3 −x(Bi 0.5 Ag 0.5)ZrO 3 [NKNS−(0.04−x)BZ−xBAZ] ceramics are well textured along the [001] direction using 3.0 mol% NaNbO 3 seeds. The textured-NKNS−0.02BZ−0.02BAZ thick film has a rhombohedral-orthorhombic-tetragonal (R-O-T) structure with a large proportion of the O-R structure (> 80%). This specimen exhibits the largest values for d 33 (805 pC/N) and d 33 × g 33 (29.5 ×10−12 m2/N), which are the largest d 33 and d 33 × g 33 values of NKN-based piezoceramics to date. It exhibits a large strain (0.17% at 4.0 kV/mm). Therefore, it is an outstanding piezoceramic material for piezoelectric energy harvesters (PEHs) and actuators. A PEH and actuator are fabricated using this specimen. The PEH shows a large power density (4.3 mW/cm3), which is the largest value among the PEHs produced by lead-free piezoceramics. The actuator exhibits a large acceleration (50.8 G) and displacement (3.9 mm), which are the best actuating properties among the actuators produced by lead-free piezoceramics. Therefore, texturing is an excellent technique for improving the piezoelectricity of NKN-based piezoceramics. • Textured NKNS-0.02BZ-0.02BAZ has an R-O-T structure with a large fraction of R-O. • This sample shows the largest d 33 (805 pC/N) among the NKN-based piezoceramics. • A PEH fabricated using this specimen shows a large output power density (4.3 mW/cm3). • An actuator produced using this specimen exhibits excellent actuating properties. • Texturing is a good method for improving the piezoelectricity of NKN-based ceramics. [ABSTRACT FROM AUTHOR]

The development of (K, Na)NbO 3 (KNN)-based lead-free materials with excellent piezoelectric properties has become an vital aspects in recent years, based on the environmental friendliness and potential for device. As the typical electromechanical property, the electrostrictive effect is tightly linked to piezoelectric response, which is dominating the market of high-precision actuators. However, the electrostriction behaviors of KNN-based piezoelectric materials have been little studied as yet, evoking the exploration for the electrostrictive effect potential urgently. Here, a typical KNN-based piezoelectric material of (1- x)K 0.5 Na 0.5 NbO 3 - x Bi 0.5 Na 0.5 ZrO 3 (KNN- x BNZ, x = 0.09, 0.10, 0.11) has been concentrated on the enhanced relaxor characteristic due to destroyed ferroelectric long-range orders via introducing high content of BNZ, aiming to strengthen the electrostriction. A giant electrostrictive coefficient (Q 33 ∼ 0.067 m4/C2) is achieved in KNN-0.1BNZ materials, nearly three times higher than that of reported Pb(Zr, Ti)O 3 -based materials, and comparable to some typical BaTiO 3 -based materials. The optimization of Q 33 roots in the co-doped appropriate of Bi3+ and Zr4+ at A or B site, which induces the heterogeneous structure and then limits the range of movement for ions on B site. Significantly, a pretty frequency stability of the remarkable Q 33 (>0.054 m4/C2 under the frequency of 1–100 Hz) is revealed, benefiting to application for some commercial fuel injectors' actuators. This research provides a high-performance electrostrictive material, promoting the research of eco-friendly piezoelectric materials. [ABSTRACT FROM AUTHOR]

Purpose: Piezoelectric materials are widely used as actuators, due to the advantages of quick response, high sensitivity and linear strain-electric field relationship. The previous work on the piezoelectric material plate structures is not enough; however, such structures play a very important role in the practical design. In this paper, the actuation performance of piezoelectric laminated plate actuator (PLPA) is analyzed based on Galerkin method to parametric study the shape control. Design/methodology/approach: In this paper, the actuation performance of PLPA is analyzed based on Galerkin method to parametric study the shape control. The stress components of the matrix plate are formulated based on electro-mechanical coupling theory and Kirchhoff's classical laminated plate theory. The effectiveness of the developed method is validated by the comparison with finite element method. Findings: The actuation performance of PLPA and its influencing factors are numerically analyzed through the developed method. The deflection of PLPA is reasonably increased by optimizing the electric fields, the piezoelectric patch and the matrix plate. Originality/value: The Galerkin method can be used for engineering applications more easily, and it does not require to rebuild the calculation model as finite element method during the calculation and analysis of PLPA. This paper is a valuable reference for the design and analysis of PLPAs. [ABSTRACT FROM AUTHOR]

Piezoelectric materials reversibly deform when exposed to an electric field. This property is indispensable to modern engineering devices, enabling a wide range of sensors and actuators. However, unfortunately conventional piezoelectric materials are limited to operating temperatures of below approximately 200 °C. Lithium niobate is a promising candidate for high temperature applications (above 500 °C), as it has a high Curie temperature (1200 °C) and good piezoelectric properties. Nevertheless, degradation mechanisms occurring at elevated temperatures are not fully understood, although they are known to interfere with the piezoelectric behavior. In addition, the material properties of this technologically promising ceramic have not been adequately characterized at high temperatures, particularly when excited at high frequencies, due to the difficulty of performing such measurements. We therefore employ an electrochemical impedance spectroscopy resonance method using a novel analytical model to determine the material properties of single crystal lithium niobate over the wide frequency range of 100 kHz to 7MHz for temperatures up to 750 °C. We find that lithium niobate retains its good piezoelectric properties over this entire frequency and temperature range and rules out suspected degradation mechanisms involving ionic conductivity or vacancy diffusion. [ABSTRACT FROM AUTHOR]

The piezoelectric effect of piezoelectric quasicrystalline materials is coexcited by phonon and phason fields. Piezoelectric quasicrystalline materials have excellent properties of both piezoelectric materials and quasicrystalline materials, which are expected to be used as actuators in the fields of aerospace, automotive, and intelligent manufacturing. Based on the three-dimensional elastic theory of piezoelectric quasicrystals, the state space equation for axisymmetric piezoelectric quasicrystal circular plate actuators is derived by using the state space method. Afterwards, the finite Hankel transformation is performed on the state equation, and a system of ordinary differential equations and corresponding boundary conditions are obtained. Finally, the exact solution of axisymmetric bending of one-dimensional hexagonal piezoelectric quasicrystal circular actuators under generalized elastic simply supported boundary conditions is obtained by using the propagator matrix method. Numerical results are given to compare the degradation results in this paper with those in the literature, and present the influences of the thickness-to-span ratio and stacking sequence on the phonon, phason, and electric fields when the surface of the laminated circular actuators is subjected to mechanical load. The exact solution obtained does not introduce any deformation assumption; therefore, the exact solution can provide references for numerical calculations of the mechanical behavior of piezoelectric quasicrystals. [ABSTRACT FROM AUTHOR]

Since the introduction of adaptive systems for corrective measures, static and dynamic disturbances have been reduced through the manipulation of surface shape in a well-controlled manner. One important application where adaptive systems are highly needed is in the future photo-lithography machines, particularly the wafer table where disturbances affect overlay and focus performance. To reduce overlay and focus errors, a dense array of actuators must be integrated into the wafer table to apply both in- and out-of-plane corrective deformations to the wafer surface. To realize a certain wafer shape, influence functions are linearly superimposed. Accurate models of the influence functions result in an accurate prediction of the final wafer shape. To reduce calibration errors, the influence function of every actuator needs to be determined. Here, we propose a technique to rapidly measure the influence function: the influence function measurement (IFM) technique. Using the actuate-sense property of piezoelectric materials, the influence function is determined by activating one piezo-actuator and measuring the charge induced on the neighboring piezo-actuators. The measured charges are compared to the results of finite element simulations and the absolute difference of 0.3 % is reported for the inter-actuator charge coupling parameters. This clearly indicates the potential of the proposed technique. Note to Practitioners—A critical step during the integrated-circuit lithographic fabrication process is the exposure. A particular practical challenge in this step is to correct for the mismatch between the optical image plane and the wafer surface, caused by wafer deformations. The mismatch negatively impacts the overlay and focus performance. To reduce the mismatch, actuators can be embedded into the wafer table to counteract wafer deformations, where the overall wafer surface shape is a superposition of each actuator’s influence function. As part of the calibration for the embedded actuators, their influence functions are measured and stored. However, errors arise when influence functions are not measured for every actuator. Additionally, for different wafers, the influence functions vary hence the calibration should be done per wafer. This calibration process takes time and should not influence throughput. Our paper presents a viable approach that reduces the calibration time of active wafer tables, which is also relevant for other adaptive systems such as deformable mirrors. Since the technique requires the actuators to be mechanically coupled, it is limited to continuous surfaces. The proposed technique is numerically tested and experimentally verified to demonstrate performance. [ABSTRACT FROM AUTHOR]

Vibration is one of the most dangerous phenomena that happens to a structure. It leads to premature fatigue and eventually failure, with potentially fatal consequences. A smart structure is an excellent solution to this problem; it adds an actuator, a sensor, and an appropriate control law to the system to reduce/eliminate the vibration. This study developed a complete analytical model for a cantilever beam with a collocated PZT sensor/actuator pair. First, we used a coupling of a collocated PZT sensor and an actuator to measure and control vibration levels based on a PID control law considering the physical constraints associated with PZT operation as the voltage level of the actuator. Next, the damping coefficient of the structure was determined by using genetic algorithms best fit to satisfy specific vibration conditions. Finally, we conducted a complete optimization for sensor/actuator position and PID parameters, using genetic algorithms. Thus, this paper gives a thorough understanding of the potential vibration control of the cantilever beam. [ABSTRACT FROM AUTHOR]

The possibility of designing a highly efficient multiphase piezoceramic composite material for use in precision displacement actuators was explored. The aim of the study was to obtain a piezoceramic material with optimal characteristics based on two ferroelectric compositions. The research objective was to test the obtained piezoceramic material for consolidation by the sintering process. The performance testing of the obtained material was carried out with the use of multilayer actuators. [ABSTRACT FROM AUTHOR]

Severe challenges such as depletion of natural resources, natural catastrophes, extreme weather conditions, or overpopulation require intelligent solutions especially in architecture. Built environments that are conceived from smart materials based on actuator and sensor functionality provide a promising approach in order to address this demand. The present paper reviews smart materials-based technologies which are currently applied or developed for application in civil structures, focusing on smart material applications for actuation or sensing. After giving a definition and categorization of smart materials, applications of the investigated materials (i.e. shape memory materials, electro- and magnetostrictive materials, piezoelectric materials, ionic polymer-metal composites, dielectrical elastomers, polyelectrolyte gels as well as magneto- and electrorheological fluids) are presented for the fields of architecture and civil engineering. While some materials are already highly advantageous in the application context, others still need further research in order to become applicable in real-world constructions. Nonetheless this review indicates their large innovation potential which should be consolidated by systematic research efforts in the near future. [ABSTRACT FROM AUTHOR]

This article presents the design and analysis of a piezoelectric-based ultrasonic actuator to be used for tactile system applications. The device made of four pieces of piezoelectric material arranged in alternate way to complete the actuator structure. When the voltages are applied on the device, and at a resonant operating frequency, two vibration modes are simultaneously activated, the first longitudinal mode (L1) and the second bending mode (B2). The actuator size is tiny and able to drive the external load with stable and low-input voltage. The proposed actuator is suited for tactile feedback device, as well as feasible for low-input applications for prolonged usage. From the study, it is observed that the maximum output force at the voltage of 50 V is 1.6 N for the proposed structure while the optimum force is 1 N. Its small dimension, 20.1 × 2 × 0.75 mm and low-input voltage of 50 V makes it portable and easy to fabricate into small and precise devices. [ABSTRACT FROM AUTHOR]

We propose and demonstrate an efficient, integrated, and customizable metal–oxide–semiconductor (MOS) actuator capable of active on-chip driving and tuning microelectromechanical resonators. A single-crystal diamond mechanical resonator with a hydrogen-terminated surface was utilized for demonstration. In this actuator, the electrical field applied to the gate tunes the width of the depletion region of the MOS capacitor on the cantilever and induces an actuation force. The proposed actuator overcomes the drawbacks of conventional actuators, such as the growth of piezoelectric materials, formation of p–n junctions, high dc voltages, and nanoscale air gaps. The actuator has various merits, such as low-power dissipation (∼pW), low-voltage operation (∼mV), and a tailored amplitude through a low dc bias of less than 1 V. The proposed actuator is universally applicable in all semiconductors compatible with complementary metal–oxide–semiconductor. [ABSTRACT FROM AUTHOR]

In last decades, using fibrous piezoelectric materials as energy harvesters and sensors attracted huge attention. Ductile behaviors and biocompatibility are the most beneficial characteristics of polymer-based materials, particularly poly vinylidene fluoride which is used for fabrication of wearable energy harvesters and sensors. Evaluation of piezoelectric properties, especially fiber and nanofiber piezo-polymers, is one of the most important inconveniences mode, particularly to quantify the sensitivity performance of fabricated devices, i.e. output voltage divided by the applied pressure. Conventional methods mostly are indirect, irrelevant and predominantly measure a related parameter instead of the main factor; they are also time consuming, expensive, constrained and have a high error rate. In this study, based on direct effect of piezoelectric, a novel universal system (PiezoTester) is presented to characterize piezoelectric properties and sensitivity of sensors and energy harvesters, especially flexible polymeric devices. This system was used to test three samples that are different in ZnO nanoparticle percentage in poly vinylidene fluoride/ZnO electrospun mats and its results compared by other measuring methods such as XRD, FTIR and differential scanning calorimeter as indirect methods and criterion piezoelectric method as a direct method to validate its performance. Promising evidence inferred PiezoTester could be used as a reliable system to evaluate piezoelectric properties of flexible energy harvesters and sensors as well as wearable gadget and smart textiles. [ABSTRACT FROM AUTHOR]

• Concurrent multiscale design for piezoelectric actuators is conducted. • Both macrostructures and microstructures are optimized to maximize the actuation. • Influence of material distribution across the scales for design is investigated. • Transmitted displacement increases with the increase of microscale material. As an important component of smart structural devices, piezoelectric composites have strong macroscopic electromechanical coupling properties which often depend on their microstructural geometries and material parameters. Therefore, optimizing the microstructural design is crucial for achieving the desired macroscale effective properties. To this end, this paper conducts a concurrent multiscale topology optimization (TO) to optimize the material distribution of piezoelectric actuators, aiming to maximize the electrical and mechanical energy transmission to meet specific engineering requirements. Firstly, an energy method is used to homogenize the microstructures and obtain the effective parameters of the piezoelectric material. Then, the piezoelectric material with penalization and polarization (PEMAP-P) approach in conjunction with the adjoint method is employed to calculate the sensitivity of objective and constraint functions. The sensitivities at both the macroscale and microscale are obtained by considering the interscale coupling effects. Finally, the concurrent bi-level iteration based on the optimality criteria (OC) or the method of moving asymptotes (MMA) is conducted. Through this research, we have illuminated the relations between the optimized performance of the actuator and the material volume fractions at each scale. We have also compared in detail the differences between two-scale and single-scale designs, as well as the differences between the simplified half-symmetric geometric model and the full geometric model. We find that a larger volume fraction of material either at the macroscale or microscale generates a larger transmitted displacement magnitude under the same applied electric field, and for a given total material, the transmitted maximum increases with increasing microstructural volume fraction. [ABSTRACT FROM AUTHOR]

This study presents an analytical model of a flextensional actuator comprised of a piezoceramic rod or stack transducer integrated into a flexible mechanical structure. It converts and amplifies the longitudinal in-plane strains in the transducer into the out-of-plane bending of metal beams. Two curvilinear beams mounted by means of two hinged links with an offset to a centrally located piezoceramic transducer create a monolithic hinge lever mechanism. The idea behind that solution is to reduce the bending stiffness at the hinges, while maintaining enough axial rigidity of the active beams and obtain greater magnification of the out-of-plane displacement. As the main purpose of this work is to estimate the influence of piezoelectric force on the performance of flextensional actuators of different geometric shapes and mechanical parameters, two transducers have been considered. An analytical model of the actuator has been developed on the basis of the stationary value of the total potential energy principle with the use of the von Karman non-linear strains theory. Moreover, the application of structure prestressing is considered to avoid undesired stretching of the piezoceramic transducer. A vast number of results exhibit the mechanical responses of the actuator of different geometry, initial midspan rise and beam material properties to piezoelectric stimulation. The analytical method described here may be adopted for other types of flextensional actuators. Additionally, a numerical model of flexure-guided transducer is presented to show that the analytical solution can provide a set of valuable design parameters in less time than FEM simulations. Models of two configurations of flextensional actuator are analytically developed Static behavior of the structure under the electric field is examined Prestressing of the actuator is considered to prevent undesired stretching Analytical solution is verified with the results from FEM [ABSTRACT FROM AUTHOR]

This contribution presents a multidisciplinary review of the so-called field-dependent nonlinear piezoelectricity. It starts with an introduction that poses the literature analysis framework, through defining this operational (that is often met in practice) piezoelectric field-dependent nonlinearity. Indeed, the latter is a less known phenomenon although it is inherent to stress-free actuation responses of corresponding smart materials, actuators and structures. Then, related experimental observations from piezoelectric materials, actuator devices and smart structures tests are multidisciplinary surveyed for understanding the underlying mechanisms of the encountered field-dependent nonlinearity. Next, empirical material and numerical structural modelling and simulation approaches are critically reviewed from, respectively, the constitutive and finite element analysis points of view. Summary conclusions and few future directions for research are finally provided as a closure. It is worth mentioning that, although it is concise (retains only experiments and experimentally-correlated models and simulations), this critical review covers the last three decades period which is almost the whole age of the piezoelectric materials, actuators and smart structures research field.

Piezoelectric elements (PEMs) are used in a variety of applications. In this paper we developed a full analytical model of a piezoelectric actuator which includes piezostack elements and a three-stage amplification mechanism. The model was derived separately for each unit of the system. Next, the units were combined, while taking into account their coupling. The hysteresis phenomenon, which is significant in piezoelectric materials, was extensively described. A number of hysteresis calculating algorithms were investigated and a new simple method of examining piezoelectric hysteresis was demonstrated. The theoretical model was verified in a laboratory setup. This setup includes a piezoelectric actuator, measuring devices and an acquisition system. The measured results were compared to the theoretical results, while taking into account the nonlinear phenomena of the piezoelectric materials and the three-stage amplification mechanism, and were found to be very similar. Due to its simplicity, this model can easily be modified in order to be applied to other PEMs or other amplification mechanism methods. The main novelty of this work lies in its system-level approach for piezoelectric actuators. All of the system elements include non-linear phenomena, which mutually influence each other. First, each part of the system will be described separately and then, the combined subsystems and the coupling between their parts will be represented. Finally we treat this system as one whole unit. [ABSTRACT FROM AUTHOR]

Today, piezoelectric actuators are widely used in micro-positioning applications due to unique features such as high precision, fast response and high natural frequency. Despite the aforementioned characteristics, nonlinear characteristics such as hysteresis deteriorate the precision of piezoelectric actuators. In order to reduce the effect of hysteresis in control applications, external sensors are used for feedback control schemes. But, high costs and space limitations are prohibitive factors which limit the application of external sensors. Hence, an alternative is using self-sensing methods that is based on electromechanical characteristics of piezoelectric materials which eventually eliminate external sensors. In this research, self-sensing method is applied for position estimation in piezoelectric actuators. The most conventional method is based on the linear relation of electrical charge and actuator position which the position can be estimated by measuring the actuator charge. But this method is faced with serious challenges due to charge drift, especially at low frequencies. For this purpose, a method for modeling and compensating of charge drift is proposed. Then, by linearization of the electric charge-position relation, the self-sensing method is implemented based on the compensated electric charge measurement. Experiments have confirmed that this method can effectively estimate the actuator position with 1.5% estimation error in the presence of charge leakage. [ABSTRACT FROM AUTHOR]

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Using a Pt/Y3Fe5O12 (YIG) hybrid structure attached to a piezoelectric actuator, we demonstrate the generation of spin currents from sound waves. This 'acoustic spin pumping' (ASP) is caused by the sound wave generated by the piezoelectric actuator, which then modulates the distribution function of magnons in the YIG layer and results in a pure-spin-current injection into the Pt layer across the Pt/YIG interface. In the Pt layer, this injected spin current is converted into an electric voltage due to the inverse spin-Hall effect (ISHE). The ISHE induced by the ASP is detected by measuring a voltage in the Pt layer at the piezoelectric resonance frequency of the actuator coupled with the Pt/YIG system. The frequency-dependent measurements enable us to separate the ASP-induced signals from extrinsic heating effects. Our model calculation based on the linear response theory provides us with a qualitative and quantitative understanding of the ASP in the Pt/YIG system. [ABSTRACT FROM AUTHOR]

In this study, we explore the possibility of fabricating a kind of piezoelectric actuators by exploiting the converse flexoelectric effect. The phenomena of flexoelectricity demonstrate that inhomogeneous external stimuli (either mechanical or electric stimuli) can break the inversion symmetry and induce the piezoelectric response even in nonpiezoelectric materials. By using the finite element method, we approximately estimate the magnitude of the converse piezoelectric effect under such circumstances. Our simulation results have proved that the inhomogeneous electric field generated by the asymmetric configuration of electrodes can be manipulated to create the converse piezoelectric response in nonpiezoelectric dielectrics. It is also reasonable to expect that this method may provide an alternative way to overcome the negative influence of the Casimir force on micro- or nanoscale devices. [ABSTRACT FROM AUTHOR]

• 0.4PZN-0.6PZT ceramics densified to ∼ 98 % at lower sintering temperature of 950 °C. • Stable unipolar strain of ∼ 0.14–0.16 % with η hys < 10 % was observed even close to T C. • Robustness in unipolar strain response is observed up to 106 cycles till 200 °C. • Thermal and fatigue endurance showcases the potential use for actuator applications. Piezo-ceramics with low sintering temperature (<1000 °C), enhanced strain (>0.1 %), low degree of hysteresis (<10 %), fatigue resistance (>106 cycles) with better thermal stability are extremely important characteristics for the development of high performance and cost-effective actuators. In this study, temperature (−50 to 250 °C) and fatigue (100 to 106) dependence of ferro/piezoelectric (P-E/S-E) characteristics of low temperature sintered (950 °C) (0.4[Pb(Zn 1/3 Nb 2/3)O 3 -0.6Pb(Zr 0.49 Ti 0.51)O 3 ]) ceramics was investigated. A thermally stable strain response with a maximum of 0.17 % and degree of strain hysteresis (η h ys) of < 10 % was observed till 250 °C. The fatigue studies revealed a robust unipolar strain stability till 106 cycles even up to 200 °C. Interestingly, a very minimal strain asymmetry (γ S) was observed only after 104 cycles till 200 °C, unlike PZT-5A, PIC151 and PMN-PT. This study demonstrates an exceptional thermal and fatigue resistant strain response even close to the Curie transition temperature (T C ∼ 280 °C) and suggests that the low temperature sintered 0.4PZN-0.6PZT ceramics could be a promising material, exclusively for high-precision actuator applications over a wide temperature range with a cost-effective solution. [ABSTRACT FROM AUTHOR]

Piezoelectric actuators normally have complicated structures and work under severe loading conditions, e.g., high driving electric field and significant compressive preload. This study is focused on the experimental investigation of the electromechanical properties of a commercial soft lead zirconate titanate material under loading conditions simulating the in-service environment of high-strain actuators. The polarization and strain responses were first measured under a constant-stress preload. A significant enhancement of the dielectric and piezoelectric performance is observed within a small prestress range. At much higher preload levels, the predominant mechanical depolarization effect makes the material exhibits hardly any piezoeffect. In the other two series of tests, the specimen was subjected to cyclic mechanical load with different mean stresses and amplitudes. When the stress is applied in-phase with electrical loading, the polarization and strain outputs are found to monotonically decrease with an increase in stress amplitude, until mechanical loading completely impedes the piezoelectric response. An inverse effect occurs for the out-of-phase electromechanical loading tests, in which the polarization and strain outputs increase with increasing stress amplitude. In general, the enhanced polarization and strain responses are accompanied by an unfavorable increased hysteresis and, consequently, increased energy loss. An attempt has been made to explain the experimental findings by simultaneously taking into account the effects of dielectric response, elastic deformation, irreversible domain switching, and piezoeffects. [ABSTRACT FROM AUTHOR]

10.3390/app10144927 2 Liu J., Niu Z.-J., Zhu H., Zhao C.-S. Design and Experiment of a Large-Aperture Hollow Traveling Wave Ultrasonic Motor with Low Speed and High Torque. The associated research ranges from materials and device design, such as efficient transducer arrays ([[1]]), to device development, for example, in terms of lightweight ultrasonic motors able to provide high torque without generating electromagnetic interferences thanks to a large aperture ([[2]]), cross-shaped design ([[3]]) or conical design ([[4]]). Initially triggered more than a decade ago by a fruitful German-Korean collaboration, the International Workshop on Piezoelectric Materials and Applications in Actuators has rapidly reached international levels thanks to a strong community making the conference series one of the most recognized in the field. [Extracted from the article]

• Recent developments and achievements in stepping piezoelectric actuators with large working stroke were reviewed. • Three types of stepping piezoelectric actuators, inchworm type, friction-inertia type, and parasitic type, were summarized. • The future research directions of stepping piezoelectric actuators were discussed. Precision positioning systems with large working stroke (millimeter or more) and micro/nano-scale positioning resolution are widely required in both scientific research and industries. For this kind of applications, piezoelectric materials based actuators show unique advantages and have been widely employed. To overcome the demerit of the limited working stroke for single piezoelectric element, various stepping motion principles have been proposed in the past years, and accordingly, stepping piezoelectric actuators with various structures have been designed and evaluated. This review is aimed to summarize the recent developments and achievements in stepping piezoelectric actuators with large working stroke. Especially, the emphasis is on three main types of stepping piezoelectric actuators, i.e., inchworm type, friction-inertia type, and parasitic type. The motion principles of these three types of piezoelectric actuators and the corresponding developments of various actuators are discussed respectively, followed by pointing out the existing problems in these three types of piezoelectric actuators and proposing some potential research directions in this topic. It is expected that this review is helpful for relevant researchers to understand stepping motion principles as well as piezoelectric actuators, and to successfully select and design stepping piezoelectric actuators for specific applications. [ABSTRACT FROM AUTHOR]

Piezoelectric materials are a class of important functional materials applied in high‐voltage sources, sensors, vibration reducers, actuators, motors, and so on. Herein, [(CH3)3S]3[Bi2Br9](1) is a brilliant semiconducting organic–inorganic hybrid perovskite‐type non‐ferroelectric piezoelectric with excellent piezoelectricity. Strikingly, the value of the piezoelectric coefficient d33 is estimated as ≈18 pC N−1. Such a large piezoelectric coefficient in non‐ferroelectric piezoelectric has been scarcely reported and is comparable with those of typically one‐composition non‐ferroelectric piezoelectrics such as ZnO (3pC N−1) and much greater than those of most known typical materials. In addition, 1 exhibits semiconducting behavior with an optical band gap of ≈2.58 eV that is lower than the reported value of 3.37 eV for ZnO. This discovery opens a new avenue to exploit molecular non‐ferroelectric piezoelectric and should stimulate further exploration of non‐ferroelectric piezoelectric due to their high stability and low loss characteristics. As easy as pie: A semiconducting organic–inorganic hybrid perovskite‐type non‐ferroelectric piezoelectric with excellent piezoelectricity is reported. The value of the piezoelectric coefficient d33 is estimated as ≈18 pC N−1. Such a large piezoelectric coefficient in non‐ferroelectric piezoelectric has been scarcely reported. Furthermore, [(CH3)3S]3[Bi2Br9] exhibits semiconducting behavior with an optical band gap of ≈2.58 eV. [ABSTRACT FROM AUTHOR]

Abstract In this paper, optimal active vibration control of a micro sandwich beam is studied. Face sheets are made from piezoelectric materials and reinforced by functionally graded distributions of carbon nanotubes. Also bottom and top face sheets operate as distributed sensor and actuator, respectively. Based on modified strain gradient theory and Hamilton's principle, the governing equations of motion for presented smart micro Reddy beam are derived and optimal active vibration control is applied using state-space form of equations of motion and linear quadratic regulator algorithm. The results show that considering MSGT, the amplitude of the center point deflection and settling time decrease. Also CNTs distributions effect on stability and active vibration control of the smart structure and LQR algorithm is essentially an automated way of finding an appropriate state-feedback controller. This study is a theoretical background for more research and further experimental investigation, in the field of micro smart structures. Graphical abstract Image 1 Highlights • The effects of Modified strain gradient theory on active vibration control is investigated. • Linear quadratic regulator algorithm is applied to optimal active vibration control of system. • The influences of CNT volume fractions and various functionally graded distributions on stability and settling time of system is investigated. • The effects of top face sheet thickness to bottom face sheet thickness ratio on settling time, stability and natural frequencies are studied. • The influence of different core to facesheet thickness ratios on vibration control is considered. [ABSTRACT FROM AUTHOR]

The need to develop aerodynamically and structurally efficient aircraft for a variety of purposes or missions has motivated aircraft designers to seek inspiration from nature and mimic the features of avian flight. The goal is to develop a promising morphing structure based on piezoelectric smart material technology to ensure structural integrity, reduced weight penalty, and enhanced performance. The embedding of smart piezoelectric actuators within an adaptive structure provides a great opportunity to affiliate the efficiency of avian flight with a smart adaptive wing. Piezoelectric actuators for these adaptive structures are constrained to have a high-energy density, an ease of restraint, a variable stiffness, and a high proficiency for carrying substantial strains. Our study enumerates recent trends in the development of piezoelectric smart materials and actuators and their applications to morphing aircraft. These advancements will motivate the development of new morphing techniques and aid in maximizing the potential of shape shifting. [ABSTRACT FROM AUTHOR]

Inertial piezoelectric rotary actuators have been driving interests of researchers major in precision machining and precision positioning. It has great significances to model inertial driving principle more accurately and design rotary actuators with simpler structure and higher resolution. In this paper, an inertial rotary actuator with one piezoelectric element is proposed. The theoretical development and experiments of the actuator are presented. The verification of developed model proves that the model has great potentials on designing and optimizing the stick-slip rotary actuators. The experimental test of the actuator shows that stepping characteristic depends greatly on the input voltage parameters and the frictional force. This designed rotary actuator achieves the minimum resolution of 0.58 μrad with simple configuration. [ABSTRACT FROM AUTHOR]

Abstract Fluid–structure interaction (FSI) is a phenomenon caused by mutual interference between structures and the surrounding flow. Controlling FSI is important because FSI causes undesired vibration and it often affects the safety and lifetime of structures. Piezoelectric materials have excellent electromechanical properties to suppress vibration. As such, piezoelectric sensors and actuators are often used for reducing not only mechanical vibration but also FSI induced vibration. A number of studies have examined active control of FSI using piezoelectric materials. In the study of the control of FSI, numerical simulations are effective because they are proper for parametric studies and reduce the need for experiments. Although a number of numerical studies examined the control of FSI using piezoelectric materials, in these studies, detailed fluid analyses were not performed and the fluid force was modeled as a simple function. As such, the existing method cannot treat complicated FSI problems. Therefore, we herein propose a general-purpose system that conducts detailed electrostatic, structural, and fluid analyses and considers an active control algorithm. We design a structure–fluid–electrostatic interaction analysis system considering active control by inserting electrostatic analysis into FSI analysis solved by the partitioned iterative method and integrating the active control algorithm. In the present study, we verify the proposed system in three ways. First, while varying the material properties of the fluid, we analyze the motion of a bimorph piezoelectric actuator in a non-flowing fluid and compare the results with those of a previous study that did not take the fluid into consideration. Second, we reproduce vortex-induced vibration (VIV), which is an FSI phenomenon using the proposed system. Third, we confirm that the active control algorithm is implemented correctly by solving the suppression of VIV with the velocity feedback control. Based on these verifications, the proposed system is comprehensively proven to be correct. [ABSTRACT FROM AUTHOR]

Abstract This paper develops a finite element formulation and computational model for coupling electric and finite strain dynamic fields with widely discrepant frequencies, governing the behavior of piezoelectric materials. The piezoelectric materials are defined by time-dependent nonlinear constitutive laws. A fully coupled, total Lagrangian finite element formulation is developed for modeling the electric and mechanical fields. A challenge in computational modeling of piezoelectric devices arise due to large discrepancy in the frequencies of the electrical signal and mechanical vibrations, especially when a large number of mechanical cycles need to be simulated. A wavelet transformation induced multi-time scaling (WATMUS) algorithm is developed for dynamic piezoelectric simulations. The WATMUS algorithm projects the high frequency electric fields on to the lower frequency of displacement and velocity fields, on which time integration is performed. The method significantly enhances the computational efficiency in comparison with single time scale integration methods. The accuracy and efficiency of the WATMUS algorithm are validated through piezo-electric applications. Highlights • Coupled transient electric and dynamic field analysis of nonlinear piezoelectric materials. • Finite strain vibration subject to oscillatory electric signals. • Novel wavelet transformation induced multi-time scaling method (WATMUS). • Piezoelectric structures simulated with WATMUS-FE model for validation. • Results show accuracy and highly improved computational efficiency. [ABSTRACT FROM AUTHOR]

Submillimeter-scale electrically driven micromotors have the potential to revolutionize micro-robotic systems, but difficulties in their fabrication processes and unknown physical phenomena prevent their development. In this paper, we propose a submillimeter-scale rotary piezoelectric ultrasonic motor with the smallest stator (0.41 mm × 0.41 mm × 0.25 mm) reported to date. The micromachining technologies enable the creation of tiny components. A micromanipulator that can control a small amount of adhesive of sub-milligram order engenders success in manufacture of the stator. Several experiments clarify the submillimeter-scale physical behaviors, such as the admittance and the quality factor. With appropriate piezoelectric materials, submillimeter-scale ultrasonic motors are built and characterized using a rotor with 0.15 mm diameter. The motor with typical hard PZTs demonstrated maximum torque of 5.4 nNm and a maximum angular velocity of 714 rad/s at an applied voltage with amplitude of 44.8 V p−p. Furthermore, another motor with single-crystal PMN-PT piezoelectric elements presented the possibility of low-voltage actuation. These submillimeter-scale ultrasonic motors were compared with existing comparable-size micromotors. [Display omitted] • We proposed an ultrasonic motor with the smallest stator (0.41 mm × 0.41 mm × 0.25 mm). • The motor demonstrated a torque of 5.4 nNm and an angular velocity of 714 rad/s. • The smallest motor was fabricated by common machining processes used in macroscale. [ABSTRACT FROM AUTHOR]

In various practical applications, such as high power actuators, high sensitivity sensors, and energy harvesting devices, polycrystalline piezoelectric films of 1–100 µm thickness and sizes ranging from several µm 2 to several cm 2 are required. With conventional film deposition processes, such as sol-gel, sputtering, chemical vapor deposition, or pulsed laser deposition, it is difficult to fabricate films with higher thickness due to their low deposition rate and high interfacial stress. The aerosol deposition method (AD), a relatively new deposition technique, can be used to fabricate highly dense thick films at room temperature by the consolidation of submicrometer-sized ceramic particles on various ceramic, metal, glass, and polymer substrates. Ferroelectric BaTiO 3 ceramic films of different thicknesses ranging from 1 to 30 µm were fabricated on a low-cost metallic substrate at room temperature using the AD method. Surface morphology and adhesion of the film were analyzed. Analysis of internal residual stresses revealed an equibiaxial compressive stress state in the as-processed film. Electrical characterization of films annealed at 500 °C shows an enhanced polarization value of ~ 14 µC/cm 2 over that of the as-processed film. This improved property is related to the decreasing internal residual stress. In addition, the BT films prepared in this work were found to withstand electric fields greater than 100 kV/mm, which is possibly related to the inherent relatively defect-free structure of AD films. [ABSTRACT FROM AUTHOR]

This paper presents a microactuator for a dual-stage actuator (DSA) of hard disk drive (HDD) based on a lead magnesium niobate-lead titanate (PMN-PT) piezoelectric material and a comparative evaluation of its performance versus that of a traditional lead zirconate titanate (PZT) microactuator using the laser Doppler vibrometer (LDV) sensing technique. PZT microactuator technology has commonly been implemented in the read/write (R/W) magnetic head of HDD. It has a significant function, that is, it moves the magnetic head rapidly and accurately. In order to achieve both accurate positioning control on data tracks and high-speed access across another data track, advanced high-performance actuators and servo control technologies are necessary. An actuator with a wide stroke travel range is essential for HDD as it gives a high-speed access performance. In this study, we focused on comparing the proposed dual-stage PMN-PT head-based actuator with the existing PZT actuator that were mounted on a commercial head gimbal assembly (HGA) using an LDV to determine whether the proposed device could be a worthy replacement of the traditional PZT microactuator. Our experimental results show that the proposed PMN-PT microactuator provided more than twofold improvement in the stroke travel of the R/W magnetic head. Moreover, its dynamic behavior was suitable for assembling a high-density HDD in the future for big data storage without any needs to redesign the HGA nor to costly invest in new assembling machines in a production line. The comparative data of dynamic and static behaviors of PMN-PT versus PZT obtained in this study may be put to good use by sensor designers. Moreover, for many cyber-physical system designers, our data may make them take interest in PMN-PT as a better-performing sensor and an actuator for their systems. [ABSTRACT FROM AUTHOR]

For the current flexible actuators, the long-term performance and the reusability usually cannot meet the practical standards, and the bending direction is usually not controllable. To address this issue, a complicated manufacturing process employed to produce a flexible actuator with desirable bending property and durability. Here, we report an easy-to-prepare and low-cost fabrication method for the preparation of PVDF/PEDOT:PSS/CNTs composite film as a multifunctional actuator. This actuator can generate significant bending when exposed to acetone vapors, and the bending direction is adjustable by orienting the carbon nanotubes on the surface. Furthermore, the actuator can produce voltages up to 90 mV via the piezoelectricity of the PVDF. Overall, our approach provides a simple and promising strategy for producing self-powered devices. [ABSTRACT FROM AUTHOR]

Texturing is an effective method to improve the piezoelectric properties of lead-free piezoceramics. In the present study, textured (K,Na)NbO 3 -based piezoceramics with a Lotgering factor of 89.7% were successfully fabricated by the templated grain growth (TGG) method. Compared with its non-textured counterparts, great enhancements of the piezoelectric coefficient (50% improvement) and electromechanical coupling factor are observed in the textured samples. More importantly, electric-field-induced strain is also remarkably improved, as evident by a 17% higher large-signal piezoelectric coefficient (346 pm/V) of the textured sample. A relatively low strain deviation of 2% is observed between room temperature and 150 °C, and even up to 175 °C, 86% of their room temperature large-signal piezoelectric coefficient value is maintained. This temperature stability of textured (K,Na)NbO 3 -based piezoceramics is of great significance for actuators with a stable response over a broad temperature range. [ABSTRACT FROM AUTHOR]

Purpose The purpose of this paper is to study the analytical solutions of transversely isotropic thermo-piezoelectric interactions in a polygonal cross-sectional fiber immersed in fluid using the Fourier expansion collocation method.Design/methodology/approach A mathematical model is developed for the analytical study on a transversely isotropic thermo-piezoelectric polygonal cross-sectional fiber immersed in fluid using a linear form of three-dimensional piezothermoelasticity theories. After developing the formal solution of the mathematical model consisting of partial differential equations, the frequency equations have been analyzed numerically by using the Fourier expansion collocation method (FECM) at the irregular boundary surfaces of the polygonal cross-sectional fiber. The roots of the frequency equation are obtained by using the secant method, applicable for complex roots.Findings From the literature survey, it is evident that the analytical formulation of thermo-piezoelectric interactions in a polygonal cross-sectional fiber contact with fluid is not discussed by any researchers. Also, in this study, a polygonal cross-section is used instead of the traditional circular cross-sections. So, the analytical solutions of transversely isotropic thermo-piezoelectric interactions in a polygonal cross-sectional fiber immersed in fluid are studied using the FECM. The dispersion curves for non-dimensional frequency, phase velocity and attenuation coefficient are presented graphically for lead zirconate titanate (PZT-5A) material. The present analytical method obtained by the FECM is compared with the finite element method which shows a good agreement with present study.Originality/value This paper contributes the analytical model to find the solution of transversely isotropic thermo-piezoelectric interactions in a polygonal cross-sectional fiber immersed in fluid. The dispersion curves of the non-dimensional frequency, phase velocity and attenuation coefficient are more prominent in flexural modes. Also, the surrounding fluid on the various considered wave characteristics is more significant and dispersive in the hexagonal cross-sections. The aspect ratio (a/b) of polygonal cross-sections is critical to industry or other fields which require more flexibility in design of materials with arbitrary cross-sections. [ABSTRACT FROM AUTHOR]

Direct integration of electronics on piezoelectrics is attractive for large array transducers and adjustable optics systems; it allows for the possibility of reconfigurability as well as active surfaces with a greatly reduced number of electrical connections. In this work, lead zirconate titanate (PZT) piezoelectric films were co-processed with ZnO thin film transistors to explore the possibility of direct integration. The sputter deposited PZT on glass had good electrical properties on large area (cm 2 ) electrodes, with a dielectric constant of >1200 with a loss of approximately 2% and an average remanent polarization of greater than >23 μC/cm 2 . Fabrication of arrays of thin film transistors (TFTs) processed directly on top of PZT pixels for use in an adaptive optics system was demonstrated. Photoreactive benzocyclobutene (BCB) electrically isolated the ZnO TFTs, deposited using plasma enhanced atomic layer deposition, from the electrodes on the piezoelectric cell. Flex cables were bonded to the wafer using anisotropic conductive film (ACF) to connect the gates (row control) and the drains (column control) in the TFT array to a control box. It was found that when actuating the PZT cells through the TFT array with 5–10 V, the glass mirror experienced approximately 700–1000 nm of deflection, adequate for figure control in future X-ray mirrors. [ABSTRACT FROM AUTHOR]

The aim of this research work is to estimate the amount of electricity produced to power up wearable devices using a piezoelectric actuator, as an alternative to external power supply. A prototype of the device has been designed to continuously rotate a piezoelectric actuator mounted on a cantilever beam. A MATLAB® simulation was done to predict the amount of power harvested from human kinetic energy. Further simulation was conducted using COMSOL Multiphysics® to model a cantilever beam with piezoelectric layer. With the base excitation and the presence of tip mass at the beam, the natural frequencies and mode shapes have been analyzed to improve the amount of energy harvested. In this work, it was estimated that a maximum amount of power that could be generated is 250 µW with up to 5.5V DC output. The outcome from this research works will aid in optimising the design of the energy harvester. This research work provides optimistic possibility in harvesting sufficient energy required for wearable devices. [ABSTRACT FROM AUTHOR]

This paper investigates a new integrated optimization method for laminated composite structures with piezoelectric patch actuators. Three kinds of design variables, i.e. the actuators’ locations, electrical voltages applied on piezoelectric patches and host structural pseudo-densities, are simultaneously optimized to improve the overall deformation precision. To freely place piezoelectric actuator on the host structure surface regardless of coincident finite element in classic lamination theory (CLT), the multi-point constraints (MPC) method is used here to simulate the perfect bonding between actuator layer and host layer, which inherits the advantages of avoidance of remeshing process analytical sensitivity as well as efficient lamination description during the movement of actuators in optimization iterations. For applying to spatially complex shape control, a modified shape error function based on the relative error between computed and desired surfaces is used. The finite circle method (FCM) is implemented to prevent the overlaps among the actuators and those between actuators and boundaries of the global design domain. Finally, numerical examples with plane or curved host structure are tested and discussed to demonstrate the validity and efficiency of this method. [ABSTRACT FROM AUTHOR]