Showing papers on "Piezoelectric sensor published in 2005"
TL;DR: This technique, called synchronized switch harvesting (SSH), is derived from the synchronized switch damping (SSD), which is a nonlinear technique previously developed to address the problem of vibration damping on mechanical structures, results in a significant increase of the electromechanical conversion capability of piezoelectric materials.
Abstract: This paper presents a new technique of electrical energy generation using mechanically excited piezoelectric materials and a nonlinear process. This technique, called synchronized switch harvesting (SSH), is derived from the synchronized switch damping (SSD), which is a nonlinear technique previously developed to address the problem of vibration damping on mechanical structures. This technique results in a significant increase of the electromechanical conversion capability of piezoelectric materials. Comparatively with standard technique, the electrical harvested power may be increased above 900%. The performance of the nonlinear processing is demonstrated on structures excited at their resonance frequency as well as out of resonance.
949 citations
TL;DR: In this paper, the capability of embedded piezoelectric wafer active sensors (PWAS) to excite and detect tuned Lamb waves for structural health monitoring is explored.
Abstract: The capability of embedded piezoelectric wafer active sensors (PWAS) to excite and detect tuned Lamb waves for structural health monitoring is explored. First, a brief review of Lamb waves theory is presented. Second, the PWAS operating principles and their structural coupling through a thin adhesive layer are analyzed. Then, a model of the Lamb waves tuning mechanism with PWAS transducers is described. The model uses the space domain Fourier transform. The analysis is performed in the wavenumber space. The inverse Fourier transform is used to return into the physical space. The integrals are evaluated with the residues theorem. A general solution is obtained for a generic expression of the interface shear stress distribution. The general solution is reduced to a closed-form expression for the case of ideal bonding which admits a closed-form Fourier transform of the interfacial shear stress. It is shown that the strain wave response varies like sin a, whereas the displacement response varies like sinc a. ...
890 citations
TL;DR: In this paper, a self-powered piezoelectric sensor is studied, in which one piece of a PEG element is simultaneously used as a sensor and a power generator under vibration environment.
Abstract: Sensors play a crucial role in structural systems with concern over reliability/ failure issues. The development of wireless monitoring systems has been of great interest because wireless transmission has been proven as a convenient means to transmit signals while minimizing the use of many long wires. However, the wireless transmission systems need sufficient power to function properly. Conventionally, batteries are used as the power sources for the remote sensing systems. However, due to their limited lifetime, replacement of batteries has to be carried out periodically, which is inconvenient. In recent years, piezoelectric materials have been developed as sensing and actuating devices mostly, and power generators in some cases. In this article, a self-powered piezoelectric sensor is studied, in which one piece of piezoelectric element is simultaneously used as a sensor and a power generator under vibration environment. Concurrent design with piezoelectric materials in sensor and power generator is inte...
313 citations
TL;DR: In this article, fabrication arid characterization results of piezoelectric micromachined ultrasonic transducers (pMUTs) based on 2-spl mu/m-thick Pb(Zr/sub 0.53/Ti/sub 3/) (PZT) thin films are described.
Abstract: This paper describes fabrication arid characterization results of piezoelectric micromachined ultrasonic transducers (pMUTs) based on 2-/spl mu/m-thick Pb(Zr/sub 0.53/Ti/sub 0.47/O/sub 3/) (PZT) thin films. The applied structures are circular plates held at four bridges, thus partially undamped. A simple analytical model for the fully clamped structure is used as a reference to optimize design parameters such as thickness relations and electrodes, and to provide approximate predictions for coupling coefficients related to previously determined thin film properties. The best coupling coefficient was achieved with a 270-/spl mu/m plate and amounted to k/sup 2/=5.3%. This value compares well with the calculated value based on measured small signal dielectric (/spl epsi/=1050) and piezoelectric (/spl epsi//sub 31,f/=15 Cm/sup -2/) properties of the PZT thin film at 100 kV/cm dc bias. The resonances show relatively large Q-factors, which can be partially explained by the small diameters as compared to the sound wavelength in air and in the test liquid (Fluorinert 77). A transmit-receive experiment with two quasiidentical pMUTs was performed showing significant signal transmission up to a distance of 20 cm in air and 2 cm in the test liquid.
279 citations
TL;DR: An overview is provided on the preparation of cellular polymers by physical foaming, on their charging by "microstorms", on their piezo- and pyroelectricity, and on analogies to ferroelectrics.
Abstract: Cellular polymers can be internally charged by "microstorms" (silent or partial discharges) within the voids of the polymer foam. The resulting material, which carries positive and negative charges on the internal void surfaces, is called a ferroelectret. Ferroelectrets behave like typical ferroelectrics, hence they provide a novel class of ferroic materials. The soft foams are strongly piezoelectric and can be used, in a wide range of applications, as transducers for interconverting mechanical and electrical signals. Herein, an overview is provided on the preparation of cellular polymers by physical foaming (extrusion, biaxial stretching, and controlled inflation by pressure treatments), on their charging by "microstorms", on their piezo- and pyroelectricity, and on analogies to ferroelectrics. Finally, a survey of selected applications is presented.
179 citations
TL;DR: This paper examines the position control problem of piezoelectric stack actuators and presents a method for overcoming the hysteresis nonlinearity between the applied voltage and the actuator displacement.
Abstract: This paper examines the position control problem of piezoelectric stack actuators and presents a method for overcoming the hysteresis nonlinearity between the applied voltage and the actuator displacement. An inverting charge control circuit is implemented to linearize the stack actuator movement by taking advantage of the linear relationship between charge and displacement. The charge control feedback loop is analyzed in detail. It incorporates an operational amplifier to provide high loop gain, a high-voltage amplifier (HVA) to drive the stack actuator, and a lead compensator to ensure stability. Experiments were conducted to compare the responses of the stack actuator under voltage and charge control. The experimental data show that the charge control provides linear actuator operation from 1 Hz-10 Hz over approximately 35% of the actuator operating range, and from 1 Hz-20 Hz over approximately 19% of the operating range.
128 citations
TL;DR: Property of piezoelectric transducers driven by charge sources when used with resonant controllers for structural vibration control applications is investigated and it is found that it is now possible to effectively, and accurately control the charge deposited on the electrodes of a piezoeselectric transducer, and thereby avoid hysteresis altogether.
Abstract: Driving piezoelectric actuators by charge, or current rather than voltage is known to significantly reduce the hysteretic nature of these actuators. Although this feature of piezoelectric transducers has been known to the researchers for some time, still voltage amplifiers are being used as the main driving mechanism for piezoelectric devices. This is due to the perceived difficulty in building charge/current amplifiers capable of driving highly capacitive loads such as piezoelectric actuators. Recently, a new charge amplifier has been proposed which is ideal for driving piezoelectric loads used in applications such as active damping of vibration. Consequently, it is now possible to effectively, and accurately control the charge deposited on the electrodes of a piezoelectric transducer, and thereby avoid hysteresis altogether. This paper further investigates properties of piezoelectric transducers driven by charge sources when used with resonant controllers for structural vibration control applications. The paper reports experimental results of a multivariable resonant controller implemented on a piezoelectric laminate cantilever beam.
116 citations
TL;DR: Using piezoelectric diagnostics, the authors in this article measured densities and velocities of ejected particulate as well as free surface velocity of bulk tin targets loaded with high explosive.
Abstract: Using piezoelectric diagnostics, we have measured densities and velocities of ejected particulate as well as “free-surface velocities” of bulk tin targets shock loaded with high explosive. The targets had finely grooved, machined finishes ranging from 10 to 250μin. Two types of piezoelectric sensor (“piezopins”), lithium niobate and lead zirconate titanate, were compared for durability and repeatability; in addition, some piezopins were “shielded” with foam and metal foil in order to mitigate premature failure of the pins in high ejecta regimes. These experiments address questions about ejecta production at a given shock pressure as a function of surface finish; piezopin results are compared with those from complementary diagnostics such as x-ray radiography and time-resolved optical transmission techniques. The mass ejection shows a marked dependence on groove characteristics and cannot be described by a groove defect theory alone.
109 citations
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16 May 2005TL;DR: In this paper, a piezoelectric element is provided that is equipped with a seed layer formed on a base substrate and a picolectric film formed on the seed layer.
Abstract: A piezoelectric element is provided that is equipped with a seed layer formed on a base substrate and a piezoelectric film formed on the seed layer. The seed layer is formed of a perovskite type piezoelectric material preferentially oriented to pseudo cubic (100). The piezoelectric film is formed of a relaxor material that has a perovskite type rhombohedral structure, and is preferentially oriented to pseudo cubic (100).
96 citations
TL;DR: Experiments performed on AIN/diamond/Si SAW test devices have shown good agreement between experimental results and theoretical predictions and demonstrate the feasibility of SAW devices based on this technology.
Abstract: Diamond films are very desirable for application to SAW devices because of their high acoustic wave velocity, which allows the extending of the frequency limit of operation at a given interdigital transducer line-width resolution. Use of high-quality AlN as the piezoelectric layer in conjunction with diamond is also desirable because of its high SAW velocity - the highest among all piezoelectric materials - together with its excellent electrical, mechanical, and chemical properties. The problems arising in the growth of AlN films on diamond have prevented, until now, the use of this combination of materials. In this paper we present recent results on the growth of highly oriented, low-stressed AlN films on diamond. SAW propagation on AlN/diamond has been theoretically investigated together with electromechanical coupling for both the Rayleigh and the Sezawa modes. The theoretical calculations show that high SAW velocities are achievable with good coupling efficiencies. Under proper conditions very large piezoelectric couplings are predicted k/sup 2/ = 2.2 and 4% for the Rayleigh and the Sezawa wave, respectively comparable to those observed in strongly piezoelectric single crystals such as LiNbO/sub 3/, but with SAW velocities approximately two-fold higher. Experiments performed on AIN/diamond/Si SAW test devices have shown good agreement between experimental results and theoretical predictions and demonstrate the feasibility of SAW devices based on this technology.
95 citations
TL;DR: A hybrid piezoelectric/fiber optic diagnostic system has been developed for quick non-destructive evaluation and long term health monitoring of aerospace vehicles and structures as discussed by the authors, which consists of three major parts: a diagnostic layer with a network of pieziolectric elements and fiber gratings to offer a simple and efficient way to integrate a large network of transducers onto a structure; diagnostic hardware consisting of an arbitrary waveform generator and a high speed fiber grating demodulation unit together with a high-speed data acquisition card to provide actuation input, data collection,
Abstract: A hybrid piezoelectric/fiber optic diagnostic system has been developed for quick non-destructive evaluation and long term health monitoring of aerospace vehicles and structures. The hybrid diagnostic system uses piezoelectric actuators to input a controlled excitation to the structure and fiber optic sensors to capture the corresponding structural response. The system consists of three major parts: a diagnostic layer with a network of piezoelectric elements and fiber gratings to offer a simple and efficient way to integrate a large network of transducers onto a structure; diagnostic hardware consisting of an arbitrary waveform generator and a high speed fiber grating demodulation unit together with a high speed data acquisition card to provide actuation input, data collection, and information processing; and diagnostic software to determine the condition of the structure. This paper presents key development issues related to the manufacturing of the hybrid piezoelectric/fiber optic diagnostic layer and integration of a highly portable diagnostic hardware. Validation and proof testing of this integrated diagnostic system are also presented.
TL;DR: In this paper, the analysis of active constrained layer damping (ACLD) of laminated thin composite shells using piezoelectric fiber reinforced composite (PFRC) materials is considered to be made of the PFRC materials.
TL;DR: In this article, the capability of harvesting the electric energy from mechanical vibrations in a dynamic environment through a unimorph piezoelectric membrane transducer was investigated, and a power of 1.8 mW was generated at resonance frequency (2.58 kHz) across a 56 kQ optimal resistor and for a 2 g acceleration.
Abstract: In this paper we investigate the capability of harvesting the electric energy from mechanical vibrations in a dynamic environment through a unimorph piezoelectric membrane transducer. Due to the impedance matrices connecting the efforts and flows of the membrane, we have established the dynamic electric equivalent circuit of the transducer. In a first study and in order to validate theoretical results, we performed experiments with a vibrating machine moving a macroscopic 25 mm diameter piezoelectric membrane. A power of 1.8 mW was generated at the resonance frequency (2.58 kHz) across a 56 kQ optimal resistor and for a 2 g acceleration.
TL;DR: In this article, the experimental and numerical assessment of the vibration suppression of smart structures using piezoelectric shear actuators is presented for an adaptive sandwich cantilever beam.
Abstract: This article deals with the experimental and numerical assessment of the vibration suppression of smart structures using piezoelectric shear actuators. Experimental results are presented for an adaptive sandwich cantilever beam that consists of aluminum facings and a core composed of two piezoelectric shear actuators and foam. The electric field is applied perpendicular to the poling direction of the piezoelectric actuators to cause transverse shear deformation of the sandwich beam. Active vibration suppression is achieved using either positive position feedback or strain rate feedback. The control system is implemented in real-time using Matlab/Simulink and a dSPACE digital controller. First, the frequency response of the adaptive beam is investigated by using one shear actuator to excite the beam and the other to control its vibration. Parametric studies are conducted to assess the influence of controller parameters on the frequency response of the system. The experimental frequency response function co...
TL;DR: In this article, an integer-real-encoded genetic algorithm has been developed to search for the optimal placement and size of the piezoelectric patches as well as the optimal feedback control gains.
Patent•
22 Jul 2005
TL;DR: In this paper, a transducing element adapted to sense movement due to a cardiac pulse and produce piezoelectric signal data in response thereto is used to detect the presence of a cardiac signal.
Abstract: Signal data obtained from a piezoelectric sensor placed on a patient's body is used to detect the presence of a cardiac pulse. The piezoelectric sensor has a transducing element adapted to sense movement due to a cardiac pulse and produce piezoelectric signal data in response thereto. Processing circuitry analyzes the piezoelectric signal data for a feature indicative of a cardiac pulse and determines whether a cardiac pulse is present in the patient based on the feature. In one aspect, the feature may be a temporal feature such as a relative change in energy. In another aspect, the feature may be a spectral feature such as the energy or frequency of a peak in the energy spectrum of the signal. In yet another aspect, the feature may be obtained by comparing the piezoelectric signal data with a previously-identified pattern known to predict the presence of a cardiac pulse. Multiple features may also be obtained from the piezoelectric signal data and classified to determine the presence of a cardiac pulse.
TL;DR: In this paper, the free vibration analysis of piezoelectric coupled annular plates using the Kirchhoff and Mindlin plate models is presented and validated by comparing the resonant frequencies and mode shapes.
TL;DR: In this paper, a theoretical and experimental investigation of the scattering behavior of extensional and flexural plate waves by a cylindrical inhomogeneity is presented, where exact solutions are obtained by using wave function expansion method, while the Born first approximation has been employed to derive explicit solutions that form the basis for efficient parametric inversion and eigenfunction back-propagation.
TL;DR: An analytical solution is derived from the three-dimensional equations of linear piezoelectricity that shows the role of each of the physical parameters in determining the performance of such a piezOElectric device, usually measured by the output power density, the power efficiency, or both.
Abstract: We studied mechanical-to-electrical power conversion of a piezoelectric plate driven mechanically into thickness-stretch vibrations. We have derived an analytical solution from the three-dimensional equations of linear piezoelectricity that shows the role of each of the physical parameters in determining the performance of such a piezoelectric device, usually measured by the output power density, the power efficiency, or both. Numerical results are included for illustrating the dependence of the device performance upon these physical parameters.
TL;DR: Piezoelectric micromachined ultrasonic transducers, a potential alternative for conventional one-dimensional phased array ultrasonic Transducers, were investigated and modeling results indicate that the coupling coefficient is significantly affected by silicon membrane, PZT, and top electrode thickness as well as the top electrode design.
Abstract: Piezoelectric micromachined ultrasonic transducers (pMUTs), a potential alternative for conventional one-dimensional phased array ultrasonic transducers, were investigated. We used a modeling approach to study the performance of lead zirconate titanate (PZT)-driven pMUTs for the frequency range of 2-10 MHz, optimized for maximum coupling coefficient, as a function of device design. Using original tools designed for the purpose, a comprehensive build-test finite element model was developed to predict and measure the device performance. In particular, the model estimates the device coupling coefficient and the acoustic impedance, besides the readily extractable resonance frequency and bandwidth. To validate the model, a prototype device was built and tested, showing good agreement between the model predictions and experimental results. Modeling results indicate that the coupling coefficient is significantly affected by silicon membrane, PZT, and top electrode thickness as well as the top electrode design. Results also indicate considerable flexibility in maximizing the coupling coefficient while maintaining the device acoustic impedance at a level matching that of the human body. The bandwidth proved to be superior to that of conventional transducers, reaching 102% in some cases.
TL;DR: In this article, an optimal low-order accurate piezoelectric solid-shell element formulation is presented to model active composite shell structures that can undergo large deformation and large overall motion.
Abstract: In this paper, we present an optimal low-order accurate piezoelectric solid-shell element formulation to model active composite shell structures that can undergo large deformation and large overall motion. This element has only displacement and electric degrees of freedom (dofs), with no rotational dofs, and an optimal number of enhancing assumed strain (EAS) parameters to pass the patch tests (both membrane and out-of-plane bending). The combination of the present optimal piezoelectric solid-shell element and the optimal solid-shell element previously developed allows for efficient and accurate analyses of large deformable composite multilayer shell structures with piezoelectric layers. To make the 3-D analysis of active composite shells containing discrete piezoelectric sensors and actuators even more efficient, the composite solid-shell element is further developed here. Based on the mixed Fraeijs de Veubeke–Hu–Washizu (FHW) variational principle, the in-plane and out-of-plane bending behaviours are improved via a new and efficient enhancement of the strain tensor. Shear-locking and curvature thickness locking are resolved effectively by using the assumed natural strain (ANS) method. We also present an optimal-control design for vibration suppression of a large deformable structure based on the general finite element approach. The linear-quadratic regulator control scheme with output feedback is used as a control law on the basis of the state space model of the system. Numerical examples involving static analyses and dynamic analyses of active shell structures having a large range of element aspect ratios are presented. Active vibration control of a composite multilayer shell with distributed piezoelectric sensors and actuators is performed to test the present element and the control design procedure. Copyright © 2005 John Wiley & Sons, Ltd.
TL;DR: In this article, the authors presented a proof-of-concept design of a tactile sensor capable of measuring compliance of a contact tissue/sensed object, based on the ratio of force experienced by the rigid cylinder to the total force applied to the sensor.
TL;DR: The numerical simulation shows that sufficient vibration suppression can be achieved by means of the proposed general methods.
01 Oct 2005-Precision Engineering-journal of The International Societies for Precision Engineering and Nanotechnology
TL;DR: In this article, the authors presented the control performance of a high-precision positioning table using the hybrid actuators composed of the PZT actuators and voice-coil motors (VCMs).
Abstract: This paper presents the control performance of a high-precision positioning table using the hybrid actuators composed of the piezoelectric (PZT) actuators and voice-coil motors (VCMs). The combined piezo-VCM actuator features two main characteristics, i.e., a large operation range due to the long stroke of VCM, and a high precision and heavy load positioning ability due to the actuation of PZT impact force. In this paper, a one-degree-of-freedom (1-DOF) experimental setup was configured to examine the control performance and the parametric identification for the VCM was performed based on the recursive-least-square (RLS) method. The control performance was effectively demonstrated by using a switching controller configured by an integral variable structure controller (IVSC) for the VCM to conduct rough position control and an impact force controller (IFC) for the PZT actuator to conduct fine position control. The experimental results showed that the positioning table having mass 881 g was successfully positioned within the positioning accuracy of 10 nm by both the forward and backward positioning processes. In the forward control, it totally took 1.253 s for the sliding table to reach the target position of 450 μm; in the backward control, it took 1.387 s for the sliding table moving from the position of 450 μm to the target position of 200 μm.
TL;DR: In this paper, a combined theoretical, numerical, and experimental investigation of the fundamental aspects of the pulse-echo method using piezoelectric sensors and actuators is conducted.
Abstract: The application of guided wave techniques to nondestructively determine the structural integrity of various engineering materials, like alumina, laminated composites, and composite sandwiches, is presented. In particular, a combined theoretical, numerical, and experimental investigation of the fundamental aspects of the pulse-echo method using piezoelectric sensors and actuators is conducted. The dispersion effect of wave guides on these materials is first analyzed, and the transient propagation process of wave guides and its interaction with internal damage are then numerically simulated. The implementations of the pulse-echo method are illustrated in experimental testing and damage detection of aluminum beams, carbon/epoxy laminated composite plates, and composite sandwich beams. The effects of frequencies, wave forms, and types of piezoelectric material on the damage detection process are discussed, in consideration of locating damage in structures. As illustrated in this study, the pulse-echo method combined with piezoelectric material can be used effectively to locate damage in various engineering materials and structures.
TL;DR: In this paper, a dynamic passive controller for thin plate vibrations is presented, where the vibrations damping is obtained by uniformly distributing an array of piezoelectric elements on the host plate, and by interconnecting their terminals via a passive electric circuit.
TL;DR: In this paper, an instantaneous optimal close loop control algorithm coupling the direct and inverse piezoelectric effect is presented and used as an adaptive shape control of the dynamic response of the integrated laminated structure.
TL;DR: In this paper, the authors derived field equations of the coupled structure governing the coupled longitudinal and bending motions of the resonator using linear constitutive equations, slender beam approximations, and Hamilton's principle.
Abstract: Piezoelectrically excited, resonant, elastic beams find wide use as piezoelectric fans, optical choppers, MEMS sensors, and piezoelectric motors. The devices consist of either one piezoelectric ceramic patch (piezopatch) bonded on one side (asymmetric configuration), or of two oppositely poled patches placed symmetrically on either side of a thin, flexible elastic beam (symmetric configuration). Field equations of the coupled structure governing the coupled longitudinal and bending motions of the resonator are derived using linear constitutive equations, slender beam approximations, and Hamilton's principle. Analytical solutions are found to the coupled eigenvalue problem. Eigenvalues and eigenfunctions for the short-circuited and open-circuited configurations are predicted analytically and are found to be in excellent agreement with results from three-dimensional finite element simulations. Electromechanical coupling factors (EMCF) are computed using the analytical and finite element model and optimal resonator geometries are identified for maximal EMCF. The EMCF predictions are also compared with experiments for an asymmetrically configured resonator. The analytical solution provides a convenient tool for the optimal design of such devices.
TL;DR: In this article, the damage sensing and interfacial evaluation of single-glass or basalt fibers/epoxy composites were performed by micromechanical technique and acoustic emission (AE).
TL;DR: In this article, the exact solutions of both mechanical and electrical fields of the actuators are obtained based fully on the theory of elasticity, and it is found that non-zero normal stresses exist in the gradient piezoelectric curved actuator when the actuator is subjected to an external voltage.
Abstract: Bending behaviors of both a piezoelectric curved bi-morph actuator and a functional gradient piezoelectric curved actuator are studied and compared. The exact solutions of both mechanical and electrical fields of the actuators are obtained based fully on the theory of elasticity. It is found that non-zero normal stresses exist in the gradient piezoelectric curved actuator when the actuator is subjected to an external voltage, which is different from the results obtained in our previous works on the gradient piezoelectric flat actuator. It is also proved that the internal stresses are drastically reduced although the deflection of the gradient curved actuator is quite small. The present analytical solutions are compared with the FEM results and a good agreement is found.