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Showing papers on "Piezoelectric sensor published in 2006"


Journal ArticleDOI
TL;DR: In this article, a fuzzy logic system is trained to correlate the harmonic response amplitude with the concrete strength based on the experimental data, and the experimental results show that the concrete strengths estimated by the trained fuzzy correlation system matches the experimental strength data.
Abstract: At early ages of concrete structures, strength monitoring is important to determine the structures' readiness for service. Piezoelectric-based strength monitoring methods provide an innovative experimental approach to conduct concrete strength monitoring at early ages. In this paper, piezoelectric transducers in the form of 'smart aggregates' are embedded into the concrete specimen during casting. Piezoceramic materials can be used as actuators to generate high frequency vibrating waves, which propagate within concrete structures; meanwhile, they can also be used as sensors to detect the waves. The smart aggregate is a one cubic inch, pre-cast concrete block with a wired, embedded PZT (lead zirconate titanate, a type of piezoceramic) patch. The strength development of concrete structures is monitored by observing the development of harmonic response amplitude from the embedded piezoelectric sensor at early ages. From experimental results, the amplitude of the harmonic response decreases with increasing concrete strength. The concrete strength increases at a fast rate during the first few days and at a decreasing rate after the first week. Concordantly, the amplitude of the harmonic response from the piezoelectric sensor drops rapidly for the first week and continues to drop slowly as hydration proceeds, matching the development of the concrete strength at early ages. Concrete is heterogeneous and anisotropic, which makes it difficult to analyze mathematically. Fuzzy logic has the advantage of conducting analysis without requiring a mathematical model. In this paper, a fuzzy logic system is trained to correlate the harmonic amplitude with the concrete strength based on the experimental data. The experimental results show that the concrete strength estimated by the trained fuzzy correlation system matches the experimental strength data. The proposed piezoelectric-based monitoring method has the potential to be applied to strength monitoring of concrete structures at early ages.

269 citations


Journal ArticleDOI
TL;DR: A sensor diagnostics and validation process that performs in situ monitoring of the operational status of piezoelectric active-sensors in structural health monitoring (SHM) applications is presented in this article.
Abstract: A sensor diagnostics and validation process that performs in situ monitoring of the operational status of piezoelectric (PZT) active-sensors in structural health monitoring (SHM) applications is presented. Both degradation of the mechanical/electrical properties of a PZT transducer and the bonding defects between a PZT patch and a host structure could be identified by the proposed process. This study also includes the investigation into the effects of the sensor/structure bonding defects on high-frequency SHM techniques, including Lamb wave propagations and impedance methods. It has been found that the effects are significant, modifying the phase and amplitude of propagated waves and changing the measured impedance spectrum. These changes could lead to false indications on the structural conditions without an efficient sensor-diagnostic process. The feasibility of the proposed sensor diagnostics procedure is then demonstrated by analytical studies and experimental examples, where the functionality of the surface-mounted piezoelectric sensors was continuously deteriorated. The proposed process can provide a metric that can be used to determine the sensor functionality over a long period of service time or after an extreme loading event. Further, the proposed method can be useful if one needs to check the operational status of a sensing network right after its installation.

257 citations


Journal ArticleDOI
TL;DR: In this paper, a numerical study concerning the active vibration control of smart piezoelectric beams is performed in order to investigate their effectiveness to suppress vibrations in beams with PAs acting as sensors or actuators.

218 citations


Journal ArticleDOI
TL;DR: In this article, a piezoelectric sensor self-diagnostic procedure is proposed to track the changes in the capacitive value of piezolectric materials resulting from the degradation of the mechanical/electrical properties and its attachment to a host structure, which is manifested in the imaginary part of measured electrical admittances.
Abstract: This paper presents a piezoelectric sensor self-diagnostic procedure that performs in situ monitoring of the operational status of piezoelectric materials used for sensors and actuators in structural health monitoring (SHM) applications. The sensor/actuator self-diagnostic procedure, where the sensors/actuators are confirmed to be functioning properly during operation, is a critical component to successfully complete the SHM process with large numbers of active sensors typically installed in a structure. The premise of this procedure is to track the changes in the capacitive value of piezoelectric materials resulting from the degradation of the mechanical/electrical properties and its attachment to a host structure, which is manifested in the imaginary part of the measured electrical admittances. This paper concludes with an experimental example to demonstrate the feasibility of the proposed procedure.

178 citations


Journal ArticleDOI
TL;DR: It is shown that, for a given energy harvesting technique, generators using single crystals deliver 20 times more power than generators using piezoelectric ceramics.
Abstract: This paper compares the performances of vibration-powered electrical generators using a piezoelectric ceramic and a piezoelectric single crystal associated to several power conditioning circuits. A new approach of the piezoelectric power conversion based on a nonlinear voltage processing is presented, leading to three novel high performance power conditioning interfaces. Theoretical predictions and experimental results show that the nonlinear processing technique may increase the power harvested by a factor of 8 compared to standard techniques. Moreover, it is shown that, for a given energy harvesting technique, generators using single crystals deliver 20 times more power than generators using piezoelectric ceramics.

174 citations


Journal ArticleDOI
TL;DR: In this article, an enhanced semi-passive damping technique was proposed to enhance the electromechanical coupling by artificially increasing the voltage amplitude delivered by the piezoelectric patches.
Abstract: Semi-passive damping techniques have been developed recently to address the problem of structural damping. Contrary to the standard passive piezoelectric damping, these new techniques adapt to environmental variations. Moreover, they present interesting multimodal damping performances. However, their efficiency is strongly correlated with their electromechanical coupling. The enhanced semi-passive damping technique presented herein compensates for this drawback. It reinforces the electromechanical coupling by artificially increasing the voltage amplitude delivered by the piezoelectric patches. Theoretical predictions and experimental results show a −24 dB attenuation on the vibration of a resonant cantilever steel beam, while reducing the piezoelectric material volume by 83%.

167 citations


Journal ArticleDOI
TL;DR: In this paper, the authors proposed a new approach to harvest electrical energy from a mechanically excited structure equipped with piezoelectric elements. But this method is not compatible with the standard approach.
Abstract: This article describes a new approach to harvest electrical energy from a mechanically excited structure equipped with piezoelectric elements. Standard harvesting circuits using piezoelectric elements as an electric generator consist of an AC-DC converter coupled to a load. The technique proposed herein is fully compatible with the standard approach. The difference consists in adding up an electrical switching device connected in parallel with the piezoelectric elements. The switch device is triggered on the maxima or minima of the displacement and realizes a voltage inversion through an inductor. This method allows the artificial increase of the piezoelements' output voltage, resulting in a significant increase of the electrical power flow. It is shown that the power flow transfer strongly depends on the structure electromechanical coupling coefficient. For a weakly coupled structure using this new technique, the electrical power can be increased by over 400%.

165 citations


Journal ArticleDOI
TL;DR: In this paper, a PI feedback control associated with feed forward compensating based on the hysteresis observer is proposed to compensate the nonlinearity of piezoelectric actuator.

162 citations


Journal ArticleDOI
TL;DR: In this paper, the structural and compositional differences between each actuator are incorporated in the discussion of the effectiveness of each actuators as a power-harvesting device, and the differences in performance in power harvesting applications between several of these new actuators and the reasons for their relative performance characteristics.
Abstract: The use of piezoelectric materials for power harvesting has attracted significant interest over the past few years. The majority of research on this subject has sought to quantify the amount of energy generated in power harvesting applications, or to develop methods of improving the amount of energy generated. Usually, a monolithic piezoelectric material with a traditional electrode pattern and poled through its thickness is used for power harvesting. However, in recent years several companies and research institutions have begun to develop and market a broad range of piezoelectric composite sensor/actuator packages, each conceived for specific operational advantages and characteristics. Commonly, these devices are employed in control and vibration suppression applications, and their potential for use in power-harvesting systems remains largely unknown. Two frequently implemented design techniques for improving the performance of such actuators are the use of interdigitated electrodes and piezofibers. This paper seeks to experimentally quantify the differences in performance in power-harvesting applications between several of these new actuators and to identify the reasons for their relative performance characteristics. A special focus on the structural and compositional differences between each actuator is incorporated in the discussion of the effectiveness of each actuator as a power-harvesting device.

143 citations


Journal ArticleDOI
TL;DR: In this article, two types of fiber Bragg gratings (FBGs) ultrasonic sensing system were constructed using different light source: a broadband light source and a tunable laser source.

135 citations


Journal ArticleDOI
TL;DR: In this paper, the nonlinear vibration and dynamic response of a functional graded material (FGM) plate with surface-bonded piezoelectric layers in thermal environments were investigated.

Journal ArticleDOI
TL;DR: In this paper, a novel piezoelectric cantilever bimorph micro transducer electro-mechanical energy conversion model is proposed based on the curvature basis approach.

Journal ArticleDOI
TL;DR: In this paper, the authors explore the use of flexible piezoelectric materials, e.g. piezoelastic polymers such as PVDF, for sending and receiving Lamb waves to be used in the structural health monitoring (SHM) applications.
Abstract: Piezoelectric wafer active sensors (PWAS) used in structural health monitoring (SHM) applications are able to detect structural damage using Lamb waves. PWAS are small, lightweight, unobtrusive and inexpensive. They achieve direct transduction between electric and elastic wave energies. PWAS are charge mode sensors and can be used as both transmitters and receivers. The focus of this paper is to find a suitable in situ piezoelectric active sensor for sending and receiving Lamb waves to be used in the SHM of structures with a curved surface. Current SHM technology uses brittle piezoceramic (PZT) wafer active sensors. Since piezoceramics are brittle, this approach could only be used on flat surfaces. The motivation of our research was to explore the use of flexible piezoelectric materials, e.g. piezoelastic polymers such as PVDF. However, PVDF stiffness is orders of magnitude lower than the PZT stiffness, and hence PVDF Lamb wave transmitters are much weaker than PZT transmitters. Thus, our research proceeded in two main directions: (a) to model and understand how piezoelectric material properties affect the behaviour of piezoelectric wafer active sensors; and (b) to perform experiments to test the capabilities of the flexible PVDF PWAS in comparison with those of stiffer but brittle PZT PWAS. We have shown that, with appropriate signal amplification, PVDF PWAS can perform the same Lamb wave transmission and reception functions currently performed by PZT PWAS. The experimental results of PZT-PWAS and PVDF-PWAS have been compared with a conventional strain gauge. The theoretical and experimental results in this study gave a basic demonstration of the piezoelectricity of PZT-PWAS and PVDF-PWAS.

Journal ArticleDOI
TL;DR: In this article, a Lamb wave-based crack identification technique for aluminium plates was developed with an integrated active piezoelectric sensor network, and a correlation function was further established, which helped identify the crack position based on a triangulation approach with the aid of a nonlinear least-squares optimization algorithm.
Abstract: With an integrated active piezoelectric sensor network, a Lamb wave-based crack identification technique for aluminium plates was developed. Experimental results showed that the propagation of Lamb waves in aluminium plate-like structures is considerably complicated due to wave dispersion, material attenuation, boundary reflection, etc. In order to eliminate the diverse interference, a wavelet transform technique was applied to purify the acquired Lamb wave signals, and the characteristics of Lamb wave signals were extracted from the wave energy spectrum. A correlation function was further established, which helped identify the crack position based on a triangulation approach with the aid of a nonlinear least-squares optimization algorithm. Such an approach provides satisfactory results in locating the crack position in aluminium plates with cracks of 5 and 20 mm in length.

Journal ArticleDOI
TL;DR: In this article, an effective model of surface-bounded flat PZT disks based on effective force, moment and displacement is developed for Lamb wave excitation, collection and propagation in isotropic plate and quasi-isotropic laminated composite.

Journal ArticleDOI
TL;DR: In this paper, an embedded sensor network technique was developed for improving the overall integrity of functionalized composite structures engaged in aircraft, where a set of miniaturized piezoelectric wafers was designed and circuited to configure a built-in active actuator/sensor network, which was immobilized into multi-layered composite laminates.
Abstract: An embedded sensor network technique was developed for improving the overall integrity of functionalized composite structures engaged in aircraft. A set of miniaturized piezoelectric wafers was designed and circuited to configure a built-in active actuator/sensor network, which was immobilized into multi-layered composite laminates. The propagation characteristics of Lamb waves generated and collected by this built-in sensor network in carbon fibre-reinforced composite laminates were investigated. The influence of a stiffener and of the excitation frequency on the propagation of the Lamb waves generated was evaluated. A study was carried out to assess delamination in CF/EP (carbon fibre/epoxy) woven laminates, by fusing information from multiple sensing paths of the embedded network on the basis of the Hilbert transform, signal correlation and probabilistic searching. An excellent identification capability indicates the considerable application potential of the proposed sensor network approach in providing high-fidelity data acquisition and condition monitoring for composite aircraft structures.

Journal ArticleDOI
TL;DR: In this article, an analytical two-port, lumped-element model of a piezoelectric composite circular plate is presented, where the individual components of a unimorph transducer are modeled as lumped elements of an equivalent electrical circuit using conjugate power variables, and the transverse static deflection field as a function of pressure and voltage loading is determined to synthesize the twoport dynamic model.
Abstract: This paper presents an analytical two-port, lumped-element model of a piezoelectric composite circular plate. In particular, the individual components of a piezoelectric unimorph transducer are modeled as lumped elements of an equivalent electrical circuit using conjugate power variables. The transverse static deflection field as a function of pressure and voltage loading is determined to synthesize the two-port dynamic model. Classical laminated plate theory is used to derive the equations of equilibrium for clamped circular laminated plates containing one or more piezoelectric layers. A closed-form solution is obtained for a unimorph device in which the diameter of the piezoelectric layer is less than that of the shim. Methods to estimate the model parameters are discussed, and model verification via finite-element analyses and experiments is presented. The results indicate that the resulting lumped-element model provides a reasonable prediction (within 3%) of the measured response to voltage loading and the natural frequency, thus enabling design optimization of unimorph piezoelectric transducers.

Journal ArticleDOI
TL;DR: In this article, the authors used built-in piezoelectric discs as sensors and actuators in a pitch-catch mode to generate sensor data, which are sensitive to debond in reinforced concrete.
Abstract: An investigation is performed to detect debond in reinforced concrete structures. This study utilizes built-in piezoelectric discs as sensors and actuators in a pitch-catch mode to generate sensor data, which are sensitive to debond in reinforced concrete. A comparison of sensor measurements or signal changes before and after maintenance or inspection can be correlated to debonding. Both experimental and analytical works are performed during the study. Experimental study and test data are presented in this article. The test results clearly indicate that debond between concrete and rebar and yielding in rebar can be detected with built-in piezoelectric sensors and actuators in a pitch-catch mode.

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the efficiency of a system identification technique known as observer/Kalman filter identification (OKID) technique in the numerical simulation and experimental study of active vibration control of piezoelectric smart structures.

Journal ArticleDOI
TL;DR: The electrically and mechanically excited resonances in micromachined circular piezoelectric diaphragms have been investigated and the nonlinear vibration was governed by geometric nonlinearity rather than material non linearity.
Abstract: The electrically and mechanically excited resonances in micromachined circular piezoelectric diaphragms have been investigated. The diaphragm structures were piezoelectric unimorphs consisting of Pb(Zr/sub 0.52/,Ti/sub 0.48/)O/sub 3/ (PZT) films and thermally grown silicon oxide (SiO/sub 2/) layers. For electrical excitation, ring-shaped interdigitated (IDT) electrodes formed on the top of the PZT layer were used to induce strain in the diaphragms. The diaphragm structures behaved much like circular membranes in which the membrane tension was /spl sim/206 N/m, at the fundamental modes. For higher modes, the resonance frequencies deviated from the theoretical values due to the finite stiffness of the diaphragms. Under mechanical drive, both symmetric and asymmetric modes were excited. However, for electrical excitation, the symmetric modes were dominant due to the symmetry of the driving IDT electrodes. At a pressure of 727 Torr, the quality factor was /spl sim/250, and this rose to 2000 at pressures below 1 Torr. When a forward bias was applied to the diaphragm, the membrane tension decreased, but under reverse biases the tension increased. However, because of repoling under reverse biases greater than the coercive field of the PZT film, the achievable increase in the membrane tension was limited. In the diaphragm structure, the nonlinear vibration was governed by geometric nonlinearity rather than material nonlinearity. In addition, evidence of non-180/spl deg/ domain wall motion of the PZT layer in released diaphragms was observed.

Journal ArticleDOI
TL;DR: In this article, the authors presented some finite elements for the dynamic analysis of laminated plates embedding piezoelectric layers based on the principle of virtual displacements (PVD) and an unified formulation.

Journal ArticleDOI
TL;DR: In this paper, the effect of adhesive thickness and its modulus on the performance of adhesively bonded piezoelectric elements for the purpose of monitoring structural health has been experimentally investigated.

Journal ArticleDOI
TL;DR: In this paper, a mechanically excited unimorph piezoelectric membrane transducer was used to generate a power of 0.65 mW at the resonance frequency (1.71 kHz) across a 5.6 kΩ optimal resistor and for a 80 n force.

Journal ArticleDOI
TL;DR: In this article, a refined integro-partial differential model is developed for a clamped?clamped composite beam structure and used for studying the nonlinear transverse vibrations of these resonators.
Abstract: Free and forced oscillations of piezoelectric, microelectromechanical resonators fabricated as clamped?clamped composite structures are studied in this effort. Piezoelectric actuation is used to excite these structures on the input side and piezoelectric sensing is carried out on the output side. A refined integro-partial differential model is developed for a clamped?clamped composite beam structure and used for studying the nonlinear transverse vibrations of these resonators. This model accounts for the longitudinal extension due to transverse vibrations, distributed actuation and axially varying properties across the length of the structure. Free oscillations about a post-buckled position are studied, and for weak damping and weak forcing, the method of multiple scales is used to obtain an approximate solution for the response to a harmonic forcing. Analytical predictions are also compared with experimental observations. The model development and the analysis can serve as a basis for analysing the responses of other composite microresonators.

Journal ArticleDOI
TL;DR: In this paper, a new type of cement-based piezoelectric sensor developed recently for monitoring the traffic flows is proposed and investigated, and two experiments were carried out to prove the feasibility and reliability of the sensor for monitoring traffic flows including the person flow and the vehicle flow in the field of transportation.
Abstract: In this paper, the preliminary application of a new type of cement-based piezoelectric sensor developed recently for monitoring the traffic flows is proposed and investigated. The sensor was made by bonding between two cubes of hardened cement sand paste with a commercially available piezoelectric ceramic plate encapsulated by a new sealant developed especially for the sensor's fabrication, and its property was tested by dynamic loadings including harmonic loading, random loading, and pulse loading. Two experiments were carried out to prove the feasibility and reliability of the sensor for monitoring the traffic flows including the person flow and the vehicle flow in the field of transportation. The tested results show that the sensors can correctly respond to the pulse loadings induced by walking person or passing vehicle and the responses of sensors were approximately direct proportional to the peak values of pulse loadings. A conclusion is given that there is a good potential for the cement-based piezoelectric sensor in the engineering application for monitoring traffic flows in the field of transportation.

Journal ArticleDOI
TL;DR: In this paper, a micromechanics model has been derived to predict the effective elastic and piezoelectric coefficients of the composite material used for the distributed actuator of smart structures.
Abstract: This paper deals with the analysis of vertically reinforced 1–3 piezoelectric composite materials as the material used for the distributed actuator of smart structures A micromechanics model has been derived to predict the effective elastic and piezoelectric coefficients of these piezoelectric composites which are useful for the analysis of smart beams In order to investigate the performance of a layer of this 1–3 piezoelectric composite material as the distributed actuator of smart structures, active constrained layer damping (ACLD) of smart laminated composite beams has been studied The constraining layer in the ACLD treatment has been considered to be made of this piezoelectric composite A finite element model has been developed to study the dynamics of the overall beam/ACLD system Both in-plane and out-of-plane actuations of the constraining layer of the ACLD treatment have been utilized for deriving the finite element model It has been found that these vertically reinforced 1–3 piezoelectric composite materials which are in general being used as distributed sensors can be potentially used as distributed actuators of smart structures

Journal ArticleDOI
TL;DR: In this paper, an active diagnostic system using built-in piezoelectric actuator/sensor networks was developed for monitoring crack growth in a rocket engine pipe, which combines a sensor network, portable diagnostic hardware and data analysis software which allows for real-time in situ monitoring and long term tracking of the structural integrity of pressure vessels.
Abstract: An active diagnostic system using built-in piezoelectric actuator/sensor networks was developed for monitoring crack growth in a rocket engine pipe. The diagnostic system combines a sensor network, portable diagnostic hardware and data analysis software which allows for real-time in situ monitoring and long term tracking of the structural integrity of pressure vessels. Experimental data shows that the system can detect a surface crack as small as 4 mm and a through-crack as small as 2 mm in the high pressure engine pipe made of Inconel 718. It was found that the actuator-sensor paths that are most sensitive to crack growth are the ones in which the crack is growing away from, rather than towards the path. This discovery will provide important guidelines for the design of a sensor network for crack detection. It was also observed that the bending mode (equivalent to the A0 mode in plates) is more sensitive than the longitudinal mode (equivalent to the S0 mode in plates) to crack growth.

Journal ArticleDOI
TL;DR: A PZT/PZT flexible transducer showed a signal strength comparable with that obtained by a commercial room temperature broad bandwidth transducers, and the results are in reasonable agreement with experimental data.
Abstract: Flexible ultrasonic transducers (UTs) consisting of a metal foil, a piezoelectric ceramic film, and a top electrode have been developed. The flexibility is realized owing to the porosity of piezoelectric film and the thinness of metal foil. In this paper, the stainless steel (SS), lead-zirconate-titanate (PZT)/PZT composite and silver paste were chosen as metal foil, piezoelectric film, and top electrode materials, respectively. The SS foil serves as both substrate and bottom electrode. The PZT/PZT piezoelectric composite film is made by the sol-gel spray technique. PZT/PZT films of thicknesses from 40 to 70 mum were fabricated onto SS foils. The capability of these flexible sensors operated in the pulse-echo mode for nondestructive testing on flat and curved surfaces of different materials at room temperature and 160degC has been demonstrated. Numerical simulations of the effects of the metal foil thickness on the ultrasonic performance of flexible UTs also were carried out, and the results are in reasonable agreement with experimental data. In addition, a PZT/PZT flexible transducer showed a signal strength comparable with that obtained by a commercial room temperature broad bandwidth transducer

Journal ArticleDOI
TL;DR: In this article, a geometrically non-linear solid shell element is proposed to analyze piezoelectric structures based on a variational principle of the Hu-Washizu type and includes six independent fields: displacements, electric potential, strains, electric field, mechanical stresses and dielectric displacements.
Abstract: This paper is concerned with a geometrically non-linear solid shell element to analyse piezoelectric structures. The finite element formulation is based on a variational principle of the Hu-Washizu type and includes six independent fields: displacements, electric potential, strains, electric field, mechanical stresses and dielectric displacements. The element has eight nodes with four nodal degrees of freedoms, three displacements and the electric potential. A bilinear distribution through the thickness of the independent electric field is assumed to fulfill the electric charge conservation law in bending dominated situations exactly. The presented finite shell element is able to model arbitrary curved shell structures and incorporates a 3D-material law. A geometrically non-linear theory allows large deformations and includes stability problems. Linear and non-linear numerical examples demonstrate the ability of the proposed model to analyse piezoelectric devices.

Patent
12 Oct 2006
TL;DR: In this article, an electrode catheter and a method for assessing catheter-tissue contact for tissue ablation is described, where at least one piezoelectric sensor is responsive to movement of the flexible catheter shaft by generating electrical signals corresponding to the amount of movement.
Abstract: An electrode catheter and a method for assessing catheter-tissue contact for tissue ablation are disclosed. An exemplary electrode catheter comprises a flexible catheter shaft. At least one piezoelectric sensor is oriented coaxial to the flexible catheter shaft. The at least one piezoelectric sensor is responsive to movement of the flexible catheter shaft by generating electrical signals corresponding to the amount of movement. The system may also include an output device electrically connected to the at least one piezoelectric sensor. The output device receives the electrical signals for dynamically assessing a level of contact between the flexible catheter shaft and a moving tissue. In another exemplary embodiment, the system may be implemented in a hydrodynamic environment.