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Search Results: 1 - 10 of 672 matches for " piezoelectric transducers "
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Design and Instrumentation of a Measurement and Calibration System for an Acoustic Telemetry System
Zhiqun Deng,Mark Weiland,Thomas Carlson,M. Brad Eppard
Sensors , 2010, DOI: 10.3390/s100403090
Abstract: The Juvenile Salmon Acoustic Telemetry System (JSATS) is an active sensing technology developed by the U.S. Army Corps of Engineers, Portland District, for detecting and tracking small fish. It is used primarily for evaluating behavior and survival of juvenile salmonids migrating through the Federal Columbia River Power System to the Pacific Ocean. It provides critical data for salmon protection and development of more “fish-friendly” hydroelectric facilities. The objective of this study was to design and build a Measurement and Calibration System (MCS) for evaluating the JSATS components, because the JSATS requires comprehensive acceptance and performance testing in a controlled environment before it is deployed in the field. The MCS consists of a reference transducer, a water test tank lined with anechoic material, a motion control unit, a reference receiver, a signal conditioner and amplifier unit, a data acquisition board, MATLAB control and analysis interface, and a computer. The fully integrated MCS has been evaluated successfully at various simulated distances and using different encoded signals at frequencies within the bandwidth of the JSATS transmitter. The MCS provides accurate acoustic mapping capability in a controlled environment and automates the process that allows real-time measurements and evaluation of the piezoelectric transducers, sensors, or the acoustic fields. The MCS has been in use since 2009 for acceptance and performance testing of, and further improvements to, the JSATS.
Studying and Modeling Vibration Transducers and Accelerometers
Katalin ágoston
Scientific Bulletin of the ''Petru Maior" University of T?rgu Mure? , 2010,
Abstract: This paper presents types and operating mode of vibration sensors. Piezoelectric sensing elements are often used in accelerometers. It will be investigate the structure and transfer function of the seismic mass type sensing element. The article presents how the piezoelectric sensing element works and how can be modeled with an electronic circuit. The transfer functions of the electronic circuit models are studied in Matlab and the results are presented. It will be presented the influence of the seismic mass on the accelerometer’s working frequency domain.
Vibration energy harvesting using piezoelectric transducer and non-controlled rectifiers circuits
Motter, Daniel;Lavarda, Jairo Vinícius;Dias, Felipe Aguiar;Silva, Samuel da;
Journal of the Brazilian Society of Mechanical Sciences and Engineering , 2012, DOI: 10.1590/S1678-58782012000500006
Abstract: vibration energy harvesting with piezoelectric materials is of practical interest because of the demand for wireless sensing devices and low-power portable electronics without external power supply. for practical use of vibration energy harvester with piezoelectric materials, it is necessary to process the alternating current (ac) by using different rectifiers' circuits in order to charge batteries with direct current (dc) or to feed electronic devices. unfortunately, most of the models used focused on simplifying the energy harvesting circuit into a simple resistive load. in the real-world applications, the energy harvesting external circuit is more complex than a simple load resistance. in this sense, the goal of the present paper is to describe a comprehensive strategy for power harvesting device to estimate the output power provided by a cantilever beam with the electrodes of the piezoceramic layers connected to a standard rectifier circuit. the true electrical components were considered in the full-wave rectifier circuit with four diodes in bridge. a very simple and comprehensive description for choosing the capacitance and resistance loads is provided. in order to illustrate the results, numerical simulations and experimental verifications are also performed to ensure the accuracy. all tests and results are described and detailed using matlab, the simpowersystem toolbox of the simulink and an experimental setup.
Characterization of 1-3 piezoelectric polymer composites -- a numerical and analytical evaluation procedure for thickness mode vibrations
C.V. Madhusudhana Rao,G. Prasad
Condensed Matter Physics , 2010,
Abstract: Biomedical transducers widely employ piezoceramic polymer composites with 1-3 connectivity. The research is aimed at determining the effective material properties of these composites in the micrometer scale by simulation. Volume fraction of piezoceramic in the composite plays an important role in composite material properties as studied by several researchers. It is also noted that the fiber aspect ratio (a/l) also affects the composite material properties. Therefore it is intended to determine the effective material properties both analytically and by simulation using computer simulation software program ANSYS which implements finite element method (FEM). In the present work piezoelectric fiber composites are modeled, analyzed and then the results are verified by using analytical equations. Important conclusions are drawn to select the piezocomposite materials for transducer applications.
Indication of the suitable model of a mechatronic system as an introduction to the synthesis task
M. P?aczek
Journal of Achievements in Materials and Manufacturing Engineering , 2011,
Abstract: Purpose: The identification of the optimal mathematical model that meets the assumed criteria is the main purpose of this paper, which is an introduction to the task of synthesis of one-dimensional vibrating mechatronic systems. Assumed criteria are to provide the accurate analysis of the system together with maximum simplification of used mathematical tools and minimize required amount of time. The correct description of a given system by its model during the design phase is a fundamental condition for proper operation of it. Therefore, the processes of modelling, testing and verification of used models were presented. On the basis of carry out analysis the optimal (in case of assumed criteria) model was selected and it will be used to realize the task of synthesis in future works.Design/methodology/approach: A series of mathematical models with different simplifying assumptions was created. Using the created models and corrected approximate Galerkin method the dynamic characteristic of the considered system was designated. The analysis of an influence of parameters of the system’s components on obtained characteristic was conducted. The approximate method was verified to check its accuracy and decide if it can be used to analyse such kind of mechatronic systems.Findings: The main result of the work is an indication of the suitable mathematical model of the considered system.Research limitations/implications: Influence of temperature changes on the transducer’s properties was neglected in developed mathematical models. It will be considered in the future works.Practical implications: Presented method of mechatronic system’s analysis can be use in process of designing of technical devices where both, simply and reverse piezoelectric effects can be used.Originality/value: Development of the mathematical models in which the considered system is modelled as a combined beam.
La impedancia eléctrica normalizada de transductores cerámicos piezoeléctricos como herramienta de evaluación y caracterización
San Emeterio, J. L.,Ramos, A.,Sanz, P. T
Boletín de la Sociedad Espa?ola de Cerámica y Vidrio , 1999,
Abstract: The concept of normalized electrical impedance provides an important mechanism for the analysis and evaluation of piezoelectric transducers around an isolated resonance. In the case of piezoelectric resonators this methodology permits: a) to isolate the effects of the geometry (area and thickness) from those associated to the type of material and b) evaluate easily the independent effects of different types of intrinsic losses. The normalized impedance patterns corresponding to the typical parameters of three families of piezoelectric ceramic materials (PZT, Lead Metaniobate, and 1-3 PZT-Epoxy composites) are presented. It is described how this concept of normalized impedance can be extended to piezoelectric transducer elements loaded in the mechanical ports, taking into account the relative values of loading and backing mechanical impedances. Finally, experimental measurements of the normalized impedance in specific NDT transducers are presented. El concepto de impedancia eléctrica normalizada proporciona un importante mecanismo de análisis y evaluación de transductores piezoeléctricos en el entorno de una resonancia aislada. En el caso del resonador piezoeléctrico, esta metodología permite: a) aislar el efecto de la geometría (área y espesor) del asociado al tipo de material y b) evaluar cómodamente el efecto separado de distintos tipos de pérdidas intrínsecas. Se presentan patrones normalizados de impedancia correspondientes a los parámetros típicos de tres familias de materiales cerámicos piezoeléctricos (PZT, Lead Metaniobate, y 1-3 PZT-Epoxy composites). Se detalla como este concepto de impedancia normalizada, previamente definido para el resonador piezoeléctrico, se puede extender a elementos transductores cargados en sus puertas mecánicas, tomando en consideración los valores relativos de las impedancias mecánicas de carga. Por último, se presentan medidas experimentales de la impedancia normalizada en transductores específicos para ensayos no destructivos mediante pulsos ultrasónicos.
Air-Coupled Piezoelectric Transducers with Active Polypropylene Foam Matching Layers
Tomás E. Gómez Alvarez-Arenas
Sensors , 2013, DOI: 10.3390/s130505996
Abstract: This work presents the design, construction and characterization of air-coupled piezoelectric transducers using 1–3 connectivity piezocomposite disks with a stack of matching layers being the outer one an active quarter wavelength layer made of polypropylene foam ferroelectret film. This kind of material has shown a stable piezoelectric response together with a very low acoustic impedance (<0.1 MRayl). These features make them a suitable candidate for the dual use or function proposed here: impedance matching layer and active material for air-coupled transduction. The transducer centre frequency is determined by the l/4 resonance of the polypropylene foam ferroelectret film (0.35 MHz), then, the rest of the transducer components (piezocomposite disk and passive intermediate matching layers) are all tuned to this frequency. The transducer has been tested in several working modes including pulse-echo and pitch-catch as well as wide and narrow band excitation. The performance of the proposed novel transducer is compared with that of a conventional air-coupled transducers operating in a similar frequency range.
高频超声换能器技术研究进展与展望
Progress and Prospects of High-Frequency Ultrasonic Transducer Techniques

吴大伟
- , 2017, DOI: 10.16450/j.cnki.issn.1004-6801.2017.01.001
Abstract: 高频超声是超声技术前沿研究领域,可以提供更高的空间分辨率、更精准的检测诊断信息,在生物医学临床与基础研究、先进装备制造损检测等领域具有重要的应用价值,但其核心器件高频超声换能器的研制一直是高频超声技术发展的瓶颈。首先,介绍了超声换能器基本理论;然后,论述了高频超声换能器技术发展现状、面临技术难题及解决途径,并结合高频超声换能器研制实例予以说明;最后,对高频超声换能器技术进行了讨论与展望。
With its high spatial resolution and excellent detection capability, high-frequency ultrasound is a valuable tool in clinical studies, biomedical research, and nondestructive testing (NDT) of high value manufacturing (HVM). However, a major bottleneck in further progress is the development of ultrasonic transducers for high-frequency applications. In the paper, we introduce basic principles of ultrasonic transducers and briefly review existing ultrasonic transducer techniques. Following this, we address current technical challenges of high-frequency ultrasonic transducer techniques and provide practical solutions, illustrating our recent efforts to develop state-of-the-art high-freq uency ultrasonic transducer arrays. Finally, we discuss the future prospects of high-frequency ultrasonic transducer techniques.
Materiales y técnicas para el acoplamiento mecánico optimo de piezocerámicas en aire
Gómez álvarez-Arenas, T. E.,Montero de Espinosa, F.
Boletín de la Sociedad Espa?ola de Cerámica y Vidrio , 2002,
Abstract: Great efforts have been made over the last years to avoid the use of coupling agents between ultrasonic transducers and sample materials for NDE applications. Two different technologies compite for this particular application: piezoelectric and electrostatic transducers. In the first case, main problem is the huge impedance mismatch between the air and any piezoceramic. This can be partially solved using λ/4 matching layers. Low density and slow velocities of sound propagation in the materials (acoustic impedance as low as 0.1 MRayl), low attenuation of ultrasonic waves and good tuning of the λ/4- resonance to the working frequency of the ceramic are requiered. Usually, all this requirements are extremely difficult to achive at once. It is presented, in this work, the mechanical characterisation of highly porous materials to be used as λ/4- matching layers at frequencies around 1 MHz. This characterisation (both elastic constants and attenuation) is performed using airborne ultrasonic waves. The use of these materials as matching layers for piezoelectric transducers in pitch-cath mode increases the transmision by 35 dB and provides sensitivities about –20 dB. En los últimos a os se están realizando grandes esfuerzos para poder realizar inspecciones de Ensayos no Destructivos por ultrasonidos sin emplear líquidos como medio de acoplo entre los transductores piezoeléctricos y las estructuras a inspeccionar. En este campo compiten dos tecnologías de transducción, los transductores basados en piezocerámicas y los de tipo capacitivo. En el caso de los piezocerámicos, el punto crítico lo constituye la desadaptación de impedancias entre el resonador piezoeléctrico y el aire. Para soslayar este problema es posible utilizar capas de adaptación (λ/4). Para esto es necesario utilizar materiales con muy baja densidad y velocidad de propagación (impedancia acústica específica del orden de 0.1 MRayl), baja atenuación y buena sintonización a la frecuencia de trabajo. Con frecuencia, todas estas propiedades son extremadamente difíciles de conjugar. En el trabajo se presenta la caracterización de materiales con elevada porosidad y su utilización como líneas de transmisión λ/4 para frecuencias en el entorno de 1 MHz. La caracterización – constantes elásticas y coeficiente de atenuación- se realiza con acoplamiento en aire. El uso de estos materiales como línea de adaptación logra mejoras de transmisión de hasta 35 dB y sensibilidad en modo emisión-recepción de hasta –20 dB.
A Vibration-Based Strategy for Health Monitoring of Offshore Pipelines’ Girth-Welds
Pejman Razi,Farid Taheri
Sensors , 2014, DOI: 10.3390/s140917174
Abstract: This study presents numerical simulations and experimental verification of a vibration-based damage detection technique. Health monitoring of a submerged pipe’s girth-weld against an advancing notch is attempted. Piezoelectric transducers are bonded on the pipe for sensing or actuation purposes. Vibration of the pipe is excited by two means: (i) an impulsive force; (ii) using one of the piezoelectric transducers as an actuator to propagate chirp waves into the pipe. The methodology adopts the empirical mode decomposition (EMD), which processes vibration data to establish energy-based damage indices. The results obtained from both the numerical and experimental studies confirm the integrity of the approach in identifying the existence, and progression of the advancing notch. The study also discusses and compares the performance of the two vibration excitation means in damage detection.
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