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1
Pistun, Ye P., H. F. Matiko, and H. B. Krykh. "STRUCTURAL AND PARAMETRIC OPTIMIZATION OF GAS-HYDRODYNAMIC MEASURING TRANSDUCERS OF PHYSICAL AND MECHANICAL PARAMETERS OF FLUIDS." Bulletin of Kyiv Polytechnic Institute. Series Instrument Making, no. 62(2) (December 24, 2021): 23–31. http://dx.doi.org/10.20535/1970.62(2).2021.249174.
Повний текст джерелаАнотація:
The article is devoted to improving the methods for building throttle diagrams of gas-hydrodynamic measuring transducers of physical and mechanical parameters of fluids. The authors reviewed modern throttle transducers of various parameters, built on different diagrams, with different numbers and types of throttle elements, with different output signals. We established that the goodness of the measuring transducer is determined both by the structural diagram and the design characteristics of the throttle elements of a specific measuring diagram. The article proposes using structural synthesis with parametric optimization to achieve the specified characteristics of the gas-hydrodynamic transducers.
The aim is to develop an effective method for building throttle diagrams of gas-hydrodynamic measuring transducers of physical and mechanical parameters of fluids using structural optimization of diagrams and to evaluate each dia-gram using parametric optimization methods with the appropriate criterion that quantifies the goodness of the measur-ing transducer.
To achieve this goal, the authors analyzed the criteria and resources of structural and parametric optimization of gas-hydrodynamic transducers. In particular, the following resources of structural synthesis of measuring transducers’ dia-grams are analyzed: diagram order and throttle arrangement, type of throttles, output signals, supply mode of the transducer. Approaches to parametric optimization of throttle diagrams are offered: based on the mathematical model, one defines the objective function, forms restrictions on variable and fixed values, substantiates optimization parameters, chooses the optimization method.
As a result of the research, the authors developed a technique for structural and parametric optimization of gas-hydrodynamic measuring transducers, making it possible to synthesize throttle diagrams and build mathematical models of transducers of specific parameters of the fluid with optimal characteristics.
2
Iizumi, Hideaki, Hiroaki Kajikawa, and Tokihiko Kobata. "Calibration values uninfluenced by the kind of pressure medium and the setting posture for quartz Bourdon-type pressure transducers." ACTA IMEKO 8, no. 3 (September 30, 2019): 25. http://dx.doi.org/10.21014/acta_imeko.v8i3.666.
Повний текст джерелаАнотація:
<p class="Abstract">The effects of the kind of gas medium and the setting posture on the calibration values of a quartz Bourdon-type pressure transducer mounted vertically are evaluated in this study. The transducer, at the upward and downward settings, was calibrated both with nitrogen and with helium. The difference between the calibration values of the transducer with nitrogen at the upward and downward settings was about 7.0 kPa at 100 MPa. At the same setting posture, the maximum difference in the calibration values between nitrogen and helium was 3.4 kPa. For precise pressure measurement, it is recommended that the transducers are used with the same pressure medium and the same setting posture with which they were calibrated. The methods of reducing the effects of both the kind of gas medium and the setting posture are discussed. The average of two calibration values at the upward setting and at the downward setting was not affected by the kind of gas medium. When the sensing elements of two pressure transducers arranged in point symmetry with each other, the average values of two transducers were independent of both the kind of gas medium and the setting posture.</p>
3
Tuğcu, M. Barış, and Erol Feyzullahoğlu. "The investigation of effects of humidity and temperature on torque transducers calibration." tm - Technisches Messen 88, no. 3 (January 8, 2021): 156–63. http://dx.doi.org/10.1515/teme-2020-0077.
Повний текст джерелаАнотація:
Abstract Torque transducer is mechanical device that converts an energy form to another energy form. Torque transducers are calibrated by using machines such as dead weight calibration machines and reference torque transducer systems. Torque transducers are at risk of being affected by various environmental conditions such as temperature and humidity, and deviating from expected measurement results due to strain gauges on them. These factors should be kept under control, if this is not possible, contribution of ambient temperature and air humidity effects on measurement results should be taken into consideration. In this study, measurements were made according to DIN 51309 directive, and effect of other parameter changes on measurement uncertainty, while temperature and humidity kept constant in turn, was investigated. In this study, the goal was to reduce measurement uncertainty of calibration by determining the optimum temperature and humidity values in test environment. As a result of this study, the optimum values are obtained. The lowest measurement uncertainty was found at 21 °C and 50 % RH in this experimental study. In a test environment where optimum environmental conditions are obtained as a result of this study, the torque transducers will have the opportunity to work with maximum precision.
4
Zhu, Rui, Qingguo Fei, Dong Jiang, and Xiaochen Hang. "Using Sherman–Morrison theory to remove the coupled effects of multi-transducers in vibration test." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 233, no. 4 (January 18, 2018): 1364–76. http://dx.doi.org/10.1177/0954410017753805.
Повний текст джерелаАнотація:
Modal parameter identification is adversely affected by the mass loading of the transducer in experiments, especially when multi-transducers are arranged on the lightweight structure. In order to remove the coupling effects of transducers on each measurement point, a hierarchical multi-transducers eliminations method based on Sherman–Morrison theory is investigated. The method consists of two steps: (1) Decomposition: multiple elimination is decomposed into multi-levels, the relationship of the frequency response functions between each level is illustrated in the tree diagram; (2) Elimination: according to the relationship between each level, the measured frequency response functions are modified level by level. Numerical simulation is conducted by employing a three-degrees-of-freedom spring-mass system and the robustness is verified in the noise case. Experimental investigations are undertaken by employing a lightweight cantilever beam: Laser Doppler vibrometer is adopted to obtain measured frequency response functions without transducer mass loading effect, which are regarded as the target data. The initial frequency response functions are obtained in the case, in which multi-accelerometers are arranged and the effects should be removed. The result shows that the method can effectively decouple the frequency response functions due to transducers. In the elimination process, it is necessary to delete duplicate information (frequency response functions), which can greatly reduce the amount of calculation. And the effects of multi-transducers mass can be removed and the corrected frequency response functions are in quite good agreement with the target values.
5
Bilgiç, E., and Y. Durgut. "Effects of Waveform Model on Sensitivity Values of Transducers Used in Mechanical Dynamic Measurements." Acta Physica Polonica A 128, no. 2B (August 2015): B—267—B—271. http://dx.doi.org/10.12693/aphyspola.128.b-267.
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Choi, Hojong, Jongseon Johnson Jeong, and Jungsuk Kim. "Development of an Estimation Instrument of Acoustic Lens Properties for Medical Ultrasound Transducers." Journal of Healthcare Engineering 2017 (2017): 1–7. http://dx.doi.org/10.1155/2017/6580217.
Повний текст джерелаАнотація:
In medical ultrasound transducers, the transmission mode (pass-through) approach has been used to estimate the characteristics of the acoustic lens. However, it is difficult to measure the acoustic lens properties with high precision because of human, systemic, or mechanical measurement errors. In this paper, we propose a low-cost estimation instrument for acoustic lens properties connected with a customized database. In the instrument, three-axis and one-axis transmitting and material fixtures accurately align the transmitting and receiving transducers separately. Through the developed instrument, we obtained a precise standard deviation of the attenuation coefficient and velocity of the acoustic lens material of 0.05 dB/cm and 2.62 m/s, respectively. Additionally, the simultaneous alignment between the fixtures is controllable with developed programs, thus generating very accurate information of the acoustic lens about the testing ultrasound transducer. In our instrument, the database could support users in managing the result data efficiently. User programs developed using LabVIEW provide the capability to obtain precise values of the attenuation coefficient and velocity, which represent the fundamental material characteristics of the acoustic lens of the medical ultrasound transducers. The developed review program of the customized database can also search the acoustic lens information and store the experimental results.
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Awal, M. A., and T. Kundu. "V(z) Curve Synthesis Using Two Ultrasonic Transducers." Journal of Applied Mechanics 62, no. 2 (June 1, 1995): 517–22. http://dx.doi.org/10.1115/1.2895960.
Повний текст джерелаАнотація:
Traditionally V(z) curves are generated by acoustic microscopes. However, because of the high costs of the commercially available acoustic microscopes, their use is rather limited. In this paper it is shown how V(z) curves, which contain quantitative information about the material under inspection, can be generated using two ultrasonic transducers instead of an acoustic microscope. A theoretical analysis is given to synthesize V(z) curves of orthotropic plates by this technique. A basic mechanics problem of the reflection of plane waves by an orthotropic plate immersed in a fluid is solved for this purpose. Theoretically synthesized V(z) values are compared with experimental results.
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Barrientos, Gabriel, Giacomo Clementi, Carlo Trigona, Merieme Ouhabaz, Ludovic Gauthier-Manuel, Djaffar Belharet, Samuel Margueron, Ausrine Bartasyte, Graziella Malandrino, and Salvatore Baglio. "Lead-Free LiNbO3 Thick Film MEMS Kinetic Cantilever Beam Sensor/Energy Harvester." Sensors 22, no. 2 (January 12, 2022): 559. http://dx.doi.org/10.3390/s22020559.
Повний текст джерелаАнотація:
In this paper, we present integrated lead-free energy converters based on a suitable MEMS fabrication process with an embedded layer of LiNbO3. The fabrication technology has been developed to realize micromachined self-generating transducers to convert kinetic energy into electrical energy. The process proposed presents several interesting features with the possibility of realizing smaller scale devices, integrated systems, miniaturized mechanical and electromechanical sensors, and transducers with an active layer used as the main conversion element. When the system is fabricated in the typical cantilever configuration, it can produce a peak-to-peak open-circuit output voltage of 0.208 V, due to flexural deformation, and a power density of 1.9 nW·mm−3·g−2 at resonance, with values of acceleration and frequency of 2.4 g and 4096 Hz, respectively. The electromechanical transduction capability is exploited for sensing and power generation/energy harvesting applications. Theoretical considerations, simulations, numerical analyses, and experiments are presented to show the proposed LiNbO3-based MEMS fabrication process suitability. This paper presents substantial contributions to the state-of-the-art, proposing an integral solution regarding the design, modelling, simulation, realization, and characterization of a novel transducer.
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D’yachkov, E. A., E. I. Chaplygin, V. A. Goryunov, and S. G. Telitsa. "How to improve measurement jet transducers for physical values and their service characteristics." Russian Engineering Research 27, no. 3 (March 2007): 145–48. http://dx.doi.org/10.3103/s1068798x07030057.
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Du, Xiu Quan, Lin Xiang Wang, Zhi Feng Tang, and Fu Zai Lv. "Modeling the Rate Dependent Hysteretic Dynamics of Magnetostrictive Transducers." Applied Mechanics and Materials 529 (June 2014): 312–16. http://dx.doi.org/10.4028/www.scientific.net/amm.529.312.
Повний текст джерелаАнотація:
In the current paper, the rate dependent hysteretic dynamics of a magnetostrictive transducer is investigated by using a coupled nonlinear macroscopic differential model. The transducer is modeled as a one-dimensional magnetostrictive structure based on the Landau phenomenological theory of phase transition. The hysteresis loops and butterfly-shaped behaviors in the magnetic and mechanical fields are both successfully modeled with estimated model parameter values. The capability of the proposed model for capturing the driving rate dependency is illustrated by numerical experiments.
11
Mahbaz, SeyedBijan, Giovanni Cascante, and Maurice B. Dusseault. "Calibration of a Piezoelectric Transducer through Laser Measurements and Numerical Simulation." Journal of Environmental and Engineering Geophysics 24, no. 1 (March 2019): 39–48. http://dx.doi.org/10.2113/jeeg24.1.39.
Повний текст джерелаАнотація:
A piezoelectric transducer is an electromechanical sensor which converts electrical energy (voltage signal) to mechanical energy (displacement signal) and vice versa by taking advantage of the piezoelectric crystal. Depending on the physical combination of transducer parts, sensors may have a linear or non-linear response to the input signal. In seismic tests such as ultrasonic non-destructive testing (NDT) methods, analyzing stress wave propagation through the specimen gives an assessment of its condition. The signal attenuation is an important parameter to assess the condition of specimen which can be done by having the displacement signal as an output. However, instead of the displacement signal, the piezoelectric transducer provides the voltage signal as an output. Therefore, to get reliable and accurate results, it is essential to calibrate the transducers. An appropriate calibration results in a suitable Transfer Function (TF) which can be used to properly calculate the displacement signal. In this study, the output displacement of a 1 MHz piezoelectric transducer is measured using a laser vibrometer with a nanometer resolution. Measurements and calculated TF showed at frequencies of 0.1, 1, and 1.5 MHz, TF values are 0.8, 0.08, and 0.2 respectively which is a non-linear relation between displacement (absolute signal) and voltage (relative signal) as it was expected. Then, numerical simulation is implemented as part of this study to simulate all electrical and mechanical components of the piezoelectric transducer. The simulation was verified with the absolute displacement measurements result from the laser vibrometer.
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Gossweiler, C. R., P. Kupferschmied, and G. Gyarmathy. "On Fast-Response Probes: Part 1—Technology, Calibration, and Application to Turbomachinery." Journal of Turbomachinery 117, no. 4 (October 1, 1995): 611–17. http://dx.doi.org/10.1115/1.2836579.
Повний текст джерелаАнотація:
A system for fast-response probe measurements in turbomachine flows has been developed and tested. The system has been designed for 40 kHz bandwidth and used with various in-house built probes accommodating up to four piezoresistive pressure transducers. The present generation of probes works accurately up to several bar pressure and 120°C temperature. The probes were found to be quite robust. The use of a miniature pressure transducer placed in the head of a probe showed that a precise packaging technique and a careful compensation of errors can considerably improve the accuracy of the pressure measurement. Methods for aerodynamic probe calibration and off-line data evaluation are briefly presented. These aimed, e.g., in the case of a four-hole probe, at measuring the velocity fluctuations as characterized by yaw, pitch, total pressure, and static pressure and at deriving mean values and spectral or turbulence parameters. Applications of the measuring system to turbomachinery flow in a radial compressor and to a turbulent pipe flow demonstrate the performance of the measuring system.
13
Verma, Prashant K. "Observations of MI Values During Neonatal Cardiac Ultrasound Scanning." Ultrasound 16, no. 4 (November 1, 2008): 203–7. http://dx.doi.org/10.1179/174313408x353828.
Повний текст джерелаАнотація:
Aim: The on-screen Mechanical Index (MI), was recorded from eight diagnostic ultrasound machines used for cardiac scanning of neonates. The objective of the study was to compare values of MI used in neonatal cardiac scanning with those recommended by the British Medical Ultrasound Society safety guidelines. Methods: The eight scanners were based at Sheffield Teaching Hospitals NHS Trust (STH), Sheffield Children's Hospitals NHS Trust (SCH) and Leeds Teaching Hospitals NHS Trust (LTH). Two methods of recording the MI value were used. At the Sheffield sites the on-screen safety index was obtained from archived patient studies saved on the Trust PACS. At the Leeds site the on-screen safety index was recorded from the scanner when it was switched on to its default neonatal or paediatric pre-sets with the appropriate transducer connected. Results: Data from clinical examinations at the Sheffield sites show that on average the MI values, for cardiac scanning, in B-mode and colour/pulsed wave Doppler mode were 1·1±0·3 and 1·3±0·3 respectively. The maximum values of MI recorded during clinical cardiac examinations were 1·6 for B-mode and 1·7 for colour/pulsed wave Doppler mode. Data from the Leeds site recorded default MI values, using appropriate transducers with neonatal and paediatric presets. One scanner from the Leeds site defaulted to an MI value of 1·9 in colour/pulsed Doppler mode with a neonatal preset. All the MI values are well above BMUS guideline recommendations for neonates when lung tissue is present within the ultrasound beam. Conclusions: The implication of these results is that neonates undergoing cardiac ultrasound examinations, were regularly exposed to MI values at least four to six times that recommended by BMUS guidelines (MI<0·3).
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Korzhyk, Oleksii, Sergey Naida, Sergii Kurdiuk, Valeriia Nizhynska, Maxim Korzhyk, and Anton Naida. "Use of the pass-through method to solve sound radiation problems of a spherical electro-elastic source of zero order." EUREKA: Physics and Engineering, no. 5 (September 13, 2021): 133–46. http://dx.doi.org/10.21303/2461-4262.2021.001292.
Повний текст джерелаАнотація:
In the article was solved the problem of radiation of a sound by the electroacoustic transducer which is executed in the form of a thin spherical cover, using a pass-through method. The outer and inner surfaces of the shell are completely electroded.
The application of this method provides an opportunity to avoid inaccuracies that arise during the traditional formulation of boundary conditions for acoustic mechanical fields, the use of equivalent substitution schemes and the absence of boundary conditions for the electric field in general. Given methodology eliminates these shortcomings by applying conjugation conditions, taking into account the types of electroding of the surfaces of piezoceramic transducers, the introduction of boundary conditions for current and voltage. The results of the solution demonstrate the high capabilities of this pass-through method, in terms of taking into account the peculiarities of determining the characteristics of these fields, values and dependences of the main complex characteristics of the electroelastic transducer, and auxiliary material constants of the piezoelectric material.
The proposed approach is relevant, because it allows to increase the reliability of modeling the operating conditions of acoustic transducers in the context of wave problems of acoustics. Aim is to enhance the range of performances and build algorithms solving problems of stationary mode hydroelectroelasticity sound radiation. The expected results are presented in terms of improving approaches to studying the features of the oscillatory process of the active elements of sound-emitting systems and the accompanying effects of the transformation of interconnected fields involved in the formation of the acoustic signal in the liquid
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Li, Z. L., J. D. Achenbach, I. Komsky, and Y. C. Lee. "Reflection and Transmission of Obliquely Incident Surface Waves by an Edge of a Quarter Space: Theory and Experiment." Journal of Applied Mechanics 59, no. 2 (June 1, 1992): 349–55. http://dx.doi.org/10.1115/1.2899527.
Повний текст джерелаАнотація:
The reflection and transmission of a plane time-harmonic surface wave which is obliquely incident on the edge of a quarter space is investigated theoretically, numerically, and experimentally. The theoretical formulation of the problem, which takes advantage of the translational invariance along the edge of the quarter space, is reduced to a system of singular integral equations along axes normal to the edge, for the defracted displacement components on the faces of the quarter space axes normal to the edge. The truncation of these equations leads to the definition of reflection and transmission coefficients, R and T. The equations are solved for R, T, and the diffracted displacements by the use of the boundary element method. A self-calibrated experimental technique is proposed which deploys four surface wave transducers, and which removes the effects of variable coupling between the transducers and the faces of the quarter space as the positions of the transducers are varied. The technique is particularly suited for the measurement of |R/T| as a function of the angle of incidence. Excellent agreement is observed between numerically and experimentally obtained values.
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Chalioris, Constantin E., Violetta K. Kytinou, Maristella E. Voutetaki, and Chris G. Karayannis. "Flexural Damage Diagnosis in Reinforced Concrete Beams Using a Wireless Admittance Monitoring System—Tests and Finite Element Analysis." Sensors 21, no. 3 (January 20, 2021): 679. http://dx.doi.org/10.3390/s21030679.
Повний текст джерелаАнотація:
The utilization and effectiveness of a custom-made, portable and low-cost structural health monitoring (SHM) system that implements the PZT-based electro-mechanical admittance (EMA) methodology for the detection and evaluation of the damage of flexural reinforced concrete (RC) beams is presented. Tests of large-scale beams under monotonic and cyclic reversal-imposed deformations have been carried out using an integrated wireless impedance/admittance monitoring system (WiAMS) that employs the voltage measurements of PZT transducers. Small-sized PZT patches that have been epoxy-bonded on the steel bars surface and on the external concrete face of the beams are utilized to diagnose damages caused by steel yielding and concrete cracking. Excitations and simultaneous measurements of the voltage signal responses of the PZT transducers have been carried out at different levels of the applied load during the tests using the developed SHM devices, which are remotely controlled by a terminal emulator. Each PZT output voltage versus frequency response is transferred wireless and in real-time. Statistical index values are calculated based on the signals of the PZT transducers to represent the differences between their baseline response at the healthy state of the beam and their response at each loading/damage level. Finite Element Modeling (FEM) simulation of the tested beams has also been performed to acquire numerical results concerning the internal cracks, the steel strains and the energy dissipation and instability parameters. FEM analyses are used to verify the experimental results and to support the visual observations for a more precise damage evaluation. Findings of this study indicate that the proposed SHM system with the implementation of two different PZT transducer settings can be effectively utilized for the assessment of structural damage caused by concrete cracking and steel yielding in flexural beams under monotonic and cyclic loading.
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Tsyhanchuk, V. V., and L. S. Shlapak. "Investigation of the properties correlation of physical and mechanical characteristics of ferromagnets based on magnetoelastic sensors of mechanical stresses." Oil and Gas Power Engineering, no. 2(30) (December 5, 2018): 32–39. http://dx.doi.org/10.31471/1993-9868-2018-2(30)-32-39.
Повний текст джерелаАнотація:
The determination of the stress condition is a topical issue. At present, various non-destructive examination methods, such as strain gauge, magnetic, ultrasonic methods, and others are used to analyze pipelines stress condition. Each of them has its advantages and disadvantages. There is often the need to use several experimental non-destructive methods simultaneously. In this regard, the magnetic inspection holds a unique position. In this case a significant role is played by primary transducers, which directly perceive the effect of mechanical stresses and turn it into the electrical signal for further processing of the input information. The change of magnetic characteristics is closely connected with the physical effect on the monitored object. The advantages include the high mobility of equipment, the ability to perform control without the direct contact of transducer with the object under study. At the same time, there are several disadvantages inherent particularly in the magnetic methods – magnetoelastic hysteresis, in which there is the divergence of induction values during loading and unloading. The greatest divergence occurs in the lead-off cycle and decreases during repeated cycles. The best way is to embrace the complete information available in the hysteresis loop. Another method is not only to take measurements at one point (even if this measurement is carried out in two mutually perpendicular directions), but to perform surface sounding of the object in a certain plane. Therefore, the most efficient method is to compare the magnetic relief of loaded (in the structure) and unloaded (in reserve) pipes of one manufacturer and from one lot. Thus, using the examination method of pipelines stress condition, based on the evaluation of metal magnetic properties of pipes, creates the complex solution to the problems of reliability improvement of pipeline systems.
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Sanli, Ahmet K., Erdogan A. Uzgider, Ozden B. Caglayan, Kadir Ozakgul, and Jan Bien. "Testing Bridges by Using Tiltmeter Measurements." Transportation Research Record: Journal of the Transportation Research Board 1696, no. 1 (January 2000): 111–17. http://dx.doi.org/10.3141/1696-51.
Повний текст джерелаАнотація:
An efficient numerical procedure based on the cubic spline technique is developed to obtain the vertical displacements of the bridge deck using the slope values measured at selected points under the test loading. Most static load tests of bridges are performed to evaluate the stiffness characteristics of bridge structures or to check the accuracy of their computer models. From this standpoint, vertical displacements of the bridge under certain loads have a crucial importance. However, if the bridge is over a river, a lake, muddy ground, or a major highway, conventional displacement transducers cannot be used appropriately for this purpose. Furthermore, strong wind and the bridge’s height badly affect the accuracy of the transducers. Another way to obtain bridge deflection is to use an indirect method. Tiltmeters, which have been increasingly used for construction monitoring and structural testing of bridges, are suitable devices in terms of indirect deflection measurements because of their characteristics such as high sensitivity, easy installation, and small electrical drift. The testing and evaluation procedure developed was applied on a real bridge, and the results indicated that this method could be applied to obtain vertical displacements of bridges as an alternative to the use of conventional displacement transducers.
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Giri, Paritosh, Sergey Kharkovsky, Xinqun Zhu, Simon Martin Clark, Shima Taheri, and Bijan Samali. "Characterization of carbon fiber reinforced polymer strengthened concrete and gap detection with a piezoelectric-based sensory technique." Structural Health Monitoring 18, no. 1 (October 11, 2018): 172–79. http://dx.doi.org/10.1177/1475921718803790.
Повний текст джерелаАнотація:
In this article, a piezoelectric-based sensory technique is proposed for detection of the gap between surfaces of a carbon fiber reinforced polymer plate and a concrete specimen and characterization of shrinkage of early-age concrete. The proposed technique uses the propagation properties of the guided waves in the carbon fiber reinforced polymer plate excited and received by piezoelectric transducers attached to an external surface of the carbon fiber reinforced polymer–strengthened concrete specimen. Measurements are conducted with fresh and hardened early-age concrete specimens and two carbon fiber reinforced polymer plates at different gaps. A piezoelectric actuator is excited using a sine burst signal, and the generated wave is received by a sensor after propagation along the specimen. The received signal at different gap values is used to detect a gap. To quantify the gap, damage indices, including correlation coefficient, peak-to-peak amplitude of resultant signal, and root-mean-square deviation, are used. The shrinkage of concrete is detected and predicted by comparing the damage indices at different gaps with the indices at different stages of early-age concrete. The proposed technique is relatively simple method using small transducers. It is one-sided, non-destructive, and cost-effective solution for gap detection and concrete characterization.
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Dou, Pan, Tonghai Wu, Zhaopeng Luo, Peiping Yang, Zhongxiao Peng, Min Yu, and Tom Reddyhoff. "A finite-element-aided ultrasonic method for measuring central oil-film thickness in a roller-raceway tribo-pair." Friction 10, no. 6 (December 6, 2021): 944–62. http://dx.doi.org/10.1007/s40544-021-0544-y.
Повний текст джерелаАнотація:
AbstractRoller bearings support heavy loads by riding on an ultra-thin oil film (between the roller and raceway), the thickness of which is critical as it reflects the lubrication performance. Ultrasonic interfacial reflection, which facilitates the non-destructive measurement of oil-film thickness, has been widely studied. However, insufficient spatial resolution around the rolling line contact zone remains a barrier despite the use of miniature piezoelectric transducers. In this study, a finite-element-aided method is utilized to simulate wave propagation through a three-layered structure of roller-oil-raceway under elastohydrodynamic lubrication (EHL) with nonlinear characteristics of the i) deformed curvature of the cylindrical roller and ii) nonuniform distribution of the fluid bulk modulus along the circumference of the oil layer being considered. A load and speed-dependent look-up table is then developed to establish an accurate relationship between the overall reflection coefficient (directly measured by an embedded ultrasonic transducer) and objective variable of the central oil-film thickness. The proposed finite-element-aided method is verified experimentally in a roller-raceway test rig with the ultrasonically measured oil-film thickness corresponding to the values calculated using the EHL theory.
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Andò, Bruno, Salvatore Baglio, Ruben Crispino, and Vincenzo Marletta. "Polymeric Transducers: An Inkjet Printed B-Field Sensor with Resistive Readout Strategy." Sensors 19, no. 23 (December 3, 2019): 5318. http://dx.doi.org/10.3390/s19235318.
Повний текст джерелаАнотація:
Magnetic field sensors are successfully used in numerous application contexts such as position sensing, speed detection, current detection, contactless switches, vehicle detection, and electronic compasses. In this paper, an inkjet printed magnetic sensor, based on the magneto-mechanical sensing principle, is presented together with a physical model describing its physical behavior and experimental results. The main novelties of the proposed solution consist of its low cost, rapid prototyping (printing and drying time), disposability, and in the use of a commercial low-cost printer. A measurement survey has been carried out by investigating magnetic fields belonging to the range 0–27 mT and for different values of the excitation current forced in the actuation coil. Experimental results demonstrate the suitability of both the proposed sensing strategy and model developed. In particular, in the case of an excitation current of 100 mA, the device responsivity and resolution are 3700 µε/T and 0.458 mT, respectively.
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Williams, P. R., and R. L. Williams. "Cavitation Properties of Oils Under Dynamic Stressing by Tension." Journal of Fluids Engineering 127, no. 2 (October 29, 2004): 282–89. http://dx.doi.org/10.1115/1.1881692.
Повний текст джерелаАнотація:
We report measurements of the effective tensile strength Fc of commercial “multigrade” oils (in the SAE viscosity grades 5W-30 and 10W-40) over a range of temperatures T, which are representative of those encountered under their normal operating conditions (in the range 20°C⩽T⩽140°C). Also reported are the values of Fc that are obtained for Newtonian silicone oils over a range of shear viscosities. In the experiments reported herein, samples of liquid are subjected to dynamic stressing by a pressure-tension cycle, this being a feature of the conditions experienced by a lubricant within a dynamically loaded journal bearing and the method used to estimate Fc avoids reliance on direct measurements of substantial dynamic tensions using conventional pressure transducers.
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Wang, Yifan, Pongsakorn Kanjanaboos, Sean P. McBride, Edward Barry, Xiao-Min Lin, and Heinrich M. Jaeger. "Mechanical properties of self-assembled nanoparticle membranes: stretching and bending." Faraday Discussions 181 (2015): 325–38. http://dx.doi.org/10.1039/c4fd00243a.
Повний текст джерелаАнотація:
Monolayers composed of colloidal nanoparticles, with a thickness of less than ten nanometers, have remarkable mechanical strength and can suspend over micron-sized holes to form free-standing membranes. We discuss experiments probing the tensile strength and bending stiffness of these self-assembled nanoparticle sheets. The fracture behavior of monolayers and multilayers is investigated by attaching them to elastomer substrates which are then stretched. For different applied strain, the fracture patterns are imaged down to the scale of single particles. The resulting detailed information about the crack width distribution allows us to relate the measured overall tensile strength to the distribution of local bond strengths within a layer. We then introduce two methods by which freestanding nanoparticle monolayers can be rolled up into hollow, tubular “nano-scrolls”, either by electron beam irradiation during imaging with a scanning electron microscope or by spontaneous self-rolling. Indentation measurements on the nano-scrolls yield values for the bending stiffness that are significantly larger than expected from the response to stretching. The ability to stretch, bend, and roll up nanoparticle sheets offers new possibilities for a variety of applications, including sensors and mechanical transducers.
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Golovachev, Petro, Ivan Korobko, and Vitalii Krotevich. "INVESTIGATION OF THE UNCERTAINTY VALUE AT MEASURING THE TEMPERATURE OF THE COOLANT IN THE PIPELINES WITH OUTSIDE SURFACE MOUNTED TEMPERATURE SENSORS." Bulletin of Kyiv Polytechnic Institute. Series Instrument Making, no. 62(2) (December 24, 2021): 42–49. http://dx.doi.org/10.20535/1970.62(2).2021.249199.
Повний текст джерелаАнотація:
During performing technological and production processes and monitoring the modes of their operation, the problem of determining the temperature of various media transported through pipelines is solved without incut temperature sensors (TS) in them, i.e. with using outside surface mounted TS (SMTS). This method is allowing to measure mechanical values at technological processes without structure broken and without influence to physicochemical properties of measured media.
Using of SMTS possible to register heat losses on sections of heating mains, pollution degree of pipelines internal walls, to control serviceability of measurement channels of temperature of the coolant in heat meters, etc.
In the article authors presents results of research the uncertainty values for measuring of the coolant temperature in heating systems pipelines under different modes of its flow. First of all, the uncertainty value of the measurements results was estimated, which was determined by the results of the study for the calculation model and field tests at existing district heating systems.
Emphasis is paid on estimating the difference between the registration of temperature in the middle of the pipeline, determined by mortise transducers and the temperature measured by outside surface mounted temperature transducers, taking into account the temperature gradient across the pipeline and the quality of its insulation.
It is determined that: the temperature measured by temperature transducers on the surface of the pipeline at different points of its perimeter, with proper installation and sufficient thermal insulation does not depend on their location; the average temperature on the surface of the pipeline, measured using the developed method of installation of PT, slightly differs (ΔT ≈- 0.3⁰C) from the average temperature of the coolant in the middle of the flow; temperature transducers have high reproducibility of measurements and small difference in readings between channels at parallel measurements (»0,03⁰С).
It is substantiated that high metrological performances of temperature transducers allow to use them for solving other tasks: measuring the distribution of heat fluxes in heating systems of residential buildings to perform hydraulic balancing of heating systems and increase their efficiency; estimate of contamination of pipelines and heat exchange equipment to determine the need for their washing; determination of thermal resistance of buildings protective structures to assess their energy efficiency; determination of large pumps efficiency by calorimetric method; checking the correct of operation the temperature measuring channels of heat meters and cold meters; in other technology areas where measurements of small temperature differences with high accuracy are required.
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Porter, Philip R., and Tavi Murray. "Mechanical and hydraulic properties of till beneath Bakaninbreen, Svalbard." Journal of Glaciology 47, no. 157 (2001): 167–75. http://dx.doi.org/10.3189/172756501781832304.
Повний текст джерелаАнотація:
AbstractBakaninbreen, Svalbard, was in the late phase of a prolonged surge during 1995–96. In order to investigate the nature of the basal mechanical and hydraulic regime, sets of tilt sensors equipped with pore-pressure sensors were installed into the basal till layer. Water-pressure transducers were also installed in the boreholes above the ice–till interface. During 1995, the measured mean strain rate in the till was 0.44 a−1 up-glacier of the surge front, while down-glacier the rate was 0.04 a−1. Our interpretation indicates that deformation was the dominant component of basal motion. Strain rates fluctuated strongly, and periods of both positive (down-glacier) and negative (up-glacier) strain occurred. No consistent relationship was apparent between effective pressure and strain rate within the basal till layer. The viscosity of the basal sediments ranged from 1.3 × 1012 to 3.4 × 1012 Pa s. Such high values suggest that the till layer beneath Bakaninbreen may be partially frozen. Analysis of simultaneous measurements of pore-water and borehole water pressure suggests the hydraulic diffusivity of the till layer ranges from 1.2 to 5.0 × 10−6 m2 s−1, and the hydraulic conductivity from 3.2 × 10−7 to 7.7 × 10−8 m s−1.
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Workel, M. F., D. Dowson, P. Ehret, and C. M. Taylor. "Design and development of a ball impact apparatus for the direct measurement of lubricant friction under high pressures and shear rates." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 215, no. 3 (March 1, 2001): 211–22. http://dx.doi.org/10.1243/1350650011543484.
Повний текст джерелаАнотація:
The development of a new ball impact apparatus for the measurement of the traction behaviour of solidified lubricants is described. The normal and tangential forces between an oily plate and an obliquely impacting ball were measured directly on two different forms of apparatus by means of piezoelectric transducers. From the measured forces the coefficient of friction during impact could be calculated. For one particular oil, Santotrac 50, a full set of results is given and these are shown to be in good agreement with values reported previously by others using different forms of experimental equipment.
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Кузьмич, Людмила Володимирівна, Дмитро Петрович Орнатський та Володимир Павлович Квасніков. "ОПТИМІЗАЦІЯ ВИМІРЮВАЛЬНИХ ЗАСОБІВ НАПРУЖЕНО-ДЕФОРМОВАНОГО СТАНУ ЗА ДОПОМОГОЮ ТЕНЗОДАТЧИКІВ". Aerospace technic and technology, № 3 (15 липня 2019): 50–56. http://dx.doi.org/10.32620/aktt.2019.3.06.
Повний текст джерелаАнотація:
In the article, the principles of construction, design and mathematical modeling of deformation and stresses of complex technical constructions are developed with the help of strain gauges and strain gauges taking into account destabilizing factors, which allows to significantly reduce the level of errors in relation to existing measurement methods and known analogs.The method of digital compensation provides a more significant reduction in the errors of measuring transducers compared with the method of analog compensation. Features and technical indicators of this method are considered on an example of measuring pressure transducer with foil strain gauges.This method is universal, allows us to adjust not only the errors of the measurement channel nonlinearity and additional errors but also the errors associated with the effect of interferences of the general type due to ground resistance, which induces the connection between the measuring channels of the main and destabilizing factor.The disadvantages of this method include a significant amount of computations, which sharply increases with increasing order of approximating polynomials.The purpose is to develop a method and means of measuring stress-strain state using strain gauge, free from the above - mentioned shortcomings.The main destabilizing factors that limit the measurement accuracy using strain gauge are:- random processes (noises, obstacles, etc.);- changes in parameters of measuring transducers due to aging and physical degradation;- effects of external climatic and mechanical factors (temperature, humidity, etc.).The influence of the main destabilizing factors limiting the accuracy of the measurement of the stress-strain state of complex technical constructions with the help of strain gauges was analyzed, among which the influences of external climatic and mechanical factors are one of the most important ones. Regarding the systematic components, the most important in statistical measurements are the errors of nonlinearity and the temperature component of the error.For the study, two main alloys were taken, which today has the widest use as a material for strain gauges - it is constantan and karma. For these materials, the influence of the range of temperature changes, the spread of the values of temperature error on the mean-square value of the error of approximation by power polynomials was investigated.Using the NUMERY package, the dependence of the approximation error on the order of the approximating polyphony was determined. It is established that the mean square error value in the wide temperature range for both constantan and karma has a weak correlation with the order of a polynomial.
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Hajfathalian, M., Z. A. Nemati, and H. R. Madaah Hosseini. "EVALUATION OF NANOCRYSTALLINE BA(ZRXTI1-X)O3 PRODUCED BY MECHANICAL ALLOYING." International Journal of Modern Physics: Conference Series 05 (January 2012): 472–79. http://dx.doi.org/10.1142/s201019451200236x.
Повний текст джерелаАнотація:
BaTiO 3-based solid solutions involve high piezoelectric and ferroelectric properties. One of the most favorable systems of this material is Ba ( Zr x Ti 1- x ) O 3. While nano structured ceramics of which have a great potential for using them in capacitors, actuators, transducers and dielectrics to reach high K values. In this study, nano crystalline Ba ( Zr x Ti 1- x ) O 3( x =0.1-0.8) which is called BZT composite has been prepared by mechanical alloying. The parameters affecting the process and properties were evaluated. The starting powders that are used here were nano sized high pure ZrO 2; submicron sized high pure TiO 2 and BaCO 3. The prepared powder was calcined, compacted and sintered at different temperatures and in various times. The structural changes and phase developments during mechanical alloying were studied by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) and Transition Electron Microscopy (TEM). The results showed that by using mechanical alloying method, high dense nano crystalline BZT ceramics were obtained successfully at very low sintering temperature. The dielectric constant of BZT was much great, because of using nano materials in this method at the temperatures of 1250-1400°C. The effect of high energy milling in micro structural development of nano crystalline BZT has been discussed as well as dielectric properties.
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Tonnesen, J., and J. W. Lund. "Impact Excitation Tests to Determine the Influence Coefficients for Balancing Lightly Damped Rotors." Journal of Engineering for Gas Turbines and Power 110, no. 4 (October 1, 1988): 600–604. http://dx.doi.org/10.1115/1.3240177.
Повний текст джерелаАнотація:
Experiments have been conducted to evaluate a supplementary method for balancing lightly damped rotors. The rotor, while running, is excited by an impact generator, and the response is measured at the bearings by transducers for displacement, force, and acceleration. An FFT analyzer is employed to obtain the frequency-dependent transfer functions from which the corresponding influence coefficients can be calculated. The results are compared with the values obtained from the conventional trial weight method, and they are also used in a successful balancing of the rotor.
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Desideri, Daniele, Enrico Bernardo, Alain Jody Corso, Alberto Doria, Alvise Maschio, Federico Moro, and Maria Guglielmina Pelizzo. "Transverse piezoelectric constant of aluminium nitride films deposited on aluminium substrate by reactive magnetron sputtering." International Journal of Applied Electromagnetics and Mechanics 64, no. 1-4 (December 10, 2020): 607–13. http://dx.doi.org/10.3233/jae-209370.
Повний текст джерелаАнотація:
In view of high temperature applications, c-axis oriented aluminium nitride films on aluminium substrate were produced by magnetron sputtering at low pressure (0.3 and 0.5 Pa) and different values of nitrogen concentration. XRD data show the highest intensity of (002) diffraction peak with nitrogen concentration of 0.4, and the peak value decreases when the nitrogen concentration moves away from 0.4. The transverse piezoelectric constant (absolute value) was determined for all conditions, the highest values observed with nitrogen concentration of 0.4 (in agreement with XRD data) and 0.8, with a slight preference for 0.4. These new experimental data and the presence of the two peaks of similar amplitude on the estimated transverse piezoelectric constant are useful information for the identification of good practical operative conditions for AlN films sputtered on aluminium, basic structure for the development of high temperature piezoelectric transducers.
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Voutetaki, Maristella E., Maria C. Naoum, Nikos A. Papadopoulos, and Constantin E. Chalioris. "Cracking Diagnosis in Fiber-Reinforced Concrete with Synthetic Fibers Using Piezoelectric Transducers." Fibers 10, no. 1 (January 9, 2022): 5. http://dx.doi.org/10.3390/fib10010005.
Повний текст джерелаАнотація:
The addition of short fibers in concrete mass offers a composite material with advanced properties, and fiber-reinforced concrete (FRC) is a promising alternative in civil engineering applications. Recently, structural health monitoring (SHM) and damage diagnosis of FRC has received increasing attention. In this work, the effectiveness of a wireless SHM system to detect damage due to cracking is addressed in FRC with synthetic fibers under compressive repeated load. In FRC structural members, cracking propagates in small and thin cracks due to the presence of the dispersed fibers and, therefore, the challenge of damage detection is increasing. An experimental investigation on standard 150 mm cubes made of FRC is applied at specific and loading levels where the cracks probably developed in the inner part of the specimens, whereas no visible cracks appeared on their surface. A network of small PZT patches, mounted to the surface of the FRC specimen, provides dual-sensing function. The remotely controlled monitoring system vibrates the PZT patches, acting as actuators by an amplified harmonic excitation voltage. Simultaneously, it monitors the signal of the same PZTs acting as sensors and, after processing the voltage frequency response of the PZTs, it transmits them wirelessly and in real time. FRC cracking due to repeated loading ad various compressive stress levels induces change in the mechanical impedance, causing a corresponding change on the signal of each PZT. The influence of the added synthetic fibers on the compressive behavior and the damage-detection procedure is examined and discussed. In addition, the effectiveness of the proposed damage-diagnosis approach for the prognosis of final cracking performance and failure is investigated. The objectives of the study also include the development of a reliable quantitative assessment of damage using the statistical index values at various points of PZT measurements.
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Oblizajek, K. L., and A. G. Veith. "Tire Treadwear — A Comprehensive Evaluation of the Factors: Generic Type, Aspect Ratio, Tread Pattern, and Tread Composition Part IV: Laboratory Measurement of Mechanical Properties and Mechanical Actions of Tires Relating to Treadwear." Tire Science and Technology 14, no. 4 (October 1, 1986): 264–91. http://dx.doi.org/10.2346/1.2148777.
Повний текст джерелаАнотація:
Abstract Treadwear is explained by specific mechanical properties and actions of tires. Rubber shear stresses in the contact zone between the tire and the road become large at large slip angles. When normal stresses are insufficient to prevent sliding at the rear of the footprint, wear occurs at a rate that depends on test severity. Two experimental approaches are described to relate treadwear to tire characteristics. The first uses transducers imbedded in a simulated road surface to obtain direct measurements of contact stresses on the loaded, freely-rolling, steered tires. The second approach is developed with the aid of a simple carcass, tread-band, tread-rubber tire model. Various tire structural configurations; characterized by carcass spring rate, edgewise flexural band stiffness, and tread rubber shear stiffness; are simulated and lateral shear stress response in the contact zone is determined. Tires featuring high band stiffness and low carcass stiffness generate lower lateral shear stress levels. Furthermore, coupling of tread-rubber stiffness and band flexural rigidity are important in determining level of shear stresses. Laboratory measurements with the described apparatus produced values of tread-band bending and carcass lateral stiffness for several tire constructions. Good correlation is shown between treadwear and a broad range of tire stiffness and test course severities.
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Andreaus, U., F. Dell’Isola, and M. Porfiri. "Piezoelectric Passive Distributed Controllers for Beam Flexural Vibrations." Journal of Vibration and Control 10, no. 5 (May 2004): 625–59. http://dx.doi.org/10.1177/1077546304038224.
Повний текст джерелаАнотація:
Recent technological developments have made available efficient bender transducers based on the piezoelectric effect. In this paper an electrical circuit analog to the Timoshenko beam is synthesized using a Lagrangian method and by paralleling capacitive flux linkages to rotation and transverse displacement. A Piezo-ElectroMechanical (PEM) beam is conceived by uniformly distributing piezoelectric transducers on a beam and interconnecting their electric terminals via the found analog circuit, completed with suitable resistors. The high performance features of the synthesized novel circuit include the following. (i) The circuit topology is extremely reduced, the used components are all but one two-terminal elements, and the only two-port network needed is an ideal transformer. (ii) One and the same dissipative circuit ensures a multiresonance coupling with the vibrating beam and the optimal electrical dissipation of mechanical vibrations energy. (iii) For a prototype of a PEM beam, the design of the analog circuit is possible and the obtained nominal values of the circuital elements ensure that can be technically realized without any external feeding. The insertion of resistors in the analog circuit is determined according to two optimality criteria (namely minimization of strain energy time envelope and maximization of vibration time rate decay), based on specific engineering needs. The former seems to be suitable for applications in fatigue phenomena and the latter when the amplitude of vibrations must be rapidly decreased, independently of the initial conditions.
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Mihailescu, L. S., and F. L. Abel. "Intramyocardial pressure gradients in working and nonworking isolated cat hearts." American Journal of Physiology-Heart and Circulatory Physiology 266, no. 3 (March 1, 1994): H1233—H1241. http://dx.doi.org/10.1152/ajpheart.1994.266.3.h1233.
Повний текст джерелаАнотація:
This study presents an improved method for the measurement of intramyocardial pressure (IMP) using the servo-nulling mechanism. Glass micropipettes (20-24 microns OD) were used as transducers, coated to increase their mechanical resistance to breakage, and placed inside the left ventricular wall with a micropipette holder and manipulator. IMP was measured at the base of the left ventricle in working and nonworking isolated cat hearts that were perfused with Krebs-Henseleit buffer. In working hearts a transmural gradient of systolic IMP oriented from endocardium toward the epicardium was found; the endocardial values for systolic IMP were slightly higher than systolic left ventricular pressure (LVP), by 11-18%. Increases in afterload induced increases in IMP, without changing the systolic IMP-to-LVP ratio. In nonworking hearts with drained left ventricles, the systolic transmural gradient for IMP described for working hearts persisted, but at lower values, and was directly dependent on coronary perfusion pressure. Systolic IMP-to-LVP ratios were always > 1. The diastolic IMP of both working and nonworking hearts exhibited irregular transmural gradients. Our results support the view that generated systolic IMP is largely independent of LVP development.
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Clauß, Felix, Niklas Epple, Mark Alexander Ahrens, Ernst Niederleithinger, and Peter Mark. "Comparison of Experimentally Determined Two-Dimensional Strain Fields and Mapped Ultrasonic Data Processed by Coda Wave Interferometry." Sensors 20, no. 14 (July 20, 2020): 4023. http://dx.doi.org/10.3390/s20144023.
Повний текст джерелаАнотація:
Due to the high sensitivity of coda waves to the smallest structural alterations such as strain, humidity or temperature changes, ultrasonic waves are a valid means to examine entire structures employing networks of ultrasonic transducers. In order to substantiate this ex ante assessment, the viability of measuring ultrasonic waves as a valid point of reference and inference for structural changes is to be further scrutinized in this work. In order to investigate the influence of mechanical strain on ultrasonic signals, a four-point bending test was carried out on a reinforced concrete beam at Ruhr University Bochum. Thus, measurements collected from a network of selected transducer pairings arranged across the central, shear-free segment of the test specimen, were correlated to their respective strain fields. Detected ultrasonic signals were evaluated employing Coda Wave Interferometry. Such analysis comprised the initial non-cracked state as well as later stages with incremental crack depth and quantity. It was to ascertain that the test specimen can in fact be qualitatively compartmentalized into areas of compression and tension identified via Relative Velocity Changes presented in Attribute Maps. However, since results did not entail a zero crossing, i.e., neither positive nor negative values were to be calculated, only relative changes in this work displayed staggered over the height of the object under test, are discussed. Under the given methodological premises, additional information is currently required to make quantitative assertions regarding this correlation of ultrasonic and strain results. This holds true for the comparability of the ultrasonic and strain results for both non-cracked and even the cracked state.
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Musa, Veyan A., Raid A. Mahmood, Shwan M. Noori Khalifa, Omar M. Ali, and Lokman A. Abdulkareem. "Flow Patterns of Oil-Gas and Pressure Gradients in Near-Horizontal Flow Pipeline: Experimental Investigation Using Differential Pressure Transducers." International Journal of Heat and Technology 39, no. 2 (April 30, 2021): 621–28. http://dx.doi.org/10.18280/ijht.390233.
Повний текст джерелаАнотація:
The current investigation aimed to identify pressure gradients and to study the fully developed flow patterns of oil-gas as a blend in a pipe of internal diameter 50 mm and 6 m length with different orientations of 0, 30, and 45-degree. The study was performed at constant values of liquid superficial velocities 0.052, 0.157, 0.262, 0.314, 0.419, and 0.524 m/s, and inlet superficial velocities of gas were ranged from 0.05 to 4.7 m/s at atmospheric pressure. Two pressure transducers located up and downstream were used to measure pressure drops inside the tested pipe. Flow patterns were derived by using the correlation between pressure gradients and time series, the Probability Density Function of differential pressures, pressure gradients with gas superficial velocities, and total pressure losses with mean void fractions. The flow patterns of oil-gas were observed as a uniform stratified flow in the pipe on a 0-degree orientation at various superficial velocities. Stratified, wavy, and slug flow patterns were observed at 30-degree orientation, whereas, bubbly, slug, and churn flow patterns were observed in the pipe of 45-degree orientation. The experiment also showed that pressure drop gradients decreased with increased void fractions, gas superficial velocities, and degree rotations of the flow lines. Finally, the validation of using pressure transducers as a technique for estimating the flow patterns of two-phase flow showed acceptable results with some kind of patterns.
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Hanse Wampo, Fidéle Léopold, Richard Ntenga, Joseph Yves Effa, Yuri Lapusta, Guy Edgar Ntamack, and Pierre Maréchal. "Generalized homogenization model of piezoelectric materials for ultrasonic transducer applications." Journal of Composite Materials 56, no. 5 (December 27, 2021): 713–26. http://dx.doi.org/10.1177/00219983211058806.
Повний текст джерелаАнотація:
Although piezocomposite (PC) materials have increasingly attracted researchers, there is still a need to properly and easily derive their properties. We develop a generalized homogenization model (GHM) that accounts for Smith and Cha approaches to evaluate the equivalent characteristics of piezocomposites. This method could be applied to all connectivities patterns, but restricted herein to 2-2 and 1-3 piezocomposites for comparison with Smith (1-3) and Cha (2-2) analytical results. In the proposed GHM is a parameter θ, is changed for various connectivities. The 1-3 and 2-2 PZT-7A/Araldite D (PCs) data are used and equivalent characteristics of these Pcs are determined as function of volume fraction of PZT-7A piezoelectric. Results show that the electromechanical coefficients are well fitted by Voigt and Reuss models. Results obtained for some parameters show that the proposed GHM is consistent with the analytical existing models used for the 1-3 and 2-2 connectivities and is in line with measured values from Chan and Unsworth (1989). Based on the GHM 2-2 configuration results of piezocomposite materials, the electroacoustic responses of transducers having some of these properties are simulated using the KLM model. A performance trade-off was chosen, resulting in an improved thickness coupling coefficient and a lowered acoustical impedance, and a similar approach as that on a pure PZT-7A.
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Ashworth, D. A., J. E. LaGraff, and D. L. Schultz. "Unsteady Interaction Effects on a Transitional Turbine Blade Boundary Layer." Journal of Turbomachinery 111, no. 2 (April 1, 1989): 162–68. http://dx.doi.org/10.1115/1.3262251.
Повний текст джерелаАнотація:
Results are presented illustrating the detailed behavior of the suction surface boundary layer of a transonic gas turbine rotor in a two-dimensional cascade under the influence of both free-stream turbulence and simulated nozzle guide vane wakes and shocks. The instrumentation included thin film resistance thermometers along with electrical analogues of the one-dimensional heat conduction equations to obtain wide bandwidth heat transfer rate measurements in a short duration wind tunnel. This instrumentation provides sufficient time resolution to track individual wake and shock-related events and also the turbulent bursts of a transitional boundary layer. Wide bandwidth surface pressure transducers and spark Schlieren photography were used in support of these heat transfer measurements. The results showed a direct relationship between the passage of wake disturbances and transient surface heat transfer enhancements. It was possible to track both wake and transitional events along the surface and to compare these with the expected convection rates. Analysis of the signals allowed direct calculations of intermittency factors, which compared well with predictions. Additional effects due to a moving shock/boundary layer interaction were investigated. These resulted in marked variations in heat transfer rate both above and below the laminar values. These excursions were associated with separation and re-attachment phenomena.
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Gargouri, Y., G. Amaidia, and P. R. Wagstaff. "A Comparison between Different Multiple Input Array Processing Techniques for the Localisation of Correlated Acoustic Sources." Building Acoustics 3, no. 3 (September 1996): 131–43. http://dx.doi.org/10.1177/1351010x9600300301.
Повний текст джерелаАнотація:
The localisation of acoustic sources using linear microphone arrays permits source positions and power levels to be evaluated. The identification of the positions of the principal sources is essential before noise reduction methods can be defined. The work presented here concentrates on problems associated with multiple and partially coherent sources. Conventional processing techniques have limited resolution for a restricted number of transducers which can be resolved using high resolution techniques. Experiments showed the limitations of high resolution methods when dealing with correlated sources. Techniques based on the use of reference signals from selected sources were studied to try and solve this problem. This approach consists of pre-processing the cross spectral matrix in a specific way using multiple-input multiple-output (MIMO) methods. This enables the independent contributions of sources to be localised even for relatively high values of inter-source correlation.
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Zashchepkina, N. M., V. G. Zdorenko, V. Sebko, and O. M. Markina. "Identification of the eddy current method features in the implementation of computer simulation algorithms for controlling the characteristics of the food production equipment parts." Journal of Achievements in Materials and Manufacturing Engineering 1, no. 97 (November 3, 2019): 31–40. http://dx.doi.org/10.5604/01.3001.0013.7947.
Повний текст джерелаАнотація:
Purpose: The purpose of this article is to study the theoretical provisions of the operation of a vortex device in the implementation of a non-contact method of controlling the details of brewing equipment using computer simulation algorithms. Design/methodology/approach: The theoretical positions of thermal ECT operation with a copper product are obtained, which is controlled while maintaining a constant value of the magnetic field frequency f1 = 70.0 Hz, with small values of the generalized parameter x≤1.1 and increasing the parameter x due to the increase in the frequency of thermal ECT, that is, at x≥3.5. Findings: On the basis of computer simulation algorithms the results of the joint measuring control of diameter d, electrical resistance ρ and temperature t of the sample made of copper (in the temperature range from 20-160°C) and the results of determination of thermally dependent thermal ECT signals with the sample of equipment details and the values of specific normalized values that relate the ECT signals to the physical and mechanical characteristics of the samples of the equipment being monitored. Research limitations/implications: Product diameters range is 5 mm to 50 mm. The lower boundary is limited by the frequency of the magnetic field f = 20 Hz and the upper boundary by the diameter of the frame of the thermal eddy current transformer transducer is 50 mm. Perspective positions of work require further development in the direction of extending the limits of control of geometrical parameters of the samples due to the use of automated control systems based on overhead eddy current transformer transducers. Practical implications: The practical value of the work is to increase the overall likelihood of control of the parameters of brewing equipment parts by increasing its instrumental component Di, due to the reduction of measurement errors due to instrumental techniques and on the basis of computer modelling algorithms for three-parameter control of parts of brewing equipment, electrical and temperature parameters, allows to obtain the value of the overall control probability Dz = 0.998. Originality/value: The originality of the article is the study of the theoretical provisions of the eddy current transformer transducer and the implementation of a non-contact method of controlling the details of brewing equipment using computer simulation algorithms that take into account the modes of joint three-parameter control: at high values of the generalized parameter x (with three-parameter surface control), at small values of x (while controlling the value of the average cross section geometry, electrical, temperature settings) at a fixed frequency magnetic field (get information on the diameter d, resistivity ρ and temperature t with a certain depth of penetration of the magnetic field in the sample Δ).
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Bernabei, Michel, Jaap H. van Dieën, Guus C. Baan, and Huub Maas. "Significant mechanical interactions at physiological lengths and relative positions of rat plantar flexors." Journal of Applied Physiology 118, no. 4 (February 15, 2015): 427–36. http://dx.doi.org/10.1152/japplphysiol.00703.2014.
Повний текст джерелаАнотація:
In situ studies involving supraphysiological muscle lengths and relative positions have shown that connective tissue linkages connecting adjacent muscles can transmit substantial forces, but the physiological significance is still subject to debate. The present study investigates effects of such epimuscular myofascial force transmission in the rat calf muscles. Unlike previous approaches, we quantified the mechanical interaction between the soleus (SO) and the lateral gastrocnemius and plantaris complex (LG+PL) applying a set of muscle lengths and relative positions corresponding to the range of knee and ankle angles occurring during normal movements. In nine deeply anesthetized Wistar rats, the superficial posterior crural compartment was exposed, and distal and proximal tendons of LG+PL and the distal SO tendon were severed and connected to force transducers. The target muscles were excited simultaneously. We found that SO active and passive tendon force was substantially affected by proximally lengthening of LG+PL mimicking knee extension (10% and 0.8% of maximal active SO force, respectively; P < 0.05). Moreover, SO relative position significantly changed the LG+PL length-force relationship, resulting in nonunique values for passive slack-length and optimum-length estimates. We conclude that also, for physiological muscle conditions, isometric force of rat triceps surae muscles is determined by its muscle-tendon unit length as well as by the length and relative position of its synergists. This has implications for understanding the neuromechanics of skeletal muscle in normal and pathological conditions, as well as for studies relying on the assumption that muscles act as independent force actuators.
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Pandit, S. M., Y. X. Yao, and Z. Q. Hu. "Dynamic Properties of the Rigid Body and Supports from Vibration Measurements." Journal of Vibration and Acoustics 116, no. 3 (July 1, 1994): 269–74. http://dx.doi.org/10.1115/1.2930424.
Повний текст джерелаАнотація:
A novel method is presented to determine the dynamic characteristics of a multi-DOF rigid body structure from vibration measurements and coordinates of the transducers. These characteristics include the center of gravity, moment of inertia, and mass; stiffness, center of stiffness and moment of stiffness; damping, center of damping and moment of damping; and corresponding principal values and axes. The method is capable of handling complicated structures with various DOFs, from 2 up to maximum 6. The mass modified matrices M−1K and M−1C (or mass M, stiffness K, and damping C matrices) are first obtained based on measured vibration data and estimated rigid-body modes by Data Dependent Systems (DDS) methodology, which is accurate even for highly damped structures. Relationships between the physical characteristics and the mass modified matrices have been derived to solve the dynamic properties. The properties of up to 5 individual spring and dashpot supports can be determined by solving linear simultaneous equations. New concepts about the center of stiffness, moment of stiffness, center of damping, and moment of damping and the estimation method are presented. An example, using a simple structure, demonstrated the capability of the proposed method.
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Gonzalez, Jesse T., and Scott E. Hudson. "Layer by Layer, Patterned Valves Enable Programmable Soft Surfaces." Proceedings of the ACM on Interactive, Mobile, Wearable and Ubiquitous Technologies 6, no. 1 (March 29, 2022): 1–25. http://dx.doi.org/10.1145/3517251.
Повний текст джерелаАнотація:
Programmable surfaces, which can be instructed to alter their shape or texture, may one day serve as a platform for tangible interfaces and adaptive environments. But so far, these structures have been constrained in scale by a challenging fabrication process, as the numerous constituent actuators must be built and assembled individually. We look towards emerging trends in mechanical engineering and consider an alternate framework --- layer-driven design, which enables the production of dynamic, discretely-actuated surfaces at multiple scales. By centering the construction around patterning and stacking, forgoing individual assembly in favor of bulk processes such as photo-etching and laser cutting, we avoid the need for multiple manufacturing steps that are repeated for each of the many actuators that compose the surface. As an instance of this layer-driven model, we build an array of electrostatic valves, and use this composite material (which we refer to as Stoma-Board) to drive four types of pneumatic transducers. We also show how this technique may be readily industrialized, through integration with the highly mature and automated manufacturing processes of modern electronics.
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Hara, Yushin, Yuta Yamamoto, and Kanjuro Makihara. "Self-sensing state estimation of switch-controlled energy harvesters." Journal of Intelligent Material Systems and Structures 31, no. 20 (August 3, 2020): 2326–41. http://dx.doi.org/10.1177/1045389x20943944.
Повний текст джерелаАнотація:
Vibration energy harvesters are expected to become a new source of electrical power. Piezoelectric vibration energy harvesters that employ a piezoelectric transducer, a rectifier, and a storage capacitor are being used widely as electro-mechanical harvesters. Synchronized switch harvesting on inductor enhances harvesting performance due to employing a simple additional circuit and incorporating suitable switch control functionality. Switching is usually based on the displacement of a vibrating structure; hence, sensing the vibrational states is of critical importance. Conventionally, the structural displacement is measured by displacement sensors or accelerometers attached to the target vibrating structure. Although enhancement of performance through synchronized switch harvesting on inductor equipped with sensors is important, the arrangement requirements of sensors have adverse effects on the compactness and usability of the harvesters. This study aimed to eliminate the use of sensors from switch-controlled harvesters. We developed a new state estimation method that uses the piezoelectric transducer’s voltage as an observation value. Using the proposed state estimation method, the modal state values of the vibrating structure can be determined by simply measuring the voltage of the transducer. With the switch device being controlled by the estimated modal state values, no sensors are required for ensuring effective harvesting. A comparison of the harvesting performances by the proposed self-sensing state estimation method and the conventional sensor-equipped state estimation method showed that there is little difference in harvested power between the two methods over a wide range of load resistances. The proposed method is superior to the sensor-equipped method in terms of compactness and usability as it does not require any external sensors.
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Schaafsma, A., E. Otten, and J. D. Van Willigen. "A muscle spindle model for primary afferent firing based on a simulation of intrafusal mechanical events." Journal of Neurophysiology 65, no. 6 (June 1, 1991): 1297–312. http://dx.doi.org/10.1152/jn.1991.65.6.1297.
Повний текст джерелаАнотація:
1. A muscle spindle model for primary afferent firing is presented that contains two components representing a gamma d-dependent (bag1) and gamma s-dependent (bag2/nuclear chain) intrafusal fiber. Each of the intrafusal fibers is composed of a linear elastic element representing the sensory part and a muscle fiber representing the muscular part. 2. The muscular part of the bag1 was modeled as a slow twitch, that of the bag2 as a fast twitch muscle fiber. 3. The sensory regions were linear length transducers, generating a rising depolarization on increasing stretch. The input of both bags was fused by taking the largest depolarization to determine a generator potential. The rate of primary afferent firing depended on this generator potential as well as on its rate of change. 4. To simulate the high sensitivity of muscle spindles to small amplitudes of stretching, a model analogue of cross-bridge fixation (or stiction) has been included in the muscular part of the bag1 fiber. This makes use of one hundred cross-bridge regions that release one after the other, provided a certain breaking force is exceeded. 5. The values of the mechanical parameters that defined the model were selected by a computerized search procedure. 6. The values found by means of this procedure allowed the model to provide an accurate simulation of experimental data on ramp-and-hold stretches (for 6 different stretch velocities under variable conditions of fusimotor activity). 7. On sinusoidal stretches at a frequency of 1 Hz the spindle model responded with about one-half the discharge modulation reported in experimental studies. Its phase advance tended to be slightly lower than that observed for real spindles. 8. Frequency response curves showed the same high sensitivities at high frequencies as those observed in real spindles. 9. Close evaluation of the model compared with experimental results in literature reveal its merits as well as its limitations. Because the model is structural rather than phenomenologic, it provides insight into how intrafusal events may contribute to observed firing properties of real muscle spindles.
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Wen, Baogang, Meiling Wang, Xianwen Zhou, Hongjun Ren, and Qingkai Han. "Multi-harmonic motions of bearing cage affected by rotor unbalance." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 232, no. 15 (July 25, 2017): 2610–25. http://dx.doi.org/10.1177/0954406217722380.
Повний текст джерелаАнотація:
The motion of bearing cage in the rotor system displays very complicated behavior affected by rotor unbalance. In order to gain an insight into the complex cage motions due to rotor unbalance, a scaled rotor test rig is designed and developed that is made to be dynamically similar to the actual rotor system in aero-engines. Eddy transducers are used to measure the cage motions and monitor the rotor vibrations. Based on the test rig, a dynamic model of its rotor system with four degrees-of-freedom is developed to determine the reaction forces due to rotor unbalance, which are introduced as boundary conditions for the bearing dynamic analysis. And then, a three degrees-of-freedom dynamic model of bearing cage taking the obtained reaction forces into account is also proposed. Finally, the experiment and simulation of the cage motions are carried out and compared at different rotating speeds and rotor unbalances. The experimental results of the cage motions agree with the theoretical predictions and reveal that the cage motions generally contain the multiple harmonic components, such as the cage rotating frequency and its multi-frequency, the inner ring rotating frequency, and also some combination frequencies due to rotor unbalance. The amplitudes of the inner ring rotating frequency and combination frequencies of the cage motions increase with the increment of the rotor unbalance values. Besides, the trajectories of cage are affected by the rotor unbalances.
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Fidelus, J., and K. Cybul. "Study on short-term creep effect and hysteresis for the HBM Z4A force transducer under compressive and tensile forces." ACTA IMEKO 9, no. 5 (December 31, 2020): 137. http://dx.doi.org/10.21014/acta_imeko.v9i5.956.
Повний текст джерелаАнотація:
The results of creep tests (for compressive and tensile forces) for the HBM Z4A force transducer made in a Force Standard Machine (FSM) working in the range from 1 kN to 55 kN in the Central Office of Measures are described. Studies have shown that the largest indications of the force transducer (given in electrical units, mV/V) in the first seconds of testing are most likely due to the mechanical properties of the materials from which the transducer is built. Higher values of relative hysteresis error and relative measurement uncertainty were observed for the compressive forces.
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Winklberger, Markus, Christoph Kralovec, Christoph Humer, Peter Heftberger, and Martin Schagerl. "Crack Identification in Necked Double Shear Lugs by Means of the Electro-Mechanical Impedance Method." Sensors 21, no. 1 (December 23, 2020): 44. http://dx.doi.org/10.3390/s21010044.
Повний текст джерелаАнотація:
This contribution investigates fatigue crack detection, localization and quantification in idealized necked double shear lugs using piezoelectric transducers attached to the lug shaft and analyzed by the electro-mechanical impedance (EMI) method. The considered idealized necked lug sample has a simplified geometry and does not includes the typical bearing. Numerical simulations with coupled-field finite element (FE) models are used to study the frequency response behavior of necked lugs. These numerical analyses include both pristine and cracked lug models. Through-cracks are located at 90∘ and 145∘ to the lug axis, which are critical spots for damage initiation. The results of FE simulations with a crack location at 90∘ are validated with experiments using an impedance analyzer and a scanning laser Doppler vibrometer. For both experiments, the lug specimen is excited and measured using a piezoelectric active wafer sensor in a frequency range of 1 kHz to 100 kHz. The dynamic response of both numerical calculations and experimental measurements show good agreement. To identify (i.e., detect, locate, and quantify) cracks in necked lugs a two-step analysis is performed. In the first step, a crack is detected data-based by calculating damage metrics between pristine and damaged state frequency spectra and comparing the resulting values to a pre-defined threshold. In the second step the location and size of the detected crack is identified by evaluation of specific resonance frequency shifts of the necked lug. Both the search for frequencies sensitive to through-cracks that allow a distinction between the two critical locations and the evaluation of the crack size are model-based. This two-step analysis based on the EMI method is demonstrated experimentally at the considered idealized necked lug, and thus, represents a promising way to reliably detect, locate and quantify fatigue cracks at critical locations of real necked double shear lugs.
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Easton, P. A., M. Katagiri, T. M. Kieser, and R. S. Platt. "Postinspiratory activity of costal and crural diaphragm." Journal of Applied Physiology 87, no. 2 (August 1, 1999): 582–89. http://dx.doi.org/10.1152/jappl.1999.87.2.582.
Повний текст джерелаАнотація:
Because the first stage of expiration or “postinspiration” is an active neurorespiratory event, we expect some persistence of diaphragm electromyogram (EMG) after the cessation of inspiratory airflow, as postinspiratory inspiratory activity (PIIA). The costal and crural segments of the mammalian diaphragm have different mechanical and proprioceptive characteristics, so postinspiratory activity of these two portions may be different. In six canines, we implanted chronically EMG electrodes and sonomicrometer transducers and then sampled EMG activity and length of costal and crural diaphragm segments at 4 kHz, 10.2 days after implantation during wakeful, resting breathing. Costal and crural EMG were reviewed on-screen, and duration of PIIA was calculated for each breath. Crural PIIA was present in nearly every breath, with mean duration 16% of expiratory time, compared with costal PIIA with duration −2.6% of expiratory time ( P < 0.002). A linear regression model of crural centroid frequency vs. length, which was computed during the active shortening of inspiration, did not accurately predict crural EMG centroid frequency values at equivalent length during the controlled relaxation of postinspiration. This difference in activation of crural diaphragm in inspiration and postinspiration is consistent with a different pattern of motor unit recruitment during PIIA.
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Igumnov, Leonid, Ivan Markov, and Alexandr Konstantinov. "Boundary Element Modeling of Dynamic Bending of a Circular Piezoelectric Plate." EPJ Web of Conferences 183 (2018): 01025. http://dx.doi.org/10.1051/epjconf/201818301025.
Повний текст джерелаАнотація:
Accurate modelling of a coupled dynamic electro-mechanical response of circular piezoelectric plates under various loading conditions is of particular importance. Piezoelectric plates are not only basic structural elements, but with certain considerations can be conveniently fit for numerical simulation of piezoelectric sensors and transducers. In this work, a Laplace domain direct boundary element formulation is applied for dynamic analysis of three-dimensional linear piezoelectric moderately thick circular plates. Zero initial conditions, vanishing body forces and the absence of the free electrical charges are assumed. Weakly singular expressions of Laplace domain boundary integral equations for the generalized displacements are employed. Spatial discretization is based on the nodal collocation method. Mixed boundary elements are implemented. The geometry of the elements, generalized displacement and generalized tractions are represented with different shape functions: quadratic, linear and constant, accordingly. Integral expressions of the three-dimensional Laplace domain piezoelectric displacement fundamental solutions are used. After solving the problem on a set of Laplace transform parameter values, time-domain solutions are retrieved from the corresponding Laplace domain solutions by employing a numerical inversion routine. Numerical example is provided to show reliability and accuracy of the proposed boundary element formulation.