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Статті в журналах з теми "Transducers of mechanical values"
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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.
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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>
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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.
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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.
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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.
Повний текст джерела
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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.
Повний текст джерела
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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.
Дисертації з теми "Transducers of mechanical values"
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Михайленко, Ігор Всеволодович. "Напівпровідникові перетворювачі механічних величин з використанням поперечних тензоефектів". Thesis, КПІ ім. Ігоря Сікорського, 2019. https://ela.kpi.ua/handle/123456789/30025.
Повний текст джерелаАнотація:
Дисертація присвячена розробленню фізико-технологічних засад створення та дослідженню перетворювачів механічних величин на основі поперечних ефектів в анізотропних напівпровідниках.
Розроблені фізичні основи побудови перетворювачів механічних величин з використанням поперечних ефектів і проведено їх дослідження на експериментальних зразках. Продемонстрована перспективність використання перетворювачів на основі ефекту тензо-е.р.с. як в дискретному, так і в інтегральному виконанні для створення датчиків сили і тиску, які працюють в діапазоні температур 233-373 K. Виявлений ряд концентраційних ефектів у германії і запропоновані перетворювачі оригінальних конструкцій, таких як диференціальний тензотранзистор, безконтактний лінійний датчик переміщень на основі магнітоконцентраційного ефекту, порогові датчики кута повороту і сили на основі осцилісторного ефекту з можливістю управління порогом переключення. Дослідження, що проведені, підтверджують перспективність практичного використання поперечних ефектів у багатодолинних напівпровідниках для створення перетворювачів механічних величин.The purpose of the work is to develop a physical basis for transducers of mechanical values design and technology using transverse tenso-effects. The object of the research - characteristics of transverse effects caused by induced anisotropy in Si and Ge. The subject of research are transducers of mechanical values based on the transverse tenso-effects in Si and Ge. The result of the research is the development of both MEMS integrated pressure transducers and the industrial device for measuring the pressure of liquid media. The introduction substantiates the relevance of the topic, shows the relationship with scientific programs and plans, formulates purpose and objectives of scientific research, outlines the novelty and practical significance of the results obtained, indicates the personal contribution of the applicant, provides data on the validation of the results The First chapter analyzes phenomena leading to transverse effects. Consideration given in terms of anisotropy of conductivity, which is interpreted as the non-collinearity of the vectors of electric field and current. It allows using similar formal apparatus in the analysis of various effects. In particular, the cases of anisotropy induced by deformation and magnetic field have been examined. The Second chapter is devoted to the study of discrete tenso-emf transducers. In the proposed tenso-emf transducers, problems of matching the temperature dependencies of the sensitivity and impedances of individual strain gages are virtually eliminated. The dynamic range of the non-fixed tenso-emf transducer was about 120 dB. The Third chapter contains the results of the design and study of transducers using concentration effects in Ge in combination with other physical effects. New types of mechanical transducers proposed, such as differential tenso-transistor, non-contact linear displacement sensor, threshold angle sensors, and oscillistor-effect based force sensor. The Fourth chapter is devoted to the development of an integrated pressure transducer using MEMS technology. Problems of the physical principle of sensing element operation, optimization of the elastic element topology and design of the converter as a whole, as well as a choice of optimal manufacturing technology processes, are solved here. The sensitivity of the integrated transducer with a membrane thickness of 100 μm was 0.02 1/MPa at a nominal conversion range of 1 MPa and a 100% strength margin. Tests of the manufactured series of MEMS integrated transducer showed that the additive component of the error and its change in the range 233-373 K are, respectively, 1% and 1% ... 2% of the nominal signal, which is at least an order of magnitude smaller than the corresponding parameters of a strain gauge Wheatstone bridge. The Fifth chapter describes the design and test results of devices developed on the basis of tenso-emf transducers research. Such devices, introduced for industrial use, are remote manometer transducers PDM-2 and PDMT-1. These devices are designed to measure oil and bitumen wells pressure in the range 0 ... 2.5 MPa, with a nominal output signal of 100 mV. In addition, PDMT-1 transmits information about temperature. The PDM-2 device has passed the State Testing and was recommended for serial production. The conducted studies confirm the high potential of the practical application of transverse effects in multi-valley semiconductors for the development of mechanical values sensors.
Диссертация посвящена разработке физико-технологических принципов создания и исследованию преобразователей механических величин на основе поперечных эффектов в анизотропних полупроводниках. Разработаны физические основы построения преобразователей механических величин с использованием поперечных эффектов и проведено их исследование на экспериментальных образцах. Продемонстрирована перспективность использования преобразователей на основе эффекта тензо-э.д.с. как в дискретном, так и в интегральном исполнении для создания датчиков силы и давления, работающих в диапазоне температур 233-373K. Обнаружен ряд концентрационных эффектов в германии и предложены преобразователи оригинальных конструкций, таких как дифференциальный тензотранзистор, бесконтактный линейный датчик перемещений на основе магнитоконцентрационного эффекта, пороговые датчики угла поворота и силы на основе осциллисторного эффекта с возможностью управления порогом переключения. Проведенные исследования подтверждают перспективность практического использования поперечных эффектов в многодолинных полупроводниках для создания преобразователей механических величин.
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Михайленко, Ігор Всеволодович. "Напівпровідникові перетворювачі механічних величин з використанням поперечних тензоефектів". Doctoral thesis, Київ, 2019. https://ela.kpi.ua/handle/123456789/30024.
Повний текст джерелаАнотація:
Дисертація присвячена розробленню фізико-технологічних засад створення та дослідженню перетворювачів механічних величин на основі поперечних ефектів в анізотропних напівпровідниках.
Розроблені фізичні основи побудови перетворювачів механічних величин з використанням поперечних ефектів і проведено їх дослідження на експериментальних зразках. Продемонстрована перспективність використання перетворювачів на основі ефекту тензо-е.р.с. як в дискретному, так і в інтегральному виконанні для створення датчиків сили і тиску, які працюють в діапазоні температур 233-373 K. Виявлений ряд концентраційних ефектів у германії і запропоновані перетворювачі оригінальних конструкцій, таких як диференціальний тензотранзистор, безконтактний лінійний датчик переміщень на основі магнітоконцентраційного ефекту, порогові датчики кута повороту і сили на основі осцилісторного ефекту з можливістю управління порогом переключення. Дослідження, що проведені, підтверджують перспективність практичного використання поперечних ефектів у багатодолинних напівпровідниках для створення перетворювачів механічних величин.
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Smyth, Katherine Marie. "Piezoelectric micro-machined ultrasonic transducers for medical imaging." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/108938.
Повний текст джерелаАнотація:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 175-184).
Next generation medical imaging technology hinges on the development of cost effective and array compatible transducers making piezoelectric micro-machined ultrasonic transducers (pMUTs) an attractive alternative to the current bulk piezoelectric technology. This thesis aims to realize pMUT potential starting with the development of an effective single cell model that is further scaled to optimize multi-cell elements in a 1D array. In the first half of this work, a transverse mode, lead zirconate titanate (PZT) pMUT plate cell is fabricated using common micro-fabrication techniques and a PZT sol-gel deposition process. Through derivation using a novel Greens function solution technique, an equivalent circuit model with explicitly defined lumped parameters is presented and validated through electrical impedance measurements of fabricated devices and finite element modeling. The equivalent circuit is a crucial design tool as transducer performance metrics, including experimentally validated acoustic domain values, are shown to be defined directly from the lumped parameters. In the second half, figures of merit are identified from these performance metrics and an expanded multi-cell model is employed to strategically target improvements in both bandwidth and coupling while maintaining high pressure output. The resulting, optimized multicell elements in a 1D array are fabricated via a commercially viable, wafer-scale manufacturing process including a novel PZT dry etch. A top-down fabrication approach facilitates achievement of the largest active area of a multi-cell pMUT to date consisting of over 1000 cells in a 200pm x 4mm element footprint, and more substantially, results in the highest electromechanical coupling recorded for a pMUT to date measured at 9 ± 1.4% per element.
by Katherine Marie Smyth.
Ph. D.
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Cullinan, Michael A. (Michael Arthur). "Design and fabrication of precision carbon nanotube-based flexural transducers." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/65166.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student submitted PDF version of thesis.
Includes bibliographical references (p. 179-197).
As mechanical devices move towards the nanoscale, smaller and more sensitive force and displacement sensors need to be developed. Currently, many biological, materials science, and nanomanufacturing applications could benefit from multi-axis micro- and nanoscale sensors with fine force and displacement resolutions. Unfortunately, such systems do not yet exist due to the limitations of traditional sensing techniques and fabrication procedures. Carbon nanotube-based (CNT) piezoresistive transducers offer the potential to overcome many of these limitations. Previous research has shown the potential for the use of CNTs in high resolution micro- and nanoscale sensing devices due to the high gauge factor and inherent size of CNTs. However, a better understanding of CNT-based piezoresistive sensors is needed in order to be able to design and engineer CNT-based sensor systems to take advantage of this potential. The purpose of this thesis is to take CNT-based strain sensors from the single element test structures that have been fabricated and turn them into precision sensor systems that can be used in micro- and nanoscale force and displacement transducers. In order to achieve this purpose and engineer high resolution CNT-based sensor systems, the design and manufacturing methods used to create CNT-based piezoresistive sensors were investigated. At the system level, a noise model was developed in order to be able to optimize the design of the sensor system. At the element level, a link was established between the structure of the CNT and its gauge factor using a theoretical model developed from quantum mechanics. This model was confirmed experimentally using CNT-based piezoresistive sensors integrated into a microfabricated test structure. At the device level, noise mitigation techniques including annealing and the use of a protective ceramic coating were investigated in order to reduce the noise in the sensor. From these investigations, best practices for the design and manufacturing of CNT-based piezoresistive sensors were established. Using these best practices, it is possible to increase the performance of CNT-based piezoresistive sensor systems by more than three orders of magnitude. These best practices were implemented in the design and fabrication of a multi-axis force sensor used to measure the adhesion force of an array of cells to the different material's surfaces for the development of biomedical implants. This force sensor is capable of measuring forces in the z-axis as well as torques in the [theta]x and [theta]y axis. The range and resolution of the force sensor were determined to be 84 [mu]N and 5.6 nN, respectively. This corresponds to a dynamic range of 83 dB, which closely matches the dynamic range predicted by the system noise model used to design the sensor. The accuracy of the force sensor is better than 1% over the device's full range.
by Michael A. Cullinan.
Ph.D.
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Feeney, Andrew. "Nitinol cymbal transducers for tuneable ultrasonic devices." Thesis, University of Glasgow, 2014. http://theses.gla.ac.uk/5805/.
Повний текст джерелаАнотація:
In recent years, there has been notable interest in the integration of smart and active materials, such as shape memory alloys, in the design of tuneable and multiple frequency devices. There is a growing desire to be able to tune transducers for a range of applications. As an example, surgical procedures could be enhanced by using an ultrasonic device whose performance could be tailored to penetrate more than one material, such as bone and soft tissue. Research conducted on cymbal transducers, a type of Class V flextensional transducer developed at Pennsylvania State University in the early 1990s, has been largely limited to low power applications, such as for hydrophone systems, and their performance in high power applications has only recently been studied. As such, the integration of smart materials to expand the useful applications of this type of transducer has not been fully explored. In this investigation, a shape memory alloy (SMA) called nickel-titanium, or Nitinol, has been adopted in two forms, one being superelastic and the other shape memory, as the end-cap material in the classical cymbal transducer configuration. The resonant frequencies of these transducers can be tuned by changes to the temperature of the Nitinol, which alters the microstructure, and the modulus, of the material. The microstructure of Nitinol can also be controlled by changes in applied stress. The phases present in the Nitinol microstructure are relatively hard cubic austenite and comparably soft monoclinic martensite. An intermediate phase, called the R-phase, can also appear. This is a rhombohedral distortion of austenite, and has been known to be a source of inconvenience for those who wish to avoid multiple stage transformations. An advantage of using Nitinol end-caps in the classical cymbal transducer configuration is that they are very small, hence minimal thermal energy is required to generate a phase transformation. Also, cymbal transducers are very simple and inexpensive to fabricate. The first part of this research focuses on the development of a dual resonance cymbal transducer using steel and titanium as the end-cap materials. Dynamic analysis techniques comprising electrical impedance measurements, experimental modal analysis (EMA) and vibration resonance response characterisation (VRRC) using laser Doppler vibrometry are introduced and form the dynamic characterisation process. The experimental data is supported in part by finite element analysis (FEA). It is demonstrated that a major problem in cymbal transducer fabrication is the difficulty in controlling the deposition of epoxy resin which is used to create the mechanical coupling in the transducer. This means that the bond layers in a transducer will likely be dissimilar, thereby introducing asymmetry into the transducer. This asymmetry can contribute to the dual resonance in a cymbal transducer. The cymbal transducer is designed to be actively tuneable by the incorporation of Nitinol end-caps in the transducer assembly. The characterisation of Nitinol transducers is performed using the dynamic characterisation methods in conjunction with differential scanning calorimetry (DSC). This is a thermoanalytical technique which has been adopted to estimate the transformation temperatures of Nitinol, and hence the temperatures at which each transducer must be driven to generate the desired operating frequencies. It is demonstrated that in certain cases, particularly with respect to superelastic Nitinol, the estimations of the transformation temperatures from the DSC analysis of Nitinol can be misinterpreted. The dynamic performance of Nitinol vibrating at ultrasonic frequencies has not before been the subject of detailed investigation, including the influence of superelasticity on the vibration response of an ultrasonic transducer. Superelasticity occurs in the austenite phase of Nitinol, where austenite reorients to martensite after a characteristic stress threshold is passed, thereby accommodating very large strains. The results show that whilst Nitinol can be used to fabricate cymbal transducers with tuneable resonant frequencies, there is no evidence that superelasticity contributes to the vibration response of the transducers. The incorporation of shape memory Nitinol in a simple prototype actuator device is also considered, where it appears that the transformation of the shape memory Nitinol is affected by the affixed cylinders used to create the device.
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Cepni, Kerim. "A Methodology For Designing Tonpilz-type Transducers." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613526/index.pdf.
Повний текст джерелаАнотація:
Tonpilz-type transducers are the most commonly used projectors in underwater acoustic applications. However, no complete design approach is available in the literature for such transducers. The present study aims to fill this gap in the literature by providing a systematic design approach for the Tonpilz-type transducers. The proposed methodology involves the use of different analytical models and a finite element model of such transducers. Each model provides a different level of accuracy that is tightly correlated with the models complexity and computational cost. By using these models sequentially starting with the simplest and fastest model to yield an initial design and concluding with the most detailed and accurate model to yield an optimized final design the overall design time is reduced and greater flexibility is given to the designer. An overview of each of these four models is given. The constructed models are benchmarked against published experimental data. The overall design methodology is demonstrated by systematically applying the four models to design a Tonpilz-type transducer. Possible improvements to the proposed methodology are discussed.
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Sutliff, Robert William. "The Effects of Loading on Equivalent Electric Circuit Models for Piezoelectric Transducers." Miami University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=miami1533304929347075.
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Pulitzer, Seward Webb 1974. "Feasibility assessment and design of micro hydraulic solid-state transducers." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/9064.
Повний текст джерелаАнотація:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1998.Includes bibliographical references (p. 179-184).
The performance of a number of mechanical applications could be greatly improved by the introduction of transducers that are capable of exploiting the inherent power densities of piezoelectric materials. The ability of these solid-state materials to exert large forces at high frequencies engenders them with specific power levels (mass normalized) that are often several orders of magnitude greater than conventional transducers, but their utility is offset by their small achievable strains. A novel concept for a device capable of improved solid-state transduction, Micro Hydraulic Solid-State Transducers (MHSTs), is introduced and explored in this thesis. The concept is comprised of two core principles: ( 1) utilization of a hydraulic system consisting of a pump, valves, and a working fluid to rectify the high frequency reciprocations of a piezoelectric drive element into unidirectional motion, and (2) performance enhancement through miniaturization. The goal is a transducer possessing high power densities that is useful in conventional applications. Feasibility of the MHST concept is evaluated by designing, modeling, and simulating a prototype mechanism. The effects of miniattariza~ion on device performance are investigated and an optimal scale is determined. Concept feasibility is based on predicted system performance, existing issues, and manufacturing constraints. It is concluded that the concept is feasible and warrants further development.
by Seward Webb Pulitzer, III.
S.M.
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Wang, Tao. "Optimization and Characterization of Integrated Microfluidic Surface Acoustic Wave Sensors and Transducers." Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6153.
Повний текст джерелаАнотація:
Surface acoustic waves (SAWs) have a large number of applications and the majority of them are in the sensor and actuator fields targeted to satisfy market needs. Recently, researchers have focused on optimizing and improving device functions, sensitivity, power consumption, etc. However, SAW actuators and sensors still cannot replace their conventional counterparts in some mechanical and biomedical areas, such as actuators for liquid pumping under microfluidic channels and sensors for real-time cell culture monitoring. The two objectives of this dissertation are to explore the potential of piezoelectric materials and surface acoustic waves for research on actuators and sensors in the mechanical pump and biosensor areas.
Manipulation of liquids in microfluidic channels is important for many mechanical, chemical and biomedical applications. In this dissertation, we first introduced a novel integrated surface acoustic wave based pump for liquid delivery and precise manipulation within a microchannel. The device employed a hydrophobic surface coating (Cytop) in the device design to decrease the friction force and increase the bonding. Contrary to previous surface acoustic wave based pumps which were mostly based on the filling and sucking process, we demonstrated long distance media delivery (up to 8mm) and a high pumping velocity, which increased the device’s application space and mass production potential. Additionally, the device design didn’t need precise layers of water and glass between substrate and channel, which simplified the design significantly. In this study, we conducted extensive parametric studies to quantify the effects of the liquid volume pumped, microchannel size, and input applied power as well as the existence of hydrophobic surface coating on the pumping velocity and pump performance. Our results indicated that the pumping velocity for a constant liquid volume with the same applied input power could be increased by over 130% (2.31 mm/min vs 0.99 mm/min) by employing a hydrophobic surface coating (Cytop) in a thinner microchannel (250 µm vs 500 µm) design. This device could be used in circulation, dosing, metering and drug delivery applications which necessitated small-scale precise liquid control and delivery.
This dissertation also introduced a novel SAW-based sensor designed and employed for detecting changes in cell concentration. Before conducting cell concentration experiments, preliminary experiments were conducted on weight concentration differentiation of microfluidic particles based on a polydimethylsiloxane (PDMS) channel and surface acoustic wave resonator design. The results confirmed that our device exerted an ultra-stable status to detect liquid properties by monitoring continuous fluids. An improved design was carried out by depositing a 200 nm ZnO layer on top of the lithium tantalate substrate surface increased the sensitivity and enabled cell concentration detection in a microfluidic system.
Comprehensive studies on cell viability were carried out to investigate the effect of shear horizontal (SH) SAWs on both a cancerous (A549 lung adenocarcinoma) and a non-cancerous (RAW264.7 macrophage) cell line. Two pairs of resonators consisting of interdigital transducers (IDTs) and reflecting fingers were used to quantify mass loading by the cells in suspension media as well as within a 3-dimensional cell culture model. In order to predict the characteristics and optimize the design of the SH-SAW biosensor, a 3D COMSOL model was built to simulate the mass loading response of the cell suspensions. These results were compared to experimental data generated by pipetting cell concentrations of 3.125K, 6.25K 12.5K, 25K and 50K cells per 100µL into the PDMS well and measuring to obtain the relative frequency shift from the two oscillatory circuit systems (one of which functioned as a control). Frequency shift measurements were also collected from A549 cells cultured on a 3D nanofiber scaffold produced by electrospinning to evaluate the device’s ability to detect changes in cell density as the cells proliferated in culture over the course of eight days. The device’s ability to detect changes in cell density over time in a 3D model along with its biocompatibility reveal great potential for this device to be incorporated into 3D in vitro cancer research applications.
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Smith, Emily (Emily C. ). "Fabrication of a picoliter microreactor with multilayer elastomer values." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/32916.
Повний текст джерелаАнотація:
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.Includes bibliographical references (leaves 45-46).
Microfluidics has the ability to greatly reduce the time needed to do many biological tests. The development of polymers has brought about substrates with elastomeric properties that can be used to the advantage of microfluidic device design. Elastomeric polymers can be used to create small scale passive valve systems. These valves can compartmentalize reactions in devices. Current microreactors only allow researchers to do one test at a time. Devices with the capability to compartmentalize reactions using valves could perform multiple reactions simultaneously. This thesis details the fabrication and design of a microreactor that can maintain cells in the device after a reaction. The fabrication of the device was done without a clean room and using no specialized equipment. Creation of the device and using it for testing requires little training and takes less time than performing the test using conventional methods. The device could readily be made and used by researchers using equipment already in their lab and is cheaper than current devices on the market.
by Emily Smith.
S.B.
Книги з теми "Transducers of mechanical values"
1
Transducers in mechanical and electronic design. New York: Dekker, 1986.
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2
Trietley, Harry L. Transducers in mechanical and electronic design. New York: Dekker, 1986.
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3
Micro mechanical transducers: Pressure sensors, accelerometers, and gyroscopes. New York: Elsevier Science B.V., 2000.
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4
Robinson, D. C. Requirements for the calibration of mechanical shock transducers. Gaithersburg, MD: U.S. Dept. of Commerce, National Bureau of Standards, 1987.
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5
Jobes, Christopher C. Utilizing mechanical linear transducers for the determination of a mining machine's position and heading: Underground testing. Washington, D.C: U.S. Dept. of the Interior, Bureau of Mines, 1992.
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6
Jobes, Christopher C. Utilizing mechanical linear transducers for the determination of a mining machine's position and heading: The concept. Washington, D.C: U.S. Dept. of the Interior, Bureau of Mines, 1990.
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7
Jobes, Christopher C. Utilizing mechanical linear transducers for the determination of a mining machine's position and heading: The concept. Washington, DC: Dept. of the Interior, 1990.
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8
Jobes, Christopher C. Utilizing mechanical linear transducers for the determination of a mining machine's position and heading: By Christopher C. Jobes. Washington, D.C. (2401 E. St., N.W., Washington 20241-0001): U.S. Dept. of the Interior, Bureau of Mines, 1991.
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9
Hultzman, Don. Collector's guide to battery toys: Batteries not included : identification & values. Paducah, Ky: Collector Books, 1998.
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10
Hultzman, Don. Collector's guide to battery toys: Identification & values : *batteries not included. 2nd ed. Paducah, Ky: Collector Books, 2002.
Знайти повний текст джерелаЧастини книг з теми "Transducers of mechanical values"
1
Lenk, Arno, Rüdiger G. Ballas, Roland Werthschützky, and Günther Pfeifer. "Mechanical Transducers." In Microtechnology and MEMS, 137–63. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-10806-8_5.
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2
Walter, Patrick L. "Bridge Transducers." In Mechanical Engineers' Handbook, 69–115. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2006. http://dx.doi.org/10.1002/0471777455.ch3.
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Vinh, Jean Tuong, and Michel Nugues. "Transducers." In Mechanical Characterization of Materials and Wave Dispersion, 77–117. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118621264.ch5.
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Stoecker, W. F., and P. A. Stoecker. "Transducers." In Microcomputer Control of Thermal and Mechanical Systems, 61–103. Boston, MA: Springer US, 1989. http://dx.doi.org/10.1007/978-1-4684-6560-0_5.
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Moffat, Robert J. "Temperature and Flow Transducers." In Mechanical Engineers' Handbook, 131–88. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2006. http://dx.doi.org/10.1002/0471777455.ch5.
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Koshevoy, N. D., O. V. Zabolotnyi, I. I. Koshevaya, V. V. Muratov, and T. G. Rozhnova. "Fiber-Optic Pressure Instrument Transducers." In Integrated Computer Technologies in Mechanical Engineering, 11–23. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-37618-5_2.
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Suzuki, Kenichiro, Tomas Mercier, Takefumi Oguma, and Takashi Shibuya. "Mechanical Behavior of a Silicon Micro-Optical Attenuator." In Transducers ’01 Eurosensors XV, 1278–81. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-642-59497-7_301.
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Sharpe, W. N., M. A. Eby, and G. Coles. "Effect of Temperature on Mechanical Properties of Polysilicon." In Transducers ’01 Eurosensors XV, 1338–41. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-642-59497-7_315.
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Hejnowicz, Zygmunt. "Plants as Mechano-Osmotic Transducers." In Mechanical Integration of Plant Cells and Plants, 241–67. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-19091-9_10.
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Toriyama, Toshiyuki, Yasutada Tanimoto, and Susumu Sugiyama. "Single Crystalline Silicon Nano Wire Piezoresistors for Mechanical Sensors." In Transducers ’01 Eurosensors XV, 974–77. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-642-59497-7_230.
Повний текст джерелаТези доповідей конференцій з теми "Transducers of mechanical values"
1
Wilt, K. R., H. A. Scarton, G. J. Saulnier, T. J. Lawry, and J. D. Ashdown. "High-Power Operation of Acoustic-Electric Power Feedthroughs Through Thick Metallic Barriers." In ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-89496.
Повний текст джерелаАнотація:
Throughout the last few years there has been a significant push to develop a means for the transmission of electrical power through solid metallic walls using ultrasonic means. The bulk of this effort has been focused on using two coaxially aligned piezoelectric transducers on opposite sides of a thick metallic transmission barrier, where one transducer serves as the “transmit” transducer and the other as the “receive” transducer. Previous modeling has predicted reasonably high power transfer efficiencies through the wall using this type of “acoustic-electric channel” to be possible at low power levels, which implies that channel component operates in a linear range with little concern of failure. High-power testing of two acoustic-electric channels has been done in an effort to determine power limits on such channels and to determine levels at which non-linear effects on the piezoelectrics become non-negligible. The tested channels are characterized by the “power density” imposed on the transmit transducer, that is, the power applied per unit area, as the values found for maximum power density are considered to be independent of transducer radii. The constructed channels are shown to be capable of transmitting large amounts of power (over 100 watts) without failure; and further, extrapolation of the results to channels with larger diameter transducers predicts power transfer of 1 kW to be highly feasible.
2
Lai, Amit, and Richard M. White. "Optimization of the Silicon/PZT Longitudinal Mode Resonant Transducer." In ASME 1997 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/imece1997-0940.
Повний текст джерелаАнотація:
Abstract An analytical electromechanical model of a silicon/PZT laminate longitudinal mode resonant transducer is presented. The validity of this model is shown by the excellent agreement between the predicted and measured impedance of transducers with different device parameters. The experimental data also show a maximum value of 34 for the product of the quality factor and the effective electromechanical coupling. This figure of merit product, an indication of the power output capacity of a transducer, is two to three times higher than that of metal-based transducers. Additionally, silicon can sustain eight times higher ultrasonic velocities than high-strength titanium alloys, indicating that silicon-based ultrasonic transducers can produce much higher intensities efficiently.
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Cortes, Daniel H., and Sam M. Mukdadi. "An Analysis of Laminated Piezoelectric Infinite Plate for Broadband Biomedical Ultrasound Transducer Design." In ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-42289.
Повний текст джерелаАнотація:
This work investigates the use of frequency spectrum analysis of waveguide propagation in multi-layered anisotropic piezoelectric transducers. A semi-analytical finite-element analysis (SAFE) is used to model the transducer as a piezoelectric infinite plate. Dispersion curves, group velocities and displacement frequency spectra can be obtained for any multilayered piezoelectric plate. Stress-free boundary conditions were assumed for all analyses. Results for open and closed circuit boundary conditions were analyzed. Zero-Group-Velocity (ZGV) frequencies of high-order waveguide modes were observed to provide multi-resonant displacement frequency spectrum. Comparison of numerical and experimental results shows a good agreement between peak and off-peak values of the displacement spectrum. Results showed that optimization of layered structure may provide an efficient means for generating multi-thickness (ZGV) waveguide modes, thus increasing the bandwidth of harmonic ultrasound transducers for contrast imaging.
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Koivula, Timo S., Asko U. Ellman, and Matti J. Vilenius. "On Dynamic Pressure Measurement of Hydraulic Return Line." In ASME 2001 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/imece2001/fpst-25021.
Повний текст джерелаАнотація:
Abstract Rapidly fluctuating flow conditions exist in various fluid power applications. Particularly, in return lines of fast on-off valves, circumstances are very demanding as rapidly changing flow rate causes large pressure variations and cavitation downstream from the valve. Pressure measurement of such flow conditions is diverse. In order to exploit the measured data, the measurement equipment and methods have to be reliable. In this paper, several aspects affecting on dynamic pressure measurement in hydraulic return lines are dealt with. Suitability of several transducer types for such dynamic measurements is studied. The effects of various mounting methods and transducer orientations are studied as well. Considerable differences in pressure responses were found with various transducer types. In addition, mounting method and restrictors in mounting fittings were found to be significant. Cavitation was found to be present in the return line and it affected measured responses. In the paper, pressure responses acquired with various pressure transducers and mounting scenarios are presented. The effects of mounting scenarios and orientation of transducers are discussed and measured responses are presented.
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Xiros, Nikolaos I. "Nonlinear Control Modeling for Arrays of Coupled Mechatronic Transducers." In ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-89424.
Повний текст джерелаАнотація:
A typical mechatronic oscillator involving a tuned resistor-inductor-capacitor circuit driven by a voltage source and coupled to a mass-spring-damper mechanical subsystem is analyzed in order to develop a nonlinear control model. The analysis is approached using the Volterrra/Wiener framework of nonlinear systems combined with the Hilbert Transform. The former is needed since the coupling between the electrical and mechanical parts is lost, should standard linearization is adopted. The latter is needed since a very important characteristic of the system, due to the presence of the capacitance, is frequency selectivity. To use this very frequency selectivity in an application, involving more than one transducer units, modulation of the carrier signal, amplitude modulation in this case, must be implemented. Carrier modulation enables multiple units, structurally identical otherwise but for the capacitance value adjusting the tuning frequency setting, in the same application. Both a low-pass and a band-pass model are developed and subsequently simulation runs are performed. Since the modulation method employed is not of the suppressed-carrier type, the equilibrium point is of dynamic rather than static nature, corresponding to initial values for current and displacement. The model is enhanced by superimposing an external disturbance in form of a baseband force acting on the mass payload of the mechanical subsystem. Then, the response of the system to monochromatic and polychromatic excitations is investigated; making sure among others none of the constraints is violated. The transducer configuration investigated here can be employed as an energy harvesting device in cases where vibrational or oscillatory motion of a mass is involved, e.g. ocean wave energy concepts, Vortex-Induced Vibrations etc., especially if no physical contact between the driving process and the driven circuit is feasible or practical.
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Matsushita, Shinichi, Chungpyo Hong, Yutaka Asako, and Ichiro Ueno. "Experimental Investigations of Turbulent Gas Flow in a Micro-Channel." In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-63295.
Повний текст джерелаАнотація:
This paper presents experimental investigations on turbulent gas flow characteristics of nitrogen gas through a micro-channel. The micro-channels were etched into silicon wafers, capped with glass, and their hydraulic diameter is 147.76 micro meters. The micro-channel was designed with a main flow channel and seven side channels, which lead to the pressure transducers. The stagnation pressure was designated in such a way that the flow is in turbulent flow regime. The outlet of the channel faced to the atmosphere. The pressures of the main channel at seven locations were measured by gauge pressure transducers to determine local values of Mach number. And the pressure differences of each pressure ports were measured by differential pressure transducers to obtain the pressure losses precisely. The pressure distribution of turbulent gas flow through a micro-channel falls steeply and Mach number increases near the outlet with increasing the inlet pressure due to flow acceleration. Both Darcy friction factor and Fanning friction factor were obtained for turbulent flow. The result shows that the obtained both friction factors were evaluated as a function of Reynolds number on the Moody chart. The values of Darcy friction factors differ from Blasius correlation for turbulent flow regime due to the compressibility effects, however the values of Fanning friction factors coincide with Blasius correlation.
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Vipperman, Jeffrey S. "Structural Health Monitoring Applications Using Piezo-Dielectric Effects." In ASME 1999 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/imece1999-0568.
Повний текст джерелаАнотація:
Abstract A new method of sensing structural integrity using piezoceramic transducers is presented. Capacitance values of piezoceramic patches are dependent upon the prescribed mechanical boundary conditions. This dependence can be exploited to monitor the rudimentary health of a structure by monitoring the capacitance of an attached piezoceramic patch. An adaptive piezoelectric sensoriactuator is used because of its inherent ability to monitor the capacitance of piezoelectric transducers in real-time. A simple experiment is performed where the device is used to successfully detect a change in boundary conditions for a composite beam piezostructure.
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Migot, Asaad, and Victor Giurgiutiu. "Impact Localization on a Composite Plate With Unknown Material Properties Using PWAS Transducers and Wavelet Transform." In ASME 2017 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/imece2017-70140.
Повний текст джерелаАнотація:
In this work, an impact experiment on a composite plate with unknown material properties (its group velocity profile is unknown) is implemented to localize the impact points. A pencil lead break is used to generate acoustic emission (AE) signals which are acquired by six piezoelectric wafer active sensors (PWAS). These sensors are distributed with a particular configuration in two clusters on the plate. The time of flight (TOF) of acquired signals is estimated at the starting points of these signals. The continuous wavelet transform (CWT) of received signals are calculated with AGU Vallen wavelet program to get the accurate values of the TOF of these signals. Two methods are used for determining the coordinates of impact points (localization the impact point). The first method is the new technique (method 1) by Kundu. This technique has two linear equations with two unknowns (the coordinate of AE source point). The second method is the nonlinear algorithm (method 2). This algorithm has a set of six nonlinear equations with five unknowns. Two MATLAB codes are implemented separately to solve the linear and nonlinear equations. The results show good indications for the location of impact points in both methods. The location errors of calculated impact points are divided by constant distance to get independent percentage errors with the site of the coordinate.
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Ferrari, Giovanni, Margherita Capriotti, Marco Amabili, and Rinaldo Garziera. "Active Vibration Control of a Composite Sandwich Plate." In ASME 2014 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/imece2014-37611.
Повний текст джерелаАнотація:
The active vibration control of a rectangular sandwich plate by Positive Position Feedback is experimentally investigated. The thin walled structure, consisting of carbon-epoxy outer skins and a Nomex paper honeycomb core, has completely free boundary conditions. A detailed linear and nonlinear characterization of the vibrations of the plate was previously performed by our research group [1, 2]. Four couples of unidirectional Macro Fiber Composite (MFC) piezoelectric patches are used as strain sensors and actuators. The positioning of the patches is led by a finite element modal analysis, in the perspective of a modal control strategy aimed at the lowest four natural frequencies of the structure. Numerical and experimental verifications estimate the resulting influence of the control hardware on the modal characteristics of the plate. Experimental values are also extracted for the control authority of the piezoelectric patches in the chosen configuration. Single Input – Single Output (SISO) and MultiSISO Positive Position Feedback algorithms are tested and the transfer function parameters of the controller are tuned according to the previously known values of modal damping. A totally experimental procedure to determine the participation matrices, necessary for the Multiple-Input and Multiple-Output configuration, is developed. The resulting algorithm proves successful in selectively reducing the vibration amplitude of the first four vibration modes in the case of a broadband disturbance. PPF is therefore used profitably on laminated composite plates in conjunction with strain transducers, for the control of the low frequency range up to 100 Hz. The relevant tuning procedure moreover, proves straightforward, despite the relatively high number of transducers. The rigid body motions which arise in case of free boundary conditions do not affect the operation of the active control.
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Huang, Zhenjia (Jerry), Don Spencer, Robert Oberlies, Gracie Watts, and Wenting Xiao. "Wave Impact Experiment of a GBS Model in Large Waves." In ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/omae2017-61473.
Повний текст джерелаАнотація:
For the design of offshore structures in harsh wave environments, model testing continues to be the recommended industry practice for determining wave impact forces on offshore structures. Accurate measurements of wave impacts in model tests have been a challenge for several decades. Transducers are required to accurately capture the short duration, high magnitude, and dynamic nature of impact loads. The structural model, transducers, and the transducer mountings need to be designed such that mechanical vibrations in the integrated transducer-mounting-structural model system do not contaminate the wave impact measurements. In this work, the dynamic oscillations in the measurements were controlled through the design and fabrication of transducers, their mounting and the GBS model. Wave crest probability distributions were developed that included fully nonlinear effects. These distributions were used as a benchmark to qualify the waves in the wave calibration tests. The highly stochastic nature of impact loads makes it challenging to obtain converged probability distributions of the maximum impact loads (i.e. forces or pressures) from model tests. To increase the confidence in the statistical values of wave impact loads, a large number of realizations were used for a given sea state. Variability of the maximum pressure due to wave basin effects (such as wait-time between tests) was examined with fifteen repeat tests using the same wave maker control signal. These tests provided insights into the random behavior of the impact loads.
Звіти організацій з теми "Transducers of mechanical values"
1
Robinson, D. C. Requirements for the calibration of mechanical shock transducers. Gaithersburg, MD: National Bureau of Standards, 1987. http://dx.doi.org/10.6028/nbs.tn.1233.
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Galili, Naftali, Roger P. Rohrbach, Itzhak Shmulevich, Yoram Fuchs, and Giora Zauberman. Non-Destructive Quality Sensing of High-Value Agricultural Commodities Through Response Analysis. United States Department of Agriculture, October 1994. http://dx.doi.org/10.32747/1994.7570549.bard.
Повний текст джерелаАнотація:
The objectives of this project were to develop nondestructive methods for detection of internal properties and firmness of fruits and vegetables. One method was based on a soft piezoelectric film transducer developed in the Technion, for analysis of fruit response to low-energy excitation. The second method was a dot-matrix piezoelectric transducer of North Carolina State University, developed for contact-pressure analysis of fruit during impact. Two research teams, one in Israel and the other in North Carolina, coordinated their research effort according to the specific objectives of the project, to develop and apply the two complementary methods for quality control of agricultural commodities. In Israel: An improved firmness testing system was developed and tested with tropical fruits. The new system included an instrumented fruit-bed of three flexible piezoelectric sensors and miniature electromagnetic hammers, which served as fruit support and low-energy excitation device, respectively. Resonant frequencies were detected for determination of firmness index. Two new acoustic parameters were developed for evaluation of fruit firmness and maturity: a dumping-ratio and a centeroid of the frequency response. Experiments were performed with avocado and mango fruits. The internal damping ratio, which may indicate fruit ripeness, increased monotonically with time, while resonant frequencies and firmness indices decreased with time. Fruit samples were tested daily by destructive penetration test. A fairy high correlation was found in tropical fruits between the penetration force and the new acoustic parameters; a lower correlation was found between this parameter and the conventional firmness index. Improved table-top firmness testing units, Firmalon, with data-logging system and on-line data analysis capacity have been built. The new device was used for the full-scale experiments in the next two years, ahead of the original program and BARD timetable. Close cooperation was initiated with local industry for development of both off-line and on-line sorting and quality control of more agricultural commodities. Firmalon units were produced and operated in major packaging houses in Israel, Belgium and Washington State, on mango and avocado, apples, pears, tomatoes, melons and some other fruits, to gain field experience with the new method. The accumulated experimental data from all these activities is still analyzed, to improve firmness sorting criteria and shelf-life predicting curves for the different fruits. The test program in commercial CA storage facilities in Washington State included seven apple varieties: Fuji, Braeburn, Gala, Granny Smith, Jonagold, Red Delicious, Golden Delicious, and D'Anjou pear variety. FI master-curves could be developed for the Braeburn, Gala, Granny Smith and Jonagold apples. These fruits showed a steady ripening process during the test period. Yet, more work should be conducted to reduce scattering of the data and to determine the confidence limits of the method. Nearly constant FI in Red Delicious and the fluctuations of FI in the Fuji apples should be re-examined. Three sets of experiment were performed with Flandria tomatoes. Despite the complex structure of the tomatoes, the acoustic method could be used for firmness evaluation and to follow the ripening evolution with time. Close agreement was achieved between the auction expert evaluation and that of the nondestructive acoustic test, where firmness index of 4.0 and more indicated grade-A tomatoes. More work is performed to refine the sorting algorithm and to develop a general ripening scale for automatic grading of tomatoes for the fresh fruit market. Galia melons were tested in Israel, in simulated export conditions. It was concluded that the Firmalon is capable of detecting the ripening of melons nondestructively, and sorted out the defective fruits from the export shipment. The cooperation with local industry resulted in development of automatic on-line prototype of the acoustic sensor, that may be incorporated with the export quality control system for melons. More interesting is the development of the remote firmness sensing method for sealed CA cool-rooms, where most of the full-year fruit yield in stored for off-season consumption. Hundreds of ripening monitor systems have been installed in major fruit storage facilities, and being evaluated now by the consumers. If successful, the new method may cause a major change in long-term fruit storage technology. More uses of the acoustic test method have been considered, for monitoring fruit maturity and harvest time, testing fruit samples or each individual fruit when entering the storage facilities, packaging house and auction, and in the supermarket. This approach may result in a full line of equipment for nondestructive quality control of fruits and vegetables, from the orchard or the greenhouse, through the entire sorting, grading and storage process, up to the consumer table. The developed technology offers a tool to determine the maturity of the fruits nondestructively by monitoring their acoustic response to mechanical impulse on the tree. A special device was built and preliminary tested in mango fruit. More development is needed to develop a portable, hand operated sensing method for this purpose. In North Carolina: Analysis method based on an Auto-Regressive (AR) model was developed for detecting the first resonance of fruit from their response to mechanical impulse. The algorithm included a routine that detects the first resonant frequency from as many sensors as possible. Experiments on Red Delicious apples were performed and their firmness was determined. The AR method allowed the detection of the first resonance. The method could be fast enough to be utilized in a real time sorting machine. Yet, further study is needed to look for improvement of the search algorithm of the methods. An impact contact-pressure measurement system and Neural Network (NN) identification method were developed to investigate the relationships between surface pressure distributions on selected fruits and their respective internal textural qualities. A piezoelectric dot-matrix pressure transducer was developed for the purpose of acquiring time-sampled pressure profiles during impact. The acquired data was transferred into a personal computer and accurate visualization of animated data were presented. Preliminary test with 10 apples has been performed. Measurement were made by the contact-pressure transducer in two different positions. Complementary measurements were made on the same apples by using the Firmalon and Magness Taylor (MT) testers. Three-layer neural network was designed. 2/3 of the contact-pressure data were used as training input data and corresponding MT data as training target data. The remaining data were used as NN checking data. Six samples randomly chosen from the ten measured samples and their corresponding Firmalon values were used as the NN training and target data, respectively. The remaining four samples' data were input to the NN. The NN results consistent with the Firmness Tester values. So, if more training data would be obtained, the output should be more accurate. In addition, the Firmness Tester values do not consistent with MT firmness tester values. The NN method developed in this study appears to be a useful tool to emulate the MT Firmness test results without destroying the apple samples. To get more accurate estimation of MT firmness a much larger training data set is required. When the larger sensitive area of the pressure sensor being developed in this project becomes available, the entire contact 'shape' will provide additional information and the neural network results would be more accurate. It has been shown that the impact information can be utilized in the determination of internal quality factors of fruit. Until now,
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López-Soto, Jamie F., and Bryant A. Robbins. Laboratory measurements of the erodibility of gravelly soils. U.S. Army E ngineer Research and Development Center, November 2021. http://dx.doi.org/10.21079/11681/42443.
Повний текст джерелаАнотація:
The critical shear stress and erodibility of soil are fundamental parameters for modeling embankment breaching. Unfortunately, very few studies have examined the erosion characteristics of soils consisting predominantly of particles larger than sand. This report presents results of an experimental study in which the erosion characteristics of gravelly soils were measured. A flume apparatus was developed in which 0.45-m-square samples were extruded into confined flow. A mechanical laser system allowed the measurement of scour in real time, resulting in a continuous and automated erosion test. The critical shear stress of a uniform gravel was found to match the expected values based on the Shields diagram, while tests that were composed largely of gravel but contained other soils, such as sand, silt, and clay, varied significantly with the critical shear stress and erodibility, depending highly on the characteristics of the finer soils.
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MECHANICAL PRORERTIES OF EXPOSED COLUMN BASE CONNECTIONS FOR L-SHAPED COLUMNS FABRICATED USING CONCRETE-FILLED STEEL TUBES. The Hong Kong Institute of Steel Construction, December 2021. http://dx.doi.org/10.18057/ijasc.2021.17.4.4.
Повний текст джерелаАнотація:
The response of exposed column base connections for L-shaped column is investigated through finite element analysis (FEA) in this paper which is affected by complex interactions among different components. Three finite element models are constructed to simulate the response of these connections under axial and cyclic horizontal loading, which interrogate a range of variables including anchor rod strength, base plate size and thickness. The results of the simulations provide insights into internal stress distributions which have not been measured directly through experiments. The key findings indicate that thicker base plates tend to shift the stresses to the toe of the base plate, while thinner plates concentrate the stresses under the column flange. Base on the analytical results, a hysteretic model is proposed to describe the cyclic moment-rotation response of exposed column base connections. The core parameters used to define the backbone curve of the hysteretic model are calibrated through configurational details. The comparison between the simulation and the calculated values indicates that the hysteretic model is suitable to characterize the key aspects of the physical response, including pinching, recentering and flag-shaped hysteresis phenomenon. Limitations of the model are outlined.