Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 15.474
Filtrar
1.
Sensors (Basel) ; 23(2)2023 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-36679397

RESUMO

The use of thin magnetostrictive patches to generate and detect guided waves within the composite samples is investigated for defect detection. This approach has been implemented using SH0 shear horizontal guided waves in both CFRP and GFRP plates. A magnetostrictive patch transducer was able to generate SH0 waves with known directional characteristics. The synthetic aperture focusing technique (SAFT) was then used to reconstruct images of defects using multiple transmission and detection locations. The results for imaging defects in both types of material are presented.


Assuntos
Diagnóstico por Imagem , Transdutores
2.
Sensors (Basel) ; 23(2)2023 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-36679441

RESUMO

Backward acoustic waves are characterized by oppositely directed phase and group velocities. These waves can exist in isotropic and piezoelectric plates. They can be detected using a set of interdigital transducers with different spatial periods located on the same piezoelectric substrate. In this paper, the effect of a nonviscous and nonconductive liquid on the characteristics of a first-order backward antisymmetric wave in a YX plate of lithium niobate is studied theoretically and experimentally. It is shown that the presence of liquid does not lead to the transformation or disappearance of this wave. It is shown that these waves are close to the cutoff frequency and are characterized by the presence of a point with zero group velocity. The design of a liquid sensor based on these waves is proposed.


Assuntos
Acústica , Som , Transdutores
3.
Sensors (Basel) ; 23(2)2023 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-36679698

RESUMO

Temperature transducers are commonly used to monitor process parameters that are controlled by various types of industrial controllers. The purpose of this study is to design and model a simple microcontroller-based acoustic temperature transducer based on the variations of resonance conditions in a cylindrical resonance tube. The transducer's operation is based on the generation of an acoustic standing wave in the free resonance mode of generation within a cylindrical resonance tube which is converted into a train of pulses using Schmitt trigger circuit. The frequency of the generated standing wave (i.e., the train of pulses) is measured by the Arduino Uno microcontroller, where a digital pin is used to acquire pulses that are counted using a build-in software function in an Arduino IDE environment. Experimental results are performed for three sizes of diameters to investigate the effect of the diameter of resonance tube on the obtained results. The maximum nonlinearity error according to Full-Scale Deflection (FSD) is about 2.3 percent, and the relative error of the transducer is evaluated using experimental findings and the regression model. The circuit simplicity and design of the suggested transducer, as well as the linearity of its measurements, are notable.


Assuntos
Acústica , Som , Temperatura , Vibração , Transdutores
4.
Sensors (Basel) ; 23(2)2023 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-36679720

RESUMO

We demonstrate a highly sensitive acoustic vibration sensor based on a tapered-tip optical fiber acting as a microcantilever. The tapered-tip fiber has a unique output profile that exhibits a circular fringe pattern, whose distribution is highly sensitive to the vibration of the fiber tip. A piezo transducer is used for the acoustic excitation of the fiber microcantilever, which results in a periodic bending of the tip and thereby a significant output power modulation. Using a multimode readout fiber connected to an electric spectrum analyzer, we measured the amplitude of these power modulations over the 10-50 kHz range and observed resonances over certain frequency ranges. Two types of tapered-tip fibers were fabricated with diameter values of 1.5 µm and 1.8 µm and their frequency responses were compared with a non-tapered fiber tip. Thanks to the resonance effect as well as the sensitive fringe pattern of the tapered-tip fibers, the limit of detection and the sensitivity of the fiber sensor were obtained as 0.1 nm and 15.7 V/nm, respectively, which were significantly better than the values obtained with the non-tapered fiber tip (i.e., 1.1 nm and 0.12 V/nm, respectively). The sensor is highly sensitive, easy to fabricate, low-cost, and can detect sub-nanometer displacements, which makes it a promising tool for vibration sensing, particularly in the photoacoustic sensing of greenhouse gases.


Assuntos
Fibras Ópticas , Vibração , Acústica , Análise Espectral , Transdutores
5.
Sensors (Basel) ; 23(2)2023 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-36679812

RESUMO

Acoustic/ultrasonic testing is now a common method in the field of nondestructive testing for detecting material defects or monitoring ongoing mechanical changes in a structure during operation. In many applications, piezoelectric transducers are used to generate mechanical waves inside the specimen. Their actual operating frequency is highly dependent on the dimensions of the transducer. Larger dimensions of the piezoelectric transducer allow for a lower operating frequency. However, these dimensions limit the use of piezoelectric transducers in certain applications where the size of the transducer is restricted due to limited installation space and when low-frequency excitation is required. One application that places these requirements on the transducer is the monitoring of mechanical seals. Here, the transducer must be mounted on the stationary ring of the seal. In this paper, a continuously operated electromagnetic acoustic transducer (EMAT) is presented as an alternative to piezoelectric transducers as a transmitter. The advantage of a EMAT is that it meets the requirements of limited sensor size (sensor area < 10 × 6 mm) and can excite mechanical waves with frequencies below 10 kHz. A structural analysis of the stationary ring shows that the first two mechanical resonances occur around 4 and 5.5 kHz. An experimental study meterologically demonstrates the ability of the EMAT to excite these first two mechanical resonances of the ring. A comparative simulation agrees well with the measurement.


Assuntos
Acústica , Ultrassom , Desenho de Equipamento , Transdutores , Fenômenos Eletromagnéticos
6.
Sensors (Basel) ; 23(2)2023 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-36679826

RESUMO

Piezoelectric accelerometers using a lead-free (K,Na)NbO3 (KNN) piezoceramic modified by a mixture of two Bi-based perovskites, Bi(Na,K,Li)ZrO3 (BNKLZ) and BiScO3 (BS), were designed, fabricated and characterized. Ring-shaped ceramics were prepared using a conventional solid-state reaction method for integration into a compression-mode accelerometer. A beneficial rhombohedral-tetragonal (R-T) phase boundary structure, especially enriched with T phase, was produced by modifying intrinsic phase transition temperatures, yielding a large piezoelectric charge coefficient d33 (310 pC/N) and a high Curie temperature Tc (331 °C). Using finite element analyses with metamodeling techniques, four optimum accelerometer designs were obtained with high magnitudes of charge sensitivity Sq and resonant frequency fr, as evidenced by two key performance indicators having a trade-off relation. Finally, accelerometer sensor prototypes based on the proposed designs were fabricated using the KNN-BNKLZ-BS ceramic rings, which exhibited high levels of Sq (55.1 to 223.8 pC/g) and mounted fr (14.1 to 28.4 kHz). Perfect charge-to-acceleration linearity as well as broad flat frequency ranges were achieved with excellent reliability. These outstanding sensing performances confirm the potential application of the modified-KNN ceramic in piezoelectric sensors.


Assuntos
Cerâmica , Transdutores , Reprodutibilidade dos Testes , Teste de Materiais , Cerâmica/química , Sódio , Íons
7.
Sensors (Basel) ; 23(2)2023 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-36679531

RESUMO

A very compact waveguide orthomode transducer (OMT) is described in this paper. The design is characterized with a twofold rotationally symmetric cross-section in the probing area, adapted from a side-coupling OMT design, simultaneously enabling low port-to-port coupling and high cross-polarization discrimination (XPD) over a fractional bandwidth of about 15-20%. Compared to previously reported compact waveguide OMTs, the proposed design is simpler, thus facilitating its manufacture at millimeter-wave frequencies. The concept is demonstrated with a design in the K-band for a broadband communication satellite downlink over the frequency band of 17.3-20.2 GHz. For test purposes, transitions to standard waveguide WR42 are included, and the OMT is assembled with a conical horn antenna. The measured reflection and coupling coefficients are below -19.5 dB and -22.9 dB, respectively, over the nominal bandwidth, and they are in good agreement with the simulation's results. The on-axis XPD, measured in an anechoic chamber, is better than 30 dB over the nominal bandwidth, which is also in line with simulations. The proposed waveguide OMT may be designed to fit in a lattice below one wavelength at the highest operating frequency, which is desirable for dual-polarized closely spaced array antennas in low and medium Earth orbit communication satellite systems. The simple mechanical design of the proposed OMT makes it particularly appealing for additive manufacturing techniques, as demonstrated with a variant of the design having folded single-mode waveguides, which preserves the RF properties of the original design.


Assuntos
Comércio , Refração Ocular , Comunicações Via Satélite , Transdutores
8.
Opt Lett ; 48(2): 195-198, 2023 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-36638416

RESUMO

Multi-parametric photoacoustic microscopy (PAM) is uniquely capable of simultaneous high-resolution mapping of blood oxygenation and flow in vivo. However, its speed has been limited by the dense sampling required for blood flow quantification. To overcome this limitation, we have developed a high-speed multi-parametric PAM system, which enables simultaneous acquisition of ∼500 densely sampled B-scans by superposing the rapid optical scanning across the line-shaped focus of a cylindrically focused ultrasonic transducer over the conventional mechanical scan of the optical-acoustic dual foci. A novel, to the best of our knowledge, optical-acoustic combiner (OAC) is designed and implemented to accommodate the short working distance of the transducer, enabling convenient confocal alignment of the dual foci in reflection mode. A resonant galvanometer (GM) provides stabilized high-speed large-angle scanning. This new system can continuously monitor microvascular blood oxygenation (sO2) and flow over a 4.5 × 3 mm2 area in the awake mouse brain with high spatial and temporal resolutions (6.9 µm and 0.3 Hz, respectively).


Assuntos
Microscopia , Técnicas Fotoacústicas , Animais , Camundongos , Acústica , Análise Espectral , Transdutores
9.
Opt Lett ; 48(2): 343-346, 2023 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-36638453

RESUMO

Two-dimensional matrix transducer arrays are the most appropriate imaging probes for acquiring dual-modal 3D photoacoustic (PA)/ultrasound (US) images. However, they have small footprints which limit the field-of-view (FOV) to less than 10 mm × 10 mm and degrade the spatial resolution. In this study, we demonstrate a dual-modal PA and US imaging system (using a 2D matrix transducer array and a motorized 2D scanning system) to enlarge the FOV of volumetric images. Multiple PA volumes were merged to form a wide-field image of approximately 45 mm × 45 mm. In vivo imaging was demonstrated using rat sentinel lymph nodes (SLNs) and bladders stained with methylene blue. We believe that this volumetric PA/US imaging technique with a 2D matrix transducer array can be a useful tool for narrow-field real-time monitoring and wide-field imaging of various preclinical and clinical studies.


Assuntos
Imageamento Tridimensional , Técnicas Fotoacústicas , Ratos , Animais , Ultrassonografia/métodos , Imageamento Tridimensional/métodos , Imagens de Fantasmas , Azul de Metileno , Transdutores , Técnicas Fotoacústicas/métodos
10.
Sensors (Basel) ; 23(1)2023 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-36617146

RESUMO

Structural health monitoring technology can assess the status and integrity of structures in real time by advanced sensors, evaluate the remaining life of structure, and make the maintenance decisions on the structures. Piezoelectric materials, which can yield electrical output in response to mechanical strain/stress, are at the heart of structural health monitoring. Here, we present an overview of the recent progress in piezoelectric materials and sensors for structural health monitoring. The article commences with a brief introduction of the fundamental physical science of piezoelectric effect. Emphases are placed on the piezoelectric materials engineered by various strategies and the applications of piezoelectric sensors for structural health monitoring. Finally, challenges along with opportunities for future research and development of high-performance piezoelectric materials and sensors for structural health monitoring are highlighted.


Assuntos
Eletricidade , Transdutores , Estresse Mecânico
11.
Sensors (Basel) ; 23(1)2023 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-36617150

RESUMO

In this paper, we present a novel technique for passively autoranging a photonic current transducer (PCT) that incorporates a current transformer (CT), piezoelectric transducer (PZT) and fiber Bragg grating (FBG). Due to the usage of single-mode fiber and FBG, multiple PCTs can be interconnected and distributed over a long distance, for example along a power network, greatly reducing the cost of sensor deployment and offering other unique advantages. The autoranging technique relies on the usage of multiple, serially connected CT burden resistors and associated static MOSFET switches to realize instantaneous shortening of the resistors in response to increasing measured current. This functionality is realized passively, utilizing a modular, µW-power comparator circuit that powers itself from the electrical energy supplied by the CT within a small fraction of the 50/60 Hz cycle. The resultant instantaneous changes in sensor gain will be ultimately detected by the central FBG interrogator through real-time analysis of the optical signals and will be used to apply appropriate gain scaling for each sensor. The technique will facilitate the usage of a single PCT to cover an extended dynamic range of the measurement that is required to realize a combined metering- and protection-class current sensor. This paper is limited to the description of the design process, construction, and testing of a prototype passive autoranging circuitry for integration with the PCT. The two-stage circuitry that is based on two burden resistors, 1 Ω and 10 Ω, is used to prove the concept and demonstrate the practically achievable circuit characteristics. It is shown that the circuit correctly reacts to input current threshold breaches of approximately 2 A and 20 A within a 3 ms reaction time. The circuit produces distinct voltage dips across burden resistors that will be used for signal scaling by the FBG interrogator.


Assuntos
Tecnologia de Fibra Óptica , Fibras Ópticas , Tecnologia de Fibra Óptica/métodos , Transdutores
12.
Anal Chem ; 95(2): 827-835, 2023 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-36594897

RESUMO

Cell orientation is essential in many applications in biology, medicine, and chemistry, such as cellular injection, intracellular biopsy, and genetic screening. However, the manual cell orientation technique is a trial-and-error approach, which suffers from low efficiency and low accuracy. Although several techniques have improved these issues to a certain extent, they still face problems deforming or disrupting cell membranes, physical damage to the intracellular structure, and limited particle size. This study proposes a noncontact and noninvasive cell orientation method that rotates a cell using surface acoustic waves (SAWs). To realize the acoustic cell orientation process, we have fabricated a microdevice consisting of two pairs of focused interdigital transducers (FIDTs). Instead of rotating the entire cell, the proposed method rotates the intracellular structure, the cytoplasm, directly through the cell membrane by acoustic force. We have tested the rotational manipulation process on 30 zebrafish embryos. The system was able to orientate a cell to a target orientation with a one-time success rate of 93%. Furthermore, the postoperation survival rate was 100%. Our acoustic rotational manipulation technique is noninvasive and easy to use, which provides a starting point for cell-manipulation-essential tasks, such as single-cell analysis, organism studies, and drug discovery.


Assuntos
Som , Peixe-Zebra , Animais , Acústica , Análise de Célula Única , Transdutores
13.
Biomed Phys Eng Express ; 9(2)2023 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-36595267

RESUMO

pMUT (piezoelectric Micromachined Ultrasound Transducer) devices are an alternative that can overcome the limitations associated with conventional ultrasound transducers. pMUT's are reported for many applications such as range-finding, biometrics, and ultrasound imaging. However, pulse-echo measurements from fabricated pMUT devices/arrays are not commonly reported in literature, a reason being lack of desirable performance either in transmit or receive mode of operation. There is also limited information about the design, fabrication and characterization of 2D-pMUT-arrays operating at high frequencies (>15 MHz) in water medium. In this paper we review 'state-of-the-art' for pMUT-array based medical ultrasound imaging, with a focus on their pulse-echo imaging capability. Over the next 3-5 years, we expect further improvement in piezoelectric thin film deposition techniques, on-chip integration of pre-amplification circuits and further miniaturization of pMUT devices, thus paving the way for development of pMUT-array based high frequency medical imaging systems.


Assuntos
Diagnóstico por Imagem , Transdutores , Desenho de Equipamento , Ultrassonografia/métodos , Miniaturização
14.
J Neural Eng ; 20(1)2023 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-36608340

RESUMO

Objective.Ultrasound neuromodulation has become an emerging method for the therapy of neurodegenerative and psychiatric diseases. The phased array ultrasonic transducer enables multi-target ultrasound neuromodulation in small animals, but the relatively large size and mass and the thick cables of the array limit the free movement of small animals. Furthermore, spatial interference may occur during multi-target ultrasound brain stimulation with multiple micro transducers.Approach.In this study, we developed a miniature power ultrasound transducer and used the virtual source time inversion method and 3D printing technology to design, optimize, and manufacture the acoustic holographic lens to construct a multi-target ultrasound neuromodulation system for free-moving mice. The feasibility of the system was verified byin vitrotranscranial ultrasound field measurements,in vivodual-target blood-brain barrier (BBB) opening experiments, andin vivodual-target ultrasound neuromodulation experiments.Main results.The developed miniature transducer had a diameter of 4.0 mm, a center frequency of 1.1 MHz, and a weight of 1.25 g. The developed miniature acoustic holographic lens had a weight of 0.019 g to generate dual-focus transcranial ultrasound. The ultrasonic field measurements' results showed that the bifocal's horizontal distance was 3.0 mm, the -6 dB focal spot width in thex-direction was 2.5 and 2.25 mm, and 2.12 and 2.24 mm in they-direction. Finally, thein vivoexperimental results showed that the system could achieve dual-target BBB opening and ultrasound neuromodulation in freely-moving mice.Significance.The ultrasonic neuromodulation system based on a miniature single-element transducer and the miniature acoustic holographic lens could achieve dual-target neuromodulation in awake small animals, which is expected to be applied to the research of non-invasive dual-target ultrasonic treatment of brain diseases in awake small animals.


Assuntos
Terapia por Ultrassom , Ultrassom , Camundongos , Animais , Barreira Hematoencefálica , Terapia por Ultrassom/métodos , Movimento , Transdutores , Encéfalo
15.
Biosens Bioelectron ; 224: 115014, 2023 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-36628826

RESUMO

The growing use of aptamers as target recognition elements in label-free biosensing necessitates corresponding transducers that can be used in relevant environments. While popular in many fields, capacitive sensors have seen relatively little, but growing use in conjunction with aptamers for sensing diverse targets. Few reports have shown physiologically relevant sensitivity in laboratory conditions and a cohesive picture on how target capture modifies the measured capacitance has been lacking. In this review, we assess the current state of the field in three areas: small molecule, protein, and cell sensing. We critically analyze the proposed hypotheses on how aptamer-target capture modifies the capacitance, as many mechanistic postulations appear to conflict between published works. As the field matures, we encourage future works to investigate individual aptamer-target interactions and to interrogate the physical mechanisms leading to measured changes in capacitance. To this point, we provide recommendations on best practices for developing aptasensors with a particular focus on considerations for biosensing in clinical settings.


Assuntos
Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , Transdutores
16.
Biosensors (Basel) ; 13(1)2023 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-36671956

RESUMO

This work presents a novel application of ultrasound for the real-time, non-invasive investigation of occlusion of the upper airway during events of obstructive sleep apnea/hypopnea syndrome. It is hypothesized that ultrasonic pulses applied to the neck during apneic events produce spectral and temporal features that can detect apnea occurrence. Theoretical models of ultrasound propagation and an in vitro test were conducted to test this hypothesis in both transmission and reflection modes. Complete specifications and technical details of the system design and fabrication, which is mounted on each subject's neck, are presented, including the methodology. Nine patients (seven male and two female, mean age of 42 years, with a range of 25 to 56 years, and body mass index 37.6 ± 6.6 kg/m2) were recruited for a full night study, which included simultaneous nocturnal polysomnography for the validation of the results. Nine temporal features and four spectral features were extracted from the envelope of the received pulse waveform. These were used to compute 26 metrics to quantify the changes in the ultrasonic waveforms between normal breathing and apneic events. The statistical analysis of the collected ultrasonic data showed that at least two or more of the proposed features could detect apneic events in all subjects. The findings establish the feasibility of the proposed method as a cost-effective and non-invasive OSAHS screening tool.


Assuntos
Síndromes da Apneia do Sono , Apneia Obstrutiva do Sono , Humanos , Masculino , Feminino , Adulto , Pessoa de Meia-Idade , Ultrassom , Síndromes da Apneia do Sono/diagnóstico , Apneia Obstrutiva do Sono/diagnóstico , Polissonografia , Transdutores
17.
Biosensors (Basel) ; 13(1)2023 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-36671969

RESUMO

Robotic prostheses and powered exoskeletons are novel assistive robotic devices for modern medicine. Muscle activity sensing plays an important role in controlling assistive robotics devices. Most devices measure the surface electromyography (sEMG) signal for myoelectric control. However, sEMG is an integrated signal from muscle activities. It is difficult to sense muscle movements in specific small regions, particularly at different depths. Alternatively, traditional ultrasound imaging has recently been proposed to monitor muscle activity due to its ability to directly visualize superficial and at-depth muscles. Despite their advantages, traditional ultrasound probes lack wearability. In this paper, a wearable ultrasound (US) transducer, based on lead zirconate titanate (PZT) and a polyimide substrate, was developed for a muscle activity sensing demonstration. The fabricated PZT-5A elements were arranged into a 4 × 4 array and then packaged in polydimethylsiloxane (PDMS). In vitro porcine tissue experiments were carried out by generating the muscle activities artificially, and the muscle movements were detected by the proposed wearable US transducer via muscle movement imaging. Experimental results showed that all 16 elements had very similar acoustic behaviors: the averaged central frequency, -6 dB bandwidth, and electrical impedance in water were 10.59 MHz, 37.69%, and 78.41 Ω, respectively. The in vitro study successfully demonstrated the capability of monitoring local muscle activity using the prototyped wearable transducer. The findings indicate that ultrasonic sensing may be an alternative to standardize myoelectric control for assistive robotics applications.


Assuntos
Robótica , Dispositivos Eletrônicos Vestíveis , Animais , Suínos , Ultrassonografia , Músculos , Transdutores
18.
Ultrasonics ; 129: 106905, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36481720

RESUMO

Thermal stress is one of the major causes of failure of engineering structures and its measurement has attracted more attention in recent years. The ultrasonic wave method is very promising in stress measurement due to its non-destructive nature and easy manipulation. The traditional ultrasonic wave transducers require a coupling medium which would introduce large repeatability errors in travel time measurement and thus in the measured stress. In this work, a methodology based on bonded shear horizontal (SH) guided wave piezoelectric transducers was developed to monitor thermal stress in metal plates. The adhesive bonding between the transducer and the specimen ensures the repeatability in travel time measurements, and the strain gauges are also employed to monitor the wave path length. The dispersive equation of acoustoelastic SH wave propagating in an isotropic medium under the uniaxial stress is derived. Both the uniaxial tension test and thermal modulation test have been performed in aluminum and steel plates. The results show that the acoustoelastic constants of the SH0 wave are identical to that of the shear bulk wave as predicted by the acoustoelastic theory and the thermal stress measured from -60 °C to 100 °C by the proposed method has a very good repeatability (better than 2 MPa) in both the aluminum and steel plates. Considering the convenience and reliability of the bonded SH0 wave piezoelectric transducer, the proposed method is very promising for monitoring of thermal stress in engineering structures, such as rails, etc.


Assuntos
Alumínio , Transdutores , Alumínio/química , Reprodutibilidade dos Testes , Aço/química
19.
Ultrasonics ; 129: 106893, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36509006

RESUMO

Guided waves can propagate along the surface of a solid structure at a large distance with little attenuation. Hidden defects within the structure can be detected based on the abnormal reflection or transmission of guided waves. The distance between the defect and the transducer can be calculated according to the arrival time of the wave package and wave speed. Therefore, the guided wave speed should be known prior. However, existing analytical models can only predict the guided wave speed along the surface of a horizontal solid covered by a liquid layer. These models are not suited for the characterization of ultrasonic nondestructive testing of ship hulls, sluice gates, water dams, bridge piers, etc. In this study, an analytical model is proposed for the guided wave propagation along a vertical solid partially inserted into a horizontal liquid layer. A secular equation is derived and solved to predict the guided wave speed at the vertical solid-liquid interface. Twenty finite element simulations and thirty-three physical experiments are conducted on different materials with different dimensions by using varying incident frequencies. The results demonstrate that the proposed model can provide accurate analytical wave speeds to guide the nondestructive testing and structural health monitoring of underwater structures.


Assuntos
Transdutores , Ultrassom
20.
Ultrasonics ; 129: 106910, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36512990

RESUMO

Ultrasonic motors (USMs) are expected to be used in special environments: high magnetic field environments and space environments, which require lightweight and multiple degrees of freedom. However, when used as linear ultrasonic motors (LUSMs), a linear guide and a preload mechanism are required, complicating the structure. In the present paper, a hollow cylindrical linear stator without an extra linear guide has been considered. The stator consists of a metal pipe and two piezoelectric (PZT) tubes installed at both ends of the metal pipe. Their connected parts are tapered for the first longitudinal axisymmetric vibration mode of the cylinder, namely L(0,1) mode excitation, and the metal pipe is subjected to radial strain. The vibration of the stator is assumed to be one-dimensional and is modeled by an electromechanical equivalent circuit. The principle that the traveling wave is formed on the metal pipe by dual-PZT-tube phase difference excitation was clarified. Finite element analysis and some measurements were conducted to confirm that the theory was consistent. The analyses and measurements were in good agreement. Therefore, the operating principle was confirmed. The results of the transport experiment showed that the average speed of the 8.5-g slider was 7.9 mm/s.


Assuntos
Transdutores , Vibração , Desenho de Equipamento , Ultrassom , Análise de Elementos Finitos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...