Type Of Ultrasonic Transducer Research Articles

Performance Analysis and Prospect of Piezoelectric Ultrasonic Transducers Based on Vibration Modes

With the maturity of ultrasonic transducer technology, as a traditional ultrasonic transducer, piezoelectric ultrasonic transducer has leaped into the public view. This article briefly summarizes the development of ultrasonic transducers and the classification of piezoelectric ultrasonic transducers. In practical applications, different piezoelectric ultrasonic transducers are mostly selected based on the different sound source vibrations in the application scenarios. The principle analysis and structure introduction of longitudinal vibration type ultrasonic transducers, longitudinal bending vibration mode conversion type ultrasonic transducers, and torsional vibration piezoelectric ceramic ultrasonic transducers are conducted respectively, and the application fields are pointed out. Besides, heat dissipation is an important link that affects the energy transfer efficiency of piezoelectric ultrasonic transducers. For traditional air-cooled heat dissipation and phase change heat dissipation, the heat dissipation ability is investigated and analyzed separately, and the advantages and disadvantages of the two are compared. It is concluded that phase change heat dissipation can effectively solve the impact caused by excessive temperature difference inside the transducer, while traditional heat dissipation methods cannot solve this problem.

Symmetric Reflector Ultrasonic Transducer Modeling and Characterization: Role of the Matching Layer on Electroacoustic Performance.

Symmetric reflector ultrasonic transducers (SRUTs) are a new type of ultrasonic transducer that take advantage of the ultrasonic wave emitted on the rear face of the active element. In this work, the electroacoustic modeling and characterization of such a structure is reported. Using the well-known Krimholtz, Leedom, et Matthaei (KLM) model, the electroacoustic response of a SRUT based on a piezoelectric ceramic with one matching layer is calculated. Simulations show that the optimal acoustic impedance of the matching layer should be lower than for conventional transducers, leading to a relative bandwidth of approximately 50%. The characterization of such a transducer based on a piezoceramic plate has been carried out. Bandwidth and sensitivity are reported. They are found to be close to the simulation results and demonstrate that these new types of transducers need to be designed according to new rules compared to conventional ones.

Influence of different ultrasonic transducers on the precision of fastening force measurement

In the assembly process of aero-engines, the accurate measurement of bolt fastening force is particularly important, which is related to the normal operation of the entire system. Ultrasonic non-destructive testing has been applied to bolt fastening force measurement and has a broad application background. The core device of the ultrasonic transducer is a piezoelectric ceramic wafer, and the normal operation of the wafer is affected by the power frequency and external stress. For the same type of bolt with the same nominal diameter, the ultrasonic transducer wafers of different diameters will cause the transducer wafers to be subjected to different external stresses. According to the acoustoelastic effect, the relationship between the variation of time of flight (TOF) and bolt fastening force of different types of ultrasonic transducers is established. Then the measurement errors of various models are calculated and analyzed. The experimental results show that when the nominal diameter of the bolt is close to the diameter of the wafer of the ultrasonic transducer, the fastening force measurement accuracy of the bolt is the highest. When small or large size transducer is used, the measurement accuracy will be reduced due to energy and external stress. When a transducer with a higher center frequency is used to measure the fastening force of the bolt rod, the accuracy of the model established due to the faster attenuation of the sound wave is reduced, and the accuracy of the measurement result is reduced. Therefore, in order to ensure the accuracy of the fastening force measurement in the aerospace field, when selecting an ultrasonic transducer, the impact of the transducer size and center frequency should be fully considered.

Preliminary Investigation of Magnetic Resonance Imaging Guided Beamforming in Flexible Type Ultrasonic Array Transducers

A flexible-shaped ultrasonic array probe that can be used in a high magnetic field environment in an MRI gantry has been developed. Given that this probe can be fixed according to the shape of the skull’s surface, it is particularly applicable for imaging in the brain. To perform ultrasonic beamforming using a bent probe, it is necessary to measure the bent shape. Therefore, in this research, the curvature of the probe was estimated using MRI. A phantom with ellipse surface close to the shape of a skull was created using a 3D printer. The probe was arranged along the phantom surface to perform MRI and ultrasonic beamforming. The ultrasonic array transducer had 192 elements made from 1-3 composite piezoelectric materials with an element spacing of 0.3 mm. Eight MR position markers were attached to the probe in parallel in two rows of four each, with the array transducer in between. The delay time of each element in dynamic focusing for reception was calculated from its position estimated by the curvature of the probe. To evaluate the feasibility of this method, a B-mode image of 0.98 mm-diameter-thread targets placed in water was generated. The beam width at half maximum of the echo peak in the lateral direction from the thread target set up near the transmission focal point was calculated based on the B-mode image. It was found that the beam width of 1.32 mm in the proposed method, which was close to the thread diameter, whereas that was 4.38 mm in the conventional method that did not consider the bending of the probe. Consequently, the proposed beamforming technique is feasible for ultrasonic imaging through an arbitrary curved surface. Practical applications with a head phantom mimicking skull and cerebral tissue are expected.

Analytical and Numerical Study of Pre-Stress Effect in Piezoelectric Sandwich Type Ultrasonic Transducer

In this paper, the effect of pre-stress condition on the resonance frequency of the transducer is studied by using numerical and analytical methods. To compare the obtained results, two sandwich-type transducers with nominal frequency of 25 kHz and 30 kHz are considered. Experimental determination of pre-stress value in transducer is described and measured. Then resonance frequency of transducers in the presence of pre-stress is determined by impedance analyser. Numerical analysis is conducted by modelling three-dimensional transducer in details at ABAQUS software. The resonance frequency is determined with and without pre-stress. The FE results show that by applying pre-stress on the transducers, the resonance frequency of transducers decreased. Furthermore, the FE results are very close to experimental results. Furthermore, a systematic analytical solution is presented based on one-dimensional wave propagation. The resultant displacement for each sub-section of the transducer is calculated and then all of them are assembled and solved by considering the continuity conditions of displacement and force components. It is found that pre-load condition that is produced by central bolt reduces resonance frequency of the transducer. The obtained analytical results provide fast and reliable model for predicting resonance frequency of transducer.

State-of-the-art ultrasonic sensor designed to improve longwall production rates and operation safety

The article describes issues related to the development of a sensor measuring the distance from the end of the shield support canopy to the face of the longwall panel. The sensor's task is to detect rock falls because in such a case, empty spaces in the coal seam below the roof are generated. The sensor is a part of the system which task is to predict unfavourable behaviour of the longwall roof affecting the continuity of mining. Due to an untypical workplace and difficult conditions prevailing there, it was not possible to use a typical sensor. The ultrasonic technique was used for this purpose. The next research stages related to the development of the sensor were described. Tests of various types of ultrasonic transducers, working at different parameters, were described. Only transducers with a closed structure were considered because they can operate in the presence of high dustiness and humidity. The sensor casing was adapted to a specific type of shield support. The installation location should not be accidental, as an additional hinged shield is mounted at the end of the canopy, which is an obstacle in the measuring track and can even completely cover it, making measurements impossible. The sensor is mounted close to the side edge of the shield support canopy using small free space, enabling a measurement. Structural elements of the canopy are obstacles in the measuring track and are a source of interference of the received signals. The ultrasonic transducers are built-in tubes, which direct the ultrasonic wave and amplify the received signals. The results of laboratory tests of the model of the path measurement sensor are presented. They describe the impact of analysed aspects, i.e. the type of transducers used, the structure of the surface that the wave is reflected from and the mechanical solutions on the quality of received signals. A prototype of a sensor installed on shield support is presented.

Research for the Detecting Method of Concrete Structure Internal Defects with Spherical Embedded Ultrasonic Transducer

As a nondestructive detecting method, ultrasonic detection has been widely adopted in concrete structure detections. This approach would not damage the structural integrity, and could fulfill most of the detecting requirements of various concrete structures. However, for mass concrete and complicated concrete structural elements, there are still many problems of detection to be solved, such as the operating position of detection could not be achieved easily for technicians, especially in some narrow spaces, or the volume of elements might be quite large so that the detecting distance is far beyond the effective detecting distance of traditional transducers. After researching the technical performances of traditional ultrasonic transducers and ultrasonic detecting method, a brand new type of ultrasonic transducer adopted spherical piezoelectric ceramic chips has been developed. The transducer could be embedded inside concrete structure, and motivate or receive ultrasonic signal in all directions pair with external or internal transducers. Testing with the embedded transducers would not be limited by on-site conditions or other enviorenmental conditions. The transducer could be used in realtime systems for monitoring or detecting internal compactness situation of concrete elements. The technical characteristics of spherical transducer have been verified by a series of experiments in laboratory. Moreover, the detecting method with spherical transducer has been proposed, which could be used in the inspection for mass concrete and complicated structural concrete elements. Meanwhile, the appropriate technical schemes for reactor containment of nuclear power plant have been designed and has already been applied in nuclear power plant.

2Pb1-4 Measurement of acoustic characteristics of mouthpiece type ultrasonic transducer for oral treatment

2Pb1-4 Measurement of acoustic characteristics of mouthpiece type ultrasonic transducer for oral treatment

On the acoustic fountain types and flow induced with focused ultrasound

Abstract

Reception characteristics investigation and measurement of capacitive micromachined ultrasonic transducer

Purpose As a new type of ultrasonic transducer with significant advantages, capacitive micromachined ultrasonic transducer (CMUT) has good application prospect. The reception characteristic of the CMUT is one of the important factors determining the application effect. This paper aims to study the reception characteristics of CMUT. Design/methodology/approach In this paper, the state equation is deduced and the analysis model is established in SIMULINK environment based on the lumped parameter system model of the CMUT cell. Based on this analysis model, the influencing factors of CMUT reception characteristics are studied and investigated, and the time-domain and frequency-domain characteristics are investigated in detail. Findings The analysis results show that parameters directly affect the reception characteristics of the CMUT, such as direct current (DC) bias voltage, input sound pressure amplitude and frequency. At the same time, the measurement system is built and the reception characteristics are verified. Originality/value This paper provides an effective method for rapid analyzing the reception characteristics of CMUT. These results provide an important theoretical basis and reference for further optimization of CMUT structure design, and lay a good foundation for the practical application measurement.

(Invited) Sonoelectrochemistry: A Powerful Tool for Elucidating Mechanisms and for Accelerating Electrochemical Processes

Surface irradiation by power ultrasound has proven to offer beneficial effects not only for surface cleaning, but also for the modification of functional properties of metallic and organic coatings. However, the process scale-up has failed to match laboratory observations and data, in particular for the design of industrial sono-(electro)chemical reactor systems. To solve this major problem, electrochemical systems have been developed and employed as effective “sensors” for probing ultrasonic activity, in turns allowing numerous useful quantitative information to aid designing better sono-(electro)chemical reactor and process control. Indeed, it is possible to use electrochemistry as a tool to investigate phenomena occurring at the electrode surface and at a given location in the sono-(electro)chemical reactor. From a process accelerated by power ultrasound, electrochemistry becomes a very useful tool to quantify the ultrasonic energy (and power) scattered at the immediate working electrode surface vicinity. The electro-diffusional method is of great help, as it consists of measuring limiting currents generated by Linear Sweep Voltammetry (LSV) experiments. This approach has turned out to be extremely efficient and useful for the determination of acoustic intensity at various locations in the sono-(electro)chemical reactor [1]. By systematically moving a working electrode in an ultrasonic field, it is possible to map out the acoustic activity, especially in the zone close to the ultrasonic transducer where the most intense cavitation activity takes place. Then, to demonstrate the ‘portability’ of our generated data, i.e. to allow relevant comparisons between experiments performed using different ultrasonic and electrochemical equipment, we have proposed to convert the raw electrochemical values into equivalent velocities U, corresponding to normal flows directed towards the working electrode surface resulting in the same electrochemical signal than in the presence of power ultrasound [2]. Comparisons with ‘real fluid motion’ at a given location with the help of Particle Image Velocimetry (PIV) technique allows separation of the respective contributions of cavitational events occurring at the working electrode surface to the convection flow called ultrasonic wind [3]. This approach has been extended to several electrochemical systems. Moreover, new types of ultrasonic transducers (for example, focalized ultrasonic transducers) and new progress in the modulation of ultrasonic transducer excitation have pave the way to industrialization of sono-(electro)chemical reactors [4]. [1] Hihn J.-Y., Doche M.L, Mandroyan A., Hallez L. and Pollet B.G., Chapter 23 "Ultrasound and Better Reactor design" in Handbook on Applications of Ultrasound: Sonochemistry for sustainaibility by CRC Press Taylor & Francis, 2011, p599-622 [2] Pollet B.G., Hihn J.-Y., Doche M.L, Mandroyan A., Lorimer J.P., Mason T.J “Transport limited currents close to an ultrasonic horn: equivalent flow velocity determination”, Journal of Electrochemistry Society, 2007, 154(10), p E131-E138 [3] J.Y. Hihn, M.L. Doche, A. Mandroyan, L. Hallez, B.G. Pollet, "Respective contribution of cavitation and convective flow to local stirring in sonoreactors" Ultrasonics Sonochemistry 18(4), 881-887, (2011) [4] Hallez L., Lee J., Touyeras F., Nevers A., Ashokkumar M., Hihn J.-Y., “Enhancement and Quenching of HIFU Cavitation Activity via Short Frequency Sweep Gaps”, Ultrasonics Sonochemistry, 2016, 29, p. 194-197 Figure 1

Attenuation of a Slow Subsonic A0 Mode Ultrasonic Guided Wave in Thin Plastic Films

The ultrasonic testing technique using Lamb waves is widely used for the non-destructive testing and evaluation of various structures. For air-coupled excitation and the reception of A0 mode Lamb waves, leaky guided waves are usually exploited. However, at low frequencies (<100 kHz), the velocity of this mode in plastic and composite materials can become slower than the ultrasound velocity in air, and its propagation in films is accompanied only by an evanescent wave in air. To date, the information about the attenuation of the slow A0 mode is very contradictory. Therefore, the objective of this investigation was the measurement of the attenuation of the slow A0 mode in thin plastic films. The measurement of the attenuation of normal displacements of the film caused by a propagating slow A0 mode is discussed. The normal displacements of the film at different distances from the source were measured by a laser interferometer. In order to reduce diffraction errors, the measurement method based on the excitation of cylindrical but not plane waves was proposed. The slow A0 mode was excited in the polyvinylchloride film by a dry contact type ultrasonic transducer made of high-efficiency PMN-32%PT strip-like piezoelectric crystal. It was found that that the attenuation of the slow A0 mode in PVC film at the frequency of 44 kHz is 2 dB/cm. The obtained results can be useful for the development of quality control methods for plastic films.

Compact and High Rigidity Structure of Slit Type Wire Bonder Ultrasonic Transducer

Ultrasonic Transducer in the wire bonding machine is a key component to determine its bonding speed, and is demanded to be downsized with keeping high rigidity performance for high-speed bonding process. In this paper, a modeling of the ultrasonic transducer vibration and a new ultrasonic transducer with slit structure near the fixation parts is discussed. The piezoelectric element designed by an analytical model has 45% lighter weight than the conventional one. The slit type ultrasonic transducer newly proposed and simulation by finite element method has 66% lighter weight and 2.44-times higher rigidity than the conventional one. As a result, the slit type ultrasonic transducer enable 200G acceleration motion at Z direction of wire bonder from 160G by previous one and it shorten 33% of rising ultrasonic vibration time. Finally, it makes 17% faster cycle time to make wire, it has a potential to improve productivity a lot.

Investigation of standing wave acoustic levitation with Bernoulli principle and bolt-clamped Langevin type ultrasonic transducer

Investigation of standing wave acoustic levitation with Bernoulli principle and bolt-clamped Langevin type ultrasonic transducer

Post-processing of ultrasonic signals for the analysis of defects in wind turbine blade using guided waves

In this work, the most promising ultrasonic signal processing methods—discrete wavelet transform, variational mode decomposition and Hilbert transform—are applied for the analysis of disbond-type defects in the segment of wind turbine blade. Two disbond-type artificial defects having diameters of 81 and 25 mm were located on the main spar of wind turbine blade. The low-frequency ultrasonic system developed by Ultrasound Research Institute of the Kaunas University of Technology was used for the experimental investigation of wind turbine blade using guided waves and only one side of the blade segment was accessed. Two contact type ultrasonic transducers separated by 50 mm distance and fixed on a movable mechanical panel were used as a transmitter–receiver pair during the experiment for the ultrasonic signals recording up to the scanning distance of 250 mm with the scanning step of 1 mm. Both types of defects were marginally detected from the conventional experimental B-scan and therefore appropriate signal processing techniques were used to improve the accuracy of the analysis of defects. The discrete wavelet transform was combined with the amplitude detection method for estimating the size and location of defects. Finally, the variational mode decomposition is combined with the Hilbert transform to compare the instantaneous frequencies and amplitudes of the defect-free and defective signals as well as for the measurement of time-delays between the defect-free and defective signals.

2D Analytical Model for the Directivity Prediction of Ultrasonic Contact Type Transducers in the Generation of Guided Waves.

In this paper, a novel 2D analytical model based on the Huygens’s principle of wave propagation is proposed in order to predict the directivity patterns of contact type ultrasonic transducers in the generation of guided waves (GWs). The developed model is able to estimate the directivity patterns at any distance, at any excitation frequency and for any configuration and shape of the transducers with prior information of phase dispersive characteristics of the guided wave modes and the behavior of transducer. This, in turn, facilitates to choose the appropriate transducer or arrays of transducers, suitable guided wave modes and excitation frequency for the nondestructive testing (NDT) and structural health monitoring (SHM) applications. The model is demonstrated for P1-type macro-fiber composite (MFC) transducer glued on a 2 mm thick aluminum (Al) alloy plate. The directivity patterns of MFC transducer in the generation of fundamental guided Lamb modes (the S0 and A0) and shear horizontal mode (the SH0) are successfully obtained at 80 kHz, 5-period excitation signal. The results are verified using 3D finite element (FE) modelling and experimental investigation. The results obtained using the proposed model shows the good agreement with those obtained using numerical simulations and experimental analysis. The calculation time using the analytical model was significantly shorter as compared to the time spent in experimental analysis and FE numerical modelling.

Electroacoustic modeling and characterization of an ultrasonic projector

Ultrasonic projectors are new type ultrasonic transducers that take advantage of the ultrasonic wave emitted on the rear face of the transducer. It consist in an acoustic symmetrical design where both waves generated on the faces of the piezoelectric ceramic are collected in phase with a 45° angle wedge resulting in an increase of the sensitivity. In this case, the absence of backing endows that the conventional design rules of a transducer cannot be directly applied. In this work, the electroacoustic modeling and characterization of such projector is reported. Using the KLM well known model, the electroacoustic response of a projector in based on a piezoelectric ceramic with one matching layer is calculated. Simulations show that the optimal acoustic impedance of the matching layer should be lower than for conventional transducers leading to a bandwidth of approximately 50%. The characterizations of such transducer based on PZ27 (Meggit/Ferroperm) and a lead free material PIC700 (PI Ceramic) have been carried out. Bandwidth and sensitivity are reported. They are found close to the simulation results and demonstrate that these new types of transducers has to be designed according new trends compared to conventional transducers.

Contactless microparticle control via ultrahigh frequency needle type single beam acoustic tweezers.

This paper reports on contactless microparticle manipulation including single-particle controlled trapping, transportation, and patterning via single beam acoustic radiation forces. As the core component of single beam acoustic tweezers, a needle type ultrasonic transducer was designed and fabricated with center frequency higher than 300 MHz and -6 dB fractional bandwidth as large as 64%. The transducer was built for an f-number close to 1.0, and the desired focal depth was achieved by press-focusing technology. Its lateral resolution was measured to be better than 6.7 μm by scanning a 4 μm tungsten wire target. Tightly focused acoustic beam produced by the transducer was shown to be capable of manipulating individual microspheres as small as 3 μm. "USC" patterning with 15 μm microspheres was demonstrated without affecting nearby microspheres. These promising results may expand the applications in biomedical and biophysical research of single beam acoustic tweezers.

Ultrasound as tool for diagnosis of diseases of the reproductive tract bulls

Abstract The purpose of this study was to evaluate by ultrasound and breeding soundness examination (BSE) the major diseases affecting the reproductive system of Nelore bulls, bred extensively in the state of Para, Brazil. Fifty-nine pure Nelore bulls were used, aged between 5 to 10 years, raised extensively in a commercial farm in the municipality of Paragominas, Para state, Brazil. Scrotal circumference, testicular length and width were measured. Semen collection for evaluation of ejaculate volume, turbulence, motility, vigor, concentration and sperm pathologies was performed. Ultrasound examination was performed by equipment type Ultrasonic Transducer - CHISON/D600vet, linear transducers, where the frequency used was 5 MHz, being held two images of each testis, the longitudinal-lateral, lateral and transverse planes. The images were processed using the program Image J. The data were analyzed using the statistical program SAS (2000) and means were compared using Tukey's test (p 0.05). Thus, it can be concluded that ultrasonography is an essential complementary tool in the diagnosis of reproductive disorders in animals subjected to BSE and its use should be recommended.

Researches and applications of the ultrasonic emulsifications and dispersions

This paper defines power ultrasonics and their two important directions: Ultrasonic emulsification and dispersion from a practical point of view, brief reports on recent research results are ultrasonic emulsification to be used for the preparation of composite electrorheological fluid, and ultrasonic dispersion to be used dispersion as a new type cold cloud catalytic agent metaldehyde [CH3CH]4-6 (this is used for artificial rain), etc., and produce good results or gain progress. Then, the principle and applications of power ultrasonics (including magnetostriction type ultrasonic transducer and piezoelectric type ultrasonic transducer) in the emulsification or dispersion, are pointed out. Also, ultrasonic extensive applications in chemistry, materials, and life sciences are briefly introduced.