Ultrasonic Phased Array Transducer Research Articles

합금강 빌릿의 결함탐상을 위한 수침식 위상배열 초음파 탐촉자 개발 및 성능평가

현재 제철소에서는 여러 개의 단일 초음파 탐촉자를 접촉식 방법으로 탐상부 기계장치를 구성하여 합금강 빌릿의 검사를 수행한다. 이러한 접촉식 단일 초음파 검사방법은 연속 검사과정에서 검사면의 마찰로 기구부가 마모되면서 물에 의한 음향결함이 불안정하여 음향전달의 기복이 발생하거나 초음파의 입사각이 틀어지면서 결함 검출감도가 떨어지는 문제가 발생한다. 따라서 본 연구에서는 수침식 위상배열 초음파 검사기법을 합금강 빌릿에 적용하여 단일 초음파 검사기법의 문제를 해결하고 검사신뢰성을 향상하고자 하였다. 이를 위하여 CIVA 시뮬레이션 소프트웨어를 이용하여 합금강 빌릿 검사에 최적화 된 수침식 위상배열 초음파 탐촉자를 설계 및 제작하였고, 제작된 수침식 위상배열 초음파 탐촉자의 성능을 평가하기 위해 합금강 빌릿의 인공결함 시험편을 제작하고 결함 검출능 연구를 수행하였다. 특성실험결과 제작된 수침식 위상배열 초음파 탐촉자를 이용한 검사기법은 접촉식 단일 초음파 검사기법 보다 신호대 잡음 비율이 4배 이상 우수함을 확인하였으며, 합금강 빌릿의 수침식 위상배열 초음파 자동 검사시스템의 적용 가능성을 검증하였다.

Application of Dual Focused Ultrasonic Phased Array Transducer in Two Orthogonal Cross-Sections for Inspection of Multi-Layered Composite Components of the Aircraft Fuselage.

Our previous studies have shown that the application of the proposed technique of a dual focused ultrasonic beam in two orthogonal cross-sections in passive (elevation) and active (azimuth) apertures of linear ultrasonic phased array transducer (ULPAT) enhances the 3D spatial resolution in the case of the inspection of conventional defects (flat bottom holes) or measurement of thickness of multi-layered metal composites. The objective of this work is to apply the proposed technique to enhance the spatial resolution of the ULPAT in the cases of detection and sizing demonstration of internal defects possessing spatially complex geometry, and during the inspection of defective multi-layered thin composite components (e.g., GLARE) of the aircraft fuselage. The specially prepared aluminium specimen possessing an internal defect of complicated geometry (crescent-shaped) was investigated. The simulation results and experiments demonstrate the resolution enhancement, higher amplitude of the reflections (e.g., 2.5 times or +8 dB) and spatial improvement in the defect detection even in the case of the non-perpendicular incidence of ultrasonic waves to the complex geometry surface of the internal defect. During the experiments, the multi-layered GFRP-metal based composite sample GLARE 3-3/2 was investigated in the case of the single-side access to the surface of the sample. The internal artificial delamination type defect of 25 mm was detected with a higher accuracy. Compared to the limitations of conventional ULPAT, the relative error (32%) (at the −6 dB level) of lateral defect dimensions estimation was completely reduced.

Design of an Ultrasonic Phased Array Launch System Based on Gigabit Ethernet Transmission

To better use ultrasonic phased array detection technology for underwater object detection and real-time imaging, an ultrasonic phased array launch system based on Gigabit Ethernet transmission was proposed in this work. The principle of phased focusing emission and the UDP communication protocol are analysed. Due to abundant I/O pin resources and internal logic resources, FPGA is used to excite the 32-channel ultrasonic phased array transducer, and the communication protocol is Gigabit Ethernet UDP. Generally, the delay parameters are sent to the FPGA in real time and high-speed, and then transmitted to the pulse signals. By using an integrated chip Max4940, the pulse signals are amplified and delivered to the phased array transducers. According to experiment, it is conformed that this system can transmit a large amount of data in real time at high speed; realize phase-controlled focus transmission, and the delay precision reaches 2.5 ns. This study provides a good hardware foundation for underwater imaging systems.

Acoustic Field of a Linear Phased Array: A Simulation Study of Ultrasonic Circular Tube Material.

As ultrasonic wave field radiated by an ultrasonic transducer influences the results of ultrasonic nondestructive testing, simulation and emulation are widely used in nondestructive testing. In this paper, a simulation study is proposed to detect defects in a circular tube material. Firstly, the ultrasonic propagation behavior was analyzed, and a formulation of the Multi-Gaussian beam model (MGB) based on a superposition of Gaussian beams is described. The expression of the acoustic field from a linear phased-array ultrasonic transducer in the condition of a convex interface on the circular tube material is proposed. Secondly, in order to make the tapered probe wedge better fit the curved circular tube material and carry out the ultrasonic inspection of the curved surface, it was necessary to pare the angle probe wedge. Finally, acoustic field simulations in a circular tube were carried out and analyzed. The simulation results indicated that the method of ultrasonic phased-array inspection is feasible in circular tube testing. Tube materials with different curvatures need different array element lengths and widths to get the desired focused beam.

Preparation and Performance Test of Orthotropic Piezoelectric Composite Material Ultrasonic Phased Array Transducer

Preparation and Performance Test of Orthotropic Piezoelectric Composite Material Ultrasonic Phased Array Transducer

A Microscale Linear Phased-Array Ultrasonic Transducer Based on PZT Ceramics.

In this paper, a microscale high-frequency ultrasonic transducer was prepared by combining traditional planar ultrasonic phased-array technology and micro processing technology. The piezoelectric ceramic material PZT was used as the functional material of the transducer. The number of the arrays was 72, the width of each array was 50 μm, the pitch of each array was 70 μm, and the length of each array was 3 mm. The PZT chip was finely ground to a thickness of 130 μm and could reach a frequency of 10 MHz. The experimental platform of micron-scale precision was set up for a beam-forming lateral sound field test and imaging experiment to validate the theoretical analysis. The echo imaging test showed that a mold with a feature size of about 400 μm could be imaged well.

Design and comparison of PMN-PT single crystals and PZT ceramics based medical phased array ultrasonic transducer

The design, fabrication and comparison of PMN-PT single crystals and PZT ceramics based 3 MHz phased array ultrasonic transducers were investigated. The resonance mode and electromechanical properties for PMN-PT single crystal were simulated by using the COMSOL Multiphysics software. Simulation results indicate that the electromechanical coupling coefficient k33' keeps at 0.86–0.87 when the aspect ratio G < 0.7, as well as a pure height-extensional mode was obtained. Two types of ultrasonic phased arrays using PMN-PT single crystal and PZT ceramic were fabricated and compared. The experimental results revealed that more than 27.7% broader -6 dB bandwidth, 5.2 dB higher relative sensitivity, and shorter pulse length can be obtained by using PMN-PT single crystal compared to the PZT array. The experimental results agreed well with the predictions of simulation by using the PiezoCAD software. Furthermore, PMN-PT array has the same good consistency of the performance as the PZT array, while the better acoustic performance and higher electromechanical properties compared to PZT array as a whole. In the end, the ultrasonic imaging which uses the PMN-PT based array transducer has the better definition, the higher axial resolution and lateral resolution compared to those of PZT based array transducer.

Optimization Design of Phased Array Ultrasonic Transducer Arrays

The design and selection of the transducer array parameters directly affect the performance of the audio directional transmission system. In this paper, the influence of the number of array element, the pitch, the frequency and the deflection angle on the array directivity is analyzed in detail. The relationship between the above parameters and the directivity is obtained by computer simulation and the relationship between the array performance and the actual manufacturing cost of the design. It provided a basis for performance evaluation and optimization design of phased array ultrasonic transducer arrays.

Crack detection using serrated columnar phased array transducers

This paper presents an ultrasonic non-destructive technique for detecting cracks on the outside surface of hollow shafts, specifically on the hollow axles used in high-speed railway trains. Traditionally, the cracks on the outside surface of hollow shafts have been detected from the inside of the central bore with monocrystal or phased array (PA) ultrasonic transducers. However, this approach still requires wedges and mechanical rotation to scan the entire cross-section while moving along the axial direction. This paper studies the performance of a serrated columnar phased array ultrasonic transducer (SCPAUT) in the detection of longitudinal cracks on the outside surface of a hollow axle specimen. By rotating each rectangular element of a columnar phased array with a proper angle, the SCPAUT was designed to transmit shear waves through the curved inner interface and rotationally scan the outside surface with electrical control. A prototype SCPAUT probe was made and evaluated on a cut hollow specimen with a certain number of artificial longitudinal cracks on the outside surface. The depths of the cracks ranged from 1 mm to 5 mm and numerous cracks were manufactured with a certain inclined angle relative to the normal direction of the outside surface. The finite element method (FEM) technique was used to study the ultrasonic wave propagation and the results were compared to those from a dynamic photoelastic experiment. The results demonstrated that the wave beam transmitted from the SCPAUT could be rotated axially and focused on the outside surface by using electrical control. The artificial longitudinal cracks were detected in the experimental test and the results of B-scan imaging of the cracks were presented.

Phased Array Focusing for Acoustic Wireless Power Transfer.

Wireless power transfer (WPT) through acoustic waves can achieve higher efficiencies than inductive coupling when the distance is above several times the transducer size. This paper demonstrates the use of ultrasonic phased arrays to focus power to receivers at arbitrary locations to increase the power transfer efficiency. Using a phased array consisting of 37 elements at a distance nearly 5 times the receiver transducer diameter, a factor of 2.6 increase in efficiency was achieved when compared to a case equivalent to a single large transducer with the same peak efficiency distance. The array has a total diameter of 7 cm, and transmits through air at 40 kHz to a 1.1-cm diameter receiver, achieving a peak overall efficiency of 4% at a distance of 5 cm. By adjusting the focal distance, the efficiency can also be maintained relatively constant at distances up to 9 cm. Numerical models were developed and shown to closely match the experimental energy transfer behavior; modeling results indicate that the efficiency can be further doubled by increasing the number of elements. For comparison, an inductive WPT system was also built with the diameters of the transmitting and receiving coils equivalent to the dimensions of the transmitting ultrasonic phased array and receiver transducer, and the acoustic WPT system achieved higher efficiencies than the inductive WPT system when the transmit-to-receive distance is above 5 cm. In addition, beam angle steering was demonstrated by using a simplified seven-element 1-D array, achieving power transfer less dependent on receiver placement.

KR60 레일의 결함 탐상을 위한 위상배열 초음파 변환기 개발 (Ⅰ)

KR60 레일의 결함 탐상을 위한 위상배열 초음파 변환기 개발 (Ⅰ)

KR60 레일의 결함 탐상을 위한 위상배열 초음파 변환기 개발 (Ⅱ)

KR60 레일의 결함 탐상을 위한 위상배열 초음파 변환기 개발 (Ⅱ)

Acoustic field characteristics of serrated ultrasonic phased array transducers

Acoustic field characteristics of serrated ultrasonic phased array transducers

Fabrication and Characterization of a 20-MHz Microlinear Phased-Array Transducer for Intervention Guidance.

This paper describes the design and fabrication of a miniature ultrasonic phased-array transducer used for intervention guidance. Currently, ultrasound probes are often placed at the body surface of the patients, leading to several drawbacks including the limitation of penetration and image quality. In order to improve the reliability of the guiding process, we propose a miniature phased-array transducer that can be placed adjacent to the intervention device during the interventional procedure. In this paper, we report the work that has been carried out on the development of this miniature phased-array transducer. It comprised 48 elements housed in a 3-mm-diameter needle. A specially designed flexible circuit was used for accommodating the transducer array in the long, thin needle housing. The center frequency and the fractional bandwidth were approximately 20 MHz and 42%, respectively, with an average crosstalk lower than -30 dB. The axial and azimuth resolutions were approximately 80 and [Formula: see text], respectively. The imaging capability of the transducer was further evaluated by acquiring the B-mode images of a needle in a cow liver. The performance of the proposed phased-array transducer demonstrates the feasibility of such an approach for interventional guidance.

Development of the technique for independent dual focusing of contact type ultrasonic phased array transducer in two orthogonal planes

Due to a low lateral resolution in elevation plane, the application of linear ultrasonic phased array transducers (ULPAT) is limited. The objective is to enhance the spatial resolution by means of spatial dual focusing technique of ULPAT in two orthogonal planes – azimuth and elevation.A design of a special delay line possessing a convex cylindrical lens has been proposed. The lens enables fixed geometrical focusing of the excited beam in the elevation plane, while in the other, azimuth, plane the beam is electronically focused at an arbitrary point by the active aperture of the ULPAT. The simulation results demonstrate the extended possibilities of resolution enhancement. Experiments show that the undetectable defect is detected using the designed acoustic lens. In addition, the interfaces of the intermediate layer of metal composite were detected.

Quantitative analysis of pit defects in an automobile engine cylinder cavity using the radial basis function neural network–genetic algorithm model

In the automotive remanufacturing movement, the inspection of the corrosion defects on the engine cylinder cavity is a key and difficult problem. In this article, based on the ultrasonic phased array technology and the radial basis function neural network–genetic algorithm model, a new quantitative analysis method is proposed to estimate the size of the pit defects on the automobile engine cylinder cavity. Echo signals from the small pit defects with different sizes are acquired by an ultrasonic phased array transducer. According to the ultrasonic signal characteristics, the feature vectors are extracted using wavelet packet, fractal technology, peak amplitude method, and some routine extract methods. The radial basis function neural network–genetic algorithm model is investigated for the quantitative analysis of the pit defects, which can obtain an optimal quantitative model. The results show that the proposed model is effective in the corrosion estimation work.

Two-dimensional analytic modeling of acoustic diffraction for ultrasonic beam steering by phased array transducers

Phased array ultrasonic transducers enable modulating the focal position of the acoustic waves, and this capability is utilized in many applications, such as medical imaging and non-destructive testing. This type of transducers also provides a mechanism to generate tilted wavefronts in acousto-optic deflectors to deflect laser beams for high precision advanced laser material processing. In this paper, a theoretical model is presented for the diffraction of ultrasonic waves emitted by several phased array transducers into an acousto-optic medium such as TeO2 crystal. A simple analytic expression is obtained for the distribution of the ultrasonic displacement field in the crystal. The model prediction is found to be in good agreement with the results of a numerical model that is based on a non-paraxial multi-Gaussian beam (NMGB) model.

A Fast Method to Calculate the Spatial Impulse Response for 1-D Linear Ultrasonic Phased Array Transducers.

A method is developed to accurately determine the spatial impulse response at the specifically discretized observation points in the radiated field of 1-D linear ultrasonic phased array transducers with great efficiency. In contrast, the previously adopted solutions only optimize the calculation procedure for a single rectangular transducer and required approximation considerations or nonlinear calculation. In this research, an algorithm that follows an alternative approach to expedite the calculation of the spatial impulse response of a rectangular linear array is presented. The key assumption for this algorithm is that the transducer apertures are identical and linearly distributed on an infinite rigid plane baffled with the same pitch. Two points in the observation field, which have the same position relative to two transducer apertures, share the same spatial impulse response that contributed from corresponding transducer, respectively. The observation field is discretized specifically to meet the relationship of equality. The analytical expressions of the proposed algorithm, based on the specific selection of the observation points, are derived to remove redundant calculations. In order to measure the proposed methodology, the simulation results obtained from the proposed method and the classical summation method are compared. The outcomes demonstrate that the proposed strategy can speed up the calculation procedure since it accelerates the speed-up ratio which relies upon the number of discrete points and the number of the array transducers. This development will be valuable in the development of advanced and faster linear ultrasonic phased array systems.

Lorentz force electrical impedance tomography using magnetic field measurements

In this study, magnetic field measurement technique is investigated to image the electrical conductivity properties of biological tissues using Lorentz forces. This technique is based on electrical current induction using ultrasound together with an applied static magnetic field. The magnetic field intensity generated due to induced currents is measured using two coil configurations, namely, a rectangular loop coil and a novel xy coil pair. A time-varying voltage is picked-up and recorded while the acoustic wave propagates along its path. The forward problem of this imaging modality is defined as calculation of the pick-up voltages due to a given acoustic excitation and known body properties. Firstly, the feasibility of the proposed technique is investigated analytically. The basic field equations governing the behaviour of time-varying electromagnetic fields are presented. Secondly, the general formulation of the partial differential equations for the scalar and magnetic vector potentials are derived. To investigate the feasibility of this technique, numerical studies are conducted using a finite element method based software. To sense the pick-up voltages a novel coil configuration (xy coil pairs) is proposed. Two-dimensional numerical geometry with a 16-element linear phased array (LPA) ultrasonic transducer (1 MHz) and a conductive body (breast fat) with five tumorous tissues is modeled. The static magnetic field is assumed to be 4 Tesla. To understand the performance of the imaging system, the sensitivity matrix is analyzed. The sensitivity matrix is obtained for two different locations of LPA transducer with eleven steering angles from to at intervals of . The characteristics of the imaging system are shown with the singular value decomposition (SVD) of the sensitivity matrix. The images are reconstructed with the truncated SVD algorithm. The signal-to-noise ratio in measurements is assumed 80 dB. Simulation studies based on the sensitivity matrix analysis reveal that perturbations with mm size can be detected up to a 3.5 cm depth.

Thermal dispersion method for an ultrasonic phased-array transducer

When the driving voltage of an ultrasonic transducer is increased to improve the quality of ultrasound images, heat is generated inside the transducer, which can burn the patient’s skin and degrade transducer performance. In this study, the method to disperse the heat inside an ultrasonic phased-array transducer has been examined. The mechanism of temperature rise due to heat generation inside the transducer was investigated by numerical analysis and the effects of the thermal properties of the components of the transducer such as specific heat and thermal conductivity on the temperature rise were analyzed. On the basis of the results, a heat-dispersive structure was devised to reduce the temperature at the surface of the acoustic lens of the transducer. Prototype transducers were fabricated to check the efficacy of the heat-dispersive structure. By experiments, we have confirmed that the new heat-dispersive structure can reduce the internal temperature by as much as 50% in comparison with the conventional structure, which confirms the validity of the thermal dispersion mechanism developed in this work.