Ring Transducer Research Articles

Mode control of guided wave in magnetic hollow cylinder using electromagnetic acoustic transducer array

The aim of this work is to demonstrate a method for exciting and receiving torsional and longitudinal mode guided waves with an electromagnetic acoustic transducer (EMAT) ring array. First of all, a three-dimensional guided wave simulator is developed in order to numerically analyze the propagation of the guided wave. The finite difference time domain method is used for the simulator. Second, two guided wave testing systems using an EMAT ring array are provided: one is for torsional mode (T-mode) guided wave and the other is for longitudinal mode (L-mode). The EMATs used in the both systems are the same in design. A method to generate and receive the T- and L-mode guided waves with the same EMAT is proposed. Finally, experimental and numerical results are compared and discussed. The results of experiments and simulation agree well, showing the potential of the EMAT ring array as a mode controllable guided wave transmitter and receiver.

Resolution of Image Compounding with a Ring Array Transducer

This work describes an automated system based on a ring transducer aimed to the early detection of breast cancer. Such equipment allows compounding multiple sector echographic images acquired at angular intervals around the breast in a water bath. A theoretical analysis of the resolution of this kind of image is presented. First, the impulse response (Point Spread Function) in any point of the imaged area is computed by numerical means. From this, several quality maps were built to quantify resolution, homogeneity and sensitivity of the resulting image. The effect of aperture size, number of partial images and ring dimensions is also analyzed. A low cost prototype has been used to validate the model. A thin wire has been accurately positioned in different locations of the imaged area, using a 128-element and 3.5 MHz linear array transducer. Experimental results are in agreement with developed theory.

Bubble-Like Response of Living Blood Cells and Microparticles in an Ultrasound Field

The bilayer sonophore model suggests that ultrasound induces a pulsating structure in the intra-membrane hydrophobic space between the two lipid monolayer lea ets of the cell membrane, assembled by dissolved gas of the surrounding area, which absorbs acoustic energy and transforms it by creating intra-cellular structural changes. This void has been referred to as a bilayer sonophore. The bilayer sonophore in ates and de ates periodically when exposed to ultrasound and may itself radiate acoustic pressure pulses in the surrounding medium in the same way a gas bubble does: once exposed to ultrasound the bilayer sonophore becomes a mechanical oscillator and a source of intracellular cavitation activity. In this paper, we describe observations of the clustering behaviour of living cells and several other particles in a standing sound eld generated inside a ring transducer. Upon sonication, blood cells and monodisperse polystyrene particles were observed to have been trapped in the same locations, corresponding to nodes of the ultrasound eld. Because polystyrene is hydrophobic, it behaves like a particle trapped inside a thin gas shell. In fact, the sonophore model treats biological cells in a similar way. Microbubbles that form the ultrasound contrast agent Quantison— behave di erently, however. These microbubbles accumulated in circles faster than blood cells and polystyrene particles. In addition, they form tightly packed clusters at the nodes, indicating very strong secondary Bjerknes forces. Cluster formation is not to be expected in cells with predicted sonophore sizes on the order of 10 100 nm.

Study About the Design and Experiments of the Vibrating Resistance Reduction Force Measuring Device

The force measuring device is designed to the study of the relationship between vibration amplitude, frequency, speed and traction resistance of the tractor If the design of the force measuring device which consists of a force measuring frame and three octagonal ring transducers is successful, the goal of real-time monitoring of the traction resistance in the process of vibrating sub soil may be reached. Also, the up, down, left and right margin of frame is designed to be adjustable, so that different kinds of tractor could link up with the force measuring device. With the vibrating sub-soiler machine, the vibrating resistance reduction experiments, which are mainly based on the change of the vibration amplitude, frequency and the speed of the tractor, may be done. The three levels of the vibration amplitude, frequency, and speed are as follows: vibration amplitude: 0.001 m, 0.002 m, and 0.003 m; frequency: 9 Hz, 10 Hz, and 12 Hz; speed: 0.1 m/s, 0.2 m/s, and 0.3 m/s. The experiment results showed that with the same speed and bigger vibration frequency, the tractor traction resistance is small and when the amplitude is 0.001 m, the vibration frequency is 10 Hz, and forward speed is 0.2 m/s, and the tractor traction resistance is the minimum.

High-resolution harmonic motion imaging (HR-HMI) for tissue biomechanical property characterization.

Elastography, capable of mapping the biomechanical properties of biological tissues, serves as a useful technique for clinicians to perform disease diagnosis and determine stages of many diseases. Many acoustic radiation force (ARF) based elastography, including acoustic radiation force impulse (ARFI) imaging and harmonic motion imaging (HMI), have been developed to remotely assess the elastic properties of tissues. However, due to the lower operating frequencies of these approaches, their spatial resolutions are insufficient for revealing stiffness distribution on small scale applications, such as cancerous tumor margin detection, atherosclerotic plaque composition analysis and ophthalmologic tissue characterization. Though recently developed ARF-based optical coherence elastography (OCE) methods open a new window for the high resolution elastography, shallow imaging depths significantly limit their usefulness in clinics. The aim of this study is to develop a high-resolution HMI method to assess the tissue biomechanical properties with acceptable field of view (FOV) using a 4 MHz ring transducer for efficient excitation and a 40 MHz needle transducer for accurate detection. Under precise alignment of two confocal transducers, the high-resolution HMI system has a lateral resolution of 314 µm and an axial resolution of 147 µm with an effective FOV of 2 mm in depth. The performance of this high resolution imaging system was validated on the agar-based tissue mimicking phantoms with different stiffness distributions. These data demonstrated the imaging system's improved resolution and sensitivity on differentiating materials with varying stiffness. In addition, ex vivo imaging of a human atherosclerosis coronary artery demonstrated the capability of high resolution HMI in identifying layer-specific structures and characterizing atherosclerotic plaques based on their stiffness differences. All together high resolution HMI appears to be a promising ultrasound-only technology for characterizing tissue biomechanical properties at the microstructural level to improve the image-based diseases diagnosis in multiple clinical applications.

Interrogation of Extrinsic Fabry–Perot Sensors Using Path-Matched Differential Interferometry and Phase Generated Carrier Technique

Fiber optic extrinsic Fabry-Perot interferometer (EFPI) sensors utilizing the state-of-the-art MEMS technology have been intensively studied on sensor fabrication for various applications, whereas the signal interrogation technique is still inadequate for some particular applications especially those involving dynamic sensing with high frequency. In this paper, we proposed a white light path-matched differential interferometer system utilizing phase generated carrier (PGC) demodulation method for dynamic EFPI sensors interrogation. A fiber Michelson interferometer (MI) is cascaded with the EFPI sensor as a readout interferometer. One arm of the MI contains a step-motor-assisted movable mirror-collimator pair to realize exactly path matching, and another arm is wound on a piezoelectric transducer ring to introduce the carrier signal for PGC demodulation. The general design principles of the system are presented in detail. Experimental results shown that the sensing signal can be correctly recovered with low distortion. The spectrum level of the phase noise is as low as -103 dB re. rad/√Hz at 1 kHz. The presented interrogation scheme may find promising applications in lots of dynamic EFPI sensing fields, such as acoustic and vibration sensing etc.

Algorithm of Exact Methods Obtaining of the Solution and Dynamical Flexibilities of Subsystem of the Mechatronic system

AbstractIn this paper the application of analysis of transverse vibrating subsystem of mechatronic systems by means of the exact were the main purposes of work to solve the task of assignment of frequency‐modal analysis and characteristics of mechatronic system. At first the problem of analysis in the form of the one differential equation of motion of mechanical subsystem or of the set of state equations of considered mechatronic model of object has been formulated and solved. Classic method to solve this problem have been used. The considered transverse vibrating mechanical subsystems of mechatronic system are a continuous beams with constant cross‐section, with free ends and/or clamped on one end. A ring transducer, which is the integral part of mechatronic system, extorted by harmonic force or voltage excitation, is assumed to be perfectly bonded to the beam surface. Parameters of the transducer have important influence on values of natural frequencies and on form of characteristics of considered mechatronic system. The poles of dynamical characteristic calculated by mathematical exact method and the Galerkin's method have approximately different or the same values; it is depended on the combination of boundary conditions of elementary beam. The results of the calculations were not only presented in mathematical form but also as a transients of examined dynamical characteristic which are function of frequency of assumed excitation. Practical implications of this work is to present the introduction to synthesis of considered class of mechanical and/or mechatronic beam‐systems with a constant changeable cross‐section. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)

링형 압전 변환기의 면내 진동 특성

ABSTRACT This paper experimentally deals with the vibration characteristics of flat ring transducers used for ultrasonic sensors and actuators. Radial vibration mode, which is the fundamental mode of a thin piezoelectric transducer, was measured by a laser in-plane vibrometer. An impedance analyzer was used to measure natural frequencies. The results measured by experiments verified theoretical predictions. The vibration characteristics of ring transducers were identified according to the outer di-ameter size. The shape of the fundamental mode is almost uniform but slightly decreases from the inner to the outer circumferential surfaces. The natural frequency of the fundamental mode decreases as the outer diameter increases. It appears that the ring type transducer is suitable to excite uni-formly distributed vibration on a flat surface. * 1. 서 론 초음파 센서 또는 액추에이터에서 역학적 진동과 전기적 신호 간의 상호 변환에 압전 변환기 (transdu-cer)가 많이 사용된다 (1) . 변환기의 압전소자는 대개 원판형이다. 압전소자를 적층할 필요가 있을 때, 중심을 관통하는 볼트로 체결하므로 중앙이 비어있는 링형 압전 원판을 사용한다

Modelling of Torsional Vibrating Systems with Composite Piezoelectric Assemblies

Work presents a proposal of mathematical algorithm used to analyse torsional vibrating systems with composite piezoelectric assemblies. In this paper systems with composite piezoelectric assemblies made of a combination of piezoelectric segments forming a ring transducer are considered. This is why such kind of transducers can be easily used in torsional vibrating systems. A mathematical model of the system was created and characteristics of the system were calculated using an approximate method. Obtained results are presented on charts and analysed. The main aim of this work is to prove that the mathematical algorithm that was presented in the previous authors works can be easily used in order to analyse systems with new, advanced and non-classical piezoelectric transducers.

Singulation for imaging ring arrays of capacitive micromachined ultrasonic transducers

Singulation of MEMS is a critical step in the transition from wafer-level to die-level devices. As is the case for capacitive micromachined ultrasound transducer (CMUT) ring arrays, an ideal singulation must protect the fragile membranes from the processing environment while maintaining a ring array geometry. The singulation process presented in this paper involves bonding a trench-patterned CMUT wafer onto a support wafer, deep reactive ion etching (DRIE) of the trenches, separating the CMUT wafer from the support wafer and de-tethering the CMUT device from the CMUT wafer. The CMUT arrays fabricated and singulated in this process were ring-shaped arrays, with inner and outer diameters of 5 mm and 10 mm, respectively. The fabricated CMUT ring arrays demonstrate the ability of this method to successfully and safely singulate the ring arrays and is applicable to any arbitrary 2D shaped MEMS device with uspended microstructures, taking advantage of the inherent planar attributes of DRIE.

The behavior of tillage tools with acute and obtuse lift angles

An experimental investigation was conducted to study the trend of draft force against forward speed and working depth for a range of lift angles beyond acute angles for a simple plane tillage tool. The experiments were performed in an indoor soil bin facility equipped with a tool carriage and a soil preparation unit propelled by an integrated hydraulic power system. The system was also equipped with electronic instrumentation including an Extended Octagonal Ring Transducer (EORT) and a data logger. The factorial experiment (4×3×3) with three replications was used based on Randomized Complete Block Design (RCBD). The independent variables were lift angle of the blade (45, 70, 90 and 120°), forward speed (2, 4 and 6 km h-1) and working depth (10, 25 and 40 cm). The variance analysis for the draft force shows that all independent variables affect the draft force at 1% level of significance. The trend of the draft force against working depth and forward speed had almost a linear increase. However, the trend of the draft force against the lift angle is reversed for lift angles >90. This finding, conflicts with the results of analytical and numerical studies which extrapolate the results achieved for acute lift angles to obtuse lift angles and have not been reported experimentally.

A Smartphone Based System for Kite and Board Measurements in Kitesurfing

This study introduces a smartphone based measurement system to obtain dynamic parameters of board and kite during kitesurfing. A built-in GPS receiver tracked the path and speed of the kitesurfer. Orientation values from inertial sensors in the smartphones attached to the kite were used to visualise kite movement patterns through projection onto the surface of a sphere. Ring transducers on kite lines measured forces acting between the kite and kitesurfer. The measurement system was tested with one participant. The total distance covered was 6654 m at an average speed of 8.17 m/s. Accelerations during a jump were evaluated to estimate jump height and duration. Board orientations and kite movements were found to be reasonable and in alignment with video recordings. Kite steering and lift force traces comprehensibly described the interaction between kitesurfer and kite. Jump parameters were in agreement with visual observations.

Development of hydraulic normal loading device for single wheel test rig

A study was conducted to develop a hydraulic normal loading device for a single wheel test rig available in the Agricultural and Food Engineering Department of IIT Kharagpur. A hydraulic circuit was designed to apply additional normal load up to 2000 kg on wheel axle. The same circuit also can be used to remove 1350 kg load from the initial load. The circuit uses a fixed displacement pump, a 3-way-4 port-solenoid operated- spring centered directional control valve, a pressure relief valve and a double acting hydraulic cylinder. The normal load is sensed by a ring transducer and recorded in a data acquisition system. This device was used to study the effect of normal load on a radial-ply tire (14.9 to 28) under soft and hard soil condition. It was observed that, with hydraulic loading device the normal load on the wheel axle under dynamic condition was found to increase in the range of 1 to 5% for soft and hard bed soil surface. Key words: Static normal loads, dynamic normal load, radial-ply tire, drawbar pull, slip.

Investigation of Ultrasonic Emulsifying Processes of a Linseed Oil and Water Mixture

Abstract Ultrasonic emulsifying processes of immiscible liquids can be used to obtain stable emulsions. The authors used an ultrasonic sandwich head with an energy concentrator to obtain a suitable value of the energy density necessary for the emerge of ultrasonic cavitation. Two piezoelectric ring (Dext = 50 mm) transducers of Pz-26 type produced by FERROPERM were used to design the ultrasonic sandwich head. The frequency of the ultrasonic wave was 18.4 kHz and the excitation time of the ultrasonic transducer exiting 5 minutes. Visible bubbles during the generation of ultrasonic waves appeared in the mixture after exceeding the cavitation threshold. The authors determined also the cavitation threshold by measuring the electrical voltage conducted to the transducers. To receive long-lasting emulsion, the electrical voltage attained 300 Vpeak. The dispersion dependence on the emulsifying time was determined. The emulsion of linseed oil and water was stable through some months without surfactants.

A Standing Wave Piezoelectric Ultrasonic Motor Using a Single Flexural Vibration Ring Transducer

This paper presents a rotary standing wave ultrasonic motor using single flexural vibration ring transducer. The motor consists of three main components, the stator, rotor and housing unit. The stator is a piezoelectric transducer ring. The rotor is designed of a compact driving wheel and shaft. The housing unit is made of a transparent thermoplastic Perspex material and is part of the motor working mechanism. The motor design, structure, working principles and modelling using finite element analysis is discussed and presented in this paper. A prototype of the motor was fabricated and its characteristics measured. Experimental tests showed that the motor electrical working parameters are: Current: 100 m-amps, Voltage: 100 volts, Frequency: 41.7 kHz, typical speed of 32 revolutions per minute, a resolution of less than 50μm and maximum load of 1.5 Newton.

In-vivo mitral annuloplasty ring transducer: Implications for implantation and annular downsizing

Mitral annuloplasty has been a keystone to the success of mitral valve repair in functional mitral regurgitation. Understanding the complex interplay between annular-ring stresses and left ventricular function has significant implications for patient-ring selection, repair failure, and patient safety. A step towards assessing these challenges is developing a transducer that can be implanted in the exact method as commercially available rings and can quantify multidirectional ring loading. An annuloplasty ring transducer was developed to measure stresses at eight locations on both the in-plane and out-of-plane surfaces of an annuloplasty ring's titanium core. The transducer was implanted in an ovine subject using 10 sutures at near symmetric locations. At implantation, the ring was observed to undersize the mitral annulus. The flaccid annulus exerted both compressive (−) and tensile stresses (+) on the ring ranging from −3.17 to 5.34MPa. At baseline hemodynamics, stresses cyclically changed and peaked near mid-systole. Mean changes in cyclic stress from ventricular diastole to mid-systole ranged from −0.61 to 0.46MPa (in-plane direction) and from −0.49 to 1.13MPa (out-of-plane direction). Results demonstrate the variability in ring stresses that can be introduced during implantation and the cyclic contraction of the mitral annulus. Ring stresses at implantation were approximately 4 magnitudes larger than the cyclic changes in stress throughout the cardiac cycle. These methods will be extended to ring transducers of differing size and geometry. Upon additional investigation, these data will contribute to improved knowledge of annulus-ring stresses, LV function, and the safer development of mitral repair techniques.

Piezoelectric circular ring flexural transducers

An analytical treatment of the piezoelectric ceramic complete ring transducer undergoing flexural vibrations is presented. Conditions for the electromechanical excitation of the flexural vibrations are discussed and it is shown that the fundamental mode of the flexural vibration of a complete ring can be considered as sufficiently dominant over a broad frequency range. Hence, the one-dimensional equivalent electromechanical circuit representation of the transducer is applicable and all the parameters of the equivalent circuit are determined. Possibilities to optimize the effective coupling coefficient of the transducer by changing the extent of the electrodes on the piezoelectric body are considered. It is shown that for effective operation of the flexural ring transducer as a low frequency hydroacoustic projector the opposing quadrants (or three quadrants in case of a planar array configuration) have to be covered with baffles. The radiation impedance and directional factors of the transducers with baffles are considered. Limitations of the acoustical power radiated by the transducers are discussed.

Piezoelectric slotted ring transducer

Analytical treatment of a slotted piezoelectric ceramic ring transducer vibrating in flexure is presented. The mode shape of the slotted ring vibration is determined, and parameters of the equivalent electromechanical circuit of the transducer are calculated. Possibilities to optimize the effective electromechanical coupling coefficient of the transducer by combining active and passive materials are considered. Acoustic loading for typical projectors made from slotted rings is estimated. Challenges in implementing the slotted ring transducers in terms of depth limitation and radiated power are discussed.

Design, Construction and Calibration of a Triaxial Dynamometer for Measuring Forces and Moments Applied on Tillage Implements in Field Conditions

In this research, a dynamometer was designed, constructed and calibrated to measure the forces and moments applied on tillage implements. This dynamometer is able to measure the three orthogonal forces acting on the implement and the three moments acting around the orthogonal axes, up to a maximum force of 20 kN and a maximum moment of 20 kN m. The dynamometer uses two extended octagonal ring transducers mounted in a back-to-back arrangement with their axes at right angles and has a tubular torque meter for torque measurement. For mechanical design of the dynamometer frame and its units, the finite element method and CATIA software were used. The device was machined from the solid part and high tensile steel. The forces and moments acting on the dynamometer were measured by using the strain gauge bridges on two extended octagonal ring transducers and on the torque meter tube. The results of data analysis, including forces applied on the dynamometer, the designing method of rings and torque meter tubes, the mounting arrangement of load cell parts on each other, the mounting method of load cell on frame and the position of strain gauge on load cell, in other words, the position of different parts of the dynamometer relative to each other has been explained in this paper. Calibration of the measurement unit was done by a calibration system which was designed for static calibration of the triaxial dynamometer. The results of calibration of the measurement unit showed that the designed and constructed dynamometer has appropriate precision, sensitivity and good repeatability for measuring the desired forces and moments. The results showed a high degree of linearity between output voltage of bridges and applied forces and moments. The interaction effects of the applied forces and moments were very negligible.

Thirty years progress of underwater sound projectors in china

Progress in the development of underwater sound projectors over the past thirty years in China is presented in this paper. This progress may be divided into four parts: (i) The development of new underwater sound projectors based on new transducer materials such as rare earth giant magnetostrictive materials, relaxation ferroelectric materials and piezoelectric composite materials. (ii) The design of new structures and energy transfer mechanisms such as flex-tensional transducers, mosaic cylindrical transducers, longitudinal transducers, flexural disk and beam transducers. (iii) The development of new configurations that broaden transducer bandwidth such as free-flooded ring transducers, broadband free-flooded flex-tensional transducers, doubly-excited longitudinal transducers, hybrid longitudinal transducers and matching layer technology. (iv) The development of new transducer design and analysis tools such as finite-element models for complex geometries, structure and fluid coupling mechanisms. These models have been used to optimize the design of a variety of projectors including low-frequency transducers, high power transducers and broadband wide-beam transducers.