Vibration Transducer Research Articles

A square-type rotary ultrasonic motor with four driving feet

This paper presents and verifies a new idea for constructing rotary ultrasonic motor that may effectively make use of the longitudinal vibrations of the bolt-clamped transducers. Based on the idea of generating elliptical motion on the driving tip by superimposing longitudinal vibrations, a square-type rotary ultrasonic motor with four driving feet is proposed. This new motor consists of four longitudinal vibration transducers, which are located in square-type and form an enclosed construction. The longitudinal vibrations of the four transducers are superimposed to produce the same circular movements on the four feet, which can push the rotor into motion when a preload is applied. By using FEM method, the proposed motor is designed and analyzed, and circular trajectories on the driving feet are gained. The vibration and input impedance characteristics of the motor are measured after the fabricating of a prototype, and the test results are in good agreement with the FEM analysis results. Typical output of the prototype is no-load speed of 71r/min and maximum torque of 12.3Nm at an exciting voltage of 200Vrms.

Radially composite cylindrical piezoelectric ultrasonic transducers

A new type of radially composite cylindrical piezoelectric ultrasonic transducers is presented and its radial vibration is studied. The composite transducer is composed of a radially polarized piezoelectric ceramic short tube with arbitrary wall thickness and a metal tube. The radial vibrations of the radially polarized piezoelectric tube and the metal tube are analyzed and their electro-mechanical equivalent circuits are obtained. Based on the mechanical boundary conditions between the piezoelectric tube and the metal tube, the six-port electro-mechanical equivalent circuit of the radially composite ultrasonic transducer is obtained and the frequency equation is given. The theoretical relationship between the resonance/anti-resonance frequency and the effective electro-mechanical coupling coefficient with the ratio of the inner radius over the outer radius of the composite transducer is analyzed. At the same time, the radial vibration of the composite transducer is simulated by using Finite Element Method. The vibrational modal shape and the harmonic response are given numerically. At last, some radially composite ultrasonic transducers are designed and manufactured; their resonance/anti-resonance frequencies are measured. It is shown that the analytical resonance/anti-resonance frequencies are in good agreement with the numerically simulated and experimental results. It is expected that this type of radially composite ultrasonic transducers can be used in large scale ultrasonic liquid processing, such as ultrasonic extraction, ultrasonic sonochemistry and other applications where large radiation surface and ultrasonic power are needed.

High Curie temperature relaxor piezoelectric single crystal broadband transducers

Lead indium niobate-lead magnesium niobate-lead titanate (PIMNT) crystals have been used to fabricate longitudinal vibrator broadband tonpilz transducers as active piezoelectric material. Compared to lead magnesium niobate-lead titanate (PMNT), rhombohedral-to-tetragonal phase transition temperature (Trt) of PIMNT increases to higher than 120° C and coercive field (Ec) can reach 5kV/cm, while possessing the similar electromechanical properties. The PIMNT single crystal transducer can work under high temperature exceeding 80° C and large drive voltage over 0.6MVpp/m with a DC bias field of 0.27MV/m.Simultaneously, the device shows a smaller size, as much as 10dB higher transmitting voltage response and 8dB higher receiving voltage response than lead zirconate titanate (PZT) longtitudinal vibrator(tonpliz) transducer with a broad bandwidth over 150%. The PIMNT device demonstrates tremendous performance for sonar and ultrasonic technology.

A novel capacitive accelerometer with a highly symmetrical double-sided beam-mass structure

This paper reports a novel capacitive accelerometer with highly symmetrical double-sided beam-mass structure. The highly symmetrical structure is fabricated from single wafer by a novel vertical sidewall protection technique. The good device performance is obtained by highly symmetrical double-sided beam-mass structure and fabrication process that enable formation of a large proof mass, controllable thickness of beam, and a narrow uniform capacitive gap over a large area. The resonance frequency of the accelerometer is measured in open loop system by a network analyzer. The quality factor and the resonant frequency are 34 and 787Hz, respectively. The accelerometer with closed loop interface circuit is calibrated on B&K Vibration Transducer Calibration System (Type 3629). The typical measurement range of the device is 1g, and the maximum range is 2g. The capacitance sensitivity of the fabricated accelerometer is 11.7pF/g. The sensitivity of the device with closed loop interface circuit is 1V/g, and the nonlinearity is 0.39% over the range of 1g. The cross-sensitivity x/z is 0.72% and y/z is 0.50%, respectively. The accelerometer with closed loop circuit has wide bandwidth of DC to 1kHz (3dB). Also the bias stability is 255μg. The device with closed loop circuit has signal to noise ratio (SNR) of 106dB, the average noise floor is 3.1 μg/Hz (0–100Hz).

발포스펀지 의자시트의 진동전달 특성

Recently, in the movie theater, the special chair is installed to maximize the viewing effect of movies. It is structured to convey a vibrational stimulus to a specially-designated parts of human body by attaching a vibration transducer to a existing theater chair. This paper describes the analysis of the vibration transfer characteristic of a foaming sponge seat for the design of the special chair. We could not apply the structural analysis S/W because it is difficult to obtain the mechanical properties and damping coefficients of the various type sponges. And then we computed the transfer functions by the global curve fitting program based on experimental modal analysis. The experimental response results comparatively coincide with those by the global curve fitting program. We also could obtain the natural frequencies, the modal damping coefficient ratio, the modal vectors and the whole transfer functions. Therefore we could analyze the dynamic characteristic for design of foaming sponge seat.

1P5-10 A Study on Speckle Suppression by Stochastic Vibration of Ultrasound Transducer(Poster Session)

1P5-10 A Study on Speckle Suppression by Stochastic Vibration of Ultrasound Transducer(Poster Session)

DYNAMIC BALANCING APPARATUS AND METHOD USING SIMPLE HARMONIC ANGULAR MOTION

Provided is a dynamic balancing apparatus using a simple harmonic angular motion, including a rotational shaft on which a rotational body having an unbalanced mass is installed; a simple angular motion generator for periodically vibrating the rotational shaft; a support for supporting both sides of the rotational shaft; an angular vibration measuring sensor for measuring the simple harmonic angular motion of the rotational shaft; and force or vibration transducers for measuring applied force acting on or vibration transferred to the support by means of the simple harmonic motion of the unbalance mass.

Unidirectional multimode piezoelectric spherical transducers

Analytical and experimental results are presented for unidirectional broadband multimode piezoelectric acoustic transducers utilizing axisymmetric vibrations of spherical transducers. The analysis covers the acoustic radiation and reception by including the acoustic impedance's and diffraction coefficients for transducers with conformal baffles. The energy method is used to obtain equivalent parameters for a multi-contour electromechanical circuit representation of the transducer and to calculate performance. Experimental data obtained are in good agreement with analytical results.

Piezoelectric thin films for a high frequency ultrasound transducer with integrated electronics

Lead zirconate titanate (PZT) piezoelectric films were integrated into prototype one-dimensional array transducers. Linear arrays of diaphragm transducers were prepared using PZT films of 0.5–1.7 μm in thickness and surface micromachining techniques. For this purpose, the PZT and remaining films in the stack were patterned using ion-beam or reactive ion etching and partially released from the underlying silicon substrate by XeF2 etching. The PZT films were prepared by chemical solution deposition, and have e31,f piezoelectric coefficients of −6 to −12 C/m2, depending on the crystallographic orientation. Impedance measurements on the fabricated structures showed resonance frequencies between 3 and 70 MHz for fully and partially released structures depending on the transducer dimensions and vibration modes. In-water transmit and receive functionalities have been demonstrated. A bandwidth on receive of 66% has been determined. Because of the small thickness of the piezoelectric element, the elements can be driven at less than 5 V. This enables the ultrasound system to be CMOS compatible, and hence massive miniaturization. A custom designed CMOS chip which enables beamforming on transmit, transducer excitation, amplification, digitization, and data storage was designed and fabricated.

Comparison of Minimum Detectable Crack Size in a Geared System From Three Different Vibration Transducer Types

Acoustic and vibration signals contain distinctive patterns useful for detecting defects in machinery. A number of signal processing strategies have been proposed for detecting and quantifying incipient defects in gears. Nonintrusive measurement techniques like those based on laser Doppler vibrometry (LDV) and microphones need to be studied in order to help users in selecting the appropriate transducer according to the application. This article presents an experimental design to determine, as a novel contribution, the minimum detectable crack size in a geared system comparing three different transducers: a microphone, an accelerometer, and an LDV. The comparison intends to discriminate the three transducers with respect to its early detection capability. Experiments were conducted in a closed loop torque test rig for several torque levels and speeds. Experimental factorial design was used to determine the main effects and their interactions in the detection process. The well-known Hilbert and wavelet transforms have been used as signal processing technique. Their advantages in the detection of incipient defects are highlighted in this article. The results indicate that the acoustic signal stands out as the method that first detects an incipient progressive crack in gears (it detected 1.3-mm-long cracks), although, as a drawback, the results obtained using the microphone signal are more sensitive to speed and torque. The second place was for LDV with 1.8-mm crack detection, and the third place for the accelerometer with 2.3-mm crack detection.

A Polishing Method of Single-Incentive Ultrasonic Elliptical Vibration for Tungsten Carbide Mould

The basic principles of ultrasonic transducer and ultrasonic elliptical vibration polishing are investigated. A new kind of single-incentive ultrasonic transducer is designed, and the finite element simulation is conducted, a polishing device is developed based on the ultrasonic elliptical vibration. The polishing experiment is adopted to polish a tungsten carbide mold with the diameter 5cm. The experimental result shows that the tungsten carbide mould surface roughness changes from the original 0.026μm to 0.017μm.

Wet Gas Flow Regime Identification Based on WPT and PNN

A novel noninvasive approach to the online flow regime identification for wet gas flow in a horizontal pipeline is proposed. Research into the flow-induced vibration response for the wet gas flow was conducted, with the conditions of pipe diameter 50 mm, pressure from 0.25 MPa to 0.35 MPa, Lockhart-Martinelli parameter from 0.02 to 0.6, and gas Froude Number from 0.5 to 2.7. The flow-induced vibration signals were measured by a vibration transducer installed by outside wall of pipe, and then the normalized energy features from different frequency bands in the vibration signals were extracted through 4-scale wavelet package transform (WPT) with mother wavelet db7. A probabilistic neural network (PNN) classifier with the extracted features as inputs was developed to identify the three typical flow regimes including stratified wavy flow, annular mist flow, and slug flow for wet gas flow. The results show that the method can identify effectively flow regimes and its identification accuracy arrives at above 92.1%. The noninvasive measurement approach has great application prospect in online flow regime identification.

Study on Ultrasonic Micromateriel Transmission System

A new type ultrasonic materiel transmission system is proposed in this study. In this new design, bending vibration traveling wave is generated in an elastic pipe by using two uniform sandwich type longitudinal vibration transducers. Thus, elliptical trajectory motions can be formed at particles on the pipe wall, which can drive the materiel by frictional force. The adopting of sandwich transducer in this device can gain large vibration amplitude and improve the electromechanical coupling efficiency. The structure and working principle of the proposed design are introduced. The transducer and the pipe are designed and analyzed by using FEM method. The longitudinal vibration mode of the transducer and the bending vibration mode of the pipe are analyzed, and the resonant frequencies of these two modes are tuned to be close. A prototype system is fabricated and measured.

A Standing Wave Ultrasonic Motor Using Longitudinal Vibration Transducers

A new type standing wave ultrasonic motor is proposed in this study. In this design, three longitudinal vibration transducers are clamped on the inner side of a ring with driving teeth by screws. Bending standing wave can be generated in the ring by the longitudinal vibrations of the transducers. Thus, oblique linear simple harmonic vibrations are formed on the teeth, which can drive the rotor by frictional force. The structure and working principle of the proposed design are introduced. The motor is designed and analyzed by using FEM method. A standing wave is gained after the degeneration between the bending vibration of the ring and the longitudinal vibration of the transducer. The test results of the prototype motor verify the feasibility of the proposed design.

Selectively Mitigating Multiple Vibration Sources In A Computer System

One embodiment of the present invention provides a system that mitigates the effects of multiple vibration sources on a set of hard disk drives (HDDs) within a computer system. During operation, the system identifies a target HDD in the set of HDDs, wherein the performance of the target HDD is affected by mechanical vibrations. The system also identifies one or more primary vibration sources from the multiple vibration sources that affect the performance of the target HDD. Next, for each of the primary vibration sources, the system measures a first time-domain signal associated with the operation of the primary vibration source using a first vibration transducer associated with the primary vibration source. The system also measures a second time-domain signal associated with the target HDD using a second vibration transducer associated with the target HDD. Next, for each of the primary vibration sources, the system then computes a cross-power-spectral-density (CPSD) between the first and the second time-domain signals. The system then selectively mitigates the primary vibration sources based on the CPSDs between the primary vibration sources and the target HDD.

A cylindrical standing wave ultrasonic motor using bending vibration transducer

A cylindrical standing wave ultrasonic motor using bending vibration transducer was proposed in this paper. The proposed stator contains a cylinder and a bending vibration transducer. The two combining sites between the cylinder and the transducer locate at the adjacent wave loops of bending vibration of the transducer and have a distance that equal to the half wave length of bending standing wave excited in the cylinder. Thus, the bending mode of the cylinder can be excited by the bending vibration of the transducer. Two circular cone type rotors are pressed in contact to the end rims of the teeth, and the preload between the rotors and stator is accomplished by a spring and nut system. The working principle of the proposed motor was analyzed. The motion trajectories of teeth were deduced. The stator was designed and analyzed with FEM. A prototype motor was fabricated and measured. Typical output of the prototype is no-load speed of 165 rpm and maximum torque of 0.45 N m at an exciting voltage of 200 V rms.

Minimum radiation force target size for power measurements in focused ultrasonic fields with circular symmetry

The time-averaged ultrasonic power emitted by medical ultrasonic equipment is mostly measured using a radiation force balance, and the question of the necessary target size is of practical importance. The question is answered here by calculations based on a Rayleigh integral algorithm for fields from circular, focusing transducers. This case occurs particularly in the field of high-intensity therapeutic ultrasound. The calculation yields the necessary size of an absorbing target so that the radiation force is 98% of that exerted on an absorber of infinite lateral size, and this as a function of the transducer-to-target distance, of the transducer radius in comparison with the wavelength and of the focus (half-)angle. Several distributions of the transducer vibration amplitude are considered. The Rayleigh integral strictly applies only to planar transducers, but among the amplitude distributions there is also one that allows the simulation of the spherically curved transducer type often found in practice.

고효율 전자기형 정원창 구동 트랜스듀서의 설계

Implantable middle ear hearing devices(IMEHDs) have being actively studied to overcome the problems of conventional hearing aids. Vibration transducer, an output devices of IMEHDs, is attached on the ossicular chain and transmits mechanical vibration to cochlea. This approach allows us to hear more clear sound because mechanical vibration is effective to transfer high frequency acoustics, but occurs some problems such as fatigue accumulation to ossicular chian and reduction of vibration displacement caused by mass loading effect. Recently, many studies for the round window stimulation are announced, because it does not cause such problems. It have been studied by older transducers designed for attaching on ossicular chain. In this paper, we proposed a new electromagnetic transducer which consists of two magnets, three coils and a vibration membrane. The magnet assembly, magnet coupled in opposite direction, were placed in the center of three coils, and the optimum length of each coil generating maximum vibrational force was calculated by finite element analysis(FEA). The transducer was implemented as the calculated length of each coil, and measured vibration displacement. From the results, it is verified the vibration displacement can be improved by optimizing the length of coils.

Comparisons of electromagnetic and piezoelectric floating-mass transducers in human cadaveric temporal bones

Electromagnetic floating-mass transducers for implantable middle-ear hearing devices (IMEHDs) afford the advantages of a simple surgical implantation procedure and easy attachment to the ossicles. However, their shortcomings include susceptibility to interference from environmental electromagnetic fields, relatively high current consumption, and a limited ability to output high-frequency vibrations. To address these limitations, a piezoelectric floating-mass transducer (PFMT) has recently been developed. This paper presents the results of a comparative study of these two types of vibration transducer developed for IMEHDs. The differential electromagnetic floating-mass transducer (DFMT) and the PFMT were implanted in two different sets of three cadaveric human temporal bones. The resulting stapes displacements were measured and compared on the basis of the ASTM standard for describing the output characteristics of IMEHDs. The experimental results show that the PFMT can produce significantly higher equivalent sound pressure levels above 3 kHz, due to the flat response of the PFMT, than can the DFMT. Thus, it is expected that the PFMT can be utilized to compensate for high-frequency sensorineural hearing loss.

A Cylindrical Traveling Wave Ultrasonic Motor Using Longitudinal Vibration Transducers

A cylindrical type traveling wave ultrasonic motor using longitudinal vibration transducers is proposed in this paper. A flexural traveling wave is excited in the cylinder by the longitudinal vibrations of transducers. The working principle of proposed motor is analyzed. The function of flexural traveling wave and motion trajectory of particle on the tooth are developed. The longitudinal resonant frequency of transducer and bending resonant frequency of cylinder are degenerated. A prototype motor is fabricated and measured. Typical output of the prototype is no-load speed of 290r/min and maximum torque of 1.95N·m at a voltage of 200Vrms.