共查询到20条相似文献,搜索用时 0 毫秒
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Shigematsu T Kurosawa MK Asai K 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2003,50(4):376-385
High resolution (from nanometer to subnanometer) stepping drives of a surface acoustic wave motor are presented. It was shown that step displacement was easily controlled by adjusting a number of driving waves, using a steel ball slider equipped with permanent magnet for preload. By means of this open loop control, the step displacement was controlled from centimeter-order to submicrometer-order. In this paper, using a silicon slider equipped with a ball bearing linear guide, the stepping motions of a surface acoustic wave motor were investigated. A laser interferometer equipped with a 2-picometer resolution displacement demodulator was introduced. Motions of the slider ranging from several hundreds of nanometers to several nanometers in each step displacement were observed. Reduction of the driving waves down to 25 cycles, under a 100 V/sub peak/ driving voltage and a 30 N preload condition, generated about 2 nm stepping motion using our experimental setup under an open loop condition. We also demonstrated subnanometer step movements. These experimental results indicated that the surface acoustic wave motor has an ability of subnanometer positioning with a centimeter-level stroke. 相似文献
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Morita T Kurosawa MK Higuchi T 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》1999,46(4):929-934
The operation of a surface acoustic wave (SAW) motor using spherical-shaped sliders was demonstrated by Kurosawa et al. (1994). It was necessary to modify the previous simulation models for usual ultrasonic motors because of this slider shape and the high frequency vibration. A conventional ultrasonic motor has a flat contact surface slider and a hundredth driving frequency; so, the tangential motion caused by the elasticity of the slider and stator with regard to the spherical slider of the SAW motor requires further investigation. In this paper, a dynamic simulation model for the SAW motor is proposed. From the simulation result, the mechanism of the SAW motor was clarified (i.e., levitation and contact conditions were repeated during the operation). The transient response of the motor speed was simulated. The relationships between frictional factor and time constant and vibration velocity of the stator and the slider speed were understood. The detailed research regarding the elastic deformation caused by preload would be helpful to construct an exact simulation model for the next work. 相似文献
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Asai K Kurosawa MK 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2005,52(10):1722-1734
This paper describes the air film characteristic in the interface between the slider and stator substrate of a surface acoustic wave (SAW) motor, and the difference of the squeeze film effect by the form of the slider. Because the vibration amplitude of the SAW motor is several 10 nm order, analysis of pressure was performed by using the molecular gas-film lubrication (MGL) equation. In the analysis, the MGL equation was split into advection phase and nonadvection phase, and calculation of advection and nonadvection phases was performed by using the cubic interpolated propagation (CIP) method and the finite difference method, respectively. From analysis results it was found that the time to steady pressure of air film depends on the radius of projection arranged on the contact surface of the slider. Also found was that the steady pressure in the interface does not depend on the radius and height of the projection, but it depends on the minimum spacing between the slider and the stator substrate. 相似文献
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S. G. Suchkov 《Technical Physics Letters》1998,24(9):731-732
It was observed that the propagation of an internal acoustic wave near a surface is accompanied by the excitation of a surface
acoustic wave directed at an angle to the internal wave.
Pis’ma Zh. Tekh. Fiz. 24, 57–61 (September 26, 1998) 相似文献
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Nikitov SA Popov RS Lisenkov IV Kim CK 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2008,55(8):1831-1839
Elastic wave propagation along the structure of hollow cylinders in a linear isotropic medium is investigated. The multipole method for modeling elastic waves propagation in such structures is formulated and implemented. Using the multipole method, dispersion dependencies of the structures (microstructured fibers) containing 3, 6, and 7 hollow cylinders are calculated. Comparison with wave dispersion properties along one cylinder is made. Also, an approximate physical model based on an equivalent coaxial waveguide and multipole method is proposed. Exploiting this model, wave dispersion of the wave propagating along a structure with 18 hollow cylinders is calculated. Validation of the model is also proposed. 相似文献
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The Mason crossed-field circuit model is generalized to simulate apodized interdigital transducers without channel division. The apodized transducer model is based on the transmission line model, and the artificial transformer with different voltage and current coupling ratios is used to independently obtain the transfer function and radiation admittance. In addition, a heuristic expression for transformer current ratios is used to approximate the radiation admittance of apodized transducers. Through comparing with the multichannel model, this unichannel model is illustrated to successfully describe the frequency response of apodized interdigital transducers. 相似文献
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Lee YC Kuo SH 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2004,51(1):114-120
A new acoustic transducer and measurement method have been developed for precise measurement of surface wave velocity. This measurement method is used to investigate the acoustoelastic effects for waves propagating on the surface of a polymethylmethacrylate (PMMA) sample. The transducer uses two miniature conical PZT elements for acoustic wave transmitter and receiver on the sample surface; hence, it can be viewed as a point- source/point-receiver transducer. Acoustic waves are excited and detected with the PZT elements, and the wave velocity can be accurately determined with a cross-correlation waveform comparison method. The transducer and its measurement method are particularly sensitive and accurate in determining small changes in wave velocity; therefore, they are applied to the measurement of acoustoelastic effects in PMMA materials. Both the surface skimming longitudinal wave and Rayleigh surface wave can be simultaneously excited and measured. With a uniaxial-loaded PMMA sample, both acoustoelastic effects for surface skimming longitudinal wave and Rayleigh waves of PMMA are measured. The acoustoelastic coefficients for both types of surface wave motions are simultaneously determined. The transducer and its measurement method provide a practical way for measuring surface stresses nondestructively. 相似文献
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Surface acoustic wave (SAW) devices are presently receiving careful scrutiny for applications in chemical sensing as well as in polymer characterization. Gas monitors based on SAW sensors have the potential for miniaturization and high sensitivity to a wide variety of substances. Polymer characterization is applicable to such diverse fields as protective coating design and decontamination of polymers. To better understand the physical mechanisms behind SAW response, the effects of the elastic properties in comparison to the mass loading of polymer coatings on SAW substrates were investigated. A theoretical basis for the effects of vapor-induced swelling or of thermal expansion was established. Compressive tension and its effect on SAW frequencies were found to be simple to describe, if there is no film slippage or polymer flow. The response of quartz substrate SAW crystals coated with polycarbonate and polyimide (glassy polymers) upon exposure to toluene and methanol was measured. Practical problems as to film uniformity, thickness measurement, and environmental control necessary in such measurements are described. Contrary to recent reports in the literature, no significant elastic tightening effect was observed with these vapor/polymer pairs. 相似文献
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Ultrasonic linear motor using surface acoustic waves 总被引:4,自引:0,他引:4
Kurosawa M. Takahashi M. Higuchi T. 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》1996,43(5):901-906
The first success in the operation of an ultrasonic linear motor at HF band driving frequency using the Rayleigh wave is described. The substrate material is a 127.8° Y-cut LiNbO3 wafer whose diameter is three inches. Four interdigital transducers (IDT's) are arranged to excite x- and y-propagation waves in both directions. The dimensions of the IDT are 25 mm aperture size, 400 μm pitch, 100 μm strip width, and 10 pairs. The operation area is about 25 mm square, The driving frequency is about 9.6 MHz in the x direction and about 9.1 MHz in the y direction. The most important point of the success is the shape of the contact surface and slider materials. For the contact materials, small balls about 1 mm in diameter are introduced to obtain sufficient contact pressure around 100 MPa. The use of ruby balls, steel balls, and tungsten carbide balls is investigated. Each slider has three balls to enable stable contact at three points. The maximum transfer speed is about 20 cm/s. The transfer speed is controllable by changing the driving voltage 相似文献
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Kenderian S Djordjevic BB Green RE 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2003,50(8):1057-1064
Laser generation and air-coupled detection were combined as a hybrid ultrasonic technique for the inspection of surface flaws in rails. Narrowband acoustic signals were generated using a formed laser source by focusing the laser light to a point and to a line on the surface of the rail. The pulse energy, and therefore the intensity of the laser source, varied such that the generated signal transitioned from the weak thermoelastic to the strong ablative regime. The detection of flaws using a laser-generated surface acoustic wave, in the presence of surface flaws, was compared between both point and line laser sources operating under different pulse energy levels. The line source was found to be more sensitive to the presence of surface flaws than a point source. The sensitivity of the laser-generated acoustic signal appeared to be independent of the severity of the flaw and, within the ablative regime, independent of the laser-pulse energy. Theoretical analysis is provided to explain the underlying cause that influences the interaction of a formed laser-generated surface acoustic wave to surface flaws and how this sensitivity may vary between the thermoelastic and ablative regimes. 相似文献
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N. M. Mikhin 《Materials Science》1969,4(2):149-152
Expressions for the friction coefficient were derived for the case of elastic contact between rough materials. The computation was based on the assumption that the friction force in the case under consideration is due to hysteresis losses during the deformation of a thin surface layer of one friction pair component by protuberances on the counterpart surface and due to molecular interaction at the solid/solid interface in the contact zones. The minimum value of the friction coefficient was calculated, and it was shown that it depends on the degree of surface roughness, physicomechanical properties of friction pair materials and the magnitude of tangential stresses 0 at the solid/solid interface. 相似文献
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Elastic surface wave devices based on piezoelectric thick-films 总被引:5,自引:0,他引:5
de Cicco G. Morten B. Prudenziati M. 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》1996,43(1):73-77
A study has been performed for the development of elastic-waves structures, involving screen printed and fired piezoelectric layers on nonpiezoelectric substrates, intended for new families of thick film sensors. This study approached the electroacoustic effects, i.e., the coupling between electromechanical parameters of the layers and elastic properties of the substrate, related to the wave propagation. In this work, particular attention is devoted to devices implemented on alumina substrates where SAW as well as (symmetric and antisymmetric) Lamb's waves are generated. The realization processes and the performance characteristics of these structures are presented 相似文献
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Evaluation of a novel surface acoustic wave gyroscope 总被引:3,自引:0,他引:3
Woods RC Kalami H Johnson B 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2002,49(1):136-141
A novel type of gyroscope sensor using metal dot arrays on the surface of a surface acoustic wave (SAW) device has recently been independently proposed. In this paper, we report experimental trials of several devices fabricated to evaluate the effects described and also an order-of-magnitude estimate of the sensitivity to be expected. The conclusions are that this device is extremely insensitive as currently proposed 相似文献
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We present the results of an experimental investigation of nonlinear processes accompanying the interaction of surface acoustic waves (SAWs) with real cracking defects and contact lines. The dynamic characteristics of the nonlinear reflection of higher harmonics are presented. It is shown that the third harmonic generation has a pronounced threshold character, the dynamic characteristics exhibit hysteresis, and the efficiency of nonlinear response depends on the duration of SAW action on the defect. The results lead to a conclusion that the nonlinear reflection of SAWs from a contact line provides an adequate model of reflection from a real cracking defect. 相似文献