Wave transducer

The technique presented above has been extensively evaluated experimentally using ultrasonic data acquired from a test block made of cast stainless steel with cotirse material structure. Here we briefly present selected results obtained using two pressure wave transducers, with refraction angles of 45° and 0°. The -lOdB frequency ranges of the transducers were 1.4-2.8 MHz and 0.7-1.4 MHz, respectively. The ultrasonic response signals were sampled at a rate of 40 MHz, with a resolution of 8 bits, prior to computer processing. 

P.D. Wilcox, R.S.C. Monkhouse, M.J.S. Lowe and P. Cawley, The use of Huygens principle to model the acoustic field from interdigital Lamb wave transducers, Review of Progress in Quantitative NDE, Vol 17, Plenum Press, New York, 1998 (in press). 

This report presents the results of investigations aimed at the creation of the surface wave transducer for the automated control. The basic attention is drawn to the analysis of the position of the front meniscus of the contact liquid when the surface waves excite through the slot gap and to the development of system for acoustic contact creation. 

A shear wave transducer with the height H, and the width W on the wedge and at the angle a, transmitted shear waves, at the frequency f and perpendicular to the paper. The limited plane SH Waves were transmitted to the test surface. The height H of the transducer was considered by dividing it into N pieces. On the test surface in the areafW XHl), the transducer vibrated perpendicular to the paper where Hl=H/cos , the... 

Special contact transducers having wedges providing incidence angles for specific appHcations are used widely in industry. For example, normal incidence is used in tests for laminations within sheets, and for sheet or plate thickness where the back surface of the test material parallels, to within perhaps 10°, the front surface. Shear wave transducers typically used for weld examination have 45°, 60°, or 70° inspection (refracted) angles. To locate discontinuities, the transducers may be moved back and forth over selected surface areas until the angled search beam approaches normal incidence on the... 

Of all the piezoelectric crystals that are available for use as shock-wave transducers, the two that have received the most attention are x-cut quartz and lithium-niobate crystals (Graham and Reed, 1978). They are the most accurately characterized stress-wave transducers available for stresses up to 4 GPa and 1.8 GPa, respectively, and they are widely used within their stress ranges. They are relatively simple, accurate gauges which require a minimum of data analysis to arrive at the observed pressure history. They are used in a thick gauge mode, in which the shock wave coming through the specimen is... 

UFM detection is obtained by measuring the cantilever deflection as the ultrasound amplitude is modulated (Fig. 13.3). The ultrasonic excitation from a longitudinal wave transducer fixed to the bottom of the sample causes normal vibration of its surface. As the ultrasonic amplitude is increased, contact is eventually broken at the pull-off point (aI = hi), giving a discontinuity in the time-averaged displacement. We refer to this ultrasonic amplitude as the threshold amplitude, and the corresponding inflection in the displacement... 

Chou, C.-H., Khuri-Yakub, B. T., and Liang, K. K. (1987). Acoustic microscopy with shear wave transducers. IEEE 1987 Ultrasonics Symposium, pp. 813-16. IEEE, New York. [56, 69]... 

Based on the evanescent wave transducing principle, atrazine was detected at concentrations around 0.1 ig L-1 (Schipper et al., 1997 Schipper et al., 1998) and cyclodiene insecticides in the xgL 1 range (Brummel et al., 1997). 

NoNaq"). The shear wave transducer for this sample was a 10 MHz lithium niobate transducer bonded with a cyanoacrylate polyester. For the lower density sample both PZT and quartz transducers operating at nominally 3 to 4 MHz were used for both longitudinal and shear wave propagation. They were bonded with either an alcohol-glycerine-based couplent or phenyl salicylate. The detected ultrasonic echoes were rectified and displayed on an oscilloscope equipped with time-delay circuitry for the transit time measurements. 

Ippolito S. J., Kalantar-zadeh K., Powell D. A., and Wlodarski W., A finite element approach for 3-dimensional simulation of layered acoustic wave transducers, presented at Optoelectronic and Microelectronic Materials and Devices, December 11-13, 2002, Sydney, Australia. 

To machine the broach debris, ellptlcal nosed cutters of various angles were tried and non contact stand off ultrasonic techniques similar to that used for fishplate Interfaclal oxide measurements (6) evaluated. After a number of trials It was found that If the socket was machined out to a flat base of approximately 4mm diameter a 0° compression wave transducer could be used to generate an ultrasonic beam parallel to the bolt axis In a conventional contact type test, the machined socket head conveniently providing a reservoir for couplant (In this case ethylene glycol) prior to application of the probe. 

Figure 5.17 Principle of acoustophorcsis. Concerning the UVP (Ultrasonic Vibration Potential - top), an ultrasonic wave applied on a liquid (transducer) induces solvent motion. As the two charged species have a different masses and frictional coefficients, its move differently. The charge heterogeneonsness which appeared in this way generate a macrr opic and thus measurable electric field (electrodes). Concerning the ESA (Electro Sonic Amplitude - bottom), an alternative electric field is applied (electrodes). Eachs ion species moves in opposite direction. This motion induces a detectable ultrasonic wave (transducer).

This motion induces a detectable ultrasonic wave (transducer).. . . 317... 

As mentioned above rectangular AFM cantilever beams can also be forced to torsional vibrations. In this case the experimental set-up is such that an ultrasonic transducer emits shear waves into the sample causing in-plane surface vibrations. The shear wave transducer is oriented so that the surface vibrations are polarized perpendicular to the long axis of the cantilever. If low excitation amplitudes (0.1 nm) are applied and if the excitation frequency is set close to a contact resonance frequency, the amplitude and the phase of the cantilever vibration contain now information about the local lateral tip-sample stiffness. Used as imaging quantity, they yield images of shear stiffness. By increasing the lateral excitation amplitude much above... 

Figure 1.10 Schematic setup for capillary wave-type experiment. The wave transducer excites surface waves. The laser diffraction and detector measure damping of the waves.

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