Shear horizontal

Time-of-Flight Measurements with Shear Horizontal Waves. 

Shear Horizontal (SH) waves generated by Electromagnetic Acoustic Transducer (EMAT) have been used for sizing fatigue cracks and machined notches in steels by Time-of-Flight Diffraction (TOED) method. The used EMATs have been Phased Array-Probes and have been operated by State-of-the-art PC based phased array systems. Test and system parameters have been optimised to maximise defect detection and signal processing methods have been applied to improve accuracy in the transit time measurements. 

Figure 12.43 can be used to estimate condensate film coefficients in the absence of appreciable vapour shear. Horizontal and downward vertical vapour flow will increase the rate of heat transfer, and the use of Figure 12.43 will give conservative values for most practical condenser designs. 

The calculated Rayleigh mode (SJ, the lowest lying phonon branch, is in good agreement with the experimental data of Harten et al. for all three metals. Due to symmetry selection rules the shear horizontal mode just below the transverse bulk band edge can not be observed by scattering methods. The mode denoted by Sg is the anomalous acoustic phonon branch discussed above. Jayanthi et al. ascribed this anomalous soft resonance to an increased Coulomb attraction at the surface, reducing the effective ion-ion repulsion of surface atoms. The Coulomb attraction term is similar for all three metals... 

Fig. 11.4. Velocities of bulk and surface waves in an (001) plane the angle of propagation in the plane is relative to a [100] direction, (a) Zirconia, anisotropy factor Aan = 0.36 (b) gallium arsenide, anisotropy factor Aan = 1.83 material constants taken from Table 11.3. Bulk polarizations L, longitudinal SV, shear vertical, polarized normal to the (001) plane SH, shear horizontal, polarized in the (001) plane. Surface modes R, Rayleigh, slower than any bulk wave in that propagation direction PS, pseudo-surface wave, faster than one polarization of bulk shear wave propagating in...

A piezoelectric mass sensor is a device that measures the amount of material adsorbed on its surface by the effect of the adsorbed material on the propagation of acoustic waves. Piezoelectric devices work by converting electrical energy to mechanical energy. There are a number of different piezoelectric mass sensors. Thickness shear mode sensors measure the resonant frequency of a quartz crystal. Surface acoustic wave mode sensors measure the amplitude or time delay. Flexure mode devices measure the resonant frequency of a thin Si3N4 membrane. In shear horizontal acoustic plate mode sensors, the resonant frequency of a quartz crystal is measured. 

Fig. 12.3. Mercury sensor based on surface acoustic waves (SAW) with shear-horizontal acoustic plate mode. This approach was tested in Ref. [8].

Better sensitivity has been reported (32,33) with a surface guided wave, known as a Love wave. A shear horizontal wave is directed along the surface on top of the device a layer is deposited in which the acoustic waves are carried at a lower velocity. 

Figure 3.1 Schematic sketches of the four types of acoustic sensors, (a) Thickness-Shear Mode (TSM) resonator (b) Surface-Acoustic-Wave (SAW) sensor, (c) Shear-Horizontal Acoustic-Plate-Mode (SH APM) sensor, and (d) Flexural-Plate-Wave (FPW) sensor.

Figure 3.33 Schematic of an acoustic plate mode (APM) device showing the shear horizontal (SH) displacement of the mode as it propagates between input and output transducers. (Reprinted with permission. See Ref. (54). 1989 Elsevier Publishers.)...

Figure 3.34 Cross-sectional displacement profiles for the four lowest-order shear horizontal plate modes. These profiles are normalized equal power flow per width of the plate. (Reprinted with permission. See Ref. [M). 1989 Elsevier PuMishers.)...

SH-APM shear-horizontal acoustic plate mode (SH-APM) sorption (sorb) ST-cut quartz... 

D Mcallister Biode, Inc. Cape Elizabeth, ME DoE Developing a simple sensor for use in waste, surface, and groundwater using a shear horizontal acoustic plate mode (SHAPM) sensor, a form of piezoelectric sensor... 

Although this chapter is concerned with bulk acoustic wave (BAW) devices, some of the concepts apply to shear horizontal surface acoustic wave (SH-SAW) devices in a similar way [33,34]. When modeling SH-SAW devices, one usually decomposes the wave vector into a vertical and a lateral component. The vertical component obeys similar laws as the shear wave in a BAW resonator. This being said, we confine the discussion to BAW devices (also termed thickness-shear resonators) in the following. 

Fig. 2 A Schematic cross-section depicting the shear horizontal wave in a QCM device. B Contact mode AFM image of a QCM electrode surface at 0 V and 30 V. The horizontal displacement hy applying voltage can clearly he seen hy the surface scratch. C AFM traces recorded on the siuface at 30 V and 0 V, respectively. These measurements are optimal for quantifying the displacement, which is 3 nm in the given case...

Figure 17. Surface phonon dispersion for KBrfOOl). The data are compared to a Green s function calculation used to determine the bulk bands (shown by the shaded regions with polarizations perpendicular or parallel to the surface as indicated in the figure) and the surface localized modes (shown as solid lines). The predominant polarizations of the modes are indicated by perpendicular and parallel symbols, and the labels of the modes follow the notation in Fig. 16. Note that modes Sy and S5 are polarized shear horizontal and cannot be observed in this scattering arrangement. The data plotted as triangles are obtained from weaker peaks in the TOF spectra than the points represented by open circles. (Reproduced from Fig. 8 of Ref. 49, with permission.)...

Figure 20. Surface phonon dispersion for Rbl(OOl). The upper panel shows a comparison of the HAS data with a slab dynamics calculation for the unrelaxed surface, while the lower panel is a comparison of the same data with a similar calculation for a relaxed surface. The sagittal plane and shear horizontal modes are labeled by SP and SH, respectively, and the superscripts indicate which ion (Rb or T) is predominantly involved in the motion of the mode. The other labels follow the notation of Figs. 16 and 17. (Reproduced from Fig. 3 of Ref. 68, with permission.)...

In the rx region of the SBZ, no points corresponding to the S2 mode were found. However, the relaxation appears to introduce a sagittal plane mode with perpendicular polarization just below the shear horizontal mode S5, for which a number of data points are rather close. Again, there are some points that appear to be associated with crossing and longitudinal... 

Figure 27. Extended zone plot for MgO(001) showing the data obtained from a number of TOF spectra. The solid curve is the calculated Rayleigh wave dispersion, while the dashed curve in the <110> direction is the S7 shear horizontal mode which lies below the sagittal plane modes for this crystal in this direction. The dot-dashed line is a scan curve at the angles indicated. (Reproduced from Fig. 3 of Ref. 82, with permission.)...

Figure 32. Surface phonon dispersion for Nb(OOl). The data are the solid points which were taken at 900 K. Panels a and b correspond to slab dynamics calculations with two different force constant models the calculation in panel b uses the force constants from the bulk phonon fits. The solid lines represent the surface phonons and resonances polarized mainly longitudinally (or parallel), the lines with long dashes represent phonons polarized mainly perpendicularly, and those with short dashes are shear horizontal. (Reproduced from Fig. 6 of Ref. 107, with permission.)...

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