Wave propagation measurements shear

In the future, it is expected to be possible to make more routine use of additional wave types, specifically shear or S waves (polarised to horizontal and vertical components) which have a transverse mode of propagation, and are sensitive to a different set of rock properties than P waves. The potential then exists for increasing the number of independent attributes measured in reflection surveys and increasing the resolution of the subsurface image. 

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. 

QCM can be described as a thickness-shear mode resonator, since weight change is measured on the base of the resonance frequency change. The acoustic wave propagates in a direction perpendicular to the crystal surface. The quartz crystal plate has to be cut to a specific orientation with respect to the ciystal axis to attain this acoustic propagation properties. AT-cut crystals are typically used for piezoelectric crystal resonators[7]. The use of quartz crystal microbalances as chemical sensors has its origins in the work of Sauerbrey[8] and King [9] who... 

This chapter is concerned with just one of this class of thickeners, namely a hydrophobically modified (hydroxyethyl)cellulose (HMHEC), Hercules WSP D-47. Gelman and Barth (i) reported on the viscosity of such HMHECs. This sample contained up to four hexadecyl chains grafted to the cellulose backbone. The preparative route was that described by Landoll (2). The dilute solution properties were characterized by capillary viscom-etry, whereas the more concentrated solutions were characterized by continuous-shear viscometry, forced oscillation measurements, and shear-wave propagation. In addition, the adsorption onto polymer latex particles was investigated. 

Shear Wave Propagation. A pulse shearometer (Rank Bros.) was used to measure the propagation velocity of a shear wave through the weak gels formed by the solutions of HMHEC in dilute NaCl. The polymer concentration range studied was 0.5-2.0%. With this apparatus, the frequency of the shear wave is approximately 1200 rad s" and the strain is <10 . At this strain, n pst systems behave in a linear viscoelastic fashion, and the wave-rigidity modulus, G is... 

Field tests which are most commonly employed in geotechnical earthquake engineering can be grouped into those that measure low-strain properties and those that measure properties at intermediate to high strains. Low-strain field tests t5q)ically induce seismic waves in the soil and seek to measure the velocities at which these waves propagate. Due to low strain amplitudes the measured shear wave velocity (V ) along with soil density (p) is used to compute low-strain shear modulus. 

The shear wave velocity measurement in the field can be carried out either using borings or without borings. Seismic reflection and seismic refraction are staples of conventional geophysical exploration and can provide information on subsurface layer thickness and velocities of propagating waves without need for soil borings. 

Three estimates of the shear magnetostriction parameter have been made for Tb (fig. 6.34). By measuring the field dependence of the velocity of transverse sound waves propagating in the c-direction, Moran and Luthi 119701 deduced A" = 7.3 x 10 at 140 K (o- = 0.82). Jensen and Houmann (1975) determined a value of 8.5 x 10 at 53 K (a = 0.97) from their analysis of magnon-phonon interactions in the c-axis dispersion relation. These results are consistent with the strain gauge measurements of De Savage and Clark (1965), taken in the paramagnetic phase. 

It was these studies of the complex dielectric constant as a function of frequency which led to the search for euialogous methods of studying viscoelasticity hy measuring a complex viscosity or elastic modulus. The first success was observation of shear wave propagation in polymer solutions . The only theoretical treatment of wave propagation which could he found as a clue to analysis of the measurements was in a geophysical journal. From the wave propagation the complex shear modulus and its frequency dependence could be derived. 

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