Measurement of wave velocities and attenuation using an ultrasonic test system

The use of ultrasonic testing to determine pulse velocities and small-strain elastic constants for rocks has been standardized in American Society for Testing and Materials (ASTM) standard D2845-95. However, the use of ultrasonic testing to determine pulse velocities and small-strain elastic constants of soils is less common, as soils have higher damping characteristics which result in measurement difficulty. The signal transmitted through soil is weak and very noisy. As a result, the signal must be properly processed to provide a reliable estimate of the wave travel time. In this paper, an ultrasonic test system consisting of compression and shear wave transducers, a pulser, and a data-acquisition system is evaluated for measurement of both compression and shear wave velocities. Among the specimens tested were fully saturated and unsaturated soil specimens. The effects of acoustic coupling and signal processing on the transmitted pulse were investigated. The strain levels associated with the determination of the wave velocities were also measured. Furthermore, a method for determining attenuation characteristics for soil specimens from the frequency spectra is suggested.Key words: laboratory, compression wave, shear wave, velocity, attenuation, ultrasonic.

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Sonic logging of compressional‐wave velocities in a very slow formation

Geophysics ◽

10.1190/1.1443895 ◽

1995 ◽

Vol 60 (6) ◽

pp. 1627-1633 ◽

Cited By ~ 12

Author(s):

Bart W. Tichelaar ◽

Klaas W. van Luik

Keyword(s):

Shear Wave ◽

Wave Velocity ◽

Compressional Wave ◽

P Wave ◽

Dipole Source ◽

Frequency Spectra ◽

Unconsolidated Sands ◽

Wave Velocities ◽

Shear Wave Velocities ◽

Sonic Logging

Borehole sonic waveforms are commonly acquired to produce logs of subsurface compressional and shear wave velocities. To this purpose, modern borehole sonic tools are usually equipped with various types of acoustic sources, i.e., monopole and dipole sources. While the dipole source has been specifically developed for measuring shear wave velocities, we found that the dipole source has an advantage over the monopole source when determining compressional wave velocities in a very slow formation consisting of unconsolidated sands with a porosity of about 35% and a shear wave velocity of about 465 m/s. In this formation, the recorded compressional refracted waves suffer from interference with another wavefield component identified as a leaky P‐wave, which hampers the determination of compressional wave velocities in the sands. For the dipole source, separation of the compressional refracted wave from the recorded waveforms is accomplished through bandpass filtering since the wavefield components appear as two distinctly separate contributions to the frequency spectrum: a compressional refracted wave centered at a frequency of 6.5 kHz and a leaky P‐wave centered at 1.3 kHz. For the monopole source, the frequency spectra of the various waveform components have considerable overlap. It is therefore not obvious what passband to choose to separate the compressional refracted wave from the monopole waveforms. The compressional wave velocity obtained for the sands from the dipole compressional refracted wave is about 2150 m/s. Phase velocities obtained for the dispersive leaky P‐wave excited by the dipole source range from 1800 m/s at 1.0 kHz to 1630 m/s at 1.6 kHz. It appears that the dipole source has an advantage over the monopole source for the data recorded in this very slow formation when separating the compressional refracted wave from the recorded waveforms to determine formation compressional wave velocities.

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Measuring shear and compression wave velocities of soil using bender–extender elements

Canadian Geotechnical Journal ◽

10.1139/t09-026 ◽

2009 ◽

Vol 46 (7) ◽

pp. 792-812 ◽

Cited By ~ 64

Author(s):

E. C. Leong ◽

J. Cahyadi ◽

H. Rahardjo

Keyword(s):

Shear Wave ◽

Wave Velocity ◽

Shear Wave Velocity ◽

Compression Wave ◽

Small Strain ◽

Reliable Determination ◽

Digital Oscilloscope ◽

Compression Waves ◽

Wave Velocities

Piezoceramic elements have been used for laboratory measurement of wave velocity in soil and rock specimens. Shear-wave piezoceramic elements (bender elements) are commonly used to measure shear wave velocity for the determination of small-strain shear modulus. Compression-wave piezoceramic elements (extender elements), on the other hand, are less commonly used as compression wave velocity is less frequently measured. In this paper, the performance of a pair of bender–extender elements for the determination of both shear and compression wave velocities is examined with respect to the resolution of the recorder, bender–extender element size. and excitation voltage frequency. The evaluation showed that the performance of the bender–extender elements test can be improved by considering the following conditions: (i) the digital oscilloscope used to record the bender–extender element signals should have a high analog to digital (A/D) conversion resolution; (ii) the size of the bender–extender elements plays an important role in the strength and quality of the receiver signal, especially for compression waves; and (iii) using a wave path length to wavelength ratio of 3.33 enables a more reliable determination of shear wave velocity.

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DETERMINATION OF THE ELASTIC CONSTANTS OF AN ISOTROPIC SOLID USING A “PLATE” VELOCITY MEASUREMENT

Geophysics ◽

10.1190/1.1439830 ◽

1966 ◽

Vol 31 (5) ◽

pp. 984-986 ◽

Cited By ~ 4

Author(s):

Ernest A. Kaarsberg

Keyword(s):

Shear Wave ◽

Elastic Constants ◽

High Frequency ◽

Velocity Measurement ◽

Infinite Plate ◽

Wave Velocities ◽

Shear Wave Velocities ◽

Plate Velocity ◽

Isotropic Solid

From the longitudinal and shear wave velocities measured in a solid, all of its elastic constants can be determined. Jamieson and Hoskins (1963) have shown how shear wave velocities can be measured in solids with an arrangement which converts high frequency longitudinal wave pulses from axially polarized ceramic transducers into shear wave pulses. This note illustrates how such elastic constants can also be determined with the aid of longitudinal “infinite plate” velocities.

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THE MEASUREMENT OF SHEAR‐WAVE VELOCITIES IN SOLIDS USING AXIALLY POLARIZED CERAMIC TRANSDUCERS

Geophysics ◽

10.1190/1.1439152 ◽

1963 ◽

Vol 28 (1) ◽

pp. 87-90 ◽

Cited By ~ 8

Author(s):

John C. Jamieson ◽

Hartley Hoskins

Keyword(s):

Wave Propagation ◽

Shear Wave ◽

Excellent Agreement ◽

Elastic Constants ◽

Convenient Method ◽

High Frequency ◽

Critical Angle ◽

Mode Conversion ◽

Wave Velocities ◽

Shear Wave Velocities

A double mode conversion obtained by critical‐angle reflection allows the velocity of shear‐wave propagation to be determined using longitudinally polarized ceramic discs. This method provides a simple and convenient method of obtaining high‐frequency shear waves of predeterminable polarization in the laboratory. Elastic constants of brass and Pyrex obtained with this method are in excellent agreement with those measured by the PnSP method of Hughes. This mode conversion technique, unlike the PnSP method, can be used on anisotropic materials of noncylindrical geometries.

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Determination of small-strain stiffness of Shanghai clay on prismatic soil specimen

Canadian Geotechnical Journal ◽

10.1139/t2012-050 ◽

2012 ◽

Vol 49 (8) ◽

pp. 986-993 ◽

Cited By ~ 14

Author(s):

Q. Li ◽

C.W.W. Ng ◽

G.B. Liu

Keyword(s):

Stress State ◽

Shear Wave ◽

Small Strain ◽

Triaxial Tests ◽

Shear Moduli ◽

Small Strain Stiffness ◽

Wave Velocities ◽

Shear Wave Velocities ◽

Stiffness Anisotropy ◽

Elastic Shear

Although a large number of tunnels and deep excavations have been constructed in Shanghai, small-strain stiffness properties of natural Shanghai clay have rarely been reported in the literature. In this study, the degree of inherent stiffness anisotropy of natural Shanghai clay was investigated in a triaxial apparatus equipped with local strain transducers and a shear-wave velocity measurement system. Three sets of side-mounted bender elements, consisting of one transmitter and two receivers each, were installed on a prismatic specimen. Two series of triaxial tests on prismatic specimens of intact Shanghai clay were carried out under an isotropic stress state. Shear-wave velocities and hence elastic shear moduli in different planes were determined from bender element measurements. The cross-correlation method using two received signals gives rise to the most objective and repeatable results on shear-wave velocities in comparison with other commonly used methods. Intact Shanghai clay clearly exhibits inherent stiffness anisotropy in terms of its elastic shear modulus ratio (G0(hh)/G0(hv)) of about 1.2 for a mean effective stress varying from 50 to 400 kPa. The measured higher stiffness in the horizontal plane may be attributed to the stronger layering structure in the horizontal bedding plane. A unique relationship is found that relates the normalized shear moduli to the stress state in each plane by incorporating a void ratio function in the form of F(e) = e–2.6.

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Pressure dependent ultrasonic properties of hcp hafnium metal

Zeitschrift für Naturforschung A ◽

10.1515/zna-2021-0013 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Ramanshu P. Singh ◽

Shakti Yadav ◽

Giridhar Mishra ◽

Devraj Singh

Keyword(s):

Elastic Constants ◽

Pressure Range ◽

Room Temperature ◽

Ultrasonic Attenuation ◽

Coupling Constants ◽

Ultrasonic Properties ◽

Acoustic Coupling ◽

Third Order Elastic Constants ◽

The Stability ◽

The Given

Abstract The elastic and ultrasonic properties have been evaluated at room temperature between the pressure 0.6 and 10.4 GPa for hexagonal closed packed (hcp) hafnium (Hf) metal. The Lennard-Jones potential model has been used to compute the second and third order elastic constants for Hf. The elastic constants have been utilized to calculate the mechanical constants such as Young’s modulus, bulk modulus, shear modulus, Poisson’s ratio, and Zener anisotropy factor for finding the stability and durability of hcp hafnium metal within the chosen pressure range. The second order elastic constants were also used to compute the ultrasonic velocities along unique axis at different angles for the given pressure range. Further thermophysical properties such as specific heat per unit volume and energy density have been estimated at different pressures. Additionally, ultrasonic Grüneisen parameters and acoustic coupling constants have been found out at room temperature. Finally, the ultrasonic attenuation due to phonon–phonon interaction and thermoelastic mechanisms has been investigated for the chosen hafnium metal. The obtained results have been discussed in correlation with available findings for similar types of hcp metals.

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