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This work explores the investigation of tin monochalcogenides i.e. SnX (X: S, Se, Te) at room temperature (300 K). The mechanical, thermophysical and ultrasonic properties of SnX (X: S, Se, Te) have been evaluated using the computed values of second- and third-order elastic constants (SOECs and TOECs). The SOECs and TOECs have been obtained using Born–Mayer potential model at 0 K and 300 K. The brittleness behavior of tin monochalcogenides is detected by Pugh's ratio. It is observed that phonon–phonon interaction mechanism is dominant in tin monochalcogenides leading to high ultrasonic attenuation. The obtained temperature dependence behavior of tin monochalcogenides is validated via comparison with available works of literature data in previous works done experimentally as well as theoretically by others. [ABSTRACT FROM AUTHOR]

In this work, we have verified how non-destructive ultrasonic evaluation allows for acoustically characterizing different varieties of wine. For this, a 3.5 MHz transducer has been used by means of an immersion technique in pulse-echo mode. The tests were performed at various temperatures in the range 14–18 °C. The evaluation has been carried out studying, on the one hand, conventional analysis parameters (velocity and attenuation) and, on the other, less conventional parameters (frequency components). The experimental study comprised two stages. In the first, the feasibility of the study was checked by inspecting twelve samples belonging to six varieties of red and white wine. The results showed clearly higher ultrasonic propagation velocity values in the red wine samples. In the second, nine samples of different monovarietal wine varieties (Grenache, Tempranillo and Cabernet Sauvignon) were analyzed. The results show how ultrasonic velocity makes it possible to unequivocally classify the grape variety used in winemaking with the Cabernet Sauvignon variety having the highest values and the Grenache the lowest. In addition, the wines of the Tempranillo variety are those that present higher values of the attenuation coefficient, and those from the Grenache variety transmit higher frequency waves. [ABSTRACT FROM AUTHOR]

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The ultrasonic characteristics of dysprosium monochalcogenides, DyX (X = S, Se and Te) as a function of temperature and crystallographic direction, are studied in present investigation. First, the second- and third-order elastic constants (SOECs and TOECs) have been computed using Coulomb and Born-Mayer potential from 0K to 500K. The mechanical properties have been evaluated with the achieved values of SOECs for finding the intrinsic properties, stability and futuristic performance of DyX. The mechanical stability and elastic moduli follow the order DyS > DySe > DyTe. Supplemental the acoustic velocities including Debye average velocity, thermal relaxation time, Debye temperature and nonlinear parameter have been computed along <100>, <110> and <111> directions in the temperature range 100K to 500K. The Debye average velocity is found to be highest for wave propagating along <110> and polarized along <...0>. Finally, the ultrasonic attenuation using the modified Mason's approach has been computed in the temperature regime 100-500K along different crystallographic directions and calculated results predict that Akheiser damping dominates over the thermal attenuation. The obtained results have been analyzed and discussed with the available literature. [ABSTRACT FROM AUTHOR]

Real time online detection of the particle size of the overflow in the selection and classification of fine-grained coal can be carried out, and the classification parameters can be adjusted to reduce the content of coarse particles in the overflow and improve the total clean coal recovery rate. The current research generally limits the detection of overflow particle size to around 180 μm, and the upper limit of slurry volume concentration is 10%. It cannot meet the requirements of overflow particle size detection for fine-grained coal classification cyclones with coarse particle size, wide particle size range, and high volume concentration. A set of ultrasonic online particle size detection system has been developed to improve the upper limit of coal particle size and slurry volume concentration detection. Based on the ultrasonic attenuation model, a coal particle size detection model suitable for on-site conditions of fine-grained coal classification with coal particle size of 44.5-600 μm and slurry volume concentration of 0-40% is constructed. A coal particle size distribution prediction model is established using a BP neural network optimized by particle swarm optimization algorithm, achieving the prediction of the particle size distribution of the overflow slurry in a fine-grained coal classification cyclone. The simulation results based on the coal particle size detection model show that the ultrasonic attenuation value decreases first and then increases with the increase of coal particle size, and increases with the increase of ultrasonic frequency and slurry volume concentration. The ultrasonic online particle size detection system and coal particle size distribution prediction model are respectively used to detect the distribution of overflow particle size (actual value is 150.0, 215.0, 315.0 μm) in a hydraulic classification cyclone of a certain mine. The results show that the relative errors of the measurement values of the detection system are 10.87%, 9.81%, 8.48%, and the relative errors of the predicted values of the prediction model are 9.27%, 6.05%, and 6.92%. It indicates that the research have achieved accurate detection of overflow particle size in fine-grained coal classification.

Ultrasonic attenuation measurements were conducted on cross-ply and quasi-isotropic lay-ups of eight types of carbon-fiber reinforced composites (CFRPs) using through-transmission methods with diffraction correction. Attenuation values were substantially higher than those of unidirectional composites and other structural materials. Wave modes, fiber distributions, matrix resins, and consolidation methods affected total attenuation. Transverse mode, quasi-isotropic lay-up, and polyimide and thermoplastic resins generally produced higher attenuation. No clear trends from the fiber distribution were revealed, indicating that it is not feasible presently to predict the attenuation of various lay-ups from the unidirectional values. That is, direct attenuation tests for different laminate lay-ups are needed. This work expanded the existing attenuation database by properly determining the attenuation coefficients of two additional layup types of CFRP laminates. Results showed the merit of ultrasonic attenuation measurements for quality control and structural health monitoring applications. A crucial benefit of the through-transmission methods is that they enable the prediction of Lamb wave attenuation in combination with software like Disperse (ver. 2.0.20a, Imperial College, London, UK, 2013). [ABSTRACT FROM AUTHOR]

In this paper, ultrasonic attenuation of the transverse waves of engineering materials is evaluated, covering metals, ceramics, polymers, fiber-reinforced plastics, and rocks. After verifying experimental methods, 273 measurements are conducted and their results are tabulated. Fifty of the tests are for the longitudinal mode. Attenuation behavior is determined over broadband spectra. The attenuation spectra are characterized in four patterns, with 2/3 of the tests showing linear frequency dependence and another ¼ linear spectrum plus Rayleigh scattering (Mason-McSkimin relation). The longitudinal and transverse damping factors varied from 0.004 to 0.065, which are 1/3 to 5 times those of polymethyl methacrylate, suggesting that almost all the engineering materials tested may be viscoelastic. The present test results make the term dynamic viscosity more appropriate for exploring the underlying processes. The observed results were compared between the longitudinal and transverse modes and among similar material types. In more than a half of the tests, the transverse attenuation coefficients were higher than the corresponding longitudinal attenuation coefficients by 1.5× or more. Some material groups had similar attenuation coefficients for the two modes. Since the physical basis for viscous damping is hardly understood, especially in hard solids, further studies from new angles are keenly desired. This collection of new attenuation data will be of value for such works. Practically, this will assist in materials selection and in designing structural health monitoring and non-destructive inspection protocols.

In this paper, ultrasonic attenuation of engineering materials is evaluated comprehensively, covering metals, ceramics, polymers, fiber-reinforced composites, wood, and rocks. After verifying two reliable experimental methods, 336 measurements are conducted and their results are tabulated. Attenuation behavior is determined over broadband spectra, extending up to 15 MHz in low attenuating materials. The attenuation spectra are characterized in combination with four power law terms, with many showing linear frequency dependence, with or without Rayleigh scattering. Dislocation damping effects are re-evaluated and a new mechanism is proposed to explain some of the linear frequency dependencies. Additionally, quadratic and cubic dependencies due to Datta–Kinra scattering and Biwa scattering, respectively, are used for some materials to construct model relations. From many test results, some previously hidden behaviors emerged upon data evaluation. Effects of cold working, tempering, and annealing are complex and sometimes contradictory. Comparison to available literature was attempted for some, but most often prior data were unavailable. This collection of new attenuation data will be of value in materials selection and in designing structural health monitoring and non-destructive inspection protocols.

This article reports on the characterization of the "as-fabricated" state of Inconel 718 samples fabricated using laser directed energy deposition (DED). Laser-DED is known to produce complex metastable microstructures that can significantly influence the baseline ultrasonic response compared to conventional processing methods. The present work uses three parameters to characterize the samples: (a) ultrasonic velocity, (b) an attenuation coefficient, and (c) a backscatter coefficient. The baseline ultrasonic response from the DED sample was compared against the ultrasonic properties of conventional IN718 samples reported in the literature. The results suggest that strong grain boundary scattering from large macrograins can lead to attenuation and backscatter values that are significantly higher than conventional samples. Additionally, the results including velocities, attenuation and backscatter coefficients were found to be dependent on the fabrication direction, with the build direction being different from the transverse directions. Finally, destructive analysis was used to develop conjectures to explain the experimentally observed ultrasonic response. [ABSTRACT FROM AUTHOR]

Concentrated suspensions were prepared from submicron cerium oxide particles, and particle size distribution (PSD) and zeta potential of the particles were researched by ultrasonic attenuation technology and electroacoustic theory. The influences of particle concentration, base solution and pH value on particle dispersion behavior in suspensions were analyzed. It was found that for suspensions with concentration from 10 wt% to 30 wt%, the ceria particles were dispersed most sufficiently in the suspensions with sodium hexametaphosphate (SHP), while for suspensions with concentration 40 wt%, the particles were dispersed most sufficiently in the suspensions with deionized water (DIW) only. On the other hand, the particles agglomerated most remarkably in all suspensions with sodium carboxymethyl cellulose (CMC), and they had the lowest value of zeta potential. It was deduced that higher zeta potential could be helpful for particle dispersion in these concentrated suspensions, while non-DLVO interaction and dispersing process might play important roles too. [ABSTRACT FROM AUTHOR]

Flow accelerated corrosion generates not only pipe-wall thinning but also roughness on an inside wall. In some flow conditions, the increase in roughness can increase the mass transfer coefficient by up to 80%. It is then very important to have an evaluation tool to monitor and quantify the roughness of a pipe. This study aims to estimate the roughness by using ultrasonic attenuation. The advantage of using ultrasonic attenuation is that it utilizes the signals measured by existing ultrasonic probes, and does not require significant changes to the equipment. To evaluate the inner rough surface, this study compares ultrasonic attenuations on random and periodic rough surfaces. We used an ultrasonic broadband probe on specimens with random and periodic rough surfaces in experiments. The results indicate a significant difference between the attenuation values estimated on random and periodic roughness. In addition, attenuation of amplitude at specific frequencies also was observed. These specific frequencies implied having the potential to estimate the pitch of periodic flaws on the rough surface. [ABSTRACT FROM AUTHOR]

This work reports measurements of the speed of sound and ultrasonic attenuation in high concentration (up to 3 g · L−1) aqueous TiO2 slurries close to neutral pH. Measurements were made at frequencies of 1675, 5545, and 9340 kHz using ultrasonic transducers submerged in the slurry. The experimental setup may be applied to slurries in practical reactors while in operation. Within an experimental uncertainty of ±0.5 m · s−1, the speed of sound in the slurry was the same as in pure water, at all the studied catalyst concentrations and frequencies. The excess ultrasonic attenuation with respect to pure water increases linearly with the catalyst concentration and is inversely proportional to the square of the excitation frequency. This indicates that viscous and thermal acoustic losses predominate over scattering. For TiO2 concentrations in the range of 0.15–3 g · L−1, the catalyst concentration in the slurry may be estimated as a linear function of the excess ultrasonic attenuation, with an uncertainty of 0.1 g · L−1. [ABSTRACT FROM AUTHOR]

The paper investigates the occurrence of relaxation processes in enzymatic hydrolysis of whey proteins in phosphate buffer using high-resolution ultrasonic spectroscopy. The hydrolysis produces a frequency-dependent evolution of ultrasonic velocity and attenuation originated by the proton transfer between the phosphate ions and the terminal − N H 2 group of protein hydrolysates. Such frequency dependence is absent in other systems, e.g., Tris buffer. Real-time profiles of ultrasonic velocity and attenuation measured during the hydrolysis of β–lactoglobulin, α–lactalbumin and bovine serum albumin by α–chymotrypsin were employed in quantitative analysis of the relaxation mechanisms, relaxation times, determination of the proton transfer rate constants and the reaction volume. The proton transfer is characterised by the rate constant 9.4 × 107 L mol−1 s−1 and the adiabatic reaction volume 24 × 10−6 m3 mol−1. The obtained reaction volume agrees well with thermodynamic data for ionisation volumes and enthalpies of the terminal amino group and phosphate. The described methodology for estimating the relaxation contribution to ultrasonic characteristics allows for precision real-time ultrasonic measurements of the concentration of peptide bonds cleaved during protein hydrolysis in a broad range of environmental conditions. [Display omitted] • Precision real-time monitoring of protein hydrolysis with HR-US. • Evolution of ultrasonic characteristics during hydrolysis is frequency dependent. • Relaxation processes accompanying protein hydrolysis were analysed. • Kinetics and thermodynamics of peptide-phosphate proton transfer was studied. • Ionic effects on kinetics and thermodynamics of the proton transfer were described. [ABSTRACT FROM AUTHOR]

Ultrasonic attenuation coefficients of ceramic and inorganic materials were determined for the longitudinal and transverse wave modes. Sample materials included hard and soft ceramics, common ceramics, ceramic-matrix composites, mortars, silicate glasses, rocks, minerals and crystals. For ceramic attenuation measurements, a standardized method has existed, but this method based on a buffer-rod arrangement was found to be inconsistent, producing vastly different results. Resonant ultrasound spectroscopy was also found to be unworkable from its sample preparation requirements. Experimental reevaluation of the buffer-rod method showed its impracticality due to unpredictable reflectivity parameters, yielding mostly negative attenuation coefficients. In this work, attenuation tests relied on a through-transmission method, which incorporated a correction procedure for diffraction losses. Attenuation exhibited four types of frequency (f) dependence, i.e., linear, linear plus f4 (called Mason-McSkimin relation), f2 and f3. The first two types were the most often observed. Elastic constants of tested materials were also tabulated, including additional samples too small for attenuation tests. Observed levels of attenuation coefficients will be useful for designing test methods for ultrasonic nondestructive evaluation and trends on ultrasonic attenuation are discussed in terms of available theories. However, many aspects of experimental findings remain unexplained and require future theoretical developments and detailed microstructural characterization. This study discovered a wide range of attenuation behaviors, indicating that the attenuation parameter can aid in characterizing the condition of intergranular boundaries in combination with imaging studies. [ABSTRACT FROM AUTHOR]

In this paper, ultrasonic attenuation and electroacoustic techniques are proposed to study the dispersion behaviors and properties of binary particles in high-concentration suspension, to provide an effective characterization method for the design, preparation, and application of complex suspensions with nano- and microparticles. Both suspensions with binary and identical particles were prepared, with submicron cerium oxide (CeO2) particles and micron carbonyl iron powder (CIP) particles, respectively. The particle size distribution (PSD) in suspensions with binary particles was analyzed based on ultrasonic attenuation spectra with different models, and their zeta potential was analyzed based on electroacoustic measurements with different models too. The results showed that the zeta potential signs of CeO2 and CIP particles in suspensions with identical particles were opposite, and the pH value, zeta potential, and dispersion state of CeO2 and CIP particles changed significantly after mixing. The PSD and zeta potential of the binary particles obtained from the effective medium model had large deviations. The binary phase model can obtain accurate zeta potential of binary particles in suspensions, but it obtained PSD of binary particles with some deviation due to agglomeration. The equivalent volume model was brought forward to analyze the actual state of these particles with small density contrast. In these suspensions, the binary particles could be dispersed more efficiently than those in suspensions with identical particles, although there still did exist some agglomerates in the binary suspensions. These results provide a new technique and method for studying the behavior and properties of binary particles in high-concentration complex suspensions. [ABSTRACT FROM AUTHOR]

In the present study, elastic, mechanical, thermo-physical and ultrasonic properties of boron monopnictides BX (X = N, P, As) in both NaCl (B1) and CsCl (B2) phases have been investigated at room temperature. Coulomb and Born–Mayer potential model has been used for the calculation of second- and third-order elastic constants (SOECs and TOECs) of BX in both B1 and B2 phases. The calculated values of SOECs have been applied for the evaluation of the mechanical properties of these compounds using Voigt–Reuss–Hill approximation. The Born stability criteria and Vicker's hardness parameter (H) have been used for the analysis of nature and strength of the chosen materials. Later on, ultrasonic velocities including Debye average velocities have been evaluated utilizing calculated values of SOECs and density of the chosen materials. Thermal properties of the materials such as the lattice thermal conductivity, thermal relaxation time, thermal energy density and acoustic coupling constant have been also computed along < 100 > direction. These computed thermo-physical properties indicate that BP and BAs show metallic behaviour in B1 phase, while BN shows a metallic behaviour in both phases. Finally, ultrasonic attenuation has been estimated for these materials at room temperature along < 100 > direction. The obtained results have been compared with available results and discussed with available findings on these types of materials. [ABSTRACT FROM AUTHOR]

Non-destructive pulse-echo ultrasonic testing was conducted to measure ultrasonic parameters, i.e. longitudinal velocity (Vl), shear velocity (Vs) and attenuation coefficient (α) in Al–Al2O3 nanocomposites. Elastic constants were also determined using the relationship between Vl and Vs. The aim was to reveal the correlation between ultrasonic parameters and the microstructural features of Al–Al2O3 nanocomposites. The effect of addition of Al2O3 nanoparticles on the Vl and Vs velocities is mainly attributed to variation in the elastic modulus of Al–Al2O3 nanocomposites. Both Vl and Vs velocities and Young's modulus (E) were found to vary approximately in linear fashion with the increase of Al2O3 content. A considerable effect of milling process on Vl and Vs velocities was revealed, where they increase by increasing the milling time. The increment of Vl and Vs is owing to refinement of Al particles, homogenous dispersion of Al2O3 and particularly reducing porosity by proceeding milling time. In addition, increasing of Al2O3 content, better dispersion uniformity of Al2O3 and refinement of Al particles contribute to increase α values. Elastic constants were found to vary in the same manner as ultrasonic velocities. Interestingly, the improvement in E values by increasing Al2O3 content and milling time is attained, while the ductility did not change significantly.

A flow pattern identification method combining ultrasonic transmission attenuation with an ultrasonic reflection echo is proposed for oil–water two-phase flow in horizontal pipelines. Based on the finite element method, two-dimensional geometric simulation models of typical oil–water two-phase flow patterns are established, using multiphysics coupling simulation technology. An ultrasonic transducer test system of a horizontal pipeline with an inner 50 mm diameter was built, and flow pattern simulation experiments of oil–water two-phase flow were carried out in the tested field area. The simulation results show that the ultrasonic attenuation coefficient is extracted to identify the W/O&O/W dispersion flow using the ultrasonic transmission attenuation method, and the identification accuracy is 100%. By comparison, using the ultrasonic reflection echo method, the echo duration is extracted as an input feature vector of support vector machine (SVM), and the identification accuracy of the stratified flow and dispersed flow is 95.45%. It was proven that the method of the ultrasonic transmission attenuation principle combined with the ultrasonic reflection echo principle can identify oil–water two-phase flow patterns accurately and effectively, which provides a theoretical basis for the flow pattern identification of liquid–liquid multiphase flow. [ABSTRACT FROM AUTHOR]

The control of lubricating oil degradation is usually done by physical-chemical techniques. However, these techniques are not practical because they are time-consuming and destructive. In order to examine the feasibility of quality control in a non-destructive manner, the ultrasonic technique by reflection under normal incidence with immersion in water has been used. In this experimental study, the evolution of the ultrasonic parameters has been followed in different oil samples, taken every 10000 km, i.e. as a function of the mileage covered by the vehicle. In parallel to these ultrasonic measurements, the evolution of the physical parameters (hot and cold kinematic viscosity, dynamic viscosity, viscosity index) has been also followed in order to verify the existence of such a correlation between these parameters and the ultrasonic measurements. The analysis of the experimental results obtained shows the existence of a perfect correlation between ultrasonic attenuation and viscosity. This experimental work enables to find out that attenuation is the most decisive ultrasonic parameter to characterize the quality of lubricating oil. [ABSTRACT FROM AUTHOR]

The acoustic coupling constant D, is related to the change in elastic modulus caused by strain: HT ht Graph (16)Where HT ht and HT ht are square average and average square Grüneisen parameters, respectively. [Extracted from the article]

This work determined the attenuation coefficients of Lamb waves of ten engineering materials and compared the results with calculated Lamb-wave attenuation coefficients, α–S and α–A. The Disperse program and a parametric method based on Disperse results were used for calculations. Bulk-wave attenuation coefficients, αL and αT, were required as input parameters to the Disperse calculations. The calculated α–S and α–A values were found to be dominated by the αT contribution. Often α–Ao coincided with αT. The values of αL and αT were previously obtained or newly measured. Attenuation measurement relied on Lamb-wave generation by pulsed excitation of ultrasonic transducers and on surface-displacement detection with point contact receivers. The frequency used ranged from 10 kHz to 1 MHz. A total of 14 sheet and plate samples were evaluated. Sample materials ranged from steel, Al, and silicate glass with low attenuation to polymers and a fiber composite with much higher attenuation. Experimentally obtained Lamb-wave attenuation coefficients, α–S and α–A, for symmetric and asymmetric modes, were mostly for the zeroth mode. Plots of α–So and α–Ao values against frequency were found to coincide reasonably well to theoretically calculated curves. This study confirmed that the Disperse program predicts Lamb-wave attenuation coefficients for elastically isotropic materials within the limitation of the contact ultrasonic techniques used. Further refinements in experimental methods are needed, as large deviations often occurred, especially at low and high frequencies. Methods of refinement are suggested. Displacement measurements were quantified using Rayleigh wave calibration. For signals below 300 kHz, 1-mV receiver output corresponded to 1-pm displacement. Peak displacements after 200-mm propagation were found to range from 10 pm to 1.5 nm. With the use of signal averaging, the point-contact sensor was capable of detecting 1-pm displacement with 40 dB signal-to-noise ratio and had equivalent noise of 4.3 fm/√Hz. Approximate expressions for α–So and α–Ao were obtained, and an empirical correlation was found between bulk-wave attenuation coefficients, i.e., αT = 2.79 αL, for over 150 materials. [ABSTRACT FROM AUTHOR]

This paper described the behaviours of four divalent metal fluorides ( CaF 2 , SrF 2 , CdF 2 and BaF 2) in terms of their superior elastic, mechanical and thermophysical properties. Initially, higher-order elastic constants of the chosen divalent metal fluorides have been calculated using the Coulomb and Born–Mayer interaction potential in the temperature regime 100–300 K. With the help of these constants, other elastic moduli, such as Young’s modulus (Y), bulk modulus (B), shear modulus (G), Poisson’s ratio (σ) and Pugh’s ratio (B/G) have been computed using Voigt–Reuss–Hill approximation. The Born stability criteria and Vicker’s hardness parameter (H ν) have been used for analysing the nature and strength of the materials. Later on, ultrasonic velocities including Debye average velocities were evaluated using calculated values of second-order elastic constants and density in the same physical conditions. Thermal properties such as the lattice thermal conductivity, thermal relaxation time, thermal energy density and acoustic coupling constant have also been computed at the same physical conditions and along ⟨ 100 ⟩ . The temperature-dependent ultrasonic properties have been correlated with other thermophysical properties to extract important information about the microstructural quality and the nature of the materials. The obtained results have been analysed to explore the inherent properties of the chosen divalent metal fluorides, which are useful for numerous industrial applications. [ABSTRACT FROM AUTHOR]

Determinations of higher order elastic constants, thermal properties, mechanical properties and ultrasonic behavior have been done for fermium monopnictides. Initially, the lattice and non-linearity parameters were used to compute the higher order elastic constants at temperatures of0K, 100K, 200K and 300K by means of the Born potential mode. Variation of Cauchy’s relations has been found at higher temperature due to weak atomic interactions. The second order elastic constants (SOECs) were used to estimate mechanical parameters such as the Young’s modulus, bulk modulus, Pugh’s ratio, shear modulus, Zener’s anisotropy factor, hardness, and Poisson ratio. On the basis of the values of these parameters, we found a brittle nature of fermium monopnictides. Furthermore, the SOECs were applied to compute the wave velocities for shear and longitudinal modes of propagation along , and crystallographic orientations. Properties such as the lattice thermal conductivity, acoustic coupling constant, thermal relaxation time and attenuation of ultrasonic waves due to thermo-elastic and phonon-phonon interaction mechanisms have been calculated at room temperature. The results of present investigation have been analysed with available findings on other rare-earth materials.

Bubbles with a diameter less than 1μm are called ultrafine bubbles (UFB). And UFB is expected to be applied in the environment, agriculture and medical treatment. In this study, we will examine the possibility by using ultrasonic waves and ultrapure water (UPW), also the attenuation characteristics of UFB water, to analyze the properties of UFB. The attenuation characteristics of UFB water in broadband ultrasound waves up to 32.5 MHz were investigated. In the 1.5-2.5 MHz ultrasonic band, the attenuation coefficient in the near-field was relatively close to the theoretical value calculated from the bubble density measurement results. For the 32.5 MHz ultrasound, there was a clear difference in the attenuation coefficient for the bubble density distribution between the UPW and the UFB water. In addition, the change in the number density distribution of bubbles and the change in the attenuation coefficient were observed depending on the elapsed days after UFB generation. It is possible that the change is related to the increase in the bubble diameter of the UFB. [ABSTRACT FROM AUTHOR]

Ultrasonic attenuation coefficients of ceramic and inorganic materials were determined for the longitudinal and transverse wave modes. Sample materials included hard and soft ceramics, common ceramics, ceramic-matrix composites, mortars, silicate glasses, rocks, minerals and crystals. For ceramic attenuation measurements, a standardized method has existed, but this method based on a buffer-rod arrangement was found to be inconsistent, producing vastly different results. Resonant ultrasound spectroscopy was also found to be unworkable from its sample preparation requirements. Experimental reevaluation of the buffer-rod method showed its impracticality due to unpredictable reflectivity parameters, yielding mostly negative attenuation coefficients. In this work, attenuation tests relied on a through-transmission method, which incorporated a correction procedure for diffraction losses. Attenuation exhibited four types of frequency (f) dependence, i.e., linear, linear plus f4 (called Mason-McSkimin relation), f2 and f3. The first two types were the most often observed. Elastic constants of tested materials were also tabulated, including additional samples too small for attenuation tests. Observed levels of attenuation coefficients will be useful for designing test methods for ultrasonic nondestructive evaluation and trends on ultrasonic attenuation are discussed in terms of available theories. However, many aspects of experimental findings remain unexplained and require future theoretical developments and detailed microstructural characterization. This study discovered a wide range of attenuation behaviors, indicating that the attenuation parameter can aid in characterizing the condition of intergranular boundaries in combination with imaging studies.

Dispersion behaviors of ceria (CeO2) particles in polishing slurries have direct influence on surface quality, especially for ultra-smooth optics, but their actual states have not been characterized and understood well due to much low concentration limit of traditional analysis technologies. In this work, we study dispersion and agglomeration behaviors of submicron ceria particles in concentrated slurries with ultrasonic attenuation technology and electroacoustic technology, where particle size distribution (PSD) models and their base transformation are analyzed at beginning. It is found that obtained volume-based PSDs are much wide lognormal ones, and they should be transformed to number-based ones and corrected. The number-based upper size, d99, is in the range from 0.1 to 0.8 μm mainly. And zeta potential of the ceria particles in these slurries could be obtained by the advanced electroacoustic theories in direct measurement, with values between 0 and − 60 mV. The ceria particles have different dispersion behaviors and zeta potential values in these slurries, and higher zeta potential values could promote particle dispersion in the slurry with de-ionized water, which can be explained well by the extended Derjaguin–Landau–Verwey–Overbeek theory. These results would provide useful guideline to characterize, understand, and optimize dispersion behaviors of engineered particles in concentrated slurries. The volume-based d99 and zeta potential of the ceria particles in 20 wt% slurries with different carrier liquids. [ABSTRACT FROM AUTHOR]

• A novel ultrasonic coda wave method is developed for grain size evaluation. • A piecewise energy attenuation scheme deals with different attenuation modes. • It evaluates a whole part from a single location using one-pass testing data. • Lab specimens and realistic parts verify relative errors are less than 20% Grain size is one of the key microstructural factors affecting the mechanical properties of polycrystalline metal materials. In this study, a novel method for grain size evaluation using ultrasonic coda waves is proposed. Different from conventional bulk wave methods that require a point-by-point scanning of the structure, the proposed method allows for a rapid evaluation of the average grain size of the whole part from a single inspection location using one-pass testing data. A piecewise energy attenuation function dealing with different attenuation mechanisms is proposed to obtain the effective attenuation coefficient of coda waves. A power-law model is constructed to correlate the effective attenuation coefficient with the average grain size. Ultrasonic testing on nickel-based superalloy plate specimens with different average grain sizes is performed for model calibration and method verification. The applicability and robustness of the proposed method are further validated using a realistic turbine disk specimen with an irregular shape and non-uniform grain sizes. Results show that the proposed method yields a reliable and accurate estimation of the average grain size with a maximum relative error less than 20 %. [ABSTRACT FROM AUTHOR]

Internal casting defects that are detected by radiography may also be detected by ultrasonic method. Ultrasonic testing allows investigation of the cross-sectional area of a casting, it is considered to be a volumetric inspection method. The high frequency acoustic energy travels through the casting until it hits the opposite surface or an interface or defect. The interface or defect reflects portions of the energy, which are collected in a receiving unit and displayed for the analyst to view. The pattern of the energy deflection can indicate internal defect. Ultrasonic casting testing is very complicated in practice. The complications are mainly due to the coarse-grain structure of the casting that causes a high ultrasound attenuation. High attenuation then makes it impossible to test the entire volume of material. This article is focused on measurement of attenuation, the effect of probe frequency on attenuation and testing results.

In the present study, ultrasonic and thermophysical behaviour of thermoelectric hexagonal structured HfX2 (X = S, Se) compounds have been analysed by the theoretical evaluation of second and third order elastic constants (SOECs and TOECs) using many body interaction potential model. The computed SOECs have been used to determine the temperature dependent specific heat, thermal energy density, elastic coupling constants, Grüneisen parameters, ultrasonic velocities, Debye average velocity, ultrasonic attenuation, and thermal relaxation time. We have observed that the temperature dependent ultrasonic attenuation and thermal relaxation time for HfX2 are mainly affected by thermal conductivity. The elastic properties of the material are compared with existing data in literature for the validation of the work. The obtained values of elastic stiffness are found very large in comparison to that of other material from transition metal dichalcogenides of group IVB indicating better mechanical properties than the same group materials. Calculated elastic, thermal, and ultrasonic properties are correlated for better characterization of the materials which are useful for thermoelectric and energy transport applications. [ABSTRACT FROM AUTHOR]

In this paper, we present a method to recover the complex wavenumber dispersion relations using spatial Laplace transform from experimental spatiotemporal signals measured by laser ultrasonic technique. The proposed method was applied on zero-group-velocity Lamb modes in order to extract the ultrasonic attenuation in a polycrystalline aluminum plate of about 70 μm thickness. The difference between the experimental and theoretical Laplace Fourier transforms was minimized in the least square sense to extract the complex amplitudes and complex wavenumbers of the modes at about 40 MHz. The experimental results were compared to values reported in the literature that were measured by other means and those estimated by using the quality factor extracted from a single temporal signal. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This work determined the attenuation coefficients of Lamb waves of ten engineering materials and compared the results with calculated Lamb-wave attenuation coefficients, α–S and α–A. The Disperse program and a parametric method based on Disperse results were used for calculations. Bulk-wave attenuation coefficients, αL and αT, were required as input parameters to the Disperse calculations. The calculated α–S and α–A values were found to be dominated by the αT contribution. Often α–Ao coincided with αT. The values of αL and αT were previously obtained or newly measured. Attenuation measurement relied on Lamb-wave generation by pulsed excitation of ultrasonic transducers and on surface-displacement detection with point contact receivers. The frequency used ranged from 10 kHz to 1 MHz. A total of 14 sheet and plate samples were evaluated. Sample materials ranged from steel, Al, and silicate glass with low attenuation to polymers and a fiber composite with much higher attenuation. Experimentally obtained Lamb-wave attenuation coefficients, α–S and α–A, for symmetric and asymmetric modes, were mostly for the zeroth mode. Plots of α–So and α–Ao values against frequency were found to coincide reasonably well to theoretically calculated curves. This study confirmed that the Disperse program predicts Lamb-wave attenuation coefficients for elastically isotropic materials within the limitation of the contact ultrasonic techniques used. Further refinements in experimental methods are needed, as large deviations often occurred, especially at low and high frequencies. Methods of refinement are suggested. Displacement measurements were quantified using Rayleigh wave calibration. For signals below 300 kHz, 1-mV receiver output corresponded to 1-pm displacement. Peak displacements after 200-mm propagation were found to range from 10 pm to 1.5 nm. With the use of signal averaging, the point-contact sensor was capable of detecting 1-pm displacement with 40 dB signal-to-noise ratio and had equivalent noise of 4.3 fm/√Hz. Approximate expressions for α–So and α–Ao were obtained, and an empirical correlation was found between bulk-wave attenuation coefficients, i.e., αT = 2.79 αL, for over 150 materials.

This work evaluates the ultrasonic scattering attenuation of structures with complex scatterer distributions via experimental and simulation studies. The proposed approach uses experimental attenuation knowledge to infer the scatterer size and its concentration in the studied structures, which are important for the effective construction of simulated models. The MATLAB k-Wave toolbox has been used to implement the simulator. Several cast-iron samples have been used to demonstrate the importance of simulation in the characterization of such structures. First, the scattering attenuation was evaluated using the Truell and Papadakis models, and then the results were compared with experimental ones. Emphasis was given to the Papadakis approach because it takes into account the scatterer size distribution. It is demonstrated that both analytical models provide results that are far from the experimental ones. The developed simulator for the studied samples led to a predictive model, in which the attenuation was proportional to the fifth power of the scatterer size, and the corresponding formulation is close to the one proposed by the analytical models. [ABSTRACT FROM AUTHOR]

An appropriate concentration of micro/nano aluminum powder (MNAP) cloud is necessary for fuel air explosive (FAE) detonation. However, because of the fast dynamics, uncertainty interference, and transient characteristics of MNAP diffusion, experimental research on the measurement of MNAP cloud concentration is still lacking. Here, a pair of ultrasonic transducers were developed based on pulse drive, to measure the dynamic MNAP cloud concentration during MNAP diffusion in a standard 20-L explosion vessel. The measurement method was based on Lloyd-Berry ultrasonic attenuation theory. The experimental results showed that the ultrasonic pulse had a strong anti-interference ability, high precision, and real-time response to enable the characterization of MNAP diffusion concentration. The diffusion concentration gradients of MNAP were established and agreed well with the trend predicted by computational fluid dynamics simulations. The results also indicated that aluminum nanoparticles have better distribution characteristics than those of aluminum microparticles. These analyses provide technical support to improve FAE detonation energy. Unlabelled Image • Thecalculation modelis establishedofMNAP concentrationbased on Lloyd and Berry ultrasonic scattering model. • The restrictions and approximations of the used attenuation model has been detailed stated. • A CFD simulation model isestablished to analysisthe distributioncharacteristics of MNAPconcentrationcomparatively. • A dynamic concentration measurement systemof MNAPisestablishedin the 20-L spherical vessel. • The results shown thatthe feasibility and noveltyof the dynamic concentration detection system. [ABSTRACT FROM AUTHOR]

One of the important features of the fracture of heterogeneous materials with a stress concentrator is the scale effect associated with the dependence of the nominal stress on the specimen size. This effect should be taken into account by studying the fracture process of concrete to improve the operational safety of concrete structures. The aim of this work is to study the effect of sizes of the concrete specimens with a notch (concrete class B25, = 28 MPa) on the strength characteristics and parameters of acoustic emission (AE) recorded during the fracture process. Three-point bending tests with registration of AE signals were performed using specimens with three sizes (1075, 465, and 215 mm long), the geometry of which corresponded to two-dimensional similarity, since the specimen thickness remained unchanged, and both length to width ratios for the specimen and notch remained constant. The size of the zone of fracture localization at different stages of crack development was estimated on the larger specimens using the planar AE location and the time dependence of the zone size was plotted. For small specimens, the size of the localization zone was determined by measuring the ultrasonic attenuation coefficient. Analysis of the loading diagrams combined with the time dependences of the AE parameters showed that the specimen size affected the fracture staging. The dependences of the nominal strength, fracture energy, bAE parameter, and the total number of AE signals on the specimen size were plotted. It was shown that, for the large-sized specimens, the size effect was associated with the decrease in the nominal stress and number of accumulated acoustic emission signals, as well as with the increase in the fracture energy and bAE parameter. It is assumed that the change in the AE characteristics with the increase in the specimen size is determined by the decrease in the relative fraction of structural heterogeneity (the ratio of the average size of granite macadam to the specimen size) in large-size specimens. New data were obtained on the effect of the size of concrete specimens on the acoustic characteristics. [ABSTRACT FROM AUTHOR]

The elastic, thermal and ultrasonic properties of zirconium nanowire (Zr-NW) have been investigated at room temperature. The second and third order elastic constants (SOECs and TOECs) of Zr-NW have been figured out using the Lennard–Jones Potential model. SOECs have been used to find out the Young's modulus, bulk modulus, shear modulus, Poisson's ratio, Pugh's ratio, Zener anisotropic factor and ultrasonic velocities. Further these associated parameters of Zr-NW have been utilized for the evaluation of the Grüneisen parameters, thermal conductivity, thermal relaxation time, acoustic coupling constants and ultrasonic attenuation. On the basis of the above analyzed properties of Zr-NW, some characteristics features of the chosen nanowire connected with ultrasonic and thermo-physical parameters have been discussed. [ABSTRACT FROM AUTHOR]

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In this study, ultrasonic measurements were performed on a single crystal of cubic PrNi2Cd20, down to a temperature of 0.02 K, to investigate the crystalline electric field ground state and search for possible phase transitions at low temperatures. The elastic constant (C11−C12)/2, which is related to the Γ3-symmetry quadrupolar response, exhibits the Curie-type softening at temperatures below ∼30 K, which indicates that the present system has a Γ3 non-Kramers doublet ground state. A leveling-off of the elastic response appears below ∼0.1 K toward the lowest temperatures, which implies the presence of level splitting owing to a long-range order in a finite-volume fraction associated with Γ3-symmetry multipoles. A magnetic field–temperature phase diagram of the present compound is constructed up to 28 T for H || [110]. A clear acoustic de Haas–van Alphen signal and a possible magnetic-field-induced phase transition at H ∼26 T are also detected by high-magnetic-field measurements. [ABSTRACT FROM AUTHOR]

The present work explores the diameter- and temperature-dependent ultrasonic characterization of wurtzite indium phosphide nanowires (WZ-InP-NWs) using a theoretical model based on the ultrasonic non-destructive evaluation (NDE) technique. Initially, the second- and third-order elastic constants (SOECs and TOECs) were computed using the Lennard-Jones potential model, considering the interactions up to the second nearest neighbours. Simultaneously, the mechanical parameters (Young's modulus, shear modulus, elastic anisotropy factor, bulk modulus, Pugh's ratio and Poisson's ratio) were also estimated. Finally, the thermophysical properties and ultrasonic parameters (velocity and attenuation) of the InP-NWs were determined using the computed quantities. The obtained elastic/mechnical properties of the InP-NWs were also analyzed to explore the mechanical behaviors. The correlations between temperature-/size-dependent ultrasonic attenuation and the thermophysical properties were established. The ultrasonic attenuation was observed to be the third-order polynomial function of the diameter/temperature for the InP nanowire. [ABSTRACT FROM AUTHOR]

Determinations of higher order elastic constants, thermal properties, mechanical properties and ultrasonic behavior have been done for fermium monopnictides. Initially, the lattice and non-linearity parameters were used to compute the higher order elastic constants at temperatures of 0K, 100K, 200K and 300K by means of the Born potential mode. Variation of Cauchy's relations has been found at higher temperature due to weak atomic interactions. The second order elastic constants (SOECs) were used to estimate mechanical parameters such as the Young's modulus, bulk modulus, Pugh's ratio, shear modulus, Zener's anisotropy factor, hardness, and Poisson ratio. On the basis of the values of these parameters, we found a brittle nature of fermium monopnictides. Furthermore, the SOECs were applied to compute the wave velocities for shear and longitudinal modes of propagation along <100>, <110> and <111> crystallographic orientations. Properties such as the lattice thermal conductivity, acoustic coupling constant, thermal relaxation time and attenuation of ultrasonic waves due to thermo-elastic and phonon-phonon interaction mechanisms have been calculated at room temperature. The results of present investigation have been analysed with available findings on other rare-earth materials. [ABSTRACT FROM AUTHOR]

The article deals with ultrasonic testing possibilities of the copper alloy centrifugal casts. It focused on the problems that arise when testing of castings is made of non-ferrous materials. Most common types of casting defects is dedicated in theoretical introduction of article. Ultrasonic testing technique by conventional ultrasound system is described in the theoretical part too. Practical ultrasonic testing of centrifugal copper alloy cast - brass is in experimental part. The experimental sample was part of centrifugally cast brass ring with dimensions of Ø1200x34 mm. The influence of microstructure on ultrasonic attenuation and limitations in testing due to attenuation is describes in experimental part. Conventional direct single element contact ultrasound probe with frequencies of 5 MHz, 3.5 MHz and 2 MHz were used for all experimental measurements. The results of experimental part of article are recommendations for selecting equipment and accessories for casting testing made of non-ferrous metals.

In this paper, we present a method to recover the complex wavenumber dispersion relations using spatial Laplace transform from experimental spatiotemporal signals measured by laser ultrasonic technique. The proposed method was applied on zero-group-velocity Lamb modes in order to extract the ultrasonic attenuation in a polycrystalline aluminum plate of about 70 μm thickness. The difference between the experimental and theoretical Laplace Fourier transforms was minimized in the least square sense to extract the complex amplitudes and complex wavenumbers of the modes at about 40 MHz. The experimental results were compared to values reported in the literature that were measured by other means and those estimated by using the quality factor extracted from a single temporal signal.

The quality factor (or Q value) is an important parameter for characterizing the inelastic properties of rock. Achieving a Q value estimation with high accuracy and stability is still challenging. In this study, a new method for estimating ultrasonic attenuation using a spectral ratio based on an S transform (SR-ST) is presented to improve the stability and accuracy of Q estimation. The variable window of ST is used to solve the time window problem. We add two window factors to the Gaussian window function in the ST. The window factors can adjust the scale of the Gaussian window function to the ultrasonic signal, which reduces the calculation error attributed to the conventional Gaussian window function. Meanwhile, the frequency bandwidth selection rules for the linear regression of the amplitude ratio are given to further improve stability and accuracy. First, the feasibility and influencing factors of the SR-ST method are studied through numerical testing and standard sample experiments. Second, artificial samples with different Q values are used to study the adaptability and stability of the SR-ST method. Finally, a further comparison between the new method and the conventional spectral ratio method (SR) is conducted using rock field samples, again addressing stability and accuracy. The experimental results show that this method will yield an error of approximately 36% using the conventional Gaussian window function. This problem can be solved by adding the time window factors to the Gaussian window function. The frequency bandwidth selection rules and mean slope value of the amplitude ratio used in the SR-ST method can ensure that the maximum error of different Q values estimation (Q > 15) is less than 10%. [ABSTRACT FROM AUTHOR]

• Theory of higher order elastic constants is justified for the of MgB 2 single crystal. • The behaviour of sound attenuation with pressure is similar to inverse of resistivity. • At low temperature electron–phonon interaction is the prominent cause in attenuation. • The value of ultrasonic attenuation decreases as pressure increases. • The electron viscosity depends on electrical resistivity. Higher order elastic constants have been calculated in semi-metallic superconducting single crystal magnesium diboride (MgB 2) at low temperatures following the interaction potential model. Second order elastic constants are used for the determination of other ultrasonic parameters. The pressure variation of the ultrasonic velocities is evaluated using the second order elastic constants. The ultrasonic attenuation due to electron-phonon interaction has been computed at different pressures and in low temperatures range 40–90 K. We have also calculated the electron-viscosity at different low temperature, needed for the calculation of ultrasonic attenuation. The behaviour of ultrasonic attenuation is almost similar to its inverse electrical resistivity. The electron–phonon interaction, which is the dominating cause of ultrasonic attenuation, occurs at lower temperatures in MgB 2 single crystal. It has been found that the electrical resistivity is the main contributor to the behaviour of ultrasonic attenuation as a function of temperature and the responsible cause of attenuation is phonon-phonon interaction. [ABSTRACT FROM AUTHOR]