Ultrasonic Sounding Research Articles

THE COMPARATIVE STUDY OF THE EFFECT OF LOW-INTENSITY BROADBAND AND LOW-INTENSITY PULSED ULTRASOUND ON B16 MELANOMA CELLS IN VITRO

Aim. To evaluate the effect of low-intensity broadband ultrasound (UMUS) and low-intensity pulsed ultrasound (LIPUS) on B16 melanoma cells in vitro. Methods. The research was conducted on B16 melanoma cells under two modes of low-intensity ultrasonic sounding of cells, for which an SDG 2082 X Siglent generator (USA) with an ultrasonic emitter diameter of 20 mm was used; with a frequency for UMUS of 1-7 MHz, intensity of 30 mW/cm, pulse duration of 50 μs, and for LIPUS with a frequency of 1.5 MHz, intensity of 30 mW/cm, pulse duration of 200 μs. Both modes of cell sounding were carried out with threefold irradiation, once a day after which the distribution of cells by cycle phases, the level of apoptosis and proliferative activity was determined by the method of ductal cytofluorimetry. Results. Under the influence of UMUS ultrasonic sounding, the inhibition of the proliferation of melanoma cells by 1.6 times (P<0.05), a 2-fold decrease in the content of aneuploid cells, compared to the control, was found, however, cytostatic and proapoptotic effects were not recorded. Under the influence of LIPUS sounding, an anti-proliferative effect, an increase in the content of dead and apoptotic cells and a decrease in the DI-index compared to the corresponding control were found. Conclusions. Under the action of low-intensity broadband ultrasound (UMUS) and low-intensity pulsed ultrasound (LIPUS), a cytotoxic/cytostatic and pro-apoptotic effect and a decrease in the content of the aneuploid cell population were revealed.

Comparison of ultrasonic and GPR methods for investigation of reinforced concrete columns

The presence of internal concreting defects such as pores, cavities, sinks, in load-bearing vertical structures can lead to serious consequences, up to accidents. In this regard, it is especially important to identify such defects is an important and relevant task during surveys of load-bearing structures of buildings and structures. At the same time, the search for internal defects is complicated by the fact that they may not be visible on the surface, but may be present in the body of structures. In order to control the quality of the erected monolithic structures, their instrumental examination is carried out with the identification of the possible presence of internal defects by the method of through ultrasonic sounding. The article discusses the comparison of ultrasonic and GPR methods for searching for internal defects in concreting reinforced concrete columns. The studies were carried out on real construction sites in which there were suspicions of internal defects in concreting of high columns. Conclusions are drawn about the possibilities and limitations of the methods. The resolution limits of the methods are presented. The results of the conducted studies show that, despite the relative modern popularity of ground-penetrating radar, ultrasonic methods can work equally well in this type of specific research scenario and have shown a high potential to overcome some inherent limitations of ground-penetrating radar when working with saturated reinforcement.

Multi-Parameter Methodology for Assessing Quality Indicators of Nanomodified Fiber-Reinforced Concrete for Construction Site

Nanomodified fiber-reinforced concrete is a building material for which the required characteristics of fracture toughness are a distinctive feature. Determination of the stress intensity factor of fiber-reinforced concrete makes it possible to correctly assess the resistance of the material during the formation and development of cracks. The proposed multi-parameter methodology for assessing the quality indicators of nanomodified fiber-reinforced concrete makes it possible to evaluate the quality of a fiber-reinforced concrete structure in construction and laboratory conditions. To carry out control at the construction site, modern and long-used methods of non-destructive testing are used: ultrasonic sounding, ultrasonic tomography, elastic rebound, separation with chipping. For laboratory studies, the technique provides for the manufacture of prism samples that can be molded or cut from the body of the structure. This methodology makes it possible to obtain in laboratory conditions such material parameters as tensile strength in bending, tensile strength in splitting, critical stress intensity factor for normal separation, critical stress intensity factor for transverse shear, energy consumption for individual stages of deformation and destruction of the sample, as well as to evaluate the uniformity of distribution fibers. Moreover, it is provided to obtain all the parameters on one sample from the series, which eliminates errors and inaccuracies in the quality indicators of the material associated with different conditions of hardening, molding, inaccuracies in duplicating the composition.

FRACTURE TOUGHNESS OF CARBON NANOTUBES MODIFIED CEMENT BASED MATERIALS

In order to increase the fracture toughness of concrete, dispersed fiber reinforcement is increasingly used in practice. The initiation of crack initiationoccurs at the nanoscale in the cement matrix. Thus, the use of nano-reinforcement with dispersed nanoparticles can have a positive effect on thefracture toughness of the cement composite. It is proposed to consider carbon nanotubes (CNTs) as such nanofibers.This article discusses the possibility of using nanocarbon tubes as elements for restraining the development of cracks at the nanoscale incement composite. The results of testing nanomodified cement stone for strength indicators, fracture toughness indicators, results ofnanoindentation, ultrasonic sounding and infrared spectroscopy are presented. A structural model of a cement stone dispersed-reinforced withnanocarbon tubes is considered.

Intrinsic Elastic Anisotropy of Westerly Granite Observed by Ultrasound Measurements, Microstructural Investigations, and Neutron Diffraction

AbstractWesterly granite (WG) has been generally accepted as an isotropic homogeneous rock. Here, we return to WG and observe significant elastic anisotropy using multidirectional ultrasonic sounding on spherical samples at pressures up to 400 MPa. Thermal treatment of WG leads to formation of microcracks that reduce elastic wave velocities and increase its elastic anisotropy. The 3D distribution of P‐wave velocities at low pressure is close to orthorhombic symmetry. Application of hydrostatic pressure closes most of thermally induced microcracks and decreases elastic anisotropy of WG, but at high pressure the anisotropy is practically reversed compared to low pressure: maximum P‐wave velocity direction at low pressures is near minimum velocity direction at high pressure and vice versa. To understand this effect, microstructures of the rock were investigated by optical and scanning electron microscopy. Preferred orientations of four major rock‐forming minerals—quartz, orthoclase, plagioclase, and biotite—were measured by time‐of‐flight neutron diffraction, which confirms significant crystal alignment. All these data were used to numerically model anisotropic elastic properties of WG. It is shown that WG possesses weak intrinsic elastic anisotropy related mainly to the preferred orientation of feldspars formed during igneous crystallization. Observed microcracks are mostly related to the cleavage planes of feldspars and biotite, and thus also demonstrate preferred orientation. Higher preheating temperatures produce larger quantity of longer microcracks. A numerical model shows that these microcracks act against the weak intrinsic elastic anisotropy of WG, and define the elastic anisotropy at low pressures.

Experimental study of coal fracture dynamics under the influence of cyclic freezing\u2013thawing using shear elastic waves

Cyclic freezing–thawing can lead to fracture development in coal, affecting its mechanical and consumer properties. To study crack formations in coal, an ultrasonic sounding method using shear polarized waves was proposed. Samples of three coal types (anthracite, lignite and hard coal) were tested. The research results show that, in contrast to the shear wave velocity, the shear wave amplitude is extremely sensitive to the formation of new cracks at the early stages of cyclic freezing–thawing. Tests also show an inverse correlation between coal compressive strength and its tendency to form cracks under temperature impacts; shear wave attenuation increases more sharply in high-rank coals after the first freezing cycle. Spectral analysis of the received signals also confirmed significant crack formation in anthracite after the first freeze–thaw cycle. The initial anisotropy was determined, and its decrease with an increase in the number of freeze–thaw cycles was shown. The data obtained forms an experimental basis for the development of new approaches to preserve coal consumer properties during storage and transportation under severe natural and climatic conditions.

Rayleigh surface waves in assessing the state of metal structures

The work is devoted to the search of a method of ultrasonic sounding for identification of the material state, permitting to refer the diagnosed structure to the class of structures, whose state is connected with the appearance of plastic deformations. The study has shown the application of surface Rayleigh waves allows to estimate the stress-strain state of metal structures in the field of both elastic and plastic deformation.

Press-fit joints study by multiangle ultrasonic sounding method

In the article the authors consider the problem and the way of press-fit joints quality quantitative estimation with an ultrasonic echo-impulse method. It is shown that the reflection coefficient is the general characteristics of press-fit joint quality rather its load carrying capacity defined by the maximum rotation moment transmitted by the press-fit joint, because it is bound with the normal stresses appearing on the joint surfaces. The equation for calculation of the coefficient of ultrasound reflection from the interference area of a joint by echo-impulse amplitudes measured from the quill cylinder and from a joint is received. Peculiarities of the research procedure are accentuated and described. The peculiarities allow receiving exact estimation of press-fit joints quality by a non-destructive method either on the localized areas of the interference or the estimation of an averaged value around the joint during multiangle study of the object on different directions in the definite ultrasonic sounding plane. Special attention is paid by the authors to the possibility and practicability of automation of the process of control on the basis of the multiangle ultrasonic sounding method in order to improve the joint quality studying process.

A method for multilayer liquids density and viscosity integrated control in tanks based on ultrasonic sounding

A method for multilayer liquids density and viscosity integrated control in tanks based on ultrasonic sounding

Study of the Defective Structure of Metal by the Method of Ultrasonic Sounding

A methodological approach to study the defective structure of metal by the ultrasonic sounding method was proposed. It was shown that the presentation of the processes determining the influence of the material conditions on the parameters of the sound impulse by the static model in the form of the Dirichlet distribution allows us to characterize qualitatively the change in the sounding impulse with account of the change in the metal defective structure and to improve our understanding of the integration phenomena of the sound wave with the environment.

Fracturing of Migmatite Monitored by Acoustic Emission and Ultrasonic Sounding

Here, we present an experimental study of the fracturing of anisotropic migmatite with plane-parallel structure (foliation). Four specimens, with different dips of foliation, including subhorizontal (13°), subvertical (86°), and oblique (47°, 67°), were uniaxially loaded up to failure. Acoustic emission monitoring and ultrasonic sounding were applied for fracturing characterization. In case of subhorizontal and subvertical foliation, the tensile source type played an important role before reaching nucleation stress when shearing became dominant. The dominance of non-tension microcracking was characteristic for oblique foliation. The uniaxial loading of migmatite resulted in triaxial stress state regardless of the foliation dip. The minimum stress axis was in the subhorizontal direction of the foliation dip. The triaxial stress state caused the preferential orientation of induced shear and tension microcracks that had the same azimuthal orientation as the foliation. Preferential microcracking resulted in preferential orientation of the failure plane. Based on the anisotropic behavior of migmatite’s characteristic mechanical properties, as well as its mechanism of failure that is typical for anisotropic rocks, the obtained conclusions may be generalized for other types of metamorphic anisotropic rocks with a plane-parallel structure.

Deriving micro- to macro-scale seismic velocities from ice-core <i>c</i> axis orientations

Abstract. One of the great challenges in glaciology is the ability to estimate the bulk ice anisotropy in ice sheets and glaciers, which is needed to improve our understanding of ice-sheet dynamics. We investigate the effect of crystal anisotropy on seismic velocities in glacier ice and revisit the framework which is based on fabric eigenvalues to derive approximate seismic velocities by exploiting the assumed symmetry. In contrast to previous studies, we calculate the seismic velocities using the exact c axis angles describing the orientations of the crystal ensemble in an ice-core sample. We apply this approach to fabric data sets from an alpine and a polar ice core. Our results provide a quantitative evaluation of the earlier approximative eigenvalue framework. For near-vertical incidence our results differ by up to 135 m s−1 for P-wave and 200 m s−1 for S-wave velocity compared to the earlier framework (estimated 1 % difference in average P-wave velocity at the bedrock for the short alpine ice core). We quantify the influence of shear-wave splitting at the bedrock as 45 m s−1 for the alpine ice core and 59 m s−1 for the polar ice core. At non-vertical incidence we obtain differences of up to 185 m s−1 for P-wave and 280 m s−1 for S-wave velocities. Additionally, our findings highlight the variation in seismic velocity at non-vertical incidence as a function of the horizontal azimuth of the seismic plane, which can be significant for non-symmetric orientation distributions and results in a strong azimuth-dependent shear-wave splitting of max. 281 m s−1 at some depths. For a given incidence angle and depth we estimated changes in phase velocity of almost 200 m s−1 for P wave and more than 200 m s−1 for S wave and shear-wave splitting under a rotating seismic plane. We assess for the first time the change in seismic anisotropy that can be expected on a short spatial (vertical) scale in a glacier due to strong variability in crystal-orientation fabric (±50 m s−1 per 10 cm). Our investigation of seismic anisotropy based on ice-core data contributes to advancing the interpretation of seismic data, with respect to extracting bulk information about crystal anisotropy, without having to drill an ice core and with special regard to future applications employing ultrasonic sounding.

Experimental substantiation of acoustic method for determination of “coal bed - country rock” contact relations based on boundary inverse problem solution

The article describes the acoustic method developed by the authors to determine the contact conditions between coal seam and host rocks on the basis of boundary inverse problem solution. Justification of the applicability of the method is made by means of physical modeling, in which samples from the model material were subjected to step-by-step uniaxial loading with simultaneous ultrasonic sounding using a multichannel scheme. In this case, various friction conditions were set for different samples at the “sample-plate of the press” interface. Based on the results of sounding, the distribution of velocities in the illuminated domain of the sample was reconstructed using tomographic processing. The array of data obtained as a result of acoustic tomography was used as input data to solve the inverse problem. As a result of the solution of the inverse problem, it was shown that the appearance of slip regions at the boundaries of the sample generates tensile stresses, the magnitude of which reaches 0.8 from the axial load. The developed method makes it possible, on the basis of acoustic measurements, to identify areas with a reduced coefficient of friction between the coal seam and the host rocks, the presence of which may be the reason of dangerous dynamic phenomena.

Experimental study of fracture size effect on elastic-wave velocity dispersion and anisotropy

We have designed transversely isotropic models containing penny-shaped rubber inclusions, with the crack diameters ranging from 2.5 to 6.2 mm to study the influence of fracture size on seismic velocity under controlled conditions. Three pairs of transducers with different frequencies (0.5, 0.25, and 0.1 MHz) are used for P- and S-wave ultrasonic sounding, respectively. The P-wave measurements indicate that the scattering effect is dominant when the waves propagate perpendicular to the fractures. Our experimental results demonstrate that when the wavelength-to-crack-diameter ratio ([Formula: see text]) is larger than 14, the P-wave velocity can be described predominantly by the effective medium theory. Although the ratio is larger than four, the S-wave velocity is close to the equivalent medium results. When [Formula: see text] < 14 or [Formula: see text] is < 4, the elastic velocity is dominated by scattering. The magnitudes of the Thomsen anisotropic parameters [Formula: see text] and [Formula: see text] are scale and frequency dependent on the assumption that the transversely isotropic models are vertical transversely isotropic medium. Furthermore, we compare the experimental velocities with the Hudson theory. The results illustrate that there is a good agreement between the observed P-wave velocity and the Hudson theory when [Formula: see text] > 7 in the directions parallel and perpendicular to the fractures. For small fracture diameters, however, the P-wave velocity perpendicular to the fractures predicted from the Hudson theory is not accurate. When [Formula: see text] < 4, there is good agreement between the experimental fast S-wave velocity and the Hudson theory, whereas the experimental slow S-wave velocity diverges with the Hudson theory. When [Formula: see text] > 4, the deviation of fast and slow S-wave velocities with the Hudson prediction is stable.

Acoustic emission monitoring of crack formation during alkali silica reactivity accelerated mortar bar test

System of semi-continuous ultrasonic sounding and acoustic emission (AE) monitoring of experimental mortar bars subjected to ultra-accelerated (14-days lasting) alkali-silica reactivity (ASR) test was developed and assessed for refined interpretation of early stages of reaction. The experiments were carried out by using four different types of crushed stone (quartz from pegmatite, chert, quartzite, quartz-rich metagreywacke) exhibiting variable ASR potential from non-reactive to reactive. By analysing AE characteristics, these faithfully reflect microstructural changes during the first 3–5days of the test. Early formation of ASR damage phenomena within aggregate particles showing variable ASR potential is accompanied with non-linear interaction of propagating or released acoustic waves. During the second half of the test, rapid attenuation of AE activity, specifically in the case of the two most reactive types of aggregates (quartz metagreywacke and chert), reflects deterioration of the (micro) structure of tested materials and decrease of quality of contacts between steel wave guides and experimental mortar bars. The later fact presents major limitation of current approach during later stages of ultra-accelerated mortar bar test. Despite this limitation, ultrasonic sounding and AE monitoring seems to be much more sensitive to early stages of development of brittle damage phenomena due to ASR than standard dilation reading is. This has been confirmed by subsequent direct observation of damage phenomena by backscattered imaging in scanning electron microscope.

Semi-continuous ultrasonic sounding and changes of ultrasonic signal characteristics as a sensitive tool for the evaluation of ongoing microstructural changes of experimental mortar bars tested for their ASR potential

Semi-continuous ultrasonic sounding of experimental mortar bars used in the accelerated alkali silica reactivity laboratory test (ASTM C1260) is proposed as a supplementary measurement technique providing data that are highly sensitive to minor changes in the microstructure of hardening/deteriorating concrete mixture. A newly designed, patent pending, heating chamber was constructed allowing ultrasonic sounding of mortar bars, stored in accelerating solution without necessity to remove the test specimens from the bath during the measurement. Subsequent automatic data analysis of recorded ultrasonic signals proved their high correlation to the measured length changes (expansion) and their high sensitivity to microstructural changes. The changes of P-wave velocity, and of the energy, amplitude, and frequency of ultrasonic signal, were in the range of 10–80%, compared to 0.51% change of the length. Results presented in this study thus show that ultrasonic sounding seems to be more sensitive to microstructural changes due to ongoing deterioration of concrete microstructure by alkali–silica reaction than the dimensional changes.

Bistatic Multipositional Wave Tomography

A method of bistatic multipositional wave tomography is proposed that is applicable both for the case of radiowave sensing and for the case of ultrasonic sounding. A sensing system is considered in which the transmitter and the receiver are displaced independently in a plane above the investigated object. To acquire threedimensional radio-wave images of scattering objects, the measurement data are processed by the method of spatial matched filtering. The possibility of achieving range resolution even when using monochromatic signals is demonstrated. Results of numerical modeling and experimental studies are presented.

Laboratory measurement of elastic anisotropy on spherical rock samples by longitudinal and transverse sounding under confining pressure

Knowledge of shear wave velocities in loaded rocks is important in describing elastic anisotropy. A new high-pressure measuring head was designed and constructed for longitudinal and traversal ultrasonic sounding of spherical rock samples in 132 independent directions under hydrostatic pressure up to 60MPa. The velocity is measured using a pair of P-wave sensors and two pairs of S-wave sensors (TV/RV and TH/RH) with perpendicular polarization. An isotropic glass sphere was used to calibrate the experimental setup. A fine-grained anisotropic quartzite sample was examined using the P- and S-wave ultrasonic sounding. Waveforms are recorded by pairs of TP/RP, TV/RV and TH/RH transducers in a range of confining pressure between 0.1 and 60MPa. The recorded data showed a shear wave splitting in three basic structural directions of the sample. The measurements proved to be useful in investigating oriented micro-cracks, lattice (LPO) and shape-preferred orientation (SPO) for the bulk elastic anisotropy of anisotropic rocks subjected to hydrostatic pressure.

Ultrasonic sounding and monitoring of the excavation damaged zone in relation with drift support

Under high in situ stresses, the excavation of underground openings generally causes the creation of a disturbed (EdZ: Excavation disturbed Zone) and/or damaged (EDZ: Excavation Damaged Zone) zone, resulting from the initiation and growth of cracks and fractures and from the pre-existing stress redistribution. The EdZ or EDZ changes the mechanical and hydromechanical properties which in return, constitute a potential risk for the performance of the geologic and/or engineered structures in the context of waste underground storage. Ultrasonic experiments have been implemented to characterize the EDZ extension around drifts and its evolution in time according to the structural support type (soft or rigid) and the environmental conditions. Those studies consist of two experimental components: (1) the prior auscultation of the floor and sidewalls of the gallery by ultrasonic transmission tomography, (2) the monitoring of the time-dependant evolution of EDZ and the analysis of measurable changes in the propagation of ultrasonic waves in the medium term. A code for computing these continuous in situ velocity measurements into the elastic has been developed. Then, the five dynamic elastic constants for the assumed transverse isotropic character of the rock are derived as a function of time and the distance from the drift wall. Performed a few months after the excavation of the galleries, the tomography shows that ultrasonic velocities are higher in the orthoradial direction (both in the concrete support and rock). This velocity field highlights clearly the damaged zone and induced stress shift.

Investigation into the seismoacoustic properties of specific polycrystalline materials used in nuclear reactors

The characteristics of the wave fields observed during the transmission of quasi-longitudinal ultrasonic waves through polycrystalline graphite samples have been studied. The specific features of propagation of elastic waves in a bilayer medium, where one of the layers (isotropic) is an acrylic glass hemisphere and the other (anisotropic) is a polycrystalline porous graphite hemisphere, are considered. The velocities and propagation times of quasi-longitudinal waves in polycrystalline graphite samples and a bilayer acrylic glass-graphite sample in different directions are experimentally measured by ultrasonic spatial sounding. The experimental results are compared with theoretical calculations using the data on graphite crystallographic texture obtained previously by neutron diffraction. The reasons for the discrepancy between the theoretical and experimental characteristics of elastic waves in the media under study are established and analyzed.