Propagation Velocity Of Ultrasonic Waves Research Articles

Experimental investigation of collapsible soils under oedometric loading: effect of internal erosion

Collapsible soils, geological formations characterized by pronounced structural instability upon saturation, present a significant challenge in geotechnical engineering. This experimental study aims to deepen our understanding of the mechanisms governing the behavior of these soils, which are particularly prevalent in arid and semi-arid regions subject to extreme hydrological cycles. Collapsible soils, sensitive to climatic variability, undergo profound alterations in their hydromechanical properties due to alternating periods of prolonged drought and intense rainfall events. These fluctuations induce significant modifications in the soil's pore structure, promoting the development of internal erosion phenomena such as suffusion. The results obtained from this experimental investigation on reconstituted samples highlight the combined influence of various factors, such as water content, dry density, particle size, and flow rate, on the collapse potential. It appears that fine particles play a predominant role in the formation of fragile structures, susceptible to collapse upon saturation. Moreover, the intensity and duration of infiltration significantly influence the propagation velocity of ultrasonic waves, thus offering a promising tool for monitoring the evolution of damage within the soil mass. Furthermore, this study provides essential insights for assessing the risks associated with collapsible soils and contributes to the development of more reliable characterization and modeling methods. It emphasizes the need to consider the complex interactions between the physical, chemical, and mechanical properties of the soil, as well as the influence of environmental conditions, for better control of the risks associated with these materials.

Ultrasonic measurement method for three-dimensional assembly stress of aero-engine rotors

The precise measurement of three-dimensional stress in the rotor is a key means to ensure the assembly accuracy and operational safety of aero-engines. The unclear coupling influence mechanism of different directions of stress on ultrasonic propagation makes it challenging to establish a three-dimensional stress measurement model. This paper proposes a three-dimensional assembly stress measurement method for aero-engine rotors based on ultrasonic propagation time difference decoupling. The three-dimensional assembly stress is converted into the stress component parallel and perpendicular to the ultrasonic wave propagation direction in this method. The acoustoelastic equation including three-dimensional stress parameters is established based on the function model of different direction stress and ultrasonic wave propagation velocity. An innovative three-transducer stress measurement scheme is designed, which integrates ultrasonic wave transmitting and receiving transducers and time difference feedback transducers. The acoustoelastic equations in three propagation directions are constructed by rotating the transducer group to change the propagation direction of ultrasonic waves. Finally, the acoustoelastic equations are solved simultaneously to decouple the ultrasonic propagation time difference, thus achieving a three-dimensional assembly stress measurement of the aero-engine rotor. The experimental results show that the maximum deviation between the measured values and the simulation results in the x ,y, and z directions is 15.885 MPa, 14.113 MPa, and 17.093 MPa, respectively. This study provides effective theoretical and technical support for precisely measuring three-dimensional assembly stress in high-end equipment represented by aero-engines.

Measurement of ultrasonic pulse arrival time by constructing a signal model to determine its propagation velocity

The paper considers several methods of measuring the arrival time of ultrasonic pulses. A method for determining the pulse arrival time based on the construction of a signal model with an adaptive dictionary and the search for the minimum of the target function by the quantum swarm intelligence method is proposed. The results of numerical and modeling experiments on measuring the propagation velocity of ultrasonic waves in various samples are presented. It is shown that the proposed method of determining the time of pulse arrival is more resistant to distortion of the echo waveform arising due to frequency-dependent attenuation in the material of the control object.

Influência da variabilidade da temperatura de exposição na degradação do concreto em função da resistência à compressão e velocidade de propagação de onda ultrassônica

Abstract This study evaluated the influence of heating temperature variability on the degradation level of concrete by varying the exposure temperatures (200°C, 450°C, and 800°C) and concrete design strength (C25 and C40). The concretes were submitted to ultrasound tests (before and after heating) and then were ruptured by axial compression. After rupture, samples were taken from the fracture section of the specimens for microstructural analysis by scanning electron microscope (SEM), and molecular analysis by Raman spectroscopy. The results showed that the residual strength of the concrete can change significantly (values differing by more than 100%) with temperature variability in the oven. There were physicochemical changes in the concrete constituents. The variations in Raman spectra and morphological changes (SEM images) allowed to analyze the variation in the level of degradation of concrete after exposure to fire, at the same firing step, due to temperature variation in the ovens, being compatible with the results of compressive strength and ultrasonic wave propagation velocity (UPV). Thus, the study highlights the need for adequate mapping of the heat in the oven and monitoring of the temperature of specimens in studies of concrete at high temperatures.

Combining ultrasonic testing, infrared thermography, and stereoscopy to unveil characteristics of the adhesion capacity of metakaolin plastering mortars

In the present work, characteristics of the adhesion capacity of metakaolin plastering mortars are unveiled by combining ultrasonic testing, and infrared thermography (IRT), associated with stereoscopy. The investigation was carried out for plastering mortars with metakaolin incorporated by adding and partially replacing the Portland cement, in which incorporations of 5%, 10%, and 15% were employed. Scanning Electron Microscope (SEM), and Energy Dispersive Spectroscopy (EDS) were employed to investigate the morphological characteristics of the metakaolin mortars' surface. In addition, flexural strength tests were also performed to evaluate mechanical behavior. The SEM, and SEM/EDS results revealed aspects of the incorporation of metakaolin in the plastering mortars and revealed the formation of Portlandite, Ettringite, and the CSH phases. Considering the flexural strength behavior, only the plastering mortar with 10% incorporated metakaolin has a better mechanical performance than the reference mortar. Further, the propagation velocity of incident ultrasonic waves was useful in calculating Young's modulus, which is associated with the adhesion capacity of the plastering mortars, due to its mechanical response to the test. Furthermore, the IRT results revealed a significant water absorption by the substrate when a layer of roughcast was applied before the metakaolin plastering mortar. When the plastering mortars are directly applied to the concrete substrate, a smaller ability to transfer water to the solid surface is verified. These adhesion behaviors are associated with the capacity of the system to transfer water to the substrate. Finally, stereoscopy results showed heterogeneity in the interface area between the mortar directly applied to the concrete surface and homogeneity in the interface between the mortar and roughcast/concrete surface, corroborating previous results. In conclusion, the ability of metakaolin plastering mortars to transfer water molecules to solid substrates can be unveiled by combining ultrasonic testing, IRT, and stereoscopy, and this is particularly useful in explaining it’s adhesion property, as shown throughout the work.

The Influence of the Hardness of the Tested Material and the Surface Preparation Method on the Results of Ultrasonic Testing

Non-destructive ultrasonic testing can be used to assess the properties and condition of real machine elements during their operation, with limited (one-sided) access to these elements. A methodological question then arises concerning the influence of the material properties of such elements and the condition of their surfaces on the result of ultrasonic testing. This paper attempts to estimate the influence of material hardness and surface roughness on the result of such testing study area testing machine or plant components of unknown exact thickness. Ultrasonic testing was carried out on specially prepared steel samples. These samples had varying surface roughness (Ra from 0.34 to 250.73 µm) of the reflection surface of the longitudinal ultrasonic wave (the so-called reflectors) and hardness (32 and 57 HRC). The ultrasonic measures were the attenuation of the wave, estimated by the decibel drop in the gain of its pulses, and the propagation velocity of the longitudinal ultrasonic wave. Ultrasonic transducers (probes) of varying frequencies (from 2 to 20 MHz), excited by a laboratory and industrial defectoscope were used as the source of such a wave. The results of our research provide a basis for the recommendation of two considered ultrasonic quantities for assessing the material properties of the tested element. This is of particular importance when testing machines or plant components of unknown exact thickness and unknown roughness of inaccessible surfaces, which are the reflectors of the longitudinal ultrasonic wave used for testing. It has been demonstrated that by using the ultrasonic echo technique, it is possible to evaluate the roughness and hardness of the tested elements.

Evaluation of the Uniaxial Compressive Strength of Gneiss from Southern Togo from Non-Destructive Tests

The mechanical and physical characteristics of rocks hold significant importance across various realms of research and engineering, particularly in the field of Civil Engineering. The utilization of rocks as construction materials hinges on several of their mechanical traits (Los Angeles, Micro Deval under water presence, Young's Modulus, Compression Strength) as well as physical attributes (homogeneity, porosity, etc.). Tests for determining certain of these characteristics are expensive, challenging, and time-consuming. Among these attributes, mention can be made of determining compression strength, which necessitates substantial equipment for proper sample preparation. This renders the process very costly, laborious, and leads to the complete destruction of samples during experimental measurements. Our objective in this study is to assess the uniaxial compression strength of gneiss from southern Togo using non-destructive testing. This would help mitigate the relatively high costs associated with this test. To address this issue, the development of new methods for determining this test using non-destructive testing approaches is necessary. Among the most commonly used reference techniques for characterizing materials and determining their physical and mechanical properties are non-destructive evaluation techniques based on ultrasonic wave propagation and rebound hammer testing. The adopted methodological approach involves the collection of rock samples (amphibole and biotite gneiss) from 33 sites in southern Togo, their proper sampling, and the execution of various tests on the obtained samples. The obtained results have facilitated the examination of several approaches, notably the ANFIS model (Adaptive Neuro-Fuzzy Inference System) and the MLR model (Multiple Linear Regression), for predicting the uniaxial compression strength value based on the sclerometer index and the ultrasonic wave propagation velocity (in parallel or perpendicular orientation to the foliations). It emerges from the ANFIS model, combining ultrasonic waves in the perpendicular orientation to the foliations and the sclerometer index, that the uniaxial compression strength can be predicted with an R² of 0.9884, an RMSE of 2.9271, a MAPE of 1.160, and a VAF of 98.83. In comparison, the MLR model yields an R² of 0.9832, an RMSE of 3.686, a MAPE of 1.402, and a VAF of 98.22. The derived ANFIS models can be utilized to estimate the uniaxial compression strength of gneiss in Togo and beyond. Keywords: Gneiss, Non-destructive Testing, Sclerometer Index, Ultrasonic, Compression Strength.

Results of the COOMET 706/RU-A/16 Pilot Comparison of National Standards of the Unit of Propagation Velocity of Longitudinal Ultrasonic Waves in Solids

Results of the COOMET 706/RU-A/16 Pilot Comparison of National Standards of the Unit of Propagation Velocity of Longitudinal Ultrasonic Waves in Solids

Changes in the Vickers hardness, wettability, structural and mechanical properties of the «shielding composite» under the exposure to cosmic radiation

The article presents the results of the study of the structure and surface of the «Shielding composite» (polymer composite for radiation shielding), which was in space on the Russian segment of the ISS for 225 days. The research was conducted as part of the space experiment “Shielding Composite” on the Russian segment of the ISS in 2022. The polymer composite was used to make the container that was installed in the cosmonauts’ cabin for the entire duration of the orbital flight. Being in space resulted in a slight decrease in the microhardness of the outer surface, but did not affect the deeper layers or the inner structure of the composite: microhardness of the outer surface decreased by 0.19 HV (4.5 %); microhardness of the inner surface increased by 0.79 HV (18.6 %); cross section remained unchanged. The results of ultrasound scanning of the upper cap of the container showed a slight decrease in the ultrasonic wave propagation velocity (by 4 %) and the modulus of elasticity of the composite (by 9 %) after space tests of the composite. There is an insignificant decrease (up to 5 %) in free surface energy of the composite after being in space for 225 days. Water wetting contact angle of the composite increased from 100.98 ± 2.60° to 106.85 ± 14.28° and diiodo-methane wetting contact angle increased from 57.50 ± 8.33° to 59.55 ± 7.22° after cosmic exposure.

The use of inorganic ferrous–ferric oxide nanoparticles to improve fresh and durability properties of foamed concrete

Efforts to modify cement-based mixtures have continuously engrossed the interest of academics. Favourable impacts of nanoparticles, for instance, fine particle size and great reactivity, have made them be utilized in concrete. Foamed concrete (FC) is immensely porous, and its properties diminish with an increase in the number of pores. To enhance its properties, the FC matrix could be attuned by integrating numerous nanoparticles. The influence of ferrous–ferric oxide nanoparticles (FFO-NP) in FC was not discovered previously in the present body of knowledge. Thus, there is some uncertainty contemplating the mechanism to which extent the FFO-NP can affect the durability properties of FC. Hence, this study focuses on utilizing FFO-NP in the FC matrix. FC specimens with a density of 1000 kg/m3 were cast and tested. The objective was to assess the influence of different FFO-NP weight fractions (0.10%, 0.15%, 0.20%, 0.25%, 0.30%, and 0.35%) on durability properties such as drying shrinkage, porosity, water absorption and ultrasonic wave propagation velocity of FC. The results implied that the presence of a 0.25% weight fraction of FFO-NP in FC facilitates optimal water absorption, porosity, ultrasonic pulse velocity and drying shrinkage of FC. The presence of FFO-NP alters the microstructural of FC from loose needle-like into a dense cohesive microstructure of the cementitious composite. Besides, FFO-NP augments the FC matrix by filling the voids, microcracks, and spaces within the structure. Further than the ideal weight fraction of FFO-NP addition, the accretion of the FFO-NP was found, which caused a decline in durability properties.

IMPACT OF HIGH TEMPERATURE ON THE PROPAGATION SPEED OF ULTRASONIC WAVES IN STRONG ROCK FORMATIONS

Purpose: The purpose of the research is to establish the relationship between the velocity of ultrasonic waves in Lesnik, Maslav granites, Bukinsky gabbro, and Kateryniv labradorite at temperatures up to 800 degrees. Methods: In this study, samples of natural stone from the following rocks were heated: Maslav granite, Lesnik granite, Kateryniv labradorite, and Bukinsky gabbro. The samples were made in the form of cubes with a side size of 15×15 cm. One side of the sample was polished and the other sides were sawn. Measurements of ultrasonic wave propagation were made on the polished side. The samples were heated to temperatures of 200, 400, 600, and 800 degrees Celsius. Three cubes were taken for each temperature. Before heating, the velocity of ultrasonic waves in the samples of natural stone was measured using a handle with two piezoelectric sensors with a base of 120 mm. The ultrasonic wave was measured using a UK-14PM device. The velocity of ultrasonic wave propagation in the stone samples after heating was also measured. The velocity of ultrasonic wave propagation was calculated from the time it takes the ultrasonic wave to pass between the sensors. Results: In this research, the authors consider the effect of high temperature on the velocity of ultrasonic waves in granites, gabbro, and labradorite. The article provides an overview of the main factors that affect the velocity of ultrasonic wave propagation in natural stone. The results of studies conducted to investigate the effect of high temperature on this velocity in strong rocks are considered. The relationship between the velocity of ultrasonic wave propagation in Lesnik, Maslav granites, Bukinsky gabbro, and Kateryniv labradorite at temperatures up to 800 degrees has been established. Lesnik granite has the least loss of ultrasonic wave velocity upon heating, while Maslav granite has the greatest loss. When comparing labradorite and gabbro, labradorite has the least loss of ultrasonic wave velocity upon heating. Scientific novelty: For the first time, the dependence of the velocity of ultrasonic wave propagation in Lesnik, Maslav granites, Bukinsky gabbro, and Kateryniv labradorite at temperatures up to 800 degrees from the heating temperature has been obtained. Practical significance: Based on the obtained values, it is possible to assess the strength of natural stone after fires using a non-destructive control method. Keywords: high temperature, ultrasonic wave, natural stone, rock-forming minerals, color.

Results of the COOMET 706/RU-а/16 pilot comparison of national standards of the unit of propagation velocity of longitudinal ultrasonic waves in solids

Results of the COOMET 706/RU-а/16 pilot comparison of national standards of the unit of propagation velocity of longitudinal ultrasonic waves in solids

Reference installation for measuring acoustic parameters of solids

The issues of providing working standards of the 1st category of metrological organizations of the country with regard to modern needs in the field of ultrasonic measurements in solids are considered. There is presented a modernized reference installation designed for precision measurements of propagation velocities of longitudinal and shear ultrasonic waves and damping coefficient of longitudinal ultrasonic waves in solids. Measurements of acoustic parameters of solid media are made by pulse-echo and resonance methods using contactless broadband capacitive methods of excitation and registration of ultrasonic waves. This installation is used as working standard of the 1st category in accordance with the state verification schedule for measuring instruments of the propagation velocities and damping coefficient of ultrasonic waves in solids. The technical means included in the installation (mechanical and electronic parts) have been improved, analog measuring means have been replaced with digital ones, methods for measuring acoustic parameters of solids based on the use of digital measuring means have been developed and the thickness range of installed ultrasonic measures has been expanded. The composition and main components of the reference installation, the used measurement methods and the principles of operation of the installation in various operating modes are described. The technical and metrological characteristics of the installation are given. Sources of measurement error (uncertainty) were analyzed. The field of application of the results is high-precision measurements of the acoustic characteristics of solid media, metrological ensuring of ultrasonic non-destructive testing and diagnostics.

Analysis of the deterioration process of the dolomite with the interlayer in different directions during wetting

Taking the dolomite with anhydrite interlayer at the bottom of Huangcaoshan Tunnel in Shanghai-Wuhan-Chengdu high-speed railway as the research object, the wetting deterioration and uniaxial compression tests were performed to study the influence of different interlayer orientations on the hygroscopic deterioration characteristics of rock and to analyze the process of rock deterioration. The wetting cracking and deformation characteristics of dolomite with interlayer in different directions were analyzed respectively from the time effect of rock micro-expansion and the change of ultrasonic longitudinal wave velocity, and the uniaxial compression evolution process of samples with different moisture absorption conditions and interlayer directions was analyzed respectively from the aspects of crack volume strain and energy dissipation. The results show that the direction of interlayer had a significant effect on the wetting and deterioration of the rock. The sample with vertical interlayer cracked obviously during wetting, resulting in volume expansion along the axial and radial directions of the sample; However, the sample with horizontal interlayer had almost only axial volume expansion, and the expansion rate was small. After the rock was wet and deteriorated, the propagation velocity of ultrasonic longitudinal wave in the rock decreased, and the decrease amplitude in the sample with vertical interlayer was greater than that in the sample with horizontal interlayer. After rock wetting, its uniaxial compressive strength, crack initiation level, expansion level, and the threshold value of elastic strain energy density for failure decreased, while the radial peak strain, the energy conversion rate of dissipation increased, and the plastic characteristics of the sample were enhanced, and the sample with vertical interlayer changed significantly compared with the sample with horizontal interlayer.

Percolation characteristics of filled polyurethane auxetics

According to the experimental values of the propagation velocities of longitudinal and transverse ultrasonic waves, the Poisson's ratio of polyurethane systems filled with metal particles was determined. For such systems, the Poisson's ratio is negative. Its value for metal-filled polymer auxetics with polyurethane matrix allowed to determine fractal dimensions and critical percolation indices. This approach made it possible to clarify the features of structure formation in polymer auxetics. It is shown that the fractal-percolation characteristics of these systems are determined by the type of metal filler and the size of its particles.

Multi-objective optimization to evaluate the compressive strength of concrete by combining non-destructive techniques

The compressive strength of concrete is one of the most important mechanical parameters in the evaluation of the mechanical performance of reinforced concrete structures. The recent methodology for the evaluation of the mechanical strength of concrete of an existing structure combines non-destructive testing (NDT) measurements, such as rebound measurement and ultrasonic wave propagation velocity measurement, with destructive measurements (sampling) in order to develop a conversion model, between mechanical strength and non-destructive measurements. The conversion model is then used to estimate the local value of the resistance at each location of the non-destructive measurements and thus to represent the spatial variability. The goal of this study is to propose a new methodology based on multi-objective optimization to predict the compressive strength of concrete and its variability based on NDT measurements. To this end, a large experimental and synthetic database of destructive and non-destructive tests was used. The conclusions drawn from the synthetic data will be compared with the results obtained on the real database in order to test the potential of the proposed methodology. This study shows the principle of the methodology and the first results of its effectiveness in predicting compressive strength and its variability.

Influence of Stochastic Aggregate on Ultrasound Propagation in Concrete

The ultrasonic testing (UT) has been successfully utilized in many civil engineering fields (e.g. steel structures, RC structures, PC structures, highway, and railway) since the UT can provides an efficient and convenient on-site inspection of internal and external defects. However, many influential factors, such as aggregate, grading, mortar and cement porosity, may introduce various uncertainties to the UT measurement in the concrete due to its highly heterogeneities. Herein, the aggregate in concrete is one of the most influential factors of heterogeneities. To understand the influence of the aggregate on the mechanism of elastic wave propagation is essential to increase the detectability of UT in concrete. Meanwhile, it can provide the supportive evidence of detection, which can increase the reliability. In this paper, a two-dimensional concrete model with consideration of stochastic distribution of aggregate is established numerically. The influence of the quantity of concrete coarse/fine aggregate on ultrasonic attenuation is studied. It was found that the distributed condition of aggregate affects the propagation velocity and attenuation of ultrasonic wave in concrete. Therefore, the reliability of UT test depends on the UT frequency and aggregate.

Model of the acoustic path of a separatecombined optical-acoustic transducer

Ultrasonic testing methods occupy one of the key positions in flaw detection, structurescopy, in assessing the strength characteristics of materials and the stress-strain state of products. The method is based on the phenomenon of acoustoelasticity and makes it possible to control the stress-strain state of products by changing the propagation velocity of a longitudinal subsurface ultrasonic wave. To excite acoustic waves, a separate-combined optical-acoustic transducer and a laser-ultrasonic flaw detector are used. The design of a separate-combined optical-acoustic transducer should ensure the measurements accuracy of the time it takes for a longitudinal subsurface wave to reach the receiver of acoustic oscillations. To analyze the recorded acoustic signals and extract from them the signal of a longitudinal subsurface wave, in this work, a finite element model of the acoustic path of a dual-coupled optical-acoustic transducer is proposed and developed. The finite element model was implemented in the COMSOL Multiphysics software package using an explicit solver based on the discontinuous Galerkin method. The developed finite element model makes it possible to visualize the displacement fields of acoustic oscillations, obtain A-scans, and calculate the time of arrival of a longitudinal subsurface wave at the receiver of the optical-acoustic transducer. The calculated values of the arrival time of a longitudinal subsurface wave at the receiver of an optical-acoustic transducer are compared with the results of a full-scale experiment. Calculations and full-scale experiments were performed for steel plates of various thicknesses. The adequacy of the model was confirmed using the Fisher criterion (F-measure). The A-scans obtained as a result of the simulation made it possible to identify the signals recorded by the optical-acoustic transducer: the signal of the longitudinal subsurface wave, the signals of the head and reflected transverse waves, and the intrinsic noise of the optoacoustic transducer. The developed model makes it possible to single out the signal of the longitudinal subsurface wave among the recorded signals of the optical-acoustic transducer. The proposed model can be used in the design of new optical-acoustic transducers, as well as in non-destructive testing (NDT) and materials science.

Influence of Fe2O3 Content on Acoustic Properties of Backing Materials and Development and Utilization of Acoustic Emission Sensors

Fe2O3 and epoxy resin sensor substrate materials (Fe2O3/epoxy resin composite material) are prepared in this article. A series of acoustic emission sensors are prepared by using composite material as sensor substrate, and the effect of Fe2O3 content in composite material on sensor performance is studied. The effect of Fe2O3 content in the composite material on the performance of the sensor is studied through the simulated lead‐breaking experiment, and the self‐made sensor is calibrated by using the calibration system. Nondestructive testing of concrete materials with different strengths is carried out by selecting the sensor with the best performance. The results show that the content of Fe2O3 in the composite increases to 50%, the epoxy resin matrix reaches saturation point of accommodate Fe2O3 powder, and the propagation velocity of ultrasonic waves reaches the lowest point when it passes through the composite. The sensor with 50% Fe2O3 content as a backing layer has the highest sensitivity and signal‐to‐noise ratio. The relationship between the strength of concrete material and acoustic attenuation and frequency is established by using this sensor, and the law can be used to evaluate the strength and mechanical properties of concrete material without destroying them.

Methodology for assessing the uncertainty of measurements of mechanical stresses by the ultrasonic method with the help of an optical-acoustic separate-combined transducer

The work is devoted to the ultrasonic method of controlling mechanical stresses using ultrasonic head waves. The factors that contribute to the result of measurements of mechanical stresses include: the propagation velocity of the head ultrasonic wave, the temperature of the environment and the object of control, the coefficients of acoustoelastic and thermoacoustic coupling, parameters of the optical-acoustic transducer. The contribution of each of these factors to the results of measurements of mechanical stresses is assessed. A technique for assessing the uncertainty of measurements of mechanical stresses by the ultrasonic method using head waves has been developed.