Changes In Ultrasonic Velocity Research Articles

Effect of thermal change on acoustoelastic effect in concrete

Acoustoelastic technology, which measures changes in ultrasonic wave velocity to determine structural stress, shows significant potential for assessing stress in concrete structures. However, environmental temperature variations can affect ultrasonic wave velocity, thereby influencing the accuracy of acoustoelastic measurements. This study examines the impact of thermal changes on ultrasonic wave velocity in concrete (thermo-acoustoelastic effect) and compares it with changes caused by stress variations (classical acoustoelastic effect). Theoretical expressions for both thermal and classical acoustoelastic effects in a natural coordinate system are derived, and the sensitivity coefficients for each effect are provided. Equivalent elastic constant method is proposed for preliminary numerical analysis of both effects. Experimental investigations further explore how the thermal changes influence the classical acoustoelastic effect. Results reveal that the velocity change due to a unit temperature variation is approximately 40 % of that caused by a unit stress variation. This underscores the significant impact of temperature fluctuations on the application of classical acoustoelastic technology and highlights the need for an effective temperature compensation mechanism to ensure measurement reliability. This finding is of substantial significance for advancing acoustoelasticity-based stress detection technology in concrete structures.

Nonlinear, elastic, piezoelectric, electrostrictive, and dielectric constants of lithium tantalate

Three third-order dielectric constants, 8 electrostrictive constants, 13 third-order piezoelectric constants, and 14 third-order elastic constants for lithium tantalate (LiTaO3) single crystals, which are mainly used in surface acoustic wave (SAW) devices, were determined as part of basic research to realize SAW devices with a low degree of nonlinearity. The third-order dielectric constants were determined by measuring the change in capacitance along selected directions when an alternating electric field was applied to the crystal. The electrostrictive constants were determined by measuring the change in capacitance when static stress was applied. Some of the piezoelectric constants were determined directly from the change in sound velocity due to the application of an alternating electric field, whereas others were obtained from the measured dielectric constants, electrostrictive constants, and the change in sound velocity due to an alternating electric field. In addition, the elastic constants (compliance) were determined using the three aforementioned determined nonlinear constants and the measured small-amplitude ultrasonic velocity change as a function of applied static stress. The measurements performed in the present study are more advanced than those reported for LiNbO3 single crystals in 1987 due to the adoption of the d-form nonlinear piezoelectric equation (instead of the e-form) and a higher degree of precision using dynamic measurement methods. The use of the d-form of the nonlinear piezoelectric equation allows many nonlinear constants to be determined independently from other nonlinear constants, eliminating measurement errors associated with these other constants. The d-form nonlinear constants obtained in the present study were converted to e-form constants to make them applicable to the analysis of nonlinear phenomena in piezoelectric devices.

Relating Hydro‐Mechanical and Elastodynamic Properties of Dynamically Stressed Tensile‐Fractured Rock in Relation to Applied Normal Stress, Fracture Aperture, and Contact Area

AbstractWe exploit nonlinear elastodynamic properties of fractured rock to probe the micro‐scale mechanics of fractures and understand the relation between fluid transport and fracture aperture under dynamic stressing. Experiments were conducted on rough, tensile‐fractured Westerly granite subject to triaxial stresses. We measure fracture permeability for steady‐state fluid flow with deionized water. Pore pressure oscillations are applied at amplitudes ranging from 0.2 to 1 MPa at 1 Hz frequency. During dynamic stressing we transmit ultrasonic signals through the fracture using an array of piezoelectric transducers (PZTs) to monitor evolution of interface properties. We examine the influence of fracture aperture and contact area by conducting measurements at effective normal stresses of 10–20 MPa. Additionally, the evolution of contact area with stress is characterized using pressure sensitive film. These experiments are conducted separately with the same fracture and map contact area at stresses from 9 to 21 MPa. The measurements are a proxy for “true” contact area for the fracture surface and we relate them to elastic properties using the calculated PZT sensor footprints via numerical modeling of Fresnel zones. We compare the elastodynamic response of the fracture using the stress‐induced changes in ultrasonic wave velocities for transmitter‐receiver pairs to image spatial variations in contact properties. We show that nonlinear elasticity and permeability enhancement decrease with increasing normal stress. Additionally, post‐oscillation wave velocity and permeability exhibit quick recoveries toward pre‐oscillation values. Estimates of fracture contact area (global and local) demonstrate that the elastodynamic and permeability responses are dominated by fracture topology.

Concrete Gas Permeability: Implications for Hydrogen Storage Applications

Concrete is widely utilized across various industries as a containment material. One essential property related to its performance is permeability, which determines its ability to allow the passage of gases or liquids through its pores and capillaries and even the transmission of aggressive agents. This study focused on investigating the permeability of gases with varying atomic weights and molecular volumes, such as helium, nitrogen, oxygen, and argon, to pass through concrete. The primary objective was to determine the significance of variation in permeability and to evaluate and differentiate their behavior. To achieve this, concrete test specimens were employed, and factors such as cold joint impact, gas pressure, and specimen saturation levels were considered. Throughout the study, changes in weight, specimen humidity, resistivity, and ultrasonic pulse velocity were monitored. The findings suggested that within concrete, the variation in permeability for these gases is negligible. By utilizing the acquired data, the present study estimated the permeability of hydrogen through mathematical models based on gas pressure and concrete thickness. These insights contribute to a deeper comprehension of concrete gas permeability and its potential impact on improving hydrogen containment.

Monitoring sodium caseinate and whey protein isolate interaction with mild preheat treatment using ultrasound spectroscopy and confocal laser scanning microscopy

Ultrasound spectroscopy and confocal laser scanning microscopy (CLSM) methods were developed to visualize the interaction between sodium caseinate (SC) and whey protein isolate (WPI) with a mild preheat treatment (57°C, 10 min) followed by adding glucono-δ-lactone (GDL). Ultrasonic velocity changes during incubation at 25°C after adding GDL for four kinds of mixtures (no-treated SC plus no-treated WPI, preheated SC plus no-treated WPI, no-treated SC plus preheated WPI and preheated SC plus preheated WPI) were monitored. The results reveal that the mild preheating treatment of the proteins affected the timing of the increase in compressibility of each system. CLSM observation with individualized dyes which have different maxima of excitation and emission wavelengths, showed the preheated SC plus no-treated WPI mixture had a slightly coarse structure and the highest correlation coefficient, suggesting the highest colocalization of the SC and WPI among the four kinds of mixed-protein systems. Furthermore, the scanning electron microscopy (SEM) observation suggests that there are some differences among the gels, namely, preheated WPI leads to the formation of developed three-dimensional gel networks with filamentous structures, whereas SC promotes the formation of cluster-like crowded networks composed of more fine aggregated particles instead of developed filamentous structures. These results demonstrated that although SC is known as a heat-stable protein, pretreated SC could lead to an increase of the collaboration with WPI in the presence of GDL. This finding anticipated the possibility creating a food material with another texture using a milk-protein mixed system.

Variation of Ultrasonic Velocity and a Few Acoustic Parameters as a Function Frequency in Some Commonly Used Edible Oils

In the present investigation an attempt is made to find out whether ultrasonic velocity and acoustic parameters vary as a function of frequency by using the ultrasonic technique. Ultrasonic velocities of commercially available edible oils were various frequencies by using Ultrasonic Multi-frequency Interferometer at room temperature. The density of the oils was determined by using a specific Gravity bottle of 10ml capacity at 30±0.1ºC. The present study gives information about the ultrasonic velocity changes as a function of frequency and the data of Ultrasonic Velocity and density obtained will be highly useful in estimating various acoustic parameters such as Acoustic impedance (Z), Bulk Modulus (K), and Adiabatic Compressibility (βad). Acoustic parameters and their variation in the systems of oils studied. The variation of ultrasonic velocity is critically discussed as a function of frequency and the data presented in the present work will be highly useful in identifying the adulteration in oils.

Effects of elevated temperature exposure on the mechanical properties of recycled fine aggregate concrete

ABSTRACT In this work, a compound waste material was made up of raw construction waste concrete, waste tiles, and waste bricks was mixed at a weight ratio of 6:3:1. They were ground into recycled fine aggregates (RFA). RFA substituted the local river sand in proportions of 0%, 30%, 50%, 70%, and 100% for preparing recycled fine aggregate concrete (RFAC) with varied water-to-cement ratios. It intended to explore concrete’s mechanical properties and ultrasonic pulse velocity changes before and after high temperatures (300–800°C). The loss on ignition (LOI) of concrete was simultaneously determined to compare the performance in resisting elevated temperature. Test results presented that the higher the replacement ratio of RFA, the gradually higher the reduction in the concrete splitting tensile, compressive, and residual compressive strengths and ultrasonic pulse velocity after elevated temperature exposure. A rapid reduction was especially found at the heated temperature of exceeding 440°C. Furthermore, the old cement paste adhered to the surface of the raw construction waste had a relatively higher LOI. This led to the consequence that the RFAC had an increased LOI with the increment of the RFA replacement ratio, while the LOI of RFAC dropped with the increment of the originally heated temperature.

Ultrasonic velocity change imaging of a human forearm

Abstract We have investigated noninvasive imaging of the adipose region in the living human body, utilizing an ultrasonic velocity change (UVC) method caused by body temperature change. Our primary goal is to determine the optimal measurement conditions for acquiring effective UVC images. To achieve this objective, we applied the UVC method to the forearm area, which is easily comprehensible in terms of the body’s internal structure and less susceptible to motion artifacts from the heartbeat. By utilizing echo data approximately 30 s after initiating ultrasonic warming, adjusting the time difference between paired images for UVC image generation to multiples of the heartbeat period, and selectively extracting and analyzing image pairs with high correlation values, we successfully obtained effective UVC images targeting humans for the first time. This process enables noninvasive differentiation between subcutaneous fat and muscle regions in the human forearm.

Investigation of physical and metallographic properties of nickel matrix composite by ultrasonic method

Ultrasonic testing (UT) is one of the most widely used non-destructive testing techniques for the characterization and evaluation of materials. In this study, the material properties of AstCrM-BN-Cr-Ti-Ni composites produced by mechanical mixing and electroless nickel plating technique were evaluated using UT. Changes in ultrasonic wave velocity, Young's modulus, density, porosity and hardness are observed in the heat-treated material at different temperatures. Samples analyzed by Scanning Electron Microscopy (SEM) and X-Ray Diffractometry (XRD) exhibited changes in grain structure at different sintering temperatures. It has been observed that the change in grain size also affects mechanical and physical properties according to ultrasonic properties. In conclusion, the experimental results showed a linear relationship between the mean grain size and the UT parameters (ultrasonic longitudinal and transverse velocity, Young's modulus), physical (sintering temperature and density) and mechanical properties (hardness and porosity) of the material. Grain growth occurs with increasing sintering temperature, porosity content decreases, hardness, Young's modulus and ultrasonic wave velocity values also increase.

Phase transformation kinetics in a coarse-grain Ti17 alloy determined by laser ultrasonics and dilatometry

Different methods are used to determine the phase transformation titanium alloys. While ex-situ methods require a large number of samples and accurate quantification of the phases, in-situ methods can provide the kinetics of transformation continuously and with less samples. However, the results are based on the changes of physical properties, and the interpretation of the results in terms of phase transformation are not direct. This study compares two in-situ methods to measure the kinetics of phase transformation for a Ti17 alloy, namely: laser ultrasonics for metallurgy (LUMet) and dilatometry. While LUMet is coupled to a Gleeble® 3500 thermo-mechanical simulator with ohmic resistance heating, the dilatometer device uses induction heating. We performed two types of experiments by heating the specimens above the β-transus temperature (∼ 865 °C) and 1) and then fast cooled below the β-transus temperature and held at different temperatures, or 2) continuously cooled at different rates. The β→α + β phase transformation is inferred by the evolution of the longitudinal wave speed with the LUMet method and by the change in the length of the specimen by dilatometry. We obtained the information about the isothermal phase transformation using the normalized changes in length for the dilatometric data and in longitudinal ultrasonic velocity. In the investigated isothermal temperature range (580 – 700 °C), the β →α + β transformation is completed within one hour of holding with the fastest transformation rates at 580 °C. For the continuous cooling treatments, the small change in length measured by dilatometry makes it impractical to use the lever rule to accurately determine the relative transformation fraction. However, we could successfully apply the lever rule to the LUMet data. Furthermore, the derivatives of the change in length and ultrasonic velocity are used to estimate the transformation temperatures as a function of the cooling rates. Further, the in-situ measurements are supplemented with ex-situ characterization of the microconstituents after heat treatments using scanning electron microscopy.

Investigation on the changes of strength properties and ultrasonic pulse velocity of granite and sandstone after high-temperature treatment and liquid nitrogen quenching

Investigation on the changes of strength properties and ultrasonic pulse velocity of granite and sandstone after high-temperature treatment and liquid nitrogen quenching

Creep and strength characteristics of cemented gangue backfill under coupling effect of load and acid corrosion.

Cemented gangue backfill technology is beneficial to the reuse of solid waste and sustainable economic development. However, mine water has a great impact on the strength and deformation of cemented gangue backfill (CGB). In this study, the CGB specimens under load were placed in simulated acid mine water (H2SO4 solution). The changes in deformation, resistivity, and ultrasonic pulse velocity (UPV) of CGB were monitored. On the 360th day, the stress-strain curve and acoustic emission (AE) energy of the specimen during loading were recorded. The degradation mechanism of CGB was discussed by scanning electron microscope (SEM) and X-ray diffraction (XRD). The results showed that the deformation of CGB increased with time. The effect of H2SO4 solution concentration on the deformation was different in the early and late stages. Applying an 80% stress-strength ratio (SSR) reduced the strength and increased the deformation. The UPV and resistivity had different characteristics at different corrosion ages, which could be used for long-term stability monitoring of CGB. The CGB showed the strongest AE energy characteristics near the peak stress. The AE energy decreased with the increase of pH value in the pore compaction stage, and the AE activity of the CGB under 80% SSR was much greater than that of the CGB under 40% SSR. The erosion of the H2SO4 solution on the CGB was inhibited by applying a small load. Excessive load aggravated the erosion deterioration of CGB due to initial plastic damage. The research results can provide a reference for the durability design of CGB.

Quadratic versus linear models to estimate the mean scattering spacing as a function of temperature in ex-vivo tissue

Previous works have shown the feasibility of temperature estimation during ultrasonic therapy using pulse-echo diagnostic ultrasound. These methods are based on the measurement of thermally induced changes in backscattered RF echoes due to thermal expansion and changes in ultrasonic velocity. They assume a joint contribution of these two parameters and a linear dependence with temperature. In this work, the contributions of velocity changes and thermal expansion to the evolution of the mean scatterer spacing of ex vivo bovine skeletal muscle tissue samples were decoupled. This was achieved by employing an experimental setup which allows measuring the absolute velocity value, using the through-transmission technique in a direct transmission configuration. The mean-scatterer spacing was estimated from spectral analysis of the backscattered signals obtained in pulse-echo mode. We propose a quadratic model of the thermal expansion coefficient to fit the evolution of the mean-scatterer spacing with temperature. The temperature increase estimated by the linear model, in the range of 29.5–47 °C, presents a percentage error (mean square error) of 11 %, while for the quadratic model the error is 4.8 %.

Experimental study on high temperatures performance of rubberized geopolymer mortar

Nowadays, fire accidents occur frequently, and both buildings and structures or traffic roads are threatened by fire to varying degrees, and the mortar structure is often in direct contact with fire. Therefore, it is necessary to study the performance of mortar under high temperature. Geopolymer is a new type of green environmental protection building material with good high temperature resistance. Waste rubber will soften and decompose under high temperature, and the holes formed can release the steam pressure inside the structure, which is helpful to ease the internal cracking of the structure. At present, it has been proved that waste rubber has a beneficial effect on the resistance of mortar to high temperature. The research of waste rubber in Portland cement mortar has made relevant achievements, but the research on the combination of geopolymer rubber is relatively small. Therefore, in view of this lack, this study supplements the material properties of geopolymer mortar under four rubber particle sizes (4, 1.7, 0.83, and 0.27 mm) and five temperatures (25, 200, 400, 600 and 800 °C), namely, surface observations, mass loss, compressive and flexural strengths, ultrasonic pulse velocity (UPV) and microstructure change. The results show that the addition of rubber particles will increase the mass loss of rubberized geopolymer mortar (RGM), but the advantage is that it can reduce the burst risk. The addition of fine particle rubber can improve the ability of RGM to resist cracking and deformation at higher temperatures. The results shows that the UPV can reflect the mass and intensity change of RGM laterally. The microscopic results shows that the main reason for the lower strength is the expansion of microcracks and pores in RGM matrix at high temperature.

Density-dependent relationship between changes in ultrasonic wave velocities, effective stress, and petrophysical-elastic properties of sandstone

The present study aims to reveal the importance of density as a moderator variable in interpretation of possible relationships between variations in compressional and shear wave velocities (ΔVp and ΔVs), effective stress, and rock’s petrophysical and elastic properties. Towards this end, fourteen subsurface sandstone samples were collected and analyzed through the measurement of ultrasonic wave velocities at standard and reservoir conditions within a Triaxial-testing cell. The results were interpreted for two groups, i.e., low density (LD) and high density (HD) samples, where greater ΔVp and ΔVs were observed for the HD group samples that have similar average porosity and permeability compared to samples from LD group. Effective stress exhibits better fit with ΔVp and ΔVs for the LD compared to HD group samples. Density was revealed to be well fitted with ΔVp of LD and ΔVs of HD samples. Porosity exhibits good fit with ΔVs of LD and permeability exhibits good fit with ΔVp of both LD and HD groups. Also, variations in estimated elastic limit (ΔEd) is well matched with ΔVs, while changes in estimated Poisson’s ratio (Δν) manifests a good fitting with ΔVp. Finally, variation in deviatoric stresses from triaxial tests is in a good agreement with ΔVp. The results of this study provide convenient insights for conversion of wave velocities and elastic properties between standard and reservoir conditions.

Impact strength and mechanical properties of high strength concrete containing PET waste fiber

This study presents results of tests done on workability, mechanical properties, first cracking impact and ultimate load impact of high strength concrete (HSC) contained polyethylene terephthalate (PET) waste fiber. Different PET fibers with regard the length (10 mm, 20 and 40 mm) were added to concrete by 0.50, 0.75, 1.00, 1.25 and 1.50% (by volume). Density, ultrasonic pulse velocity, compressive strength, splitting tensile strength, flexural strength, first crack impact (N1) and ultimate load impact (N2) tests were conducted on sixteen HSC mixes. Results showed a slight change in ultrasonic pulse velocity, while addition of PET fiber with 10 mm, 20 mm and 40 mm length reduced compressive strength by a maximum value of 15.74, 14.37 and 10.28% respectively compared to control concrete. Regardless to the fiber length and fraction volume, fiber content improves splitting tensile and flexural strengths by a maximum of 63.3% and 24.7% respectively. Striking results were recorded against impact strength property, in which improvement in N1 recorded up to 300% and N2 up to 833% depending on fiber length and fraction volume. It is concluded that PET waste fiber can improve important properties of HSC and it is recommended to be added to concrete by up to 1.5% by volume. Regression analysis was made to develop equations for calculating N1 and N2, and these properties were found to depend essentially on compressive strength of plain concrete and PET fiber parameters.

High-Resolution Ultrasonic Spectroscopy: Looking at the Interpolyelectrolyte Neutralization from a Different Perspective

In this study, the high-resolution ultrasonic spectroscopy (HR-US) technique was applied to examine interpolyelectrolyte neutralization. The mentioned method was tested on the example of complexation between poly(allylammonium) cations and poly(acrylate) anions in aqueous solutions at pH = 7. It was confirmed by HR-US that the type of titration (stepwise or abrupt), the direction of titration, and the type of background salt affect the outcome of interpolyelectrolyte neutralization. The obtained results were explained on the basis of ultrasonic velocity and attenuation changes in the context of suspension compressibility, a parameter that is extremely sensitive to molecular organization and intermolecular interactions. Moreover, the results of HR-US measurements proved to be consistent with previous results obtained by more traditional methods such as dynamic light scattering, microcalorimetry, and electrokinetics. This research demonstrates that HR-US is a convenient and reliable method that can be employed for the investigation of interpolyelectrolyte neutralization and polyelectrolyte-related processes.

Thermo-acoustoelastic effect of Rayleigh wave: Theory and experimental verification

Previous studies showed that the thermally-induced ultrasonic bulk wave velocity change could be used to measure acoustoelastic coefficients and third-order elastic constants of elastic materials. This method is naturally immune from the ambient temperature effect and has improved sensitivity and a simpler test setup than the conventional acoustoelastic test. However, Rayleigh wave is preferred for thick components or structures with only one accessible surface. In this work, the thermo-hyperelastic constitutive equation, along with acoustoelastic theory, is used to derive the expression of the thermo-acoustoelastic coefficient (TAEC) of Rayleigh wave. The numerical relationship between the TAEC of Rayleigh wave and Murnaghan constants (l, m and n) are given for common metals. The TAEC expressions for Rayleigh wave and shear wave are similar, and both are dominated by the constant m. The TAEC of Rayleigh wave was measured on an aluminum 6061 specimen using the thermal modulation experiment in a temperature range of 22 ∼35 °C. The measured TAEC shows good agreement with the theoretical calculation. Then the third-order elastic constants were calculated based on TAECs of bulk waves and Rayleigh wave.

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.

Ultrasonic and X-CT measurement methods for concrete deterioration of segmental lining under wetting-drying cycles and sulfate attack

Accurately assess the concrete deterioration of segmental lining under sulfate attack environment is important for tunnel construction and operation. Ultrasonic testing of concrete samples is generally used to determine the sulfate resistance of concrete materials. However, concrete is a porous medium material, and the internal coarse aggregate and pores will affect the sulfate attack velocity, so the ultrasonic velocity cannot directly assess the local deterioration of concrete structure under sulfate attack. In this study, the durability of concrete samples exposed to sulfate attack and wetting-drying test was studied by using the comprehensive assessment method of X-ray computed tomography (X-CT) scanning and ultrasonic testing. The ultrasonic attenuation velocity and internal pore change of deteriorated concrete were measured, and the sulfate attack depth was calculated. Test results indicate that the newly defined ultrasonic velocity after removing coarse aggregate and pores through X-CT results is a suitable index to describe the non-uniform deterioration behavior of sulfate-attacked concrete. A local deterioration assessment method of concrete structural based on X-CT, ultrasonic velocity and sulfate attack model is proposed, which provides a potential application for the deterioration assessment of sulfate-attacked tunnel segmental lining based on laboratory accelerated test results.