Temperature Dependence Of Ultrasonic Velocity Research Articles

The effect of plastic deformation on the temperature dependences of ultrasonic velocities in Al-Mg alloy

This work deals with an experimental investigation of the effect of damage resulting from plastic deformation on the temperature dependences of ultrasonic velocities in 93% Al -6% Mg alloy. For samples with different degrees of plastic deformation, the velocities of shear and longitudinal waves linearly decrease with increasing temperature from 230 K to 320 K. For both shear and longitudinal waves, results showed the average value of the temperature-velocity factor varies linearly with plastic deformation. The discovered structural sensitivity of the temperature-velocity factor opens up new possibilities for nondestructive evaluation of metal alloys with accumulated damage, but requires further research.

Influence of native structural defects activated by illumination and under the memory effect conditions on ultrasonic wave propagation in TlInS2 ferroelectric–semiconductor with incommensurate phase

This paper presents data about experimental observation and theoretical validation effect of native defect states activated by illumination and under the memory effect conditions on the velocity of longitudinal and shear elastic waves propagating in layered TlInS2 ferroelectric-semiconductor in different directions. These longitudinal and transverse ultrasonic velocities were worked out by using the pulse echo overlap technique in the range of temperature ∼90–300 K and correspond to and elastic constants of TlInS2. The investigations reveal the illumination-induced spike-like peaks in the temperature dependence of longitudinal wave velocity centered at different temperatures in the range of temperature 225–300 K of high-temperature paraelectric phase. The temperature dependence of ultrasonic velocity of shear wave corresponding to mode exhibits a steep decrease in the slope under illumination at ∼190 K. Influence of the memory effects on the velocities of ultrasonic waves, which is associated with annealing times of about five hours inside the incommensurate (INC) phase, show similar features in the same temperature ranges: a similar well-defined spike-like anomalies in the temperature dependence of longitudinal ultrasonic wave velocity at and pronounced shear acoustic-mode softening below ∼190 K. The experimental results have been discussed in the frame of phenomenological the Landau phase transition theory. It has demonstrated that native deep level defects and crystal imperfections charged under light excitation and the memory effect condition and may essentially distort a crystal lattice of TlInS2 in the high-temperature paraelectric phase.

Basic investigation on acoustic velocity change imaging method for quantitative assessment of fat content in human liver

Fatty liver is a disease caused by the excess accumulation of fat in the human liver. The early diagnosis of fatty liver is very important, because fatty liver is the major marker linked to metabolic syndrome. We already proposed the ultrasonic velocity change imaging method to diagnose fatty liver by using the fact that the temperature dependence of ultrasonic velocity is different in water and in fat. For the diagonosis of a fatty liver stage, we attempted a feasibility study of the quantitative assessment of the fat content in the human liver using our ultrasonic velocity change imaging method. Experimental results showed that the fat content in the tissue mimic phantom containing lard was determined by its ultrasonic velocity change in the flat temperature region formed by a circular warming ultrasonic transducer with an acoustic lens having an appropriate focal length. By considering the results of our simulation using a thermal diffusion equation, we determined whether this method could be applied to fatty liver assessment under the condition that the tissue had the thermal relaxation effect caused by blood flow.

Ultrasonic and Dielectric Studies of Polyurea Elastomer Composites with Inorganic Nanoparticles

The temperature dependence of ultrasonic velocity and ultrasonic attenuation were measured in polyurea elastomer composites with inorganic nanoparticles. The decrease in the ultrasonic velocity along with an attenuation maximum was observed above the glass transition temperature, Tg. The shape and position of this peak are directly proportional to the amount of embedded nanoparticles. In addition, the sharp anomalies in the ultrasonic velocity and ultrasonic attenuation were observed above the glass transition temperature in semicrystalline polyurea elastomers. These anomalies are related to the corresponding first order phase transition of these crystalline domain-containing networks. The ultrasonic attenuation peak related to glass transition is considerably smaller in these polyurea networks showing a small influence of the soft domains below the melting temperature, Tm. The first order phase transition in the semicrystalline polyurea elastomers shows a large temperature hysteresis of more than 10 K, which was confirmed by dielectric investigations. The addition of small amounts of inorganic nanoparticles resulted in a shift of the first order phase transition temperature in semicrystalline nanocomposites.

Non‐invasive characterisation method of carotid plaque composition using ultrasonic velocity‐change imaging

The instability of vessel plaque is thought to be associated with the size and distribution of the lipid core. Ultrasonic B-mode imaging (ultrasonic amplitude imaging) can visualise plaques, but it is unable to provide information about their composition. Based on the fact that the temperature dependence of ultrasonic velocity differs considerably between water and fat, the motivation for this reported work was that it was thought that ultrasonic velocity-change imaging could help characterise biological tissues. This method should be able to detect unstable plaque because it is lipid-rich. A blood vessel phantom of agar base material having similar ultrasonic properties to human soft tissue was made. A small piece of fat was inserted into the blood vessel phantom. Water (instead of blood) was passed through the model vessel using a tube pump. Ultrasonic velocity-change images were constructed from echo pulse waveforms obtained before and after warming using an ultrasonic transducer. Lipid-rich areas in the blood vessel phantom were obvious in the ultrasonic velocity-change image, but not in ultrasonic B-mode images. These results indicate that ultrasonic velocity-change imaging is able to characterise carotid artery plaque.

J042021 回転体の非接触温度センシングヘのレーザー超音波の適用

In this work, a novel ultrasonic method for monitoring temperature distributions of a rotating object has been proposed. The method provides noncontact measurements of surface and internal temperature distributions of a rotating object using a laser ultrasonic technique. The principle of the method is basically based on a combination of temperature dependence of ultrasonic velocity for surface acoustic wave (SAW) of an axial symmetric heated columnar and its heat conduction analysis. First, the validity of the propose method is numerically verified for a steel cylinder model being uniformly heated up to 120 ℃. Next, the ultrasonic method has been applied to the internal and surface temperature measurements of a rotating steel cylinder of 100 mm diameter while the outer surface is being heated up to 120 ℃. Internal temperature distributions are estimated from the measured ultrasonic waves and its variation during heating is monitored.

Ultrasonic characterization of aqueous solutions with varying sugar and ethanol content using multivariate regression methods

AbstractThis paper presents a multivariate regression method for simultaneous detection of sugar (sucrose as a sugar equivalent) and ethanol concentrations in aqueous solutions via temperature‐dependent ultrasonic velocity. Thus, several samples of different combined concentration values were exposed to a temperature spectrum ranging from 2 to 30°C to investigate the temperature dependence of ultrasonic velocity. Model calibration was performed in order to predict the concentrations of interest. With results of proceeded experiments, the equations for calculation of unknown concentrations were carried out using polynomial regression revealing two equations with functional dependence of concentrations on each other. Further, side effects or systematic errors are still included in this model. To avoid such problems as well as to increase the accuracy with respect to the absolute errors in determining unknown probes, multivariate regression methods such as partial least squares (PLS) were tested and compared to the results obtained by polynomial regression. The accuracy achieved with chemometric models on average was three times higher. In direct comparison, the values of the error for the prediction of sucrose concentration were on average around 0.4 g/100 g in the regression model with polynomial background (RMPA) and around 0.12 g/100 g in the PLS model, and for ethanol concentration 0.13 and 0.04 g/100 g, respectively. Furthermore, calculations of the concentrations are possible without knowing the concentrations of the other solute. Copyright © 2011 John Wiley & Sons, Ltd.

Anomalies of ultrasonic velocities, attenuation and elastic moduli in Nd1−xSrxMnO3 perovskite manganite materials

Nd1−xSrxMnO3 perovskite manganite material with different compositions (x=0.31, 0.35, 0.37, 0.39 and 0.41) have been prepared employing solid-state reaction technique. The ultrasonic velocities and attenuation of the above samples have been measured employing through transmission method operated at a fundamental frequency of 5MHz over wide range of temperatures. The temperature dependence of ultrasonic velocities, attenuation, relative percentage variation in velocities and elastic constants show an interesting anomaly in all compositions. The observed anomalies in ultrasonic parameters at Tc in all compositions have been revealed in terms of existence of ferromagnetic (FM) state. Similarly, the anomalies at Tco show the transition from FM to charge-ordered antiferromagnetic (AFM) state. The observed results have been used to explore the competitions between FM and AFM.

Acoustic studies of melting and crystallization of sodium nitrite nanocrystals in the pores of mesoporous silicate matrices

A conventional phase-pulse acoustic method was used to study melting and crystallization of sodium nitrite embedded in the pores of mesoporous silicate matrices. The pore diameter was 20, 37, and 52 A. The measurements were performed at a frequency of 3–8 MHz in the temperature interval 290–560 K. The temperature dependence of ultrasonic velocity was found to exhibit anomalies corresponding to phase transitions of sodium nitrite. The transitions were smeared in temperature and shifted to lower temperatures from the melting point T b of bulk sodium nitrite; the shift in crystallization temperature was greater than that of the melting temperature. The irreversible character of melting was revealed. The size dependence of the melting temperature of sodium nitrite was obtained. Phenomena observed in the experiments were discussed with the use of different size effect models.

Ultrasonic Monitoring of Internal Temperature Distribution in a Heated Material

An ultrasonic method for internal temperature monitoring is presented. The principle of the method is based on the temperature dependence of ultrasonic velocity in materials. An inverse analysis to determine the one-dimensional temperature gradient in a heated plate is developed and an experiment is carried out to verify the validity of the developed method. A single side of a silicone rubber plate of 30 mm thickness is heated and ultrasonic pulse–echo measurements are then performed during heating. A change in the transit time of ultrasonic waves in the heated rubber is monitored and used to determine the transient variation in the internal temperature gradient of the rubber. The internal temperature gradient determined ultrasonically agrees well with both results obtained using commercial thermocouples installed in the rubber and estimated theoretically.

Temperature dependence of elastic properties of ZBLAN glasses

Temperature dependence of ultrasonic velocities (both longitudinal and transverse) in two ZBLAN glasses were determined by ultrasonic pulse-echo technique. The experimental results are used to obtain elastic constants. The temperature dependence of elastic properties of these glasses shows a very interesting correlation with the glass structure and can be used to determine the glass transition temperature.

Ultrasonic Velocity in Cheddar Cheese as Affected by Temperature

ABSTRACTThe ultrasonic velocity in Cheddar cheese is temperature dependent. This relationship can be used to make corrections when determining ultrasonic texture or to determine mean temperatures in cooling/heating processes. At 0 < T < 35 °C ultrasonic velocity was 1590 to 1696 m/s, at 0 and 35 °C, respectively. Differential Scanning Calorimetry thermograms linked the temperature dependence of ultrasonic velocity to fat melting. Three parts are distinguished in the curve as a consequence of the fat melting and the appearance of free oil. The most reliable temperature interval to carry out ultrasonic measurements in Cheddar cheese is identified as 0 to 17 °C.

Temperature dependence of diffuse field phase

We report on a new method for ultrasonic interrogation of solids. Diffuse fields are usually examined by means of the time evolution of their spectral energy density. The phase information is usually discarded as resisting analysis. The phase, while unpredictable, is, however, robust; according to theory it remains constant if source, medium, and receiver are not disturbed. Nevertheless, slow drifts of phase are observed over time scales of minutes. It is hypothesized that the phase changes are due to temperature fluctuations. A wideband 1-MHz transient source in an aluminum block was used to generate a complex waveform whose phase changes on cooling from 40<th>°C to room temperature were monitored. The waveform was found to undergo a virtually pure dilation, by a factor of order 0.00025/°C, a figure which is in accord with published data on the temperature dependence of ultrasonic velocity in aluminum. Due to the low dissipation in the sample, the precision with which changes are measured exceeded a part in ten million, a figure which could be improved by employing a stronger source. The possibilities that this parameter is a measure of residual stress or other NDE parameter, is explored.

Ultrasonic evaluation of hydride concentration in zirconium-niobium alloys

An ultrasonic method has been developed to observe the solid solubility phase transition of metallic hydride in zirconium-niobium alloy. This measured the change in ultrasonic velocity with temperature as the sample was cooled through the expected solid solubility temperature (SST). At the SST, free hydrogen forms a hydride precipitate within the metallic structure on cooling, and the temperature dependence of ultrasonic velocity was seen to change at this temperature, for both longitudinal and shear waves. These results were compared to those of thermal expansion, using a dilatometer, where again the SST could be estimated. Analysis of the data indicates that both measurements could be used as the basis for a possible nondestructive estimation of hydrogen content in these alloys.

Ultrasonic Measurement of Concentration in Solutions by a Phase-Locked Loop Method

In this paper we propose a new ultrasonic technique for measuring the concentration of solutions by a phase-locked loop method. This technique has a very simple circuit system which treats only continuous sinusoidal waves. We verify experimentally its validity and usefulness using NaCl solutions as test specimens. The accurate measurement of concentration is limited by slight changes in the temperature because of the strong temperature dependence of ultrasonic velocity in the solutions. A temperature-compensation factor for NaCl solutions is derived from the equation for ultrasonic velocity in sea water. We designed a circuit compensating for this effect and added it to the measuring system. This measuring system with the compensation circuit was shown to yield accurate values independent of a temperature variation of ±1.3°C around 25° C.

Concentration and temperature dependence of ultrasonic velocity and isentropic compressibility in aqueous sodium nitrate and sodium thiosulfate solutions

N. Rohman and S. Mahiuddin, J. Chem. Soc., Faraday Trans., 1997, 93, 2053 DOI: 10.1039/A700022G

Ultrasonic study of ferroelectric phase transition in DDSP

Abstract The paper presents the results of the temperature dependence of ultrasonic velocity and attenuation of longitudinal waves in the vicinity of ferroelectric phase transition temperature of Ca2 Sr(C2D2 CO2)6 single crystals. The dispersion of ultrasonic velocity, caused by a polarization relaxation, have been observed in the [100] direction. The polarization relaxation time, obtained from ultrasonic attenuation measurements, follows the Curie-Weiss law and is similar to one obtained from the dielectric measurements.

The growth of Li2B4O7 single crystals and investigation of low temperature elastic anomalies

The growth installation and peculiarities of growth Li 2 B 4 O 7 (LBO) crystals by Czochralsky method have been described in this paper. Experimental results of temperature dependences of ultrasonic velocities for various modes and crystallographic directions were measured and some anomaly in this dependence was discovered. Our results are discussed in comparison with some previous data

Acoustic investigations of the pressure-temperature phase diagram of Rb2ZnCl4 crystals

The influence of hydrostatic pressure on the temperature dependence of ultrasonic velocities, attenuation coefficients, and electroacoustic coefficient f is studied at the phase transition temperatures of Rb2ZnCl4 crystals. The pressure-temperature phase diagram is obtained. The results are considered within the frame of phenomenological theory.

Ultrasonic properties of V 2O 5[sbnd]P 2O 5 amorphous materials at different temperatures

Investigations are reported of the acoustical properties of V2O5 P2O5 glass, on which other studies such as structural, spectroscopic, NMR and electrical conductivity have been reported in the literature. In the present investigation, the velocity and attenuation of longitudinal and transverse ultrasonic waves in four different compositions of (V2O5)x (P2O5)1−x glass system (x = 0.4769, 0.6020, 0.7487 and 0.8227) have been measured at temperatures ranging from 80 to 300 K with the help of an ultrasonic pulse echo apparatus operating at 8 MHz frequency. The velocity data have been used to find the elastic moduli and Debye temperature for each composition. The results indicate that for each composition the velocities decrease slowly and monotonically with increasing temperature and the attenuation as a function of temperature shows a broad peak which shifts to lower temperature as the V2O5 content increases. The temperature dependence of ultrasonic velocity and attenuation has been interpreted in terms of a thermally activated relaxation process which comes into play when the ultrasonic wave disturbs the equilibrium of an atom moving in a double-well potential in the glass network.