Transverse Ultrasonic Waves Research Articles

Effect of Concurrent ZnO Addition and AlF3Reduction on the Elastic Properties of Tellurite Based Glass System

New ternary zinc oxyfluorotellurite (ZOFT) with the composition(ZnO)x-(AlF3)y-(TeO2)z, where5≤x<35;5≤y≤25;60≤z≤70, has been successfully prepared by the conventional rapid melt quenching technique. Density, molar volume, and glass transition temperature have been assessed for each ZOFT glass sample. The longitudinal and transverse ultrasonic waves propagated in each glass sample were measured using a MBS8020 ultrasonic data acquisition system at 5 MHz frequency and room temperature. The longitudinal modulus (L), shear modulus (G), Young’s modulus (E), bulk modulus (K), and Poisson’s ratio (σ) are assessed from both velocity data and their respective density. The compositional dependence of the ultrasonic velocities and related parameters are discussed to understand the rigidity and compactness of the glass system studied.

Study of PD Ultrasonic Wave's Properties in Solid Medium

Longitudinal ultrasonic wave signals, transverse ultrasonic wave signals and other ultrasonic body wave signals generated by partial discharge are analyzed emphatically in the acoustic emission method of partial discharge detection in high voltage equipment [1-. Velocity of longitudinal ultrasonic wave is often used to calculate partial discharge defects position in the location study of partial discharge. In practical applications errors are always large. And a recent study finds that a class of plate ultrasonic guided waves will be inspired when ultrasonic body waves are transmitted from the gaseous medium to the metal medium [9-1. As the attenuation coefficient is small and the transmission distance is large when the waves propagate along the metal plate, in the partial discharge detection, ultrasonic signals detected by the ultrasonic sensor attached to the equipment enclosure include ultrasonic guided waves besides the ultrasonic body waves.

Ultrasonic attenuation in pearlitic steel

Expressions for the attenuation coefficients of longitudinal and transverse ultrasonic waves are developed for steel with pearlitic microstructure. This type of lamellar duplex microstructure influences attenuation because of the lamellar spacing. In addition, longitudinal attenuation measurements were conducted using an unfocused transducer with 10MHz central frequency on the cross section of a quenched railroad wheel sample. The dependence of longitudinal attenuation on the pearlite microstructure is observed from the changes of longitudinal attenuation from the quenched tread surface to deeper locations. The results show that the attenuation value is lowest and relatively constant within the quench depth, then increases linearly. The experimental results demonstrate a reasonable agreement with results from the theoretical model. Ultrasonic attenuation provides an important non-destructive method to evaluate duplex microstructure within grains which can be implemented for quality control in conjunction with other manufacturing processes.

Determination of isotropic layer parameters from spatiotemporal signals of an ultrasonic array

The paper discusses a method for measuring the velocities and attenuation of longitudinal and transverse ultrasonic waves and the density and thickness of the isotropic layer with an array placed in an immersion liquid parallel to the sample. The method is based on the recording of the total spatiotemporal signal of the array and its expansion into a spatial spectrum of pulse plane wave response. The ultrasonic velocity and sample thickness depend on the response delay of the plane wave in the layer from the transverse projection of the slowness vector. The density and attenuation are determined from the behavior of the amplitudes of spectral responses. To confirm this method in experiment, the parameters of a polystyrene plate have been measured using a linear 32-element array with a central frequency of 17 MHz.

Ultrasonic birefringence as a measure of mechanically induced fatigue damage in laminated composites

A non-destructive testing method based on polarization effects of ultrasonic transverse waves is suggested to monitor fatigue damage in polymer matrix composites. Using a transverse wave probe in reflection mode, phase and amplitude of its output signal are measured as a function of the polarization angle. From the material properties of a single ply and the proposed calculation approach, the birefringence response of carbon fibre reinforced polymers composed of many plies with different fibre orientations is predicted. The effect of ply sequence is investigated using two types of quasi-isotropic specimens with different layups. Cyclic tensile loading of composites results in fatigue damage that is characterised by matrix cracking along the fibre direction through the thickness of each ply. These myriads of transverse cracks affect the ultrasonic attenuation and degrade the homogenised stiffness of single plies. In the experiments, stepwise increase of fatigue damage is alternated with ultrasonic measurements, which show the effect of ply-dependent crack densities on the birefringence behaviour. Simulated and measured transverse wave response are matched by variation of the input parameters shear moduli and attenuations, which are therefore the final results. The obtained data from the investigated composite specimens is proposed to characterise the distinct fatigue state for each ply orientation.

Effect of AlF3 on the Density and Elastic Properties of Zinc Tellurite Glass Systems

This paper presents the results of the physical and elastic properties of the ternary zinc oxyfluoro tellurite glass system. Systematic series of glasses (AlF3)x(ZnO)y(TeO2)z with x = 0–19, y = 0–20 and z = 80, 85, 90 mol% were synthesized by the conventional rapid melt quenching technique. The composition dependence of the physical, mainly density and molar volume, and elastic properties is discussed in term of the AlF3 modifiers addition that are expected to produce quite substantial changes in their physical properties. The absence of any crystalline peaks in the X-ray diffraction (XRD) patterns of the present glass samples indicates the amorphous nature. The addition of AlF3 lowered the values of the densities in ternary oxyfluorotellurite glass systems. The longitudinal and transverse ultrasonic waves propagated in each glass sample were measured using a MBS8020 ultrasonic data acquisition system. All the velocity data were taken at 5 MHz frequency and room temperature. The longitudinal modulus (L), shear modulus (G), Young’s modulus (E), bulk modulus (K) and Poisson’s ratio () are obtained from both velocities data and their respective density. Experimental data shows the density and elastic moduli of each AlF3-ZnO-TeO2 series are found strongly depend upon the glass composition. The addition of AlF3 modifiers into the zinc tellurite causes substantial changes in their density, molar volume as well as their elastic properties.

Determination of the Minimal Operating Temperature

Abstract According to a new theory poycrystal elements are a comlex self-organized system which gives the possibility to modulate the processes of strengthening by changing temperature within a wide range. An unconventional method for non-destructive determination of the minimal operating temperature (ductile to brittle transition temperature of structural steel TDBTT), based on the results of measuring the speeds of longitudinal and transversal ultrasonic waves and the achieved values of Poisson's ratio, has been developed.

An integrated model for ultrasonic wave propagation and scattering in a polycrystalline medium with elongated hexagonal grains

Attenuation coefficients for longitudinal and transverse ultrasonic waves are obtained for polycrystals with elongated hexagonal grains using an integrated approach suitable in all frequency regions. Below the geometric limit the attenuation coefficients are obtained in a general form for ellipsoidal grains using the Born approximation while in the upper part of the stochastic frequency range and in the geometric regime the Karal and Keller [F.C. Karal, J.B. Keller, Elastic, electromagnetic, and other waves in a random medium, J. Math. Phys. 5 (1964) 537–547] scalar model is generalized and applied to obtain the dispersion equation and the attenuation coefficients for ellipsoidal grains. Both solutions are combined to describe attenuation behavior in the entire frequency range thus generalizing the Stanke and Kino unified model [F.E. Stanke, G.S. Kino, A unified theory for elastic wave propagation in polycrystalline materials, J. Acoust. Soc. Am. 75 (1984) 665–681] to a medium with elongated grains. The results show that in the Rayleigh region the attenuation is an isotropic function depending only on the effective grain volume; in the stochastic region it scales linearly with the grain dimension in the propagation direction but it is independent of the cross-section of the ellipsoidal grains, and in the Rayleigh-to-stochastic transition region it depends strongly on the ellipsoidal grain shape. In the geometric regime it is inversely proportional to the grain size in the direction of wave propagation.

Ultrasonication as a Method of Investigation of the Mechanical Properties of Doped Hafnium Barium Titanate

The purpose of this study was to fabricate dense ceramic specimens from the system of BaTiO3-BaHfO3 and then to perform mechanical tests. The effect of Hf content on a microstructure and mechanical properties of the BaTiO3-BaHfO3 solid solution was investigated at room temperature. To determine the elastic constants (the Young′s modulus E, the shear modulus G, bulk modulus K and the Poisson′s ratio v) of BaHfxTi1-xO3 a method of measurement of the longitudinal (VL ) and transverse (VT ) ultrasonic wave velocities for this type of material was developed.

Anomalies in the temperature dependence of the contribution to the speed of sound from hybridized electronic states of transition element impurities

The temperature dependence of the speed of sound in crystalline mercury selenide with low concentrations of iron impurities is studied. Experiments are conducted in the ranges of concentration and temperature where hybridized electronic states in iron impurities have been observed previously. It is found that at temperatures below 10 K the speed of slow transverse ultrasonic waves has an anomalous nonmonotonic segment of its temperature variation that is related to the influence of the impurities and reflects the existence of hybridized states. The observed anomalies in the sound speed are described in terms of a theory for the electron contribution to the elastic moduli that includes hybridization of impurity states and electron-electron interactions. Fits of the theoretical dependences to the experimental data yield quantitative information on the parameters of the hybridized states and of the Fermi-liquid interaction.

Influence of ZnO on the ultrasonic velocity and elastic moduli of soda lime silicate glasses

The effects of ZnO on longitudinal and transverse ultrasonic wave velocities of soda lime silicate (SLS) glasses have been measured using the pulse-echo method at 5 MHz frequency at room temperature. The elastic properties: Longitudinal modulus, shear modulus, Young’s modulus, bulk modulus, Poisson’s ratio, and Debye temperature are found to be rather sensitive to the glass composition. Experiments showed that these parameters depend upon the ZnO-modifier content. Key words: Glasses, annealing, ultrasonic measurements, elastic properties.

Explicit model for ultrasonic attenuation in equiaxial hexagonal polycrystalline materials

Attenuation coefficients for longitudinal and transverse ultrasonic waves are obtained in explicit form for untextured hexagonal polycrystalline materials. The equations obtained are easy to use for interpretation and evaluation of experimental results for ultrasonic characterization of microstructures. The attenuation coefficients are separated into two terms, corresponding to incident wave scattering into longitudinal and transverse waves. It is shown that the general expressions for attenuation coefficients in the long wavelength (Rayleigh) and short wavelength (stochastic) regimes transit to the known classical asymptotics. Simple equations to estimate the frequency range of the transition from the Rayleigh to stochastic regimes are also given. An example of experimental measurements in Ti alloy is provided to illustrate application of the model; the results show reasonable agreement between the experiment and the model with no adjustable parameters.

Orientation dependence of elastic properties and internal stresses in sub-microcrystalline copper produced by equal channel angular pressing

The orientation characteristics of the elastic properties of sub-microcrystalline copper produced by equal channel angular pressing (ECAP) were studied by measuring the velocities of the longitudinal and transverse ultrasonic waves in different spatial directions. It was shown that the effect of an “anomalous” reduction in the elastic moduli observed after ECAP treatment reflects a strong spatial anisotropy of the material. Internal stresses arising in copper as a result of ECAP processing were determined by means of X-ray diffraction line broadening analysis. An appreciable anisotropy of the internal stresses was also found. Possible mechanisms responsible for the anomalies of the elastic properties are discussed.

Coherent reconstruction of flaw images taking the effect of nonspecular reflection of ultrasonic pulses from the boundaries of a test object into account

The influence of the effect of nonspecular reflection of transverse ultrasonic waves from the boundaries of a test object on the quality of coherent images of flaws is considered. The existence of an effect of nonspecular reflection in a pulsed operating mode and the accuracy of its description within the framework of complex reflection coefficients is experimentally verified. It is shown that the effect does not influence the delay times of propagating pulses and only the amplitude of echo pulses changes. Such distortions slightly impair the quality of flaw images that are reconstructed by coherent methods. Nevertheless, the methods for eliminating the influence of this effect are considered for two methods, viz., FT-SAFT and SAFT. Images of flaws that were reconstructed by the FT-SAFT method without taking the nonspecular reflection effect and with its compensation into account are presented.

The acoustic properties of borosilicate glass affected by oxide of rare earth gadolinium

SiO 2–Na 2O–B 2O 3 glasses doped with different mol% content of Gd 2O 3 have been prepared by rapid-quenching method. Longitudinal and transverse ultrasonic wave velocities have been measured using the pulse-echo method at 4 MHz frequency at room temperature. Elastic moduli, Debye temperature, softening temperature and Poisson’s ratio have been obtained as a function of Gd 2O 3 modifier content and are found to be rather sensitive to the glass composition. Information about the structure of the glass can be deduced after calculating the average stretching force constant and the average ring size. A comparison between the experimental elastic moduli data obtained in this study and those calculated theoretically by other models has been discussed.

Effect of grain size on the ultrasonic parameters in stainless steels

In this study, the influence of grain size on the velocity of ultrasonic waves and ultrasonic attenuation in stainless steels was investigated. The aim of this study is to demonstrate the capability of ultrasonic techniques in the assessment of the grain size of steels. Heat treatment processes were carried out in order to obtain different grain sizes for AISI 304 stainless steel specimens. AISI 316 stainless steel specimens were produced by casting and tested in as-cast condition. Velocities of ultrasonic longitudinal and transverse waves were measured by means of pulse-echo method using contact type normal beam probes with 1 and 4 MHz frequencies. Apparent attenuation coefficient of longitudinal waves was determined at 4 MHz. Young's modulus of the specimens was also determined. The results showed that ultrasonic longitudinal and transverse wave velocities and Young's modulus were decreased with increasing grain size of the specimens. The apparent attenuation coefficient of longitudinal waves was increased with increasing grain size.

Ultrasonic investigations of the Jahn–Teller effect in a ZnSe:Fe2+ crystal

The temperature dependence of the absorption and velocity of transverse ultrasonic waves propagating in the [110] direction in a ZnSe:Fe2+ crystal with the iron impurity of n=2.2×1019cm−3 is investigated in the temperature interval 1.4–100K at a frequency of 53MHz. For the slow transverse mode an absorption peak at 7.3K and a decrease of the phase velocity below 40K are found, while no such features are observed for the fast mode. The anomalies are interpreted as manifestations of the Jahn–Teller effect. The softening of the elastic modulus (C11–C12)∕2 indicates that the local distortions in ZnSe:Fe2+ are tetragonal. Under the assumption that the absorption maximum is of a relaxational nature, the temperature dependence of the relaxation time is recovered from the data, and the values of the potential barrier height and vibronic frequency are obtained.

Low-temperature relaxation in the ZnSe : V2+ crystal

Low-temperature anomalies in absorption of the fast transverse and longitudinal ultrasonic waves are revealed in a ZnSe crystal lightly doped (5.6 × 1018 cm−3) with V2+ ions. These anomalies are interpreted as a manifestation of the Jahn-Teller effect. The temperature dependence of the relaxation time of the impurity 3d electrons is established.

A possibility of using transverse ultrasonic waves to obtain information on microflaws in steel

A technique for detecting microflaws in metals using transverse ultrasonic waves is proposed. Recommendations for choosing the optimal parameters of receiving angle probes—the probe angle, the piezoelectric-plate diameter, and the regions of arrangement of piezoelectric receivers on the detection surface—are given. The sensitivity of the proposed technique utilizing transverse waves is compared to the sensitivity of ultrasonic laser interferometry for different parameters of tilted piezoelectric receivers.

Ultrasonic monitoring of hardening concrete

Monitoring results of velocities and attenuations of compressional and transverse ultrasonic waves in hardening concrete using short pulse through-transmission are presented. A fluid concrete is a highly attenuating heterogeneous medium, composed of several phases and granular classes. Different attenuation mechanisms are considered in order to account for experimental results: high impedance mismatch between air layers and solid-fluid clusters at early ages, Energy loss by viscous dissipation and wave scattering by heterogeneities (Rayleigh scattering at low frequencies, single or multi diffusion scatterings at intermediate and high frequencies) during the beginning of hardening. At early ages, the medium may be described as composed of a succession of large slabs of fresh concrete separated by very thin slabs of air. Attenuation is then computed from the effective transmission coefficient of this medium. This model is in good agreement with experiments. During the beginning of hardening, the medium may be seen as composed of big particles immersed in an effective medium formed by the ensemble of the particles of lesser granular sizes and water. Then, the Rayleigh scattering model at low frequencies and the multiple diffusion model predictions at intermediate frequencies are in good agreement with experiments.