Pulse-echo Method Research Articles

Influence of germanate anomaly on elastic, structural, and optical properties of xNa2O-(99–x)[80GeO2:20PbO]-1Er2O3 lead–germanate glasses

Abstract A sodium–lead–germanate glass system, with a composition of xNa2O-((100–y)–x)[80GeO2:20PbO]-yEr2O3 (x = 0–25 mol.%, y = 0, 1 mol.%), was prepared by melt quenching and used to investigate the effect of Na2O and Er2O3 on the germanate anomaly. The structural and optical properties of the glass samples were investigated using X-ray diffraction, Fourier transform infrared, and UV–Vis spectroscopy analyses. Elastic properties of Er2O3-doped glasses (y = 1) were studied by measuring longitudinal and shear velocities through the pulse-echo method at 5 MHz. Based on Fourier transform infrared spectroscopy analysis of Er2O3-doped glasses, the conversion of GeO4 into GeO6 indicates that the glass system possesses the germanate anomaly characteristic but has no density anomaly. Longitudinal, shear, bulk, and Young's moduli (C L, μ, K, and E, respectively) increased to their maximum values at x = 10 mol.% but decreased with increasing amount of Na2O added. This finding reveals the elastic nature of the germanate anomaly. Increase in elastic moduli indicates enhanced network rigidity of the glass system in the germanate anomaly region, where the coordination number increased with the transformation of GeO4 to GeO6. Subsequent decrease in elastic moduli (x > 10 mol.%) denotes weakened network rigidity of the glass system because of enhanced formation of non-bridging oxygen. Furthermore, analysis using bulk compression and ring deformation models reveals the nonlinear trends of K bc /K e ratio and average ring size diameter as a result of the germanate anomaly. The anomaly also influenced optical properties of both Er2O3-doped (y = 1) and Er2O3-free (y = 0) glasses, where the optical energy gap (E opt) decreased with the addition of Na2O up to 10 mol.% and slightly increased with more than 10 mol.% Na2O. By contrast, Urbach energy (E U) and refractive index (n) showed opposite trends to that of E opt. The behavior of E U indicates changes in defect concentration, which affects E opt and n.

Chairside CAD/CAM materials. Part 1: Measurement of elastic constants and microstructural characterization

ObjectiveA deeper understanding of the mechanical behavior of dental restorative materials requires an insight into the materials elastic constants and microstructure. Here we aim to use complementary methodologies to thoroughly characterize chairside CAD/CAM materials and discuss the benefits and limitations of different analytical strategies. MethodsEight commercial CAM/CAM materials, ranging from polycrystalline zirconia (e.max ZirCAD, Ivoclar-Vivadent), reinforced glasses (Vitablocs Mark II, VITA; Empress CAD, Ivoclar-Vivadent) and glass-ceramics (e.max CAD, Ivoclar-Vivadent; Suprinity, VITA; Celtra Duo, Dentsply) to hybrid materials (Enamic, VITA; Lava Ultimate, 3M ESPE) have been selected. Elastic constants were evaluated using three methods: Resonant Ultrasound Spectroscopy (RUS), Resonant Beam Technique (RBT) and Ultrasonic Pulse-Echo (PE). The microstructures were characterized using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), Raman Spectroscopy and X-ray Diffraction (XRD). ResultsYoung’s modulus (E), Shear modulus (G), Bulk modulus (B) and Poisson’s ratio (ν) were obtained for each material. E and ν reached values ranging from 10.9 (Lava Ultimate) to 201.4 (e.max ZirCAD) and 0.173 (Empress CAD) to 0.47 (Lava Ultimate), respectively. RUS showed to be the most complex and reliable method, while the PE method the easiest to perform but most unreliable. All dynamic methods have shown limitations in measuring the elastic constants of materials showing high damping behavior (hybrid materials). SEM images, Raman spectra and XRD patterns were made available for each material, showing to be complementary tools in the characterization of their crystal phases. SignificanceHere different methodologies are compared for the measurement of elastic constants and microstructural characterization of CAD/CAM restorative materials. The elastic properties and crystal phases of eight materials are herein fully characterized.

Ultrasonic Characterisation of Epoxy Resin/Polyethylene Terephthalate (PET) Char Powder Composites

This study is carried out in order to determine the elastic properties of the Epoxy Resin (ER) / Polyethylene terephthalate (PET) Char Powder Composites by ultrasonic wave velocity measurement method. Plastic waste was recycled as raw material for the preparation of epoxy composite materials. The supplied chars were mixed with epoxy resin matrix at weight percentages of 10 %, 20 % and 30 % for preparing ER/PET Char Powder (PCP) composites. The effect of PET char powder on the elastic properties of ER/PCP composites were investigated by ultrasonic pulse-echo method. According to the obtained results, the composition ratio of 80:20 is the most appropriate composition ratio, which gave the highest elastic constants values for ER/PCP composites. On the other hand, the best electrical conductivity value was obtained for 70:30 composition ratio. It was observed that ultrasonic shear wave velocity correlated more perfectly than any other parameters with hardness. DOI: http://dx.doi.org/10.5755/j01.ms.22.4.12190

Acoustic characterization of Thiel liver for magnetic resonance-guided focused ultrasound treatment

Background: The purpose of this work was to measure the essential acoustic parameters, i.e., acoustic impedance, reflection coefficient, attenuation coefficient, of Thiel embalmed human and animal liver. The Thiel embalmed tissue can be a promising, pre-clinical model to study liver treatment with Magnetic Resonance-guided Focused Ultrasound (MRgFUS).Material and methods: Using a single-element transducer and the contact pulse-echo method, the acoustic parameters, i.e., acoustic impedance, reflection coefficient and attenuation coefficient of Thiel embalmed human and animal liver were measured.Results: The Thiel embalmed livers had higher impedance, similar reflection and lower attenuation compared to the fresh tissue.Conclusions: Embalming liver with Thiel fluid affects its acoustic properties. During MRgFUS sonication of a Thiel organ, more focused ultrasound (FUS) will be backscattered by the organ, and higher acoustic powers are required to reach coagulation levels (temperatures >56 °C).

Performance of a modified particle swarm optimization in determining the thickness of the liquid layer outside a well casing pipe

The liquid layer outside a well casing develops from flaws along the cement–casing interface, which have been identified as leakage pathways in wellbores. The thickness of the liquid layer is one of the important parameters for determining cement bond quality. However, it is difficult to accurately determine the thickness of the liquid layer outside a well casing pipe with the traditional ultrasonic pulse echo method. To address this problem, we propose a novel inversion method for determining the thickness of the liquid layer between the casing and the cement sheath. According to test specimens, multi-layered structures are modeled to determine the overall reflected wave at the mud–casing interface. An improved particle swarm optimization algorithm is used to simultaneously inverse the thicknesses of the liquid layer, the casing, and the annular space between the casing and formation. Using synthetic data, this algorithm is more robust and stable when compared with standard particle swarm optimization inversion procedures. In addition, the influences of noise in the reflected wave and deviations of medium parameters on the inversion results of the liquid layer thickness are discussed. Finally, the method was used to determine the thicknesses of the liquid layer in test specimens. Numerical and experimental results demonstrate that the improved particle swarm optimization algorithm provides an effective approach to accurately determine the thickness of the liquid layer outside a well casing pipe.

A Bayesian approach for sparse flaw detection from noisy signals for ultrasonic NDT

Ultrasonic pulse-echo methods for flaw detection have been widely employed as an effective strategy for nondestructive evaluation, and flaw detection plays an important role due to its ability to detect localized damage in structures. In practice, flaw damage typically occurs in a few areas in the material, resulting in only a few echoes that exist in a received signal, which motivates us to detect flaws using sparse representation methods. In this study, the noisy signal is modelled by a linear combination of modulated Gaussian pulses, which form an over-complete dictionary. The over-complete dictionary is designed such that the sparseness of the representation is expected. A robust sparse Bayesian learning framework is employed with the goal of enforcing model sparseness and reducing the source of ill-conditioning in the inversion problem for flaw detection. Useful information, including the range of frequency and bandwidth parameters of the flaw echoes, is also estimated. Based on this information, we propose a post-processing scheme for structure noise elimination and flaw detection. The capability of the proposed method is quantitatively evaluated by simulation studies and is further validated by the experimental data.

Characterizing full matrix constants of piezoelectric single crystals with strong anisotropy using two samples

Although the self-consistency of the full matrix material constants of a piezoelectric sample obtained by the resonant ultrasonic spectroscopy technique can be guaranteed because all constants come from the same sample, it is a great challenge to determine the constants of a piezoelectric sample with strong anisotropy because it might not be possible to identify enough resonance modes from the resonance spectrum. To overcome this difficulty, we developed a strategy to use two samples of similar geometries to increase the number of easy identifiable modes. Unlike the IEEE resonance methods, sample-to-sample variation here is negligible because the two samples have almost the same dimensions, cut from the same specimen and poled under the same conditions. Using this method, we have measured the full matrix constants of a [011]c poled 0.71Pb(Mg1/3Nb2/3)O3-0.29PbTiO3 single crystal, which has 17 independent constants. The self-consistency of the obtained results is checked by comparing the calculated elastic stiffness constants c33D, c44D, and c55D with those directly measured ones using the ultrasonic pulse-echo method.

Position and velocity measurement for moving objects by pulse compression using M-sequence-coded ultrasound

The pulse-echo method is one of the typical methods for ultrasonic distance measurement. Pulse compression using an M-sequence can improve the SNR of the echo reflected from an object and distance resolution in the pulse-echo method by the cross correlation between the received signal and the reference signal which correspond to the transmitted M-sequence-coded signal. In the case of a moving object, however, the echo is modulated due to the Doppler effect. The Doppler-shifted M-sequence-coded signal cannot be correlated with the original reference signal. Therefore, Doppler velocity estimation by autocorrelation of cyclic M-sequence-coded signal and cross correlations with Doppler-shifted reference signals which correspond to estimated Doppler velocities has been proposed. In this paper, measurement of position and velocity of the static and moving objects by the proposed method using the loud speaker and the microphone array are described. First, the Doppler velocity of the moving object is estimated in each array element. Second, received signals are correlated with the original reference signal for the static object. Then, received signals are correlated with Doppler-shifted reference signals for the moving object. Finally, positions of both objects are determined from the B-mode image formed by the synthetic aperture focusing technique.

Quantitative evaluation of strength degradation by using linear-nonlinear ultrasonic techniques

The ultrasonic nonlinear parameter, β, has been known as effective for the evaluation of material degradation, and its correlation with material degradations such as thermal aging, fatigue, creep, and plastic deformation has been reported. However, most studies were limited to the relative measurements that is effective only for the relative comparison and not able to evaluate the degradation in quantitative. To overcome this limit, this study proposes a new algorithm which is able to evaluate the quantitative strength degradation. The proposed method mainly consists of four steps: 1) Measure the linear elastic modulus (E) from the longitudinal and shear wave velocities by using pulse echo method. 2) Measure the absolute ultrasonic nonlinear parameter, β, by using piezoelectric detection method. 3) Construct the stress-strain curve by substituting the measured linear elastic modulus (E) and absolute ultrasonic nonlinear parameter β to the nonlinear stress-strain equation. 4) Estimate the 0.01% offset yield strain and yield strength. The yield strengths estimated by the proposed technique in the heat-treated Al6061-T6 and SA508 showed good agreement with the yield strength obtained by tensile test. Consequently, the proposed method makes the quantitative evaluation of strength degradation using ultrasonic measurement possible. [This research was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (NRF-2013M2A2A9043241).]

Second harmonic ultrasonic waves detection using a double-layered piezoelectric transducer

A real-time detection system for second harmonic ultrasonic pulse waves using a double-layered piezoelectric transducer (DLPT) has been constructed. We also analyzed the effective detection of the second-harmonic ultrasonic pulse waves generated by closed-cracks and/or contact surfaces of solids (CAN: contact acoustic nonlinearity) using DLPT and the pulse inversion averaging (PIA) method. Lamb waves were also detected in a double-layered piezoelectric transducer (DLPT). The second harmonic components generated from a closed crack in the glass plate were detected in the pulse-echo method. The second harmonic components in the received waveform in the closed crack area were approximately 6 dB higher than that in the crack-free area. To confirm the origin of the second harmonic components, vibration velocities were detected by using laser Doppler vibrometry. As a result, the threshold amplitude for the generation of the second harmonic components of the Lamb wave was confirmed. This result indicates the existence of the closed cracks in the glass plate.

Ultrasonic studies of texture inhomogeneities in pressure vessel steel subjected to ultrasonic impact treatment and shock compression

Abstract Specimens of Cr-Ni-Mo-V pressure vessel steel 15Kh2NМFА were cut from the achieve wall of the WWER-1000 reactor and were then deformed either using ultrasonic impact treatment (UIT) inducing low energy multiple impacts or by drop-hammer inducing high energy shock compression (HESC). With the aim of texture evaluation comprehensive ultrasonic measurements and X-ray texture analysis were carried out in different sections of the deformed specimens. A nondestructive quantitative analysis of the crystallographic texture in various layers of the deformed specimens was performed on the base of precise measurements of the bulk-wave ultrasonic velocities ( v ij ) by means of the pulse-echo method using a home-made automated apparatus. The mass densities ( ρ ) of the deformed specimens and their cut sections were also precisely measured. The obtained data allowed calculating orientation distribution coefficients ( W 4 i 0 ) of crystallites and to construct ultrasonic pole figures for different specimen layers and cut sections. The ultrasonic pole figures correlate well to the X-ray pole figures registered in the cut sections of the specimens. It is found that maximal pole intensities (Δ I [ ijk ] ) and spatial inhomogeneities of these textures depend on the used regimes of UIT and HESC. The revealed peculiarities of the texture formation correlate well to the depth distributions of microhardness and strain extents. The higher the strain extent or the longer the treatment time, the more intensive texture is registered and the deeper the textured layer is observed. The ultrasonic method applied is shown to be useful and efficient for non-destructive examination of elastically heterogeneous systems, particularly the materials with mechanically treated surfaces.

Ultrasonic characterization of andesite waste-reinforced composites

The epoxy resin used in this study is modified with 5 wt% of polyaniline. Then electrically conductive modified epoxy resin (MER) (as matrix) and different weight amounts (10–30 wt%) of andesite waste (AW) as filler are mixed together to obtain the andesite waste-reinforced epoxy resin composites. The effects of filler amount on the electrical and ultrasonic properties of the modified epoxy resin are examined. The effects of AW amount on the ultrasonic properties of the obtained MER/AW composites are investigated by ultrasonic pulse-echo method. The conductivity of the composites is measured by a four-point probe (FPP) method, and the morphologies of the samples are investigated by scanning electron microscopy (SEM). Experimental results show that increasing the amount of AW causes a linear increase in the elastic properties. On the other hand, the same amounts of AW decrease the electrical conductivity of MER.

Анализ производительности и надёжности методов неразрушающего контроля сварных швов в строительстве

Introduction. The aim of this study is to evaluate the productivity and reliability of non-destructive testing techniques for the inspection of structural welds employed in the Hong Kong construction industry.
 Method. Manual ultrasonic pulse echo method and semi-automatic ultrasonic techniques using phased array (PAUT) as well as radiographic testing were employed. Five classes of defects were analyzed: lack of penetration, lack of fusion, crack, porosity and slag inclusion. The tests were carried out on the specimen made from structural plate, on which artefacts were inserted on the weld metal. The results were being studied to compare the defect detection reliability by both ultrasonic techniques. The flaw detection productivity using phased array is also compared with conventional ultrasonic testing at a determined rate.
 Results. The reliability of PAUT was 100% compared to 96.7% with manual ultrasonic testing, however with the inclusion of defect sizing and tolerance the reliability of manual UT is dropped to 57.4%, which implies there is a chance of 42.6% of improper sizing). PAUT exhibits the reliability of 87.5%. The research will be continued with the aim of determining the most appropriate and reliable NDT methods in each case.

Use of ultrasound to monitor physical properties of soybean oil

The study of the monitoring physical properties of soybean oil was performed. The pulse-echo method allowed measuring the density and viscosity of the oil in real time and accurately. The physical property values were related to the acoustic time of flight ratio, dimensionless parameter that can be obtained from any reference. In our case, we used the time of flight at 20°C as reference and a fixed distance between the transducer and the reflector. Ultrasonic monitoring technique employed here has shown promising in the analysis of edible oils.

Young’s Modulus of Alumina Particles Reinforced Metal-Matrix Composite

Young’s modulus of alumina particles reinforced pure Al-matrix composite is characterized by different methods: the pulse-echo ultrasound method, static three point bending, resonant bending and continuous multicycle measurement by instrumented indentation. Dependency of apparent Young’s modulus on loading amplitude was observed and attributed to the local mechanical properties of both phases, especially to the development of internal damage (local plasticity and particle cracking).

Evaluation of correlation property of linear-frequency-modulated signals coded by maximum-length sequences

Ultrasonic distance measurement for obstacles has been recently applied in automobiles. The pulse–echo method based on the transmission of an ultrasonic pulse and time-of-flight (TOF) determination of the reflected echo is one of the typical methods of ultrasonic distance measurement. Improvement of the signal-to-noise ratio (SNR) of the echo and the avoidance of crosstalk between ultrasonic sensors in the pulse–echo method are required in automotive measurement. The SNR of the reflected echo and the resolution of the TOF are improved by the employment of pulse compression using a maximum-length sequence (M-sequence), which is one of the binary pseudorandom sequences generated from a linear feedback shift register (LFSR). Crosstalk is avoided by using transmitted signals coded by different M-sequences generated from different LFSRs. In the case of lower-order M-sequences, however, the number of measurement channels corresponding to the pattern of the LFSR is not enough. In this paper, pulse compression using linear-frequency-modulated (LFM) signals coded by M-sequences has been proposed. The coding of LFM signals by the same M-sequence can produce different transmitted signals and increase the number of measurement channels. In the proposed method, however, the truncation noise in autocorrelation functions and the interference noise in cross-correlation functions degrade the SNRs of received echoes. Therefore, autocorrelation properties and cross-correlation properties in all patterns of combinations of coded LFM signals are evaluated.

Effect of deep native defects on ultrasound propagation in TlInS2 layered crystal

We have investigated p-type semiconductor–ferroelectric TlInS2 by means of Photo-Induced Current Transient Spectroscopy (PICTS) technique in the temperature range 77–350K for the detection of native deep defect levels in TlInS2. Five native deep defect levels were detected and their energy levels and capture cross sections were evaluated. Focusing on these data, the influence of these defects on the longitudinal and transverse ultrasound waves propagation as well as the effect of electric field on ultrasound waves were studied at different temperatures. The acoustic properties were investigated by the pulse-echo method. The direct contribution of thermally activated charged defects to the acoustic properties of TlInS2 was demonstrated. The key role of charged native deep level defects in elastic properties of TlInS2 was shown.

Elastic moduli of pure and gadolinium doped ceria revisited: Sound velocity measurements

The Young's, shear and bulk moduli of dense (>95%) Gd-doped ceria (Ce1-xGdxO2-x/2) ceramics were determined as a function of Gd content using the ultrasonic pulse-echo method and corrected for porosity according to both static and dynamic models. With increasing defect concentration (0–20mol% Gd), the Young's and shear moduli decrease linearly by 10% while for 29mol%, the values lie above the linear fit; the bulk modulus decreases linearly within the complete range. We conclude that structural changes, induced by oxygen vacancy ordering for x>0.2, may influence the uniaxial and shear moduli, leaving the bulk modulus unaffected.

Speed of sound in saturated aliphatic alcohols (propan-2-ol, butan-2-ol, and 2-methylpropan-1-ol) and alkanediols (ethane-1,2-diol, propane-1,2- and -1,3-diol) at temperature between 253.15 K and 353.15 K and pressures up to 30 MPa

Speeds of sound have been measured in three saturated aliphatic alcohols (propan-2-ol, butan-2-ol, and 2-methylpropan-1-ol) and three alkanediols (ethane-1,2-diol, propane-1,2- and -1,3-diol) in the temperature range from (253.15 to 353.15)K and pressures up to 30MPa by use of a pulse-echo method with a double path type sensor operating at 8MHz. The expanded overall uncertainties (k=2) in the speed of sound measurements are estimated to be 0.013% for propan-2-ol, 0.019% for butan-2-ol, 0.01% for 2-methylpropan-1-ol, 0.009% for ethane-1,2-diol, 0.02% for propane-1,2-diol, and 0.07% for propane-1,3-diol. Experimental speeds of sound data were correlated with the temperature and pressure with an empirical double polynomial equation. Our results were also compared with the available literature data and a satisfactory agreement was found.

Ultrasonic spectroscopy of copolymer based P(VDF-TrFE) composites with fillers on lead zirconate titanate basis

In this work we report on the ultrasonic and dielectric properties of composites consisting of conventional piezoelectric polymer, polyvinylidene fluoride/trifluoroethylene (PVDF-TrFE) copolymer of composition 70/30 mol. %, and (Pb0.75Ba0.24Sr0.01)(Zr0.53Ti0.47)O3 (BPZT) particles. BPZT fillers concentration was varied from 10 to 50 vol.%. Investigation of ultrasonic wave attenuation, velocity and piezoelectric voltage in these composites was performed over a temperature range from 300 K to 420 K using an automatic ultrasonic pulse-echo method. The temperature dependences of ultrasonic velocity and attenuation showed anomalies attributed to the glass transition temperature Tg and Curie temperature Tc of the polymer matrix.