Ultrasonic Phase Research Articles

The Benzoin Condensation Reaction under Different Ultrasonic Frequency and Phase Transfer Catalyst

This paper summarizes the method of benzoin condensation reaction, and studied the influence of benzoin yield under different ultrasonic frequency and phase transfer catalyst, Experiments prove that benzyltriethylammonium bromide is the best phase transfer catalyst in three catalysts and the benzoin yield increased with the increase of ultrasonic frequency.

Improvement of compressive strength after impact in fibre reinforced polymer composites by matrix modification with thermally reduced graphene oxide

In this study fibre reinforced laminates with a graphene oxide modified epoxy matrix were manufactured using a filament winding technology for prepreg production. Dispersion of the nano-particles was achieved with a three roll mill. Cross-ply laminates with carbon and glass fibres and different nano-particle loadings were produced. Impact damage was introduced with an instrumented drop weight tower. Prior to mechanical testing damage size was determined using ultrasonic c-scans and pulse phase thermography. The defect size was reduced significantly with increasing graphene oxide loading in the matrix. Residual compressive properties of the laminates improved significantly for the modified specimen, with the glass fibre laminates showing the highest improvement of 55% when compared to unmodified specimens. In addition to the improved mechanical properties the matrix modification also improved the phase contrast of the thermography data thus enabling better detection of defects and improved detection limits.

Wpływ fazy drgań ultradźwiękowych na strukturę i twardość napoin stopu aluminium 2017A

W artykule przedstawiono wyniki badań struktury i twardości napoin uzyskanych metodami MIG na falowodzie w kształcie walca ze stopu aluminium 2017􏰂. Badania miały charakter porównawczy i polegały na zestawieniu wyników uzyskanych napoin ze wspomaganiem drganiami ultradźwiękowymi oraz bez stosowania drgań. 􏰖Celem zaprezentowanych badań było określenie wpływu fazy drgań ultradźwiękowych na strukturę i twardość uzyskanych napoin. Budowa strukturalna i twardość napoin uzyskanych z zastosowaniem drgań wykazywały zależność od ich fazy. Effects of the ultrasonic vibrations phase on structure and hardness surface-welds of 2017a aluminum alloy T􏰃he structure and hardness of the surface-welds and fusion-welds made on a 2017􏰂 aluminum alloy wa􏰁veguide using the MIG method with and without the participation of ultrasonic 􏰁vibrations were e􏰩xamined. 􏰖ross-sections of the fusions and surface-welds thus obtained were obser􏰁ved in a microscope and the hardness distributions were determined. 􏰃The aim of the study was to analyze the effects of the ultrasonic 􏰁vibrations applied to the melted metal pool by a 􏰁vibrating substrate which in our ex􏰩periments was a wav􏰁eguide. T􏰃he interactions of the ultrasonic 􏰁vibrations with the molten metal during its solidifi􏰧cation and also with the heat-affected zone were e􏰩xamined at 􏰁various phases of the v􏰁ibration wav􏰁e. 􏰃The ultrasonic v􏰁ibrations affected the structure of weld. 􏰃These changes are strongly depended of 􏰁vibration wav􏰁e phase.

Measurement of ultrasonic phase and group velocities in human dental hard tissue.

BackgroundThe development of ultrasound for use in dental tissues is hampered by the complex, multilayered nature of the teeth. The purpose of this preliminary study was to obtain the phase and group velocities associated with several directions of ultrasonic wave propagation in relation to the tooth structure, which would then lead to the determination of the elastic constants in dental hard tissue. Knowledge of these elastic constants can be used to feed back into numerical models (such as finite element) in order to simulate/predict ultrasonic wave propagation and behavior in the teeth. This will help to optimize ultrasonic protocols as potential noninvasive therapeutic tools for novel dental regenerative therapies.MethodsAn extracted human second molar was used to determine time-of-flight information from A-scan signatures obtained at various angles of inclination and rotation using a scanning acoustic microscope at 10 MHz. Phase and group velocities and associated slowness curves were calculated in order to determine the independent elastic constants in the human teeth.ResultsResults show that as the tooth was inclined at three azimuthal angles (Θin = 0°, 15°, and 30°) and rotated from Φin = 0° to 360° in order to cover the whole perimeter of the tooth, slowness curves constructed from the computed phase and group velocities versus angle of rotation confirm the inhomogeneous and anisotropic nature of the tooth as indicated by the nonuniform appearance of uneven circular shape patterns of the measurements when compared to those produced in a control isotropic fused quartz sample.ConclusionsThis study demonstrates that phase and group velocities of ultrasound as determined by acoustic microscopy change and are dependent on the direction of the tooth structure. Thus, these results confirm that the tooth is indeed a multilayered anisotropic structure underscoring that there is no single elastic constant sufficient to represent the complex structure of the tooth. The findings underline the importance to take into account these crucial characteristics in order to develop and optimize therapeutic as well as diagnostic applications of ultrasound in dental tissue repair, and further studies are warranted to analyze ultrasound transmission at various frequencies and intensities in different teeth to develop appropriate models for ultrasound biophysical behavior in dental tissues.

Assessment of breadmaking performance of wheat flour dough by means of frequency dependent ultrasound

Technological performance of wheat flour varies among different wheat varieties. Gluten plays a key role within the solid phase of dough in the formation and the retention of gas bubbles during breadmaking. Rheological tests are usually performed to predict breadmaking potential. The aim here was to investigate the ability of ultrasound to discriminate wheat doughs based on breadmaking qualities. The ultimate goal is the development of an online quality control system currently unavailable in the baked goods industry, rendering this work innovative. Samples were prepared from a strong wheat flour, with one control sample and one added with inulin and distilled monoglycerides, producing doughs of distinct breadmaking quality. Doughs were subjected to density determination, elongation tests, and ultrasound analysis. The ultrasound tests were performed in the frequency range of 300 kHz – 6 MHz. Ultrasonic phase velocity increased with increasing frequency to about 2 MHz, becoming constant and then decreasing from 3 MHz for the control sample. Distinct differences in attenuation coefficient between the fibre-enriched and control doughs were observed. Ultrasound can potentially add to a better understanding of dough quality and can discriminate between doughs of contrasting properties.

Measurement Algorithm of Two-Dimensional Wind Vector using Ultrasonic Transducers

Ultrasonic wind speed measurement technique obtains more and more extensive use in the field of Meteorology and Environmental Protection etc. When designing an ultrasound wind vector instrument, synthesizing wind vector information, containing wind velocity vector and wind angle, is of prime importance to accomplish accurate measurement. This paper presents synthesis algorithm of ultrasonic 2D (two-dimensional) wind vector based on phase difference wind detection method, establishes mathematical model of wind speed, ultrasonic speed and phase difference, focuses on the analysis of the quadrant critical problem in the process of synthesizing wind angle. And the ultrasonic phase difference wind speed and detection method proposed in this paper overcomes most disadvantages, e.g. complex circuit, troublesome signal processing etc., which exist in traditional time difference ultrasonic wind detection method. Through software emulation, the mathematical model established in this paper could calculate wind speed and direction precisely, based on 2D wind speed component. DOI: http://dx.doi.org/10.11591/telkomnika.v11i1.1341

Ultrasonic real-time in-die monitoring of the tablet compaction process—A proof of concept study

The mechanical properties of a drug tablet can affect its performance (e.g., dissolution profile and its physical robustness. An ultrasonic system for real-time in-die tablet mechanical property monitoring during compaction has been demonstrated. The reported set-up is a proof of concept compaction monitoring system which includes an ultrasonic transducer mounted inside the upper punch of the compaction apparatus. This upper punch is utilized to acquire ultrasonic pressure wave phase velocity waveforms and extract the time-of-flight of pressure waves travelling within the compact at a number of compaction force levels during compaction. The reflection coefficients for the waves reflecting from punch tip-powder bed interface are extracted from the acquired waveforms. The reflection coefficient decreases with an increase in compaction force, indicating solidification. The data acquisition methods give an average apparent Young's moduli in the range of 8-20 GPa extracted during the compaction and release/decompression phases in real-time. A monitoring system employing such methods is capable of determining material properties and the integrity of the tablet during compaction. As compared to the millisecond time-scale dwell time of a typical commercial compaction press, the micro-second pulse duration and ToF of an acoustic pulse are sufficiently fast for real-time monitoring.

Frequency dependence of laser ultrasonic SAW phase velocities measurements

Advances in the field of laser ultrasonics have opened up new possibilities in applications in many areas. This paper verifies the relationship between phase velocities of different materials, including hard solid and soft solid, and the frequency range of SAW signal. We propose a novel approach that utilizes a low coherence interferometer to detect the laser-induced surface acoustic waves (SAWs). A Nd:YAG focused laser line-source is applied to steel, iron, plastic plates and a 3.5% agar–agar phantom. The generated SAW signals are detected by a time domain low coherence interferometry system. SAW phase velocity dispersion curves were calculated, from which the elasticity of the specimens was evaluated. The relationship between frequency content and phase velocities was analyzed. We show that the experimental results agreed well with those of the theoretical expectations.

Ultrasonic self-calibrated method applied to monitoring of sol–gel transition

In many industrial processes where online control is necessary such as in the food industry, the real time monitoring of visco-elastic properties is essential to ensure the quantity of production. Acoustic methods have shown that reliable properties could be obtained from measurements of velocity and attenuation. This paper proposes a simple, real time ultrasound method for monitoring linear medium properties (phase velocity and attenuation) that vary in time. The method is based on a pulse echo measurement and is self-calibrated. Results on a silica gel are reported and the importance of taking into account the changes of the mechanical loading on the front face of the transducer will be shown. This is done through a modification of the emission and reception transfer parameters. The simultaneous measurement of the input and output currents and voltages enables these parameters to be calculated during the reaction. The variations of the transfer parameters are in the order of 6% and predominate other effects. The evolution of the ultrasonic longitudinal wave phase velocity and attenuation as a function of time allows the characteristic times of the chemical reaction to be determined. The results are well correlated with the gelation time measured by rheological method at low frequency.

Experimental Study on Flaw Response in Inhomogeneous Media

The objective of this paper is to predict the flaw response in an inhomogeneous solid medium. Multi-Gaussian Beam (MGB) model is used to represent the incident ultrasonic beam. The effect of ultrasonic attenuation and phase velocity dispersion due to grain scattering is included in the predictions. The effect of variation of mean diameter of the grains on the received voltage for different domain of interest is studied through the experimental results.

Numerical Calculation on Flaw Response in Inhomogeneous Media

Ultrasonic methods are used in a wide variety of applications including medical studies, geological mapping, and nondestructive evaluation (NDE) tests. In the field of ultrasonic NDE, it is necessary to treat inverse problems of various types. The objective of this paper is to predict the flaw response in an inhomogeneous solid medium. A mathematical modelling of the testing situation is very valuable for a number of reasons. The modelling helps in developing physical intuition and in the interpretation of tests. Multi-Gaussian Beam (MGB) model is used to represent the incident ultrasonic beam. The effect of ultrasonic attenuation and phase velocity dispersion due to grain scattering is included in the predictions. The variation of received voltage is analyzed against the distance of the flaw from the transducer for different dimensions of a square cylinder void. The effect of variation of mean diameter of the grains on the received voltage for different domain of interest is also studied.

Enhanced properties for ultrasonic transduction, phase transitions and thermal depoling in 0.96(Bi0.5Na0.5)TiO3-0.04BaTiO3 submicrometre-structured ceramics

Submicrometre structured (grain size ≈500 nm), dense (Bi0.5Na0.5)0.96Ba0.04TiO3 ceramics were obtained from sol–gel auto-combustion nanopowders by hot-pressing (700–950 °C) and subsequent recrystallization (1000–1050 °C). Electromechanical coefficients were obtained by analysis of the resonance spectra of thin discs using the Alemany et al software. The real part of the room temperature set of coefficients of the best performing materials (, d31 = (−22.68 + 0.55i)pC N−1, kt = 44.5%, kp = 21.1%) can be compared with those of coarse-grained ceramics and d33 (95 pC N−1) is higher. Shear-related coefficients were obtained from thickness poled and length excited plates (, d15 = (108.3 − 21.4i) pC N−1 and k15 = 39.2%). At the depolarization temperature, Td = 153 °C, the dielectric loss, tan δ(T), of poled samples shows a maximum and the planar resonance virtually vanishes. Shear resonance of thickness-poled plates and weak planar electromechanical resonance are observed above Td. The relaxor behaviour extends up to the isotropization point, Ti = 238 °C. This can be understood as due to the coexistence of the room temperature ferroelectric phase in the stability range of the low-temperature non-polar phase at zero field, between Td and Ti.

Complete determination of elastic moduli of interpenetrating metal/ceramic composites using ultrasonic techniques and micromechanical modelling

Abstract The complete stiffness matrices of several metal/ceramic composites were analysed using the complementary ultrasonic spectroscopic techniques ultrasound phase spectroscopy (UPS) and resonant ultrasound spectroscopy (RUS). Three different aluminum/alumina composites having complex interpenetrating architectures were studied: a composite based on freeze-cast ceramic preform, a composite based on open porous ceramic preform obtained by pyrolysis of cellulose fibres, and a composite based on discontinuous fibre preform. Six of the nine independent elastic constants describing orthotropic elastic anisotropy were pre-determined by ultrasound phase spectroscopy and used as initial guess input for resonant ultrasound spectroscopy analysis, making the final results of all nine elastic constants more reliable. In all cases, consistent and reproducible results are obtained. Finally the experimental results were compared with effective elastic constants calculated using micromechanical modelling and a good correspondence between both is obtained.

Bruxism and Temporal Bone Hypermobility in Patients with Multiple Sclerosis

In this study, the authors investigated the link between jaw clenching/bruxism and temporal bone movement associated with multiple sclerosis (MS). Twenty-one subjects participated in this study (10 patients with MS and 11 controls). To quantify the change in intracranial dimension between the endocranial surfaces of the temporal bones during jaw clenching, an ultrasonic pulsed phase locked loop (PPLL) device was used. A sustained jaw clenching force of 100 lbs was used to measure the mean change in acoustic pathlength (ΔL) as the measure of intracranial distance. In the control subjects the mean ΔL was 0.27 mm±0.24. In subjects with MS the mean ΔL was 1.71 mm±1.18 (p<0.001). The increase in magnitude of bi-temporal bone intracranial expansion was approximately six times greater in subjects with MS compared to controls. Therefore, jaw clenching/bruxism is associated with more marked displacement of the temporal bones and expansion of the cranial cavity in patients with MS than in control subjects.

Detection of Impact Damages in CFRP Composites Using Ultrasonic Burst Phase Thermography

Carbon fiber reinforced polymer (CFRP) composites have been used extensively because of their excellent performance, but they are susceptible to the impact damages, such as the impact of birds, runway stones and tools off can cause the failure of CFRP composites. Therefore, nondestructive testing of CFRP composites is necessary to promote the failure control and prevention. Ultrasonic burst phase thermography (UBP) developed a few years ago is a defect-selective and fast imaging tool for damage detection. This paper describes the principle of UBP, gives some UBP testing results of impact damages in five CFRP laminated boards. The shape and position of the damages are shown in the phase images visualized and the relationship between the damage areas and impact energy is discussed. The flash pulse thermography (PT) results and ultrasonic C-scan results are also shown as comparison. It is concluded that all of the three NDT methods have their own characteristics and the comparison verifies the feasibility of CFRP impact damage detection using ultrasonic burst phase thermography.

Measurements of ultrasonic phase velocities and attenuation of slow waves in cellular aluminum foams as cancellous bone-mimicking phantoms

The water-saturated aluminum foams with an open network of interconnected ligaments were investigated by ultrasonic transmission technique for the suitability as cancellous bone-mimicking phantoms. The phase velocities and attenuation of nine samples covering three pores per inch (5, 10, and 20 PPI) and three aluminum volume fractions (5, 8, and 12% AVF) were measured over a frequency range of 0.7-1.3 MHz. The ligament thickness and pore sizes of the phantoms and low-density human cancellous bones are similar. A strong slow wave and a weak fast wave are observed for all samples while the latter is not visible without significant amplification (100x). This study reports the characteristics of slow wave, whose speeds are less than the sound speed of the saturating water and decrease mildly with AVF and PPI with an average 1469 m/s. Seven out of nine samples show positive dispersion and the rest show minor negative dispersion. Attenuation increases with AVF, PPI, and frequency except for the 20 PPI samples, which exhibit non-increasing attenuation level with fluctuations due to scattering. The phase velocities agree with Biot's porous medium theory. The RMSE is 16.0 m/s (1%) at n = 1.5. Below and above this value, the RMSE decreases mildly and rises sharply, respectively.

A broadband spectroscopy method for ultrasonic wave velocity measurement under high pressure

A broadband spectroscopy method is proposed to measure the ultrasonic wave phase velocity of Z-cut quartz under high pressure up to 4.7 GPa. The sample is in a hydrostatic circumstance under high pressure, and we can get longitudinal wave and shear wave signals simultaneously in our work. By fast Fourier transform of received signals, the spectrum and phase of the received signals could be obtained. After unwrapping the phase of the received signals, the travel time of ultrasonic wave in the sample could be obtained, and the ultrasonic wave phase velocity could also be resolved after data processing. The elastic constant of measurement under high pressure is also compared with previous studies. This broadband spectroscopy method is a valid method to get ultrasonic wave travel parameters, and it could be applied for elasticity study of materials under high pressure.

Influence of aggregates and air voids on the ultrasonic velocity and attenuation in cementitious materials

ABSTRACT This paper examines the influence of the size and volume fraction of both aggregates and air voids on the ultrasonic phase velocity and attenuation coefficient measured in cementitious specimens. A multiphase approach of the Waterman-Truell (WT) model was used to study theoretically how the size and volume fraction of the constituents in cementitious materials affect velocity and attenuation profiles. To verify the theoretical results obtained by the model, ultrasonic measurements were performed in several cementitious specimens with different granulometries of elastic aggregates (glass microspheres). Both theoretical and experimental results showed that velocity information can largely identify changes in the volume fraction of aggregates, whereas attenuation information is more sensible to variations in the aggregate size.

Measurements of coating density using ultrasonic reflection coefficient phase spectrum

A nondestructive method to determine the density of coating has been proposed in this paper based on the ultrasonic reflection coefficient phase spectrum (URCPS). A model was set up first to represent the ultrasonic waves reflected from a coating system at normal incident, and the relation between the extremum of URCPS and the coating density was established to provide the principle of determining the density. The ultrasonic method was validated on a series of ZrO2–7 wt.%Y2O3 (YSZ) coatings with various density. The specimens were prepared by electric beam physical vapor deposit (EB-PVD). After deposition, the specimens were irradiated using high-intensity pulsed ion beam (HIPIB) at different ion current density of 100 and 200 A/cm2 to change coating density. The coating densities of as-deposited and post irradiation by HIPIB were derived to be 4940–5030, 5200–5320 and 5390–5470 kg/m3, respectively. The relative error between the coating density measured by the ultrasonic method and Archimedean principle ranging from 2.53% to 6.11%, indicates that the proposed ultrasonic quantification method provides a reliable nondestructive way to determine coating density.

ChemInform Abstract: The Addition of Perfluorobutyl Iodide to Carbon-Carbon Multiple Bonds and the Preparation of Perfluorobutylalkenes.

Abstract Addition of perfluorobutyl iodide to CC multiple bonds is efficiently achieved by sodium dithionite under ultrasonic irradiation or phase transfer conditions. Perfluorobutyl substituted alkenes are obtained from the β-iodo-perfluoroalkanes resp.-alkenes by base-catalyzed elimination resp. reductive cleavage.