Papers by Keyword: Ultrasonic Wave

Abstract: In this research work, bioactive Ti15Mg alloy was prepared by powder metallurgy route to investigate its biocompatibility and mechanical properties. Many tests were performed including X-ray diffraction; optical microscope analysis, scanning electron microscope analysis, ultrasonic wave test, corrosion behavior test, Static immersion test, and the wet sliding wear test. The XRD result shows that the prepared alloy sample consist of (α-Ti phase) and Mg. The microstructure of the prepared alloy sample consisted of a biodegradable Mg or pore and alpha titanium. The effect of the Mg content on degradability was tested based on simulated body fluid of Ringer solutions using electrochemical corrosion. The findings indicate that an elastic modulus of 47GPa exhibits the alloy. There were low corrosion rates of the alloy. The Ti matrix remained integrity after 14 days of immersion in the Ringer solutions, and the magnesium phase dissolved in the solution, causing a layer to form on the alloy. The wear behavior of the prepared ally at wet sliding conditions was evaluated using pin on disc method. The in vitro analysis showed good biocompatibility with Ti15Mg alloy. The prepared alloy demonstrates good biocompatibility and bioactivity.

Abstract: The non-linear diffusion-deformation theory of self-organization of nanoclusters of dot defects in semiconductor exposed to ultrasound treatment that considers the interaction of defects among themselves and with atoms of a matrix via the elastic field created by dot defects and an acoustic wave is developed. Within this theory the influence of ultrasound on the conditions of formation of spherical nanoclusters and their radius is investigated. The nanocluster size depending on average concentration of defects and amplitude of an acoustic wave is determined. It is established that ultrasonic treatment of the semiconductor in the process of formation of an ensemble of nanoclusters leads to reduction of dispersion of their sizes. In the framework of this model, a possibility of the ultrasound-stimulated the size dispersion reduction of strained InAs/GaAs quantum dots doped with an isovalent impurity are analyzed.

Abstract: Ultrasonic measurement is used to evaluate wrinkles during sheet metal forming. The authors developed a new apparatus for investigating the relationship between the wrinkles in press forming and the ultrasonic reflection characteristic of an angle beam. The new evaluation apparatus was composed of probe-fixing parts, an upper die, a middle die, and a lower die. A specimen was sandwiched by a pair of dies in the evaluation apparatus. Angle beam probes for transmission and reception were set on the upper die. Specimens in the form of plates having periodic trapezoidal wrinkles were fabricated by electro-discharge machining. In the new evaluation apparatus, the specimen is placed in contact with the die. Wrinkling was found to change the ultrasonic reflection characteristic of an angle beam. The new apparatus can thus be used to evaluate wrinkles using the angle beam technique.

Abstract: The servo press has high potential for producing high precision mechanical parts. However, small gaps between dies and workpieces tend to exist even in servo press stamping, and the potential of the servo press has not yet been fully utilized. The reason for this is conventional presses do not have feedback control systems, and the lack of a suitable method of sensing contact information in real time causes deterioration in the accuracy of products. If slide motion could be controlled by contact information, the small gaps could be removed. To solve this problem, the authors have developed a method of monitoring the contact states between dies and workpieces during the stamping process. The method uses ultrasonic wave reflection and transmission at the contact surfaces and was proved to be able to monitor contact pressure by using a simple geometry experimental die apparatus. Finite-difference time-domain (FDTD) numerical simulation was conducted in this study to obtain better understanding of wave propagation through dies and workpieces. The results obtained from this FDTD simulation visualized wave propagation that could not be experimentally measured. Some of the major results obtained are as follows. 1) When a thin metal sheet is pressed between dies that have inclined stamping surfaces, ultrasonic elastic waves are reflected and transmitted multiple times. 2) Modal conversion occurs at the die-workpiece boundary in such a way that normal waves with an inclined incident angle are transformed into normal and shear waves. 3) Elastic waves sent out from an ultrasonic transducer are mixtures of normal waves with flat wave fronts along the propagation path axis, normal waves with circular or spherical wave fronts expanding from both sides of the transducer, and shear waves. These results brought about much useful information for setting ultrasonic transducers and analyzing collected signals.

Abstract: At present, the quality inspection of drilling holes in power transmission line foundations is mainly completed by manpower with the help of the measuring rope, reinforcing cage, etc. This is a rough measuring method with low accuracy, and even the workers have to enter into deep holes to measure verticality and similar values, which brings danger to personal safety. The measuring equipment and methods for foundation holes have mature application in the industry and civil building sector, which are mainly divided into two categories, contact and non-contact measurements. The inspection methods for drilling holes in power transmission line foundation are to be proposed by referring to inspection means used in the sector.

Abstract: Earlier works have proved the potentials of altering the vapor liquid equilibrium of azeotropic mixture by sonication phenomena. In this work a mathematical model of a single stage vapor-liquid equilibrium system developed in Aspen Custom Modeler is exported to Aspen Plus to represent one stage of ultrasonic flash distillation (USF). The USF modules are connected serially to mimic a distillation process. As a case study, the separation of ethanol-ethyl acetate mixture is considered. The final targeted composition of 99 mole % of ethyl acetate was achieved when 27 USF modules were used despite the fact that the mixture form azeotrope at 55 mole % ethyl acetate. The results reinforced the anticipated potentials of sonication phenomena in intensifying distillation process to overcome azeotropes, and provide useful insights for the development of a pilot-scaled facility that is currently under development.

Abstract: The study of signals propagation inside porous media is an important field especially in the biomedical research related to compact bones. The purpose of this paper is to determine a mathematical formulation of the global coefficients of transmission and reflection of nondestructive ultrasonic waves in any bi-phase porous medium. Local coefficients of transmission and reflection on the interface of the porous medium will be determined based on a study of boundary conditions. The behavior of different waves inside the porous medium will be developed so that we can derive a new formulation of global coefficients that takes interior phenomena into consideration. Results are found independently of the geometrical and physical characteristics of the medium. Note that this study is based on normal incident ultrasonic wave propagation.

Abstract: An ultrasonic Rayleigh wave transducer was designed for nondestructive pressure measurement in vessels. Using polyimide resin as the wedge material, the Rayleigh wave transducer had two piezoelectric elements which were placed in the same wedge with a certain distance. Variations in pressure and temperature of vessels can affect the velocity of ultrasonic waves, which will affect variations in time delay in receiving of the same Rayleigh wave with the two piezoelectric elements of the designed transducer. Based on the acoustoelasticity principle and considered the effect of temperature, a practical correlation model between the time delay and both the pressure and temperature of vessels was developed. Using an air vessel as a specimen, Rayleigh wave transducers were arranged in the axial direction of the vessel. The results of temperature experiments show that effect of changes in temperature on time delay agree with the theoretical results. With the calculation temperature compensation in pressure experiment, the relationship between the variations in the time delay caused by changes of pressure and the pressure is established. The pressure measurement results show that the measurement model is effective and the maximum absolute error is 0.09 MPa, which could be acceptable in engineering application.

Abstract: High frequency vibration signal, cylinder-inside pressure and ultrasonic wave are monitored under working condition of a reciprocating compressor. High frequency vibration signal and ultrasonic wave are processed using high frequency band-pass filtering, and then enveloped. The pressure signal is filtered with a low-pass digital filter. The fault causes of the machine can be determined by the enveloped waveform of vibration signal and ultrasonic wave, as well as the pressure curve comprehensively. We can confirm the truth that this fault diagnosis method is accurate and reliable for reciprocating compressors through a number of the results of fault diagnosis.

Abstract: In order to quantitatively detect the compactness of bellows duct grouting, by studying time-histories relation curve forming by ultrasonic wave transmitting in different thicknesses concrete samples. We get the acoustic time rule after ultrasonic passed through different compactness bellows duct. At the same time, establishing empty hole estimation model corresponding to the concrete samples and providing theoretical basis for judging porosity and predicting the grouting quality in the bellows duct. Meanwhile, dividing the bellows duct into five degrees complete compactness, 3/4 compactness, 1/2 compactness, 1/4 compactness, empty by setting up defects in the bellows duct, and then embedding them in concrete slab to do ultrasonic detection. The detection result shows that ultrasonic detection method can effectively quantitive estimate the grouting quality of prestressed bellows duct with establishing empty hole estimation model.