High Power Ultrasonic Waves Research Articles

Experimental Study on Fire Smoke Particles of Power Tunnel by High-power Ultrasonic Wave

Experimental Study on Fire Smoke Particles of Power Tunnel by High-power Ultrasonic Wave

The Effects of Ultrasonication on the Precipitation Of Precipitated Calcium Carbonate (PCC) Through Mineral Carbonation in a CaCl2-NH4 Cl-NH3-H2O SYSTEM

The effects of ultrasonication on the precipitation of precipitated calcium carbonate (PCC) based on mineral carbonation are investigated in a CaCl2-NH4Cl-NH3-H2O system. The experimental results show that high ultrasonic power can delay the induction period of the reaction, and that the pH and conductivity change little as the ultrasonic power changes. The structure of PCC changes from mature, large and spherical particles into aggregates composed of a large number of loose crystals, and a larger proportion of vaterite transforms into calcite under an ultrasonic power of 0% to 30%, which leads to the ultrasonic scouring action. When the ultrasonic power is increased to 60% and 90%, the particle size of PCC decreases, and the proportion of vaterite increases as the ultrasonic power increased further as a result of the high saturation during the prolonged induction period induced by ultrasonication and of the high-power ultrasonic waves shattering the agglomerates rather than scouring the crystal surface.

Effect of Different Ultrasonic Power on the Properties of RHA Steel Welded Joints

Based on the changes of microhardness, tensile strength, and impact resistance caused by the difference of macroscopic morphology and microstructure of welded joints, this paper studied the effect of different ultrasonic power on the properties of welded joints during the welding of homogeneous armor steel. It is experimentally found that the macroscopic morphology of those joints is very different. Compared with conventional welding, ultrasonic welding can increase the weld depth and the width of the heat-affected zone (HAZ) on either side of the weld. However, only the ultrasonic wave at an appropriate power level can increase the weld width. In addition, appropriate ultrasonic power can significantly improve the grain state of the weld. With the increase of ultrasonic power, the grain size in HAZ will decrease. The microhardness of the weld will first increase and then decrease, while the microhardness of the HAZ will increase. This is basically consistent with the changing trend of impact resistance. An ultrasonic wave can also increase the tensile strength of a welded joint up to 802 MPa, 12.4% higher than that in conventional welding. However, a high-power ultrasonic wave will bring down the tensile strength. This study provides guidance for the selection of ultrasonic-assisted regulation power to achieve the different properties of homogeneous armor steel joints.

Enhanced thermal- and impact-initiated reactions of PTFE/Al energetic materials through ultrasonic-assisted core-shell construction

A facile and economical approach was developed for the large-scale production of powdered core-shell structured PTFE/Al (CS-PA) energetic materials through ultrasonic-assisted mixing. The low-cost micrometer-sized PTFE and Al particles were used as starting materials. Under high-power ultrasonic waves, the PTFE powder was dispersed into nano-to sub-micrometer-sized particles and then encapsulated the Al microparticles to form the core-shell structure. The heat of combustion, burning rate, and pressurization rate of the powdered CS-PA were measured. The thermal-initiated reaction behavior was further evaluated using thermogravimetry-differential scanning calorimetry. Subsequently, the bulk CS-PA with a uniform microstructure was obtained via cold isostatic pressing of the powdered CS-PA followed by vacuum sintering. For the bulk CS-PA, the quasi-static compression behavior was characterized, and the impact-initiated reaction processes were conducted using the Split Hopkinson Pressure Bar (SHPB) and evaluated by a high-speed camera. Compared to physically mixed PTFE/Al materials, the powdered and bulk CS-PA demonstrated enhanced thermal- and impact-initiated reaction characteristics respectively, proving the effectiveness of our approach for constructing core-shell structures.

Hybrid Welding of Metal-Polymer Composites with a Non- Conducting Polymer Layer

Metal-polymer composites (MPCs) are becoming increasingly popular primarily because of their high strength-to-weight ratio. Metal-polymer composites consist of three layers, i.e. two external metallic sheets (linings) and the core made of plastic. The presence of the internal plastic layer makes MPCs impossible to join using conventional welding processes, which significantly limits their usability. One of the solutions to the problem involves the use of hybrid methods, e.g. ultrasonic method-aided resistance welding. The research work discussed in the article involved the development of a prototype test rig and a technology enabling the joining of the Litecor® composite with steel DP600. The joining process consisted of two stages. The first stage involved the removal of the non-conducting layer of polymer from the welding area and the making of an appropriate electric contact for resistance welding. The second stage was the classical resistance spot welding process. The development of the concept posed a challenge as it was necessary to develop an appropriate acoustic waveguide for high-power ultrasonic waves which, at the same time, could transfer loads in the form of electrode force as well as provide appropriate electric and thermal conductivity without compromising acoustic parameters during the welding process. The development of the test rig was followed by the performance of numerous tests aimed to identify the appropriate window of process parameters. Test joints were subjected to macrographic, strength, ultrasonic and topographic tests.

An investigation on the microwave absorption properties of Co–Al–Ti substituted barium hexaferrite-MWCNT nanocomposites

The microwave absorption properties of Co–Al–Ti substituted barium hexaferrite-multiwalled carbon nanotubes (MWCNTs)-epoxy resin nanocomposites are thoroughly investigated in the frequency range of 1–18 GHz. The Nanoparticles with the chemical formula BaCoxAlxTixFe12−3xO19x=0.2,0.3, and 0.4 are synthesized by the sol-gel auto combustion method. The XRD patterns along with Rietveld analysis as implemented in FullProf software are used to characterize crystalline nanoparticles. The effect of the substitution on the magnetic properties of the nanoparticles is also investigated by the VSM analysis. The MWCNTs are then dispersed into the nanoparticles by high-power ultrasonic waves to fabricate nanocomposite structures. All of the nanocomposites show appropriate microwave absorption properties with a matching thickness lower than 1.75 mm. The reflection loss minimum is also lower than − 20 dB in which more than 99.9% of the electromagnetic wave energy is absorbed. The bandwidth of the nanocomposites covers practically the whole frequency range of 1–18 GHz by changing the thickness of the samples. The reflection loss minimum (RLmin) reaches −47.40dB for the sample with x = 0.3, and the nanocomposite with x = 0.2 shows the best microwave absorption performance with the bandwidth of 4.59 GHz at the matching thickness of only 1.5 mm. Therefore, these nanocomposites can be used as microwave absorbers with high efficiency, and small weight and thickness.

Promising ways to treat unpromising uterine fibroids

Background. Preventive check-ups reveal uterine fibroids for the first time in 1-5 % of women. In the presence of gynecological diseases this number is about 30-35 %. Pathomorphological examination of deceased women of different ages reveals fibroids in 77-85 % of them. The age of this diagnosis has become significantly younger, and it is important, because uterine fibroids are associated with problems with fertilization and pregnancy. Myomas are divided into types by localization (interstitial, intraligamentary, subserous, interstitial-subserous, submucosal, etc.).
 Objective. To describe current trends in the treatment of uterine fibroids.
 Materials and methods. Analysis of own experience in the treatment of fibroids and literature sources on this topic.
 Results and discussion. Conservative myomectomy can be performed laparotomically, laparoscopically and hysteroscopically. It is often impossible to perform a traditional conservative myomectomy of large nodes of II-V grades without significant damage to the uterine wall, so as a result, conservative myomectomy turns into a hysterectomy. HiFu ablation is an another method of treating fibroids. This method is based on the influence of a high-power ultrasonic wave, which is generated by a radiating lens and passes through the patient’s body to the pathological focus. Degasated water acts as a conductor between the patient’s body and the lens. The goals of treatment are to preserve the uterus and to create the possibility of pregnancy. Before treatment, magnetic resonance imaging of the pelvic organs and assessment of the potential for malignancy must be performed. Criteria for the selection for ablation include the desire to preserve the uterus; established diagnosis of uterine fibroids, local adenomyosis; obvious symptoms of fibroids (abnormal uterine bleeding, dysmenorrhea, pain, secondary anemia); node size 1-15 cm (submucosal or intramural type of growth). The preservation of a woman’s fertility is a main indication for ablation. There are no alternative methods to HiFu ablation in terms of efficacy and safety, but if the nodes were too large or too numerous, conservative myomectomy is performed after significant tumor regression after two sessions of HiFu. The nodal bed and pelvic floor should be washed with decamethoxine solution during the operation. The required volume of solution is about 2 liters. The advantages of decamethoxine include the lack of absorption by the wound surface and a powerful bactericidal effect. If the walls of the uterus are thin and it is not possible to preserve their integrity during myomectomy, plastic surgery is performed with the introduction of high molecular weight hyaluronic acid to prevent the formation of adhesions and accelerate regenerative processes.
 Conclusions. 1. Uterine fibroids are common tumors that in young women are accompanied by problems of fertilization and pregnancy. 2. It is often impossible to perform traditional conservative myomectomy of large nodes without significant damage to the uterine wall. 3. HiFu ablation is the modern method of treatment of fibroids. 4. Maintaining a woman’s fertility is a main indication for ablation.

Measuring friction at an interface using ultrasonic response.

Friction between sliding surfaces is a fundamental phenomenon prevalent in many aspects of engineering. There are many sliding contact tribometers that measure friction force in a laboratory environment. However, the transfer of laboratory data to real machine elements is unreliable. Results depend on the specimen configuration, surface condition and environment. In this work, a method has been developed that uses the nonlinear response of a high-power ultrasonic wave to deduce friction coefficient in situ at an interface. When the high-power shear wave strikes a frictional interface, relative slip can occur. It imposes a nonlinear response and causes generation of higher-order odd frequency components in received ultrasonic signals. The amplitude of the harmonics depends on contact stress and local friction coefficient. This nonlinear ultrasonic response has been investigated both numerically and experimentally. A simple one-dimensional model has been used to predict nonlinearity generation. This model has been compared with experiments conducted on aluminium rough surfaces pressed together under increasing loads. Two strategies have been used to estimate the friction coefficient by correlating experimental and numerical third-order nonlinearity. It has proved possible to determine the friction coefficient in situ at the interface; values in the range of 0.22 to 0.61 were measured for different surface configurations.

Non‐destructive testing method of micro‐debonding defects in composite insulation based on high power ultrasonic

It is crucial to ensure the adhesive quality of the interface in composite insulation equipment for power grid security. Due to viscoelasticity of silicone rubber and roughness of interface, the thickness of the local air layer in the defective interface is <100 μm. This kind of defect is called micro-debonding defect in this paper, and it is significantly smaller than the millimetre-scale air gaps which could be defected by the x-ray, THz, and traditional ultrasonic method. It remains challenging to detect the micro-debonding in composite insulation by non-destructive testing methods. In this paper, the acoustic model and bi-linear stiffness model for micro-debonding in different stages are established. Accordingly, a conjecture is proposed that the bonding property of composite insulation is related to the acoustic impedance of interface and non-linear distortion of its constitutive relation. The result obtained from numerical simulation with and without defect is compared with the high-power ultrasonic experimental data to validate the correctness of the theoretical model. In addition, it can be concluded that the non-linear distortion of high-power ultrasonic wave can be effectively used to diagnose micro-debonding defect at the interface of composite insulation in its early stage (1–20 μm).

Modifying the mechanical properties of gold nanorods by copper doping and triggering their cytotoxicity with ultrasonic wave

We proposed the use of copper (Cu) doping to modify the mechanical properties of gold nanorods (AuNRs) and demonstrated the triggering of the cytotoxicity of Cu-doped AuNRs with ultrasonic wave. The mechanical properties of Cu-doped AuNRs were analyzed theoretically by using the density-function calculation and it was found that Cu-Au bond is much weaker than Au–Au bond. In experiments, AuNRs without and with Cu doping were synthesized and they were found to be low cytotoxic to both human liver hepatocellular carcinoma (HepG2) cells and normal liver cells (L02). It was found that Cu-doped AuNRs can be broken into small gold nanoparticles (<5 nm) under high-power ultrasonic wave while undoped AuNRs were quite stable, although the amount of Cu doped into AuNRs was quite small (0.2%). The small gold nanoparticles are found to be with high toxicity to HepG2 cells. The cellular viability of the HepG2 cells dropped to nearly zero after being incubated with Cu-doped AuNRs (50 nM), which had been treated with a 300-W ultrasonic wave. Our findings suggest a novel method for modifying the mechanical properties of AuNRs and especially for triggering their cytotoxicity which is quite useful for in vitro therapy of cancer cells.

CFD study of the flow pattern in an ultrasonic horn reactor: Introducing a realistic vibrating boundary condition

Recently, great attention has been paid to predict the acoustic streaming field distribution inside the sonoreactors, induced by high-power ultrasonic wave generator. The focus of this paper is to model an ultrasonic vibrating horn and study the induced flow pattern with a newly developed moving boundary condition. The numerical simulation utilizes the modified cavitation model along with the “mixture” model for turbulent flow (RNG, k-ε), and a moving boundary condition with an oscillating parabolic-logarithmic profile, applied to the horn tip. This moving-boundary provides the situation in which the center of the horn tip vibrates stronger than that of the peripheral regions. The velocity field obtained by computational fluid dynamic was in a reasonably good agreement with the PIV results. The moving boundary model is more accurate since it better approximates the movement of the horn tip in the ultrasonic assisted process. From an optimizing point of view, the model with the new moving boundary is more suitable than the conventional models for design purposes because the displacement magnitude of the horn tip is the only fitting parameter. After developing and validating the numerical model, the model was utilized to predict various quantities such as cavitation zone, pressure field and stream function that are not experimentally feasible to measure.

Interfacial defects detection in plasma-sprayed ceramic coating components using two stimulated infrared thermography techniques

Two Lock-in InfraRed Thermography (LIRT) techniques were developed and applied to detect interfacial defects in a ceramic coated steel plate deposited by plasma spraying technology. Stimulations were performed either by electromagnetic waves (lamps) or by high power ultrasonic waves (sonotrode). The first one is based on remote optical heating of the area of interest; while the second technique is based on the mechanical loss angle effect, occurring locally and for particular defects such as cracks and delaminations. The potential of these two techniques was evaluated against artificial (calibrated holes) and real (disbonding) interfacial defects. The results show success and also some limitations of both LIRT techniques in function of sizes and depths of ceramic coating interfacial defects.

STUDY OF COMPOSITE PLATE DAMAGES USING EMBEDDED PZT SENSORS WITH VARIOUS CENTER FREQUENCY

This study presents part of an experimental and analytical survey of candidate methods for damage detection of composite structural. Embedded piezoceramic (PZT) sensors were excited with the high power ultrasonic wave generator generating a propagation of stress wave along the composite plate. The same embedded piezoceramic (PZT) sensors are used as receivers for acquiring stress signals. The effects of center frequency of embedded sensor were evaluated for the damage identification capability with known localized defects. The study was carried out to assess damage in composite plate by fusing information from multiple sensing paths of the embedded network. It was based on the Hilbert transform, signal correlation and probabilistic searching. The obtained results show that satisfactory detection of defects could be achieved by proposed method.

The Possibility of a Simultaneous Transmission οf Ultrasound and Laser Radiation via Flexible Optical Silica Glass Fibre

Glass optical fibres are a promising medium for simultaneous laser-ultrasonic applications. The proposed application system is based on simultaneous transmission of laser radiation and ultrasounds in a flexible silica glass fibre. The optical fibre’s core was made of SiO2 (97%) and GeO2 (3%) and the cladding was 100% SiO2. The material the optical fibre is made of enables simultaneous transmission of laser radiation and ultrasonic wave. Experiments were performed using a Mach–Zehnder optical waveguide interferometer with single-mode optical fibre coupler. This paper presents measurement results for delivering ultrasonic waves to the optical fibre using longitudinal vibrations generated by a sandwich ultrasonic transducer with a velocity transformer. The study presents the relations concerning simultaneous operation of both types of waves and the possibilities of transmission of low frequency, high power ultrasonic wave in optical fibres using a sandwich type transducer.

Experimental study of attenuation coefficient of ultrasonic waves in concrete and plaster

This study has been dedicated to the determination and comparison of ultrasound attenuation coefficient in two kinds of frequently used masonry, namely concrete and plaster. The results of this investigation can be mainly applied for optimum acoustical designing of buildings which are exposed to high-power ultrasonic waves. Another expected benefit of this investigation is determining the possibility of using ultrasonic wave emissions for finding people who are buried under ruined building materials due to an earthquake. In this paper, the attenuation coefficient of 19.7 kHz ultrasonic waves are presented for nine different concrete specimens and three different plaster specimens. For this purpose, the amplitude of vibration speed of the back and frontal surfaces of the specimens were measured by a non-contact laser sensor while the front surface was actuated by a 200-W ultrasonic transducer. The variables of concrete were weight proportion between water and cement, weight proportion between course aggregate and fine aggregate, weight proportion of cement replaced with micro-silica, and the type of cement. The variable for plaster pieces was the weight proportion of water and plaster.

Sonocrystallization of polycarbonate melts

AbstractIn this paper, we showed the simplified continuous process to crystallize the polycarbonate (PC) melts using sonocrystallization which is based on ultrasonic cavitation and ‘hot spot’ theory. High power ultrasonic wave was introduced to crystallize the PC prepolymers which is generally used for solid‐state polymerization (SSP) to obtain the ultra‐high molecular weight PCs. The structure and properties of PC treated with ultrasonic wave such as torque changes and crystallinities were studied. The experimental results showed that ultrasonic wave could improve the crystallinities of PCs and sonication time was proportional to their crystallinity. This is attributed to the decrease of the specific volume and the resulting shrinkage is compensated by a flux of a polymer melt toward the crystallization front. Torque data were collected directly from the Haake internal mixer and crystallinities were evaluated from differential scanning calorimeter (DSC). This process is an environmentally benign process so that no additional solvents or treatments are needed and will be very useful in the conventional solid‐state process which is used industrially. Copyright © 2007 John Wiley &amp; Sons, Ltd.

In situ compatibilization of PP/EPDM blends during ultrasound aided extrusion

Blends of isotactic polypropylene (iPP) and uncured ethylene–propylene diene rubber (EPDM) of various concentrations were treated by high power ultrasonic waves during extrusion. Die pressure and power consumption were measured. The effects of different gap sizes, blend ratios and number of ultrasonic horns were investigated. The rheological properties, morphology and mechanical properties of the blends with and without ultrasonic treatment were studied. In situ compatibilization of the blends was observed as evident by their more stable morphology after annealing, improved mechanical properties and IR spectra. The obtained results indicated that ultrasonic treatment induced the thermo-mechanical degradations and led to the possibility of enhanced molecular transport and chemical reactions at the interfaces. Processing conditions were established for enhanced in situ compatibilization of the PP/EPDM blends.

Resistance ofListeria monocytogenesto ultrasonic waves under pressure at sublethal (manosonication) and lethal (manothermosonication) temperatures

The influence of amplitude of ultrasonic waves, static pressure and temperature on the inactivation rate ofListeria monocytogenesby ultrasonic waves under pressure (manosonication; MS) has been investigated. Also the influence of growth temperature, pH and composition of treatment medium, and the presence of sodium chloride in the recovery medium on the MS resistance ofL. monocytogeneshas been investigated and compared with its heat resistance. The inactivation ofL. monocytogenesby high power ultrasonic waves (20 kHz, 117 μm) at ambient temperature and pressure was low (DUW=4.3 min). The increase of relative pressure (MS) to 200 kPa decreasedDMSto 1.5 min and the increase to 400 kPa to 1.0 min. Inactivation rate by MS increased exponentially with the amplitude of ultrasonic waves in the range of 62-150 μm. An amplitude increase of 100 μm decreased the MS resistance of approximately six times. The inactivation rate by MS was not influenced by treatment temperature up to 50°C. However at higher temperatures the lethality of this combined process (MTS) increased considerably. Inactivation by MTS was the result of the inactivation by heat in addition to that by ultrasound under pressure. Cells grown at 37°C were twice more heat resistant than those grown at 4°C but no differences were found between decimal reduction time values to MS (117 μm, 200 kPa, 40°C) of both suspensions. While the inactivation rate by heat in pH 4 buffer was two- and five-fold higher than in pH 7 buffer and skimmed milk respectively, the differences amongDMS-value in these media were lower than 60%. The addition of 57% of sucrose to the treatment medium increasedD61from 0.22 to 5.7 min andDMSfrom 1.5 to 3.1 min. The addition of 3% sodium chloride to the recovery medium decreasedD60by 1/3 but did not modifyDMS-values.

Characterization of Cured Furan Resin Prepared by High Power Ultrasonic Irradiation

High power ultrasonic wave was applied through the curing process of furfuryl alcohol condensate (furanresin) by using an ultrasonic homogenizer at the frequency of 20 kHz and the intensity of 50 W/cm2. Thestructuralproperties of cured furan resin prepared with and without sonication were examined. Combining the resultsfrom GPCmeasurement, FTIR spectroscopy, elemental analysis and XRD, it was cleared that the sonication was effective forthe increase of curing rate in furan resin, however, the structural change of the cured furan resin did not occur with and without sonication.

Microwiggler generated on the surface of an acoustic waveguide using high power ultrasonic waves

Microwiggler generated on the surface of an acoustic waveguide using high power ultrasonic waves