High Power Ultrasonics Research Articles

Surface study of the burnishing process when vertical high-power ultrasonics are applied

Surface study of the burnishing process when vertical high-power ultrasonics are applied

Role of matrix phase and electric field gradient in Na1/2Bi1/2TiO3[sbnd]BaTiO3:ZnO composites

Na1/2Bi1/2TiO3-based materials exhibit potential for applications in high-power ultrasonics. The composites of Na1/2Bi1/2TiO3-yBaTiO3 (NBTyBT; y denotes mole%) with ZnO inclusions were demonstrated to stabilize a ferroelectric equilibrium that led to enhanced thermal depolarization temperature (Td) and increased mechanical quality factor (Qm). This work addresses the influence of the matrix NBTyBT phase by investigating two limiting choices based on symmetry (tetragonal/rhombohedral) and polar (relaxor/ferroelectric) nature. While the composites constituting the tetragonal NBT9BT (non-ergodic relaxor at room temperature) matrix phase exhibit improved Td, the critical temperatures in the composites with rhombohedral NBT3BT (displaying spontaneous ferroelectric order at room temperature) exhibit only marginal changes. Further, NBT3BT composites feature a 45% increase in Qm, while the corresponding increase is roughly three-fold for the NBT9BT composites. A 3-D Finite Element Method is used to simulate the electric field gradient at the matrix/inclusion interface, with the effective field distribution estimated to be higher than the applied field for highly conducting ZnO inclusions. The electrical properties indicate that, while the deviatoric stress at the matrix/inclusion interface stabilizes the ferroelectric equilibrium for the relaxor matrix phase, the stresses disrupt the long-range order for the ferroelectric matrix phase. These results establish the volume-limit of the second phase to stabilize a ferroelectric equilibrium, in addition to substantiating the role of residual stress evidenced by changes in the polar nature. Finally, a comparison of the composites with different NBTyBT phases is presented, with NBT6BT:ZnO composites demonstrating an optimal increase in both Td and Qm.

Influence of Quenching and Subsequent Annealing on the Conductivity and Electromechanical Properties of Na1/2Bi1/2TiO3-BaTiO3.

Na1/2Bi1/2TiO3-based materials have gained considerable attention for their potential to exhibit giant strain, very-high ionic conductivity comparable to yttria stabilized zirconia or high mechanical quality factor for use in high power ultrasonics. In recent times, quenching Na1/2Bi1/2TiO3-based compositions have been demonstrated to enhance the thermal depolarization temperature, thus increasing the operational temperature limit of these materials in application. This work investigates the role of quenching-induced changes in the defect chemistry on the dielectric, ferroelectric and piezoelectric properties of quenched Na1/2Bi1/2TiO3-BaTiO3. The quenched samples indeed demonstrate an increase in the bulk conductivity. Nevertheless, while subsequent annealing of the quenched samples in air/oxygen atmosphere reverts back the depolarization behaviour to that of a furnace cooled specimen, the bulk conductivity remains majorly unaltered. This implies a weak correlation between the defect chemistry and enhanced thermal stability of the piezoelectric properties and hints towards other mechanisms at play. The minor role of oxygen vacancies is further reinforced by the negligible (10–15%) changes in the mechanical quality factor and hysteresis loss.

Investigating vibration characteristics of magnetostrictive transducers for air-coupled ultrasonic NDT of composites

In this study, high-power ultrasonics has been used for non-contact nondestructive testing of composites. Air-coupled magnetostrictive ultrasonic transducers provide reasonable amplitudes of horn oscillations even if this type of ultrasonic stimulation is close to the idle mode. Four types of ultrasonic horns have been designed and manufactured in order to choose an optimal horn configuration. For each horn, the dependence of vibration amplitude on ultrasonic unit power has been found to exhibit a good match between the theoretical and experimental results. The resonance frequencies and amplitudes of oscillatory velocity were experimentally evaluated by using the technique of scanning laser vibrometry and modeled by means of the Autodesk Inventor software. An air-coupled magnetostrictive transducer, in conjunction with an optimized horn, has been used in the evaluation of impact damage in a graphite epoxy composite and detection of water and excessive epoxy adhesive in an aviation honeycomb panel. It is expected that the technique of air-coupled ultrasonics may be useful for inspecting thin, fragile and hydrophilic materials.

Design and Analysis of Ultrasonic Horns Operating in Multiple Vibration Modes

A number of recent studies have shown that combining different modal responses can provide opportunities to improve the vibration behaviour of the output faces of tuned ultrasonic horns to provide a more effective use of the ultrasonic energy. Investigation the benefits of combining different modal responses with a view to optimizing the energy transfer from a range of power ultrasonic devices that rely on tuned horns is essential. This research will therefore aim to investigate the use of combining and exciting different vibration modes in order to design more effective resonant horns for use in high power ultrasonics applications such as metal forming, welding, cleaning and surgical devices. The research is extended to study the possibility of design an ultrasonic transducer which can operate in multiple vibration modes by modify its geometric features. The longitudinal- torsional mode is selected first because of its wide applications in ultrasonic field. The effect of geometrical modifications of transducer's matching part is being analyzed analytically, numerically and experimentally. The suggested modifications are including cut of slots and reduce the cross sectional area so that the excited longitudinal vibrational mode can be regenerated into a longitudinal-torsional mode. The considerations of simplicity of manufacturing and exciting and the efficient of energy conversion are the main advantages of the proposed transducer. Keywords–ultrasonic transducer, design horn; resonant frequency; model and harmonic analysis DOI : 10.7176/JIEA/9-3-02 Publication date :May 31 st 2019

Numerical modelling of acoustic pressure fields to optimize the ultrasonic cleaning technique for cylinders

Fouling build up is a well-known problem in the offshore industry. Accumulation of fouling occurs in different structures, e.g. offshore pipes, ship hulls, floating production platforms. The type of fouling that accumulates is dependent on environmental conditions surrounding the structure itself. Current methods deployed for fouling removal span across hydraulic, chemical and manual, all sharing the common disadvantage of necessitating halting production for the cleaning process to commence. Conventionally, ultrasound is used in ultrasonic baths to clean a submerged component by the generation and implosion of cavitation bubbles on the fouled surface; this method is particularly used in Reverse Osmosis applications. However, this requires the submersion of the fouled structure and thus may require a halt to production. Large fouled structures such as pipelines may not be accommodated. The application of high power ultrasonics is proposed in this work as a means to remove fouling on a structure whilst in operation. The work presented in this paper consists of the development of a finite element analysis model based on successful cleaning results from a pipe fouled with calcite on the inner pipe wall. A Polytec 3D Laser Doppler Vibrometer was used in this investigation to study the fouling removal process. Results show the potential of high power ultrasonics for fouling removal in pipe structures from the wave propagation across the structure under excitation, and are used to validate a COMSOL model to determine cleaning patterns based on pressure and displacement distributions for future transducer array design and optimization.

Scaled experiment investigating sonomechanically enhanced inert gas sparging mass transfer

One of the leading advanced reactor concepts is the fluoride salt high temperature reactor (FHR) currently under investigation. This design utilizes a fluoride molten salt, flibe (2LiF/BeF2), as the primary coolant. One challenge of employing flibe as a coolant is the production and release of tritium. The FHR community is currently investigating various techniques to solve this tritium management challenge. One of the methods investigated is inert gas sparging which has been investigated during the Molten Salt Reactor Experiment (MSRE) in the 1960’s and 1970’s. To enhance the efficiency of this technique, high power ultrasonics can be employed to sonomechanically enhance the mass transfer performance. Initial experimental studies coupling ultrasonics and inert gas sparging have been performed in the scaled ultrasonic mass transfer (SUMATRA) experiment. The scaling was done by matching the Sc between a water/glycerol mixture and flibe at FHR temperatures. The SUMATRA experiment evaluated the performance of inert gas sparging with and without ultrasonic enhancement. The results show a significant performance enhancement due to the sonomechanical effect which is contributed to an increase in the diffusive mass transfer contribution due to bubble breakup and the subsequent increase interfacial area.

強力超音波 (&lt特集&gt超音波)

強力超音波 (&lt特集&gt超音波)

Solid State Joining of Aluminium to Titanium by High Power Ultrasonics

In this paper selected results about process control and stability during ultrasonic torsion welding of aluminium to titanium sheets are discussed. The process parameters welding force, welding energy and oscillation amplitude were optimized for Al4N/cp-Ti-joints and AA7075/TiAl6V4-joints using modern statistical test methods. The hybrid welds are evaluated and compared based on their mechanical properties. Furthermore thermal characteristics are determined with high resolution during the welding process by thermometry. Central aspects of the current research project are detailed microscopy of the hybrid interface as well as fracture surface analysis to understand the interfacial formation. Relationships between process parameters, joint strength and the related microstructure should be understood.

A cymbal transducer for power ultrasonics applications

The flextensional class V ‘cymbal’ transducer has been widely adopted for low power ultrasonics applications, exhibiting high output displacement for low input energy, compared to a single ceramic, when used as an actuator. Despite its performance benefits, the original designs of cymbal transducers have inherent drawbacks for high power ultrasonics applications that require much higher output displacements. Asymmetries introduced during the fabrication process reduce the efficiency of the transducer, and degradation of the bonding layer between the end-caps and the electroactive material can alter the vibration response and ultimately lead to failure. A new design of the cymbal transducer is therefore proposed that delivers high output displacements. A comparison is presented between a cymbal based on the original design configuration and a new cymbal, to demonstrate the effects of input voltage levels on the dynamic characteristics and vibration response of the two different transducers. For the first cymbal the end-caps are directly bonded to the piezoceramic disc using a commercial non-conductive epoxy. The second cymbal incorporates a metal ring bonded to the outer edge of the piezoceramic disc to improve the mechanical coupling with the end-caps, thereby enhancing the operational capability of the device at higher voltages, allowing for excitation of higher output displacements by removing the problems associated with failure in the epoxy layer. This design is demonstrated to be particularly suitable for power ultrasonics applications such as miniature surgical devices, for example as drilling and cutting devices for orthopaedics procedures.

Relative Efficacy of High-Pressure Hot Water and High-Power Ultrasonics for Wine Oak Barrel Sanitization

<h3>Abstract</h3> Engineered genetic circuits with tailored functions that mimic how cells process information in changing environments (e.g. cell fate decision, chemotaxis, immune response) have great applications in biomedicine and synthetic biology. Although there is a lot of progress toward the design of gene circuits yielding desired steady states (e.g. logic-based networks), building synthetic circuits for dynamic signal processing (e.g. filters, frequency modulation, and controllers) is still challenging. Here, we provide a model-based approach to build gene networks that can operate as band-pass filters by taking advantage of molecular sequestration. By suitably approximating the dynamics of molecular sequestration, we analyze an Incoherent Feed-Forward Loop (IFFL) and a Negative Feedback (NF) circuit and illustrate how they can achieve band-pass filter behavior. Computational analysis shows that a circuit that incorporates both IFFL and NF motifs improves the filter performance. Our approach facilitates the design of sequestration-based filters, and may support the synthesis of molecular controllers with desired specifications.

Viability of common wine spoilage organisms after exposure to high power ultrasonics

Microbial spoilage of wine can lead to significant economic loss. At present sulfur dioxide is the main additive to juice/must/wine to prevent and control microbial spoilage. As an alternative, or complement to SO 2, high power ultrasonics (HPU) may be used to control microbes. Several wine spoilage yeasts and bacteria were treated with HPU in saline (0.9% w/v NaCl), juice and red wine to assess their susceptibility to HPU. Significant killing was seen across several yeasts and bacteria commonly associated with winemaking and wine spoilage. In general the viability of yeast was more affected than that of bacteria.

High-power ultrasonic processing: Recent developments and prospective advances

Although the application of ultrasonic energy to produce or to enhance a wide variety of processes have been explored since about the middle of the 20th century, only a reduced number of ultrasonic processes have been established at industrial level. However, during the last ten years the interest in ultrasonic processing has revived particularly in industrial sectors where the ultrasonic technology may represent a clean and efficient tool to improve classical existing processes or an innovation alternative for the development of new processes. Such seems to be the case of relevant sectors such as food industry, environment, pharmaceuticals and chemicals manufacture, machinery, mining, etc where power ultrasound is becoming an emerging technology for process development.The possible major problem in the application of high-intensity ultrasound on industrial processing is the design and development of efficient power ultrasonic systems (generators and reactors) capable of large scale successful operation specifically adapted to each individual process.In the area of ultrasonic processing in fluid media and more specifically in gases, the development of the steppedplate transducers and other power ge with extensive radiating surface has strongly contributed to the implementation at semi-industrial and industrial stage of several commercial applications, in sectors such as food and beverage industry (defoaming, drying, extraction, etc), environment (air cleaning, sludge filtration, etc...), machinery and process for manufacturing (textile washing, paint manufacture, etc).The development of different cavitational reactors for liquid treatment in continuous flow is helping to introduce into industry the wide potential of the area of sonochemistry. Processes such as water and effluent treatment, crystallization, soil remediation, etc have been already implemented at semi-industrial and/or industrial stage. Other single advances in sectors like mining or energy have also to be mentioned.The objective of this paper is to review some recent developments in ultrasonic processing to show the present situation and the prospective progresses of high-power ultrasonics as an innovative technology in many industrial sectors.

Power ultrasonic transducers with extensive radiators for industrial processing

High-power ultrasonics (HPU) is a green emerging technology that offers a great potential for a wide range of industrial processes. Nevertheless such potential have remained restricted during many years to a limited number of applications which reached commercial development. The possible major problem for extending the range of HPU industrial applications has been the lack of power ultrasonic transducers for large-scale application, adapted to the requirements of each specific problem with high efficiency and power capacity. A new family of HPU transducers with extensive radiators have been recently introduced. It comprises a variety of transducer types designed with the radiators adapted to different specific uses in fluids and multi-phase media. Such transducers implement high power capacity, high efficiency and radiation pattern control. In addition, their design incorporate strategies to eliminate or reduce modal interactions produced at high power as a consequence of their nonlinear behaviour. The introduction of such new transducers has significantly contributed to the development at semi-industrial and industrial level of a number of processes in the food and beverage industry, in environment and in manufacturing. This paper deals with the basic structure and main characteristics of such transducers as well as their performance in the developed application processes.

Generation and Applications of High Intensity Ultrasonics

Ultrasonics can be said to have become a subject for scientific study from the time of Langevin's invention of the quartz transducer in 1918. But the peaceful utilization of ultrasonics was initiated after the end of the Second World War in 1945. In this paper, we will outline the special characteristics, generation, transmission, radiation and applications of high power ultrasonics which can be expected on the alterations in substances or properties of matter.

1J4-3 Visualization of cavitation behavior and sonochemical efficiency of a rectangular sonochemical reactor(High Power Ultrasonics, Sonochemistry)

1J4-3 Visualization of cavitation behavior and sonochemical efficiency of a rectangular sonochemical reactor(High Power Ultrasonics, Sonochemistry)

1J4-4 Sonoluminescence of Alkali-Metal Atoms in Sulfuric Acid : Comparison with Water(High Power Ultrasonics, Sonochemistry)

1J4-4 Sonoluminescence of Alkali-Metal Atoms in Sulfuric Acid : Comparison with Water(High Power Ultrasonics, Sonochemistry)

1J4-2 Examination of Sandwich-type Multi-degree-of-freedom Spherical Ultrasonic Motor(High Power Ultrasonics, Sonochemistry)

1J4-2 Examination of Sandwich-type Multi-degree-of-freedom Spherical Ultrasonic Motor(High Power Ultrasonics, Sonochemistry)

Experimental Evaluation of the Static Strain on the Clamping Bolt in the Structure of a Bolt-Clamped Langevin-Type Transducer

Bolt-clamped Langevin-type transducers (BLTs) used in high-power ultrasonics are required to realize various characteristics depending on the technical field where they are used. Specifically for high amplitude operation, the static prestress or bearing stress imposed on the piezoelectric elements in the transducer by clamping should be large enough to compensate for their low tensile strength. The authors previously calculated prestress by the finite element method (FEM), but the numerical results have not been experimentally confirmed yet because of the difficulty of directly measuring of the prestress. In this study, the authors measured the strain on the surface of the clamping bolt using strain gauges pasted on it and compared the results with those of the numerical analysis by FEM in order to confirm the validity of the calculation. The measurement has been conducted for three BLTs of identical shape. The results of the measurement show reasonable agreement with those of the numerical analysis, and thus the authors have found that the measurement of the strain on the clamping bolt gives us a practical method for indirect evaluation of the prestress actually imposed on the piezoelectric elements that changes with the turning angle of the metal block in the clamping.

Ultrasonic innovations in the food industry: From the laboratory to commercial production

High power ultrasound has only recently (< 5 years) become an efficient tool for large scale commercial applications, such as emulsification, homogenization, extraction, crystallization, dewatering, low temperature pasteurization, degassing, defoaming, activation and inactivation of enzymes, particle size reduction and viscosity alteration. This can be attributed to improved equipment design and higher efficiencies of large scale continuous flow-through systems. Like most innovative food processing technologies, high power ultrasonics is not an off-the-shelf technology and therefore needs to be developed and scaled up for each application. The objective of the present paper is to present examples of ultrasonic applications that have made it to commercialization and to share some key learnings involving scale up of an innovative food technology in general. Due to significant technical advances in the last 5 to 10 years, high power ultrasonics has become an alternative to many conventional food processing steps, such as homogenization, milling, high shear mixing, pasteurization and solid/liquid separation. Also, it has shown to improve the efficiency of traditional processes such as filtration/screening, extraction, crystallization and fermentation (i.e., as an add-on technology). The use of ultrasonics is often driven by economic benefits, yet in some cases a unique product functionality can be achieved. This manuscript presents several examples of commercial installations of this technology in the food industry and highlights some of the challenges in scale up and development.