Power Ultrasonics Research Articles

Development of Solid Horn with Diaphragm for High Power Ultrasound Radiation. 1st Report. Natural Frequency and Vibration Mode.

Solid horns are used to magnify the displacement amplitude for power ultrasonics. They have half a wavelength and are connected vertically with the transducer. Therefore the ultrasonic vibration system usually becomes too long and heavy to handle. Thus a new type of solid horn with a metallic diaphragm has been developed by the authors. The horn transduces the little longitudinal vibration to the extremely large flexural one. Therefore it is possible to shorten and to make lighter the ultrasonic vibration system by replacing connected horns to a simple new horn. It is thought that the horn is suitable as a high power ultrasound source, further the high efficiency of the sound radiation is obtained by the larger area and in-phase vibration of sound radiation face. Thus the authors have attempted to expand the diameter of the diaphragm by keeping in-phase vibration. In this paper, the free vibration of the solid horn with a diaphragm and the one with double concentric diaphragms are analyzed using FEM and theory. The analytical results on the natural frequency and the vibration mode are confirmed experimentally.

Development of a simple round bar horn for power ultrasonics using a friction-welded joint between dissimilar metals

Summary Solid horns for power ultrasonics usually magnify the vibration amplitude by reducing the cross-sectional area along their axis. However, these horns are usually too heavy to handle easily, and their fatigue strength is reduced by the stress concentration induced by their profile. The authors have therefore attempted to develop a new type of horn based on a different magnification principle by connecting two simple round bars with different specific acoustic impedances. Vibration of the round bar horn has been analysed by longitudinal wave theory and FEM to achieve a practical design. New types of horn were fabricated and tested to confirm their displacement amplitude magnification capabilities. The analytical and experimental results showed that the simple round bar horn is satisfactory for practical use. On this basis, an attempt was made to fabricate a simple round bar horn using a friction-welded joint consisting of SUS304 stainless steel and 6061 aluminium alloy dissimilar metals. The vibration characteristics of the input-output displacement amplitude, frequency, elevated temperature, and fatigue fracture were respectively investigated for friction-welded simple round bar, step, and exponential horns consisting of SUS304 and A6061. The results obtained suggest that the simple round bar horn has better vibration characteristics than the others.

Silicon microfabricated horns for power ultrasonics

As part of a study of silicon surgical tools, silicon ultrasonic horns for impedance transformation have been made with using bulk micromachining. The ultrasonic amplification of silicon stepped, linear, exponential, and catenoidal half-wavelength horns actuated by piezoelectric lead-zirconate-titanate (PZT) plates is measured and found to agree well with predictions from a numerical model. With the catenoidal horn, a maximum ultrasonic velocity of 14.2 m s −1 is obtained with a displacement of 35 μm measured at 64.5 kHz at 150 V pp drive. By way of comparison, in cataract surgery a particle velocity of only 11.9 m s −1 is used.

Displacement Amplitude Magnification on Simple Round Bar Horn of Connected Metals.

Solid horns for "power ultrasonics" usually magnify the vibration amplitude by a decrease in sectional area along their axis. However these horns are usually too heavy to handle easily and their fatigue strength is reduced by the stress concentration induced by their profile. Thus we have attempted to develop a new type of horn based on a different magnification principle by connecting simple round bars of different specific acoustic impedances. Vibration of the round bar horn is analyzed using the longitudinal wave theory and FEM to achieve a practical design. We have fabricated the new type of horns and performed experiments to confirm their magnification capabilities. Analytical and experimental results show that the simple round bar horn is satisfactory for practical use.

Novel Ultrasonic Technology for Devulcanization of Waste Rubbers

Abstract A novel patented process and several reactors have been developed for devulcanization of waste rubbers. The technology is based on the use of the high power ultrasonics. The ultrasonic waves of certain levels in the presence of pressure and heat rapidly break up the three-dimensional network in crosslinked rubbers. The devulcanized rubber can be reprocessed, shaped and revulcanized in much the same way as a virgin rubber. The first laboratory reactor has been scaled up to pilot-plant level by the National Feedscrew and Machining, Inc. Various devulcanization experiments were carried out with model styrene-butadiene rubber (SBR) and with ground rubber tire (GRT). Curing behavior, Theological properties, and structural characteristics of rubbers devulcanized at various processing conditions were studied, as well as mechanical properties of revulcanized rubber samples. A possible mechanism of the devulcanization is discussed. The performed measurements indicate that the rubbers are partially devulcanized, and the devulcanization process is accompanied by certain degradation of the macromolecular chains. In spite of these observations, the processing conditions are identified at which the retention of the mechanical properties is found to be good. A further work is in progress to find the optimal conditions of devulcanization and to improve the selectivity of the process towards breaking up the chemical network only.

Power Flow in Solid Horns for Ultrasonics.

Solid horns for "power ultrasonics" have been evaluated and designed by considering the particle velocity and the stress distribution along their axis. And the loss of energy and the energy flow by internal friction in the horns have usually been neglected. Even if they were considered, the vibration systems were analyzed as one-dimensional systems. Therefore, in this paper, solid horns for ultrasonics are treated as three-dimensional viscoelastic bodies by using the finite-element method and introducing the concept of "power flow". Then the relationship between the loss of energy or the energy flow and the shape of the horns is studied by the FEM analysis and the experiments. The generally used solid horns were evaluated and a new shape of the solid horn was presented from the viewpoint of energy transfer.

High power ultrasonics

High power ultrasonics

Characterization of piezoelectric ceramics for power ultrasonics

Abstract The method of the characterization of ceramics used as transducers clamped in the Langevin sandwich construction is proposed. Dielectric and mechanical losses, electroacoustic efficiency and dynamic stress in transducers as a function of electric field for the most important ultrasonic power applications is found. The method is used to evaluate the suitability of two piezoelectric compositions (“hard” and “half-soft”) for those applications.

Power ultrasonics excitation of a mould in a continuous casting machine of steel billets

Power ultrasonics excitation of a mould in a continuous casting machine of steel billets

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.

The use of high power ultrasonics (macrosonics) in studying internal friction and fatigue in metals

High Power Ultrasonics has been a useful tool in studying fatigue and internal friction in metals since a large number of cycles can be obtained in a short time. It was first used by the speaker at Bell Laboratories in 1956. Further work was done at Columbia using an improved arrangement. Brass, copper, iron and titanium were studied. The first three fatigued plastically, whereas titanium fatigued elastically by slipless cracks. A correlation between internal friction and breakaway of dislocations and with two stages of plastic deformation has been found. Optical and electron microscope pictures show the various mechanisms up to the fatigue region. Electron microscope pictures show that fatigue cracks progress much faster for ultrasonic vibrations than for the slower fatigue tests. While the structure changes are somewhat different for ultrasonic vibrations than for low frequency testing, the number of cycles to fatigue is slightly larger for ultrasonic testing than for low frequency testing except for steel.

Macrosonics in industry: Ultrasonic soldering

Ultrasonic soldering is one of several uses of power ultrasonics that have been known for many years. Although it was discovered nearly 40 years ago, and has the unique capability of joining materials which are difficult to solder such as aluminium, ultrasonic soldering has never enjoyed widespread industrial use. There is a current resurgence of interest in the process, motivated mainly by the application of soldering all-aluminium heat exchangers. This and other new uses in the electronics field may yet permit ultrasonic soldering to achieve the status of a major use of power ultrasound.

Ultrasonics International 1975: Proceedings of the 9th Conference Organized and Sponsored by the Journal Ultrasonics, held in March 1975 at Imperial College of Science and Technology, London IPC

This conference, sponsored by the journal Ultrasonics attracted over 130 papers, of which 57 were presented and reproduced in the conference proceedings. Inevitably, in this expanding field, the range of topics covered by the papers is extremely wide and for the purposes of the conference these were categorized under the following eight headings: physics of ultrasonics; nondestructive testing; high power ultrasonics; visualization; signal processing; transducers and arrays; underwater ultrasonics; medical and biological ultrasonics.

Research on inductive transducers for vibration measurement

Recently in Romania the use of high power ultrasonics in electrically conductive solid media has increased. Consequently more severe conditions have been imposed on inductive transducers regarding their sensitivity and selectivity for measuring acoustic field amplitudes. In view of this the authors carried out theoretical and experimental studies on inductive transducers. Parameters that influence the back emf in an idealized physical model, can be particularized for every practical case. By reducing the magnetic reluctance of the air closed field lines, transducers with a sensitivity of about 400 mV/μm have been built. These transducers may possibly be used at higher frequencies. Also, selective transducers for longitudinal and transverse vibrations were made by altering the geometry and position of their constituent elements.

Electromagnetic generation of ultrasonic surface waves

It is shown that Rayleigh waves can be generated and received by the electro-acoustic method. The conversion factor is sufficient for the technique to find application in low power ultrasonics.

An outline of power ultrasonics : Perkins, J. Oem Des Vol 1 No 5 (February 1972) pp 42–47

Melanotic neuroectodermal tumor of infancy (MNTI) is a rare, rapidly growing pigmented neoplasm of neural crest origin generally arising in infants during the first year of life.We report a 15-month old male who presented with a 2-month history of a rapidly growing mass in the anterior. A biopsy showed melanotic neuroectodermal tumor, and complete resection with negative margins was subsequently achieved. The patient is in remission at 11 months from surgery.Due to its rapid growth potential and locally destructive behaviour, early diagnosis is extremely important to limit local expansion. The treatment of choice for melanotic neuroectodermal tumor of infancy (MNTI) is surgical excision.

High power ultrasonics in industry—a review

The value of ultrasonic energy as a form of power for industry has been known for many years, but equipment design limitations have prevented full exploitation. Recent developments are now changing the situation and progress is being made on a wider front than the established fields of cleaning and welding. The historical background provides some reasons for the slow acceptance and the future relies on increased research effort into the design of efficient transducers. A better understanding of the principles involved in high power ultrasonic propagation is also required.

Ultrasonic energy creates new rolling parameters: Metalworking Production (August 16th 1967) p 61

Metal forming is a primary manufacturing process that includes drawing, forging, rolling, and bending. Ultrasonic metal forming is the application of ultrasonic vibrations to these processes to enhance performance through increased production speeds, less tool wear, reduced forming forces, and better surface finish. The field was initiated with a 1955 note by Blaha and Langenecker that reported reduced yield stress with application of ultrasound, resulting in lines of development active to the present day. Many metal forming processes have been investigated for application of power ultrasonics, including wire and tube drawing, deep drawing, bending, forging, and rolling. These and other processes, including shearing, surface treatment, microforming, and compaction are reviewed.

Very high energy ultrasonics

The field of high power ultrasonics covers the power region where irreversible changes can be produced in the medium. In Table 1 are listed the more important effects and uses of high energy ultrasonics. The field is very large; useful applications now touch almost every industry. In the final column of the table approximate figures are quoted for the order of the ultrasonic intensity required in the various applications. In gases and liquids the intensities obtainable are severely limited. In liquids this limit is fixed by cavitation which sets in at a rather low level. Cavitation can be avoided by pressurization, and then very high energies can be transmitted. But this is inconvenient and seldom used in practice. The field of very high energy ultrasonics is therefore practically confined to solids, as indicated in the table.

Precipitation Hardening in an Ultrasonic Field

Ultrasonic vibrations have been used in the study of many of the phenomena of physics and chemistry, but to date little has been reported in the field of metallurgical processes or reactions. One of the deterrents to its use in such investigations is the problem of coupling a high power source of ultrasonics to a solid load. The use of a liquid couplant has inherent disadvantages which obviate its use, particularly where the solid under examination is to be maintained at an elevated temperature. The present study involved the construction of a transducer useful for either liquid or solid metal irradiation. An investigation was carried out on the effect of high power ultrasonics on precipitation in the solid state. Two aluminum alloys, one a high purity copper-aluminum binary, and the other an Al-Mg, Cu, Zn alloy 75S, were used in the investigation. It appears that the rate of hardening of these alloys is increased by irradiation with intense ultrasonic vibrations during aging at 100°C. Suggestions are given as to the nature of the acceleration effect, and mention is made of the probable limitations imposed on its commercial application.