Vibratory Action Research Articles

Vocal fold vibration of the canine larynx: Observation from an infraglottic view

Summary The authors studied the vibratory action of the canine vocal fold from the tracheal side utilizing high-speed cinematography. Five excised canine larynges were used, and the lower surface of the vocal fold of three of them were marked with India ink as a tracer of a specific point on the vocal fold. A mucosal prominence, called the mucosal upheaval, appeared between the anterior commissure and the vocal process. Vibration was not seen below the mucosal upheaval. The mucosal wave started to move medially from just above the mucosal upheaval. The mucosal wave then became the free edge (lower lip) and collided with that of the other side at the midline. After collision, the lower lip moved upward to become the upper lip. At the same time, a part of the lower lip reflected laterally. The mucosal wave of the next cycle started from just above the mucosal upheaval during an opening phase. The mucosal upheaval vibrated with a low amplitude and with an earlier phase than the other portion of the vocal fold. The increase in tension of the vocal fold did not change the basic vibratory pattern of the mucosal upheaval, the mucosal wave, or the free edge. However, analysis of the mark before and after the increase in tension revealed that the mucosal upheaval occurred more medially or above when the vocal fold tension increased.

Dynamic stability of a nonlinear oscillatory liquid-gas system with variable parameters

In various power-station hydro-systems and industrial machines excitable regimes of motion of liquid-gas media, subject to vibratory actions, may, in one case, exert a substantial influence on the reliability of the work of responsible power-station units and aggregates or on their functioning in general; in another case, they may contribute to an intensification of the most diverse industrial processes. In the selection of optimal regimes for the functioning of power-stations and the realization of industrial processes, studies of the basic laws of the dynamic behavior of liquid-gas media under the action of vibrations acquire a special significance.

Hydrodynamic model of the vibro-spouted bed—II. Derivation of pressure from vibratory action

The particle velocity and the pressure distribution (derived from the vibratory action) in vibro-spouted beds (Rátkai, Gy., 1976, Powder Technol. 15, 187–192) were discussed in Part I of this series. In Part II the dependence of the pressure which generates the particle flow, on the variables of the periodical motion is shown, taking into account the momentum transfer between the vibrated plate and the bed. The value of the pressure depends fundamentally on the velocity which characterizes the collisions occurring between the bed and the vibrated bottom. A detailed discussion showed that, in turn, the motion momentum transfer occurs only within a part of the period. The dependence of this effective part of the period on the frequency and the amplitude is discussed. A momentum transfer coefficient was introduced and it is shown that the momentum transfer into the bed is limited even under idealized circumstances, i.e. motion in vacuum.

Hydrodynamic model of the vibro-spouted bed—I. Velocity profile in the bed

In the vibro-spouted bed vibratory action causes a recirculating particle stream with a similar velocity profile to that in a gas-spouted bed. The particulate solid is regarded as a macromolecular fluid. Starting from the equations of motion, the cylindrical symmetry of the flow of solid particles was taken into account. To obtain a general differential equation, the domain investigated was narrowed down to an internal layer along the axis where the radial velocity components can be taken to be zero and the axial components do not depend on the axial coordinate. To resolve this equation a supposition was made about the pressure distribution along the radius. So the solution of the equation consists of two parts. The shear stress of the resulting flow pattern has been calculated and plotted vs. velocity gradient.

Beam and cylinder sound instrument

A sound producing instrument is shown having a plurality of vibrating strings supported over an elongated aluminum sounding board. The strings are solid wires of brass, bronze or steel that are tensioned to produce a range of vibrations within the audible sound range. The strings may be manipulated along their lengths in various ways to control the mode of vibration of each of the respective strings. An electronic means such as a crystal or magnetic microphone is provided adjacent to the sounding board to pick up the vibrations resulting from activating the vibratory motion of the strings, and amplifying means are used to reproduce the sounds developed by the instrument. In one embodiment, the microphone may be caused to move during the pickup by a remote controller, so as to provide different sound effects. A special cylinder is provided for creating special sound effects when used to agitate the strings. In a modification, cylindrical elements may be used when placed in contact with the strings to alter the vibratory action of the strings. The cylinders are formed of aluminum and may be manipulated in various ways to stimulate the motion of the respective strings in characteristic modes for the production of unusual sounds.

On 19th-Century Perceptions of Iron Bridge Failures

The series of communications on iron bridge failures in the October 1981 issue of Technology and Culture (22:846-50) is curious in that it pits several humanists against one another in a debate over numbers. To an engineer, exactly how many railway bridges failed in the 19th century is not so important as the fact that failures did occur. The collapse of a single bridge of a relatively new material or design should have been enough to make contemporary engineers and their customers, the railroads, reflect on the new technology. The repeated collapses of iron railway bridges could only have cast suspicion on the adequacy of technological understanding and raised doubts within and without the developing railroad industry. And they did. As Cyril Stanley Smith notes in the chapter on fracture in A History of Metallography: The Development of Ideas on the Structure of Metals before 1890 (Chicago, 1960), the introduction of the railroad train, like that of the stagecoach before it, was fraught with repeated failures of iron axles. This, along with the failure of the iron railway bridges that were being built in large numbers at the time, prompted Queen Victoria in 1847 to appoint a commission to look into the use of iron. As quoted by Smith (pp. 122-23), Her Royal Highness charged that the commission should endeavour to ascertain such principles and form such rules as may enable the Engineer and Mechanic, in their respective spheres, to apply the Metal with confidence, and shall illustrate by theory and experiment the action which takes place under varying circumstances in Iron Railway Bridges which have been constructed. The commission's report, published in 1849, promulgated a misguided idea about the fatigue of metals, that crystallization occurred under vibratory action. Nevertheless, the report did lead the English Board of Trade to formulate some requirements regarding stresses in bridge construction. Stephen P. Timoshenko notes this in comments appended to R. E. Peterson's Discussions of a Century Ago concerning the Nature of Fatigue, and Review of Some of the Subsequent

Dynamic Analysis of an Assembly of Shrouded Blades Using Component Modes

The problem of vibratory behavior of an assembly of shrouded fan blades is examined. The point of view that forms the basis for the analysis is that the vibration characteristics of an assembly of blades can be predicted from a knowledge of vibration characteristics of its components. Clearly, linear behavior is assumed. A viscous type of damping mechanism is included to account for any energy dissipation due to vibratory rubbing action at shroud interfaces. As the component modes are computed with a single blade and shroud modelled with plate elements, the extent of chordwise motion in different modes is examined. Numerical results of an application of the analysis to a typical fan design are included.

Tools for the Industry

A Selection of Equipment of Use in the Production and Maintenance of Aircraft, Missiles, Space Vehicles and Components. The 12 in. AB Vibromet polisher, recently introduced into the well‐known Buehler range, takes up to 24 metallographic samples simultaneously through both the rough and the final polishing stages. Its vibratory action imparts an outstandingly high quality finish to the specimens: surfaces are scratch‐free, inclusions are retained, and flatness and edge retention are of an exceptionally high order. Any specimen can be removed at any time without stopping the machine and, if desired, replaced by another. The polisher can be left to operate unattended while polishing is in progress, and its high, continuous rate of output can thus be maintained with minimum interruption to other work in hand in the laboratory.

Longitudinal Vibrations of a Drill String

When drilling an oil well with a rotary drill, the penetration rate often can be substantially increased by superimposing a vibratory motion on the rotating bit. In order to evaluate drilling methods that would include both rotary and vibratory action, a study has been made on the vibrational characteristics of long drill string. The resonant frequency of a drill string consisting of a length of drill pipe and a length of drill collars is determined by considering the string as a lumped-constant system and also as an acoustic transmission line. A frequency equation is derived by applying the wave equation to the system and satisfying the boundary conditions at the top and bottom of the string and also at the junction of the two sections. The frequency equation is solved graphically for a number of drill-string configurations and the results are compared with the measured frequencies.

830. Influence of superionic vibrations on some magnetic properties of thin films: N.C. Pak and S.G. Russova, Metal & Metallographical Physics, 17 (4), April 1964, 623–624

The authors studied the vibratory action of the canine vocal fold from the tracheal side utilizing high-speed cinematography. Five excised canine larynges were used, and the lower surface of the vocal fold of three of them were marked with India ink as a tracer of a specific point on the vocal fold. A mucosal prominence, called the mucosal upheaval, appeared between the anterior commissure and the vocal process. Vibration was not seen below the mucosal upheaval. The mucosal wave started to move medially from just above the mucosal upheaval. The mucosal wave then became the free edge (lower lip) and collided with that of the other side at the midline. After collision, the lower lip moved upward to become the upper lip. At the same time, a part of the lower lip reflected laterally. The mucosal wave of the next cycle started from just above the mucosal upheaval during an opening phase. The mucosal upheaval vibrated with a low amplitude and with an earlier phase than the other portion of the vocal fold. The increase in tension of the vocal fold did not change the basic vibratory pattern of the mucosal upheaval, the mucosal wave, or the free edge. However, analysis of the mark before and after the increase in tension revealed that the mucosal upheaval occurred more medially or above when the vocal fold tension increased.

836. The double layer potential of low-pressure gas discharges: T. Wasserrab and Z. Angew, Phys., 16 (6), Dec. 1963, 441–444; in German

The authors studied the vibratory action of the canine vocal fold from the tracheal side utilizing high-speed cinematography. Five excised canine larynges were used, and the lower surface of the vocal fold of three of them were marked with India ink as a tracer of a specific point on the vocal fold. A mucosal prominence, called the mucosal upheaval, appeared between the anterior commissure and the vocal process. Vibration was not seen below the mucosal upheaval. The mucosal wave started to move medially from just above the mucosal upheaval. The mucosal wave then became the free edge (lower lip) and collided with that of the other side at the midline. After collision, the lower lip moved upward to become the upper lip. At the same time, a part of the lower lip reflected laterally. The mucosal wave of the next cycle started from just above the mucosal upheaval during an opening phase. The mucosal upheaval vibrated with a low amplitude and with an earlier phase than the other portion of the vocal fold. The increase in tension of the vocal fold did not change the basic vibratory pattern of the mucosal upheaval, the mucosal wave, or the free edge. However, analysis of the mark before and after the increase in tension revealed that the mucosal upheaval occurred more medially or above when the vocal fold tension increased.

Ultrasonic Welding

This paper will discuss the design of ultrasonic transducers necessary to produce efficient spot and seam welding. In addition, there will be a discussion of experience encountered with ultrasonic welding in the laboratory and in the field. Photographs and photomicrographs of metals welded ultrasonically will be presented. There will be a discussion of some of the physical mechanisms which must be involved in the bonding of metals by vibratory action.

On the effect of impact, vibratory action, and long continued changes of load on wrought iron girders

On the effect of impact, vibratory action, and long continued changes of load on wrought iron girders

Experiments to determine the effects of impact, vibratory action, and a long-continued change of load on wrought-iron girders

The author observes that the experiments which were undertaken, nearly twenty years ago, to determine the strength and form of the Tubular Bridges which now span the Conway and Menai Straits, led to the adoption of certain forms of girder, such as the tubular, the plate, and the lattice girder, and other forms founded on the principle developed in the construction of these bridges. It was at first designed that the ultimate strength of these structures should be six times the heaviest load that could ever be laid upon them, after deducting half the weight of the tubes. This was considered a fair margin of strength ; but subsequent considerations, such as generally attend a new principle of construction with an untried material, showed the expediency of increasing i t ; and instead of the ultimate strength being six times, it was in some instances increased to eight times the weight of the greatest load.

VIII. Experiments to determine the effect of impact, vibratory action, and long-continued changes of load on wrought-iron girders

A question of great importance to science and the security of life and property has been left in abeyance for a number of years,—namely, to determine by direct experiment to what extent vibratory action, accompanied by alternate severe strains, affects the cohesive force of bodies. It is immaterial whether the body be crystalline, homogeneous, or elongated into fibre, such as cast or wrought iron; the question to be solved is, how long will a body of this description sustain a series of strains produced by impact (or the repeated application of a given force) before it breaks? In the case of bridges and girders, this is a subject on which no reliable information has yet been given which may be considered as a safe measure of strength for the guidance of the architect and engineer. It is true that regulations have been established by the Lords Commissioners for Trade; but they appear to have had their origin on limited data, and in cases where the material and workmanship are good they may be relied upon as sufficient for the public safety. What, however, is wanted is experimental data to enable the engineer to comply satisfactorily with the conditions of the Board of Trade, and cordially to unite with the Government in affording ample security to constructions in cases where the lives of the public are at stake. To remove all doubts on this question, I have been enabled, through the liberality and at the request of the Board of Trade, to undertake a series of experiments to determine, or to endeavour to ascertain, whether a continuous change of load, and the strains produced by those changes, have any effect (and to what extent) upon the ultimate strength of the structure,—or, in other words, to ascertain the rate of endurance the material is able to sustain under these trials.

Experiments to determine the effects of impact, vibratory action, and a long-continued change of load on wrought iron girders

Experiments to determine the effects of impact, vibratory action, and a long-continued change of load on wrought iron girders