bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of Parallel Damped Dynamic Vibration Absorbers
Authors: Srinivasan A. V.
Published: December 2011

The analysis of parallel damped dynamic vibration absorbers is presented. The system considered is essentially a modification of the conventional damped vibration absorber and consists of adding, in parallel, a subsidiary undamped absorber mass in addition to the damped absorber mass. The analysis clearly shows that it is possible to obtain an undamped antiresonance in a dynamic absorber system which exhibits a well-damped resonance. While the bandwidth of frequencies between the damped peaks is not significantly increased, the amplitudes of the main mass are considerably smaller within the operational range of the absorber. The damped absorber mass and the main mass attain null simultaneously so that the vibratory force is transmitted directly to the undamped absorber. Numerical results are presented for the special case when the absorber masses have the same magnitude. Two cases of tuning have been considered: (a) when the absorber masses are tuned to the frequency of the main mass, and (b) when the absorber masses are tuned to the so-called favorable tuning frequency. Comparison of the results with those of the conventional absorber indicates that the parallel damped dynamic vibration absorber has definite advantages over the conventional damped vibration absorber.
Optimization of Four-Bar Linkages Satisfying Four Generalized Coplanar Positions
Authors: Eschenbach P. W. , Tesar D.
Published: December 2011

The optimal design of crank and rocker mechanisms satisfying four prescribed multiply separated positions of the moving plane is considered. The constraints are obtained from pairs of corresponding points on the generalized Burmester curves. Sorting the ∞2 linkages which result is accomplished by zones and weighting factors as applied to necessary design criteria.
Bicycloidal Crank—A New Four-Link Mechanism
Authors: Kaufman R. E. , Sandor G. N.
Published: December 2011

Cycloidpoints were recently introduced [1]. The present paper demonstrates the existence of Burmester point trios at which the rotation of the moving plane between precision positions is a constant multiple of the rotation of the circlepoint centerpoint vector. A new geared linkage is introduced to mechanize this commensurate relationship. Equations for finite-motion generation and for both finite and infinitesimal path generation are developed. Cognates of this mechanism are shown to exist.
On the Balancing of the Fluctuating Input Torques Caused by Inertia Forces in the Crank-and-Rocker Mechanisms
Authors: Ogawa K. , Funabashi H.
Published: December 2011

Some methods have been investigated both theoretically and experimentally to reduce the fluctuating torques in the driving shafts caused by the inertia forces in the crank-and-rocker mechanisms; the spatial four-bar mechanism having two revolute and two spheric pairs is cited as an example. The fluctuating torque has been actually reduced to 1/20–1/3.
Investigation of Silo Loads in Measuring Models
Authors: Pieper Klaus
Published: December 2011

The test results described are a portion of a current comprehensive series of investigations. No attempt is made to produce the values for wall frictional and bottom loads, which were measured simultaneously with horizontal pressure. Data obtained from the measurements prove that, although standard specifications on the calculation of silo loads are incorrect in some details, adherence to these loading data will not damage silos.
An Investigation of the Gravity Flow of Noncohesive Granular Materials Through Discharge Chutes
Authors: Roberts A. W.
Published: December 2011

The flow of granular materials through curved or straight discharge chutes is classified as either “fast” or “slow.” Fast flow is the more efficient and occurs when the material flows in contact with the chute bottom and side walls, but does not make contact with the top. On the other hand, slow flow occurs when the material is in contact with all four faces of the chute. Under fast flow conditions, the grain stream thickness varies along the chute with the minimum thickness occurring near the point where the mean stream velocity is a maximum. The paper investigates the conditions governing fast flow and presents an approximate analysis to account for the grain stream thickness variation. The analysis, based on the assumption of steady flow, involves the solution of nonlinear differential equations. An equivalent friction coefficient is introduced to account for the frictional drag on the chute bottom and side walls; this friction coefficient is not constant but is found to vary with the changing stream thickness. Results of experimental investigations performed on chutes of known geometric shape are correlated with the analytical solutions. High-speed cine photography is used to determine the actual velocities and paths of individual grains in the moving stream, thus enabling the velocity profiles to be determined at different points along the stream. The paper presents data and recommendations for optimum chute design. These data include suggestions relating to the best chute shape to meet a given set of conditions and information concerning the optimum chute cutoff angles to avoid flow obstructions.
Air Pressure in the Bulk of Granular Solid Discharged From a Bin
Authors: Wlodarski A. , Pfeffer A.
Published: December 2011

Air pressure different from that in the surrounding atmosphere develops in the bulk of granular material flowing out of an open bin through the bottom orifice. When measured on the axis of a small laboratory apparatus the differences have been found to oscillate about a mean changing along the bin and reaching its maximum/negative/well above the orifice. Pressure difference at a given point inside the bed depends upon the orifice size, and upon the size of solid particles. Equalization of the air pressure just above the orifice with that of the air outside the bin influences flow rate of the material. It is suggested that the overlooking of these effects is to some extent responsible for the great variety of flow rate equations so far proposed.
Analysis and Design of Plastic Storage Tanks
Authors: Moody G. B.
Published: December 2011

The author has designed over one hundred major tanks that store plastic powders and pellets. This article gives some practical examples of how to analyze and design plastic storage tanks. Examples were taken from files of completed projects. All tanks are classified as either shallow or deep; an example of each is given. A series of four articles was written to report on a study about vessels made of aluminum or steel, and joined by bolting or welding. The first three articles are “Bolted Aluminum—Alloy Connections,” “Welded Tanks for Dry Bulk Plastic Storage,” and “Bolted Tanks for Storage of Plastics.” The state-of-the-art is presented. Although computer programs have been developed, some equations still used are empirical, and the assumptions are conservative. Not all authorities agree on the proper method of analysis. A research study of the whole tank, rather than its parts, should be made.
Gravity Flows of Ideally Plastic Materials Through Slots
Authors: Pariseau W. G.
Published: December 2011

Experimental evidence shows that plasticity theory is a suitable framework for analyzing the flow of bulk materials in bins and hoppers. It thus serves as a rational guide for the collection of requisite design data including the distribution of stress and velocity throughout the moving mass of material.
The Influence of Nuclear Radiation on Pool-Boiling Heat Transfer to Liquid Helium
Authors: Bowman H. F. , Smith J. L. , Ziebold T. O.
Published: December 2011

Pool-boiling experiments were performed in helium from high purity copper which had been exposed to various amounts of fast neutron radiation. The residual effects of the radiation influenced the pool boiling in two ways: First by decreasing the thermal conductivity of the copper substrate; and second by inducing residual radioactivity in the copper. The changes in the conductivity influenced the unsteady heat conduction process associated with nucleate boiling. The residual radiation from the copper augmented the bubble nucleation in the superheated helium in a manner similar to a bubble chamber. The relative magnitudes of the two effects were influenced by surface smoothness.
Bonded Elastic Mounts Under Combined Loading of Shear and Normal Forces
Authors: Chou S. I.
Published: December 2011

The large deformation of an elastic mount consisting of an infinite elastic strip of rectangular section bonded between two rigid plates under the combined loading of shear and normal forces is considered. The material is assumed to be homogeneous, isotropic and elastic, and has strain energy function of Mooney type. Explicit solutions are obtained for the case when strain in the normal direction is small. For this case, simple formulas relating the applied loads and deflection are given.
Analysis of an Offset Unsymmetric Gyroscope With Oblique Rotor Using (3×3) Matrices With Dual-Number Elements
Authors: Yang An Tzu
Published: December 2011

Using 3 × 3 matrices of dual-number elements, dynamic equations are obtained for an offset unsymmetric gyroscope with obliquely placed rotor, a generalized six-degree-of-freedom gyroscopic system (shown schematically in Fig. 3). Equations of motion for a special case of the system, a two-frame symmetric gyroscope, conventional in all aspects except the rotor is inclined relative to its spin axis, are deduced; these equations are applied to the study of the effects of a slightly inclined rotor on (a) a two-frame symmetric gyroscope in steady precession and (b) a Faucualt’s gyrocompass.
Comparison of Two Complete Solutions in an Axisymmetric Extrusion With Experiment
Authors: Shabaik A. H. , Thomsen E. G.
Published: December 2011

An upper-bound and a potential solution to a forward extrusion problem were compared with experimental results obtained by the visioplasticity method. The process consisted of extruding a 2-in-dia billet of preforged lead through a conical die having a half-cone angle of 45 deg under the condition of relatively low friction. The comparison was made for steady state stream lines, velocities, strain rate components, effective strain and strain rate, grid distortion, and stress distribution. It was found that the curves were generally of similar shape and that some differences existed in magnitude only. It is suggested that the theoretical solutions can be used to advantage to a first approximation in predicting all important variables.
Computerized Determination and Analysis of Cost and Production Rates for Machining Operations: Part 2—Milling, Drilling, Reaming, and Tapping
Authors: Field M. , Zlatin N. , Williams R. , Kronenberg M.
Published: December 2011

In Part 1 of this two-part paper, generalized equations for cost and production were presented for five major types of machining operations: turning, milling, drilling, reaming, and tapping. In addition, detailed cost equations were presented for the turning operation for three types of lathe tools: brazed carbide tools, throwaway tools, and solid high-speed steel tools. The present paper, Part 2, presents the detailed cost and production analysis for the remaining machining operations: milling, drilling, reaming, and tapping. Individual equations are developed within each machining category for the major types of cutters and tools involved in the operation. Examples are presented illustrating the use of these equations on specific problems. In addition, equations are developed for calculating the optimum cutting speeds and tool life corresponding to minimum costs and maximum production rates assuming that the tool life-cutting speed follows the simplified Taylor equation. The optimized equations enable one to interpolate and extrapolate the cost and production determinations. Care must be exercised to check experimentally the interpolated or extrapolated values to verify the results from the calculations.
Grinding Process Instability
Authors: Bartalucci B. , Lisini G. G.
Published: December 2011

The paper describes a theoretical investigation on chatter vibrations of cylindrical plunge grinding. The system grinding machine-grinding wheel-workpiece is represented as a closed loop system with two feedback paths, one due to the machine tool structure, the other to the regenerative effect of the grinding wheel. Theoretical results are in good agreement with the experimental tests.
Axisymmetric, Nonidentical, Flat Face Flanges With Metal-to-Metal Contact Beyond the Bolt Circle
Authors: Waters E. O. , Schneider R. W.
Published: December 2011

A method of analyzing a pair of nonidentical, axisymmetric flat face flanges with metal-to-metal contact beyond the bolt circle is described. The design method takes into account interaction between opposing flanges in a bolted closure and provides for compatibility of deformations of all elements comprising the closure. The case of a blind cover to an integral flange having a hub of uniform thickness is described in detail. However, the same analytical approach can be extended to cover a tapered, hubbed flange or the general situation where a reducing flange is substituted for the blind cover.
Building a Mathematical Model to Predict Transient Drilling Temperature Responses
Authors: Saxena U. K. , Wu S. M.
Published: December 2011

A transient drilling temperature predicting equation is developed using a statistical model-building technique. The functional form of the model is obtained by combining both theoretical considerations and an empirical approach. The parameters of this model are estimated and improved using a sequential procedure in designing the experiments. Confirmatory tests show that the model describes the transient drilling temperature responses remarkably well. The effectiveness of the design procedure for obtaining the “best” estimates of the parameters is also demonstrated.
A Study of Wear on Cemented Carbide Cutting Tools
Authors: Hsu¨ T. C.
Published: December 2011

A technique is developed for measuring accurately the flank wear by using polished tungsten carbide tool tips. The technique is applied to the study of the variation of machinability in mild steel bars and of the possible effect of surface finish of tool face on the wear rate. The specific wear rate, which is the volume of material worn away per unit contact area per unit distance of rubbing, is used to analyze the results on flank wear in this investigation and Trent’s results on crater wear. The constants in an equation representing Trent’s results and in Taylor’s equation for tool life are shown to have physical meanings and to be related to the specific wear rate. The reciprocal of the specific wear rate may be used as a machinability index.
Some Extrusion Studies of the Eutectic Alloy of Pb and Sn
Authors: Jovane F. , Shabaik A. H. , Thomsen E. G.
Published: December 2011

Flow studies in extrusion tests revealed that the Pb-Sn eutectic alloy in the superplastic state yielded velocity fields nearly identical with those obtained using lead. Slight differences observed in the velocity fields were attributed to differences in boundary friction. The test results appear to support the contention that the flow field within a plastically moving metal or alloy essentially is unique for identical boundary conditions. It is suggested that moderate variations in the properties of the material and in the flow condition will contribute only minor changes in the velocity distribution. Uniqueness is supported by the present results but not proved unequivocally.
Axial Stresses in Armor Wires of Bent Submarine Cables
Authors: Lutchansky M.
Published: December 2011

The axial stresses induced in the helically wound armor wires of a submarine cable bent over a drum are described by a simple mathematical model. The model, which represents the wire-core interaction, yields a simple description of the stress concentration at a rigid inclusion such as a clamp or apparatus housing. The “free field” expression for stresses away from an inclusion is also obtained and shows the effects of the entire range of interaction stiffness from frictionless slip to infinite interaction shear stiffness. At the latter limit beamlike outer fiber stresses are produced. Beamlike stresses are also produced in the limiting cases of infinitesimally thin wires and infinitely long lay-length where wires run parallel to the cable axis.
Principles of Self Control of Product Flatness in Strip Rolling Mills
Authors: Polakowski N. H. , Reddy D. M. , Schmeissing H. N.
Published: December 2011

Design prerequisites were examined for a strip mill which would spontaneously provide a nearly-uniform percent reduction of thickness across a metal sheet or strip regardless of the latter’s cross-sectional form. The main requirement is that the flexural rigidity of the roll assembly be small (yet finite) and that the rolls be loaded uniformly over their working length rather than be end-supported. When operated with front and back tensions, a machine built along these lines should also correct initially malshaped material. The analysis is supported by a computer-solved comprehensive example wherein a conventional 4-high and a “flexible,” hydraulically loaded cluster mill are compared.
A Study of Barreling as an Example of Free Deformation in Plastic Working
Authors: Kulkarni K. M. , Kalpakjian S.
Published: December 2011

The barreling of cylindrical specimens during upsetting is a common example of free deformation. However, there is no analytical solution to predict the extent of barreling and even experimental work is scarce. In this study tests were conducted on 7075–0 aluminum with specimens of three height-to-diameter ratios. Some specimens were upset dry, others were lubricated. A suitable parameter was chosen to characterize the extent of barreling. The influence of various process variables on this parameter was studied. A simple analysis is given to relate this parameter to other geometrical factors. The possibility of analytical prediction of barreling is considered, but appears to be as yet remote.
Analysis of Tool Wear—Part I: Theoretical Models of Flank Wear
Authors: Bhattacharyya A. , Ham I.
Published: December 2011

Cutting tools of sufficient strength against failure by brittle fracture or loss of “form stability” through rise of interface temperatures, still continue to fail by a process of “wear,” which is loss of cutting tool material through gradual interaction between the work and the tool material. Such wear can take place either at the principal flank surface or at the top face of the cutting tool for roughing and semiroughing cuts. Wear may also occur at the auxiliary flank surface resulting in grooving wear during fine machining or machining of high strength materials. The causes for such wear processes include (i) mechanical interaction (abrasion or adhesion and transfer type), (ii) thermochemical interaction (diffusion or chemical reaction). As a part of this investigation on tool wear, two theoretical models have been proposed for explaining mechanical wear at the flank surface. These models explain the nature and characteristics of wear growth and the sensitiveness and dependence of interaction phenomena between the tool-work pair.
Development and Use of a Track Quality Index
Authors: Crane L. S. , Sullivan J. J. , Kaelin C. R.
Published: December 2011

The purpose of this paper is to describe a track inspection car currently being used in the United States, and to discuss the development of a track quality index, which is a major benefit afforded by the inspection data accumulated through operation of the car. From the development of a track quality index, vital information describing the ride quality of track can be made available to guide maintenance officers in funding and scheduling track maintenance.
Problems on Hunting of Railway Vehicle on Test Stand
Authors: Matsudaira T. , Matsui N. , Arai S. , Yokose K.
Published: December 2011

The stand test in which a vehicle is set on a roller rig to simulate its running state is available as one of the effective means for experimental study on the hunting of vehicle. Here several questions arise: Whether or not a scale model test can substitute for an actual vehicle test; whether or not a bogie with a dummy load can represent a whole car in a stand test; and whether or not a stand test produces a similar result to a field test. The present paper summarizes the results of the studies about these questions conducted at the Railway Technical Research Institute of the Japanese National Railways.
A Three-Dimensional Finite Difference Solution for the Thermal Stresses in Railcar Wheels
Authors: Novak G. E. , Eck B. J.
Published: December 2011

A numerical solution is presented for both the transient temperature and three-dimensional stress distribution in a railcar wheel resulting from a simulated emergency brake application. A computer program has been written for generating thermoelastic solutions applicable to wheels of arbitrary contour with temperature variations in both axial and radial directions. The results include the effect of shear stresses caused by the axial-radial temperature gradients and the high degree of boundary irregularity associated with this type of problem. The program has been validated by computing thermoelastic solutions for thin disks and long cylinders; the computed values being in good agreement with the closed form solutions. Currently, the computer program is being extended to general stress solutions corresponding to the transient temperature distributions obtained by simulated drag brake applications. When this work is completed, it will be possible to synthesize the thermal history of a railcar wheel and investigate the effects of wheel geometry in relation to thermal fatigue.
The Dynamic Stability of Rotor/Stator Radial Rubs in Rotating Machinery
Authors: Ehrich F. F.
Published: December 2011

The classic phenomenon of “dry friction whip,” generally associated with unlubricated journal bearings, is here reconsidered as playing an important role in the dynamic stability, and consequent integrity of radial rubs in all close clearance rotating machinery, particularly in turbomachinery elements such as labyrinth seals and blade tips. A simple analysis is completed for large (runaway) amplitudes of whipping on an analytic model which includes the stator as an independent dynamic system. Whirl frequencies are computed as a function of rotor and stator natural frequencies and damping. A stability criterion is developed as a function of these same variables. Testing on a simple experimental model gives general qualitative agreement to predicted trends, but is not conclusive quantitatively, probably because of the difficulty in simulating pure Coulomb friction at the rubbing interface. The simple generality that can be inferred from the set of derived stability criteria is that the broadest band of whip-free rubbing is achieved if rotor and stator dampings are made close to one another, and if the rotor and stator natural frequencies are kept dissimilar. Systems with identical rotor and stator natural frequencies are always unstable, and will whip at that same natural frequency. Systems with large stator damping will whip at rotor natural frequency. Systems with large rotor damping will whip at stator natural frequency.
Complete Response of Distributed Systems Controlled by a Finite Number of Linear Feedback Loops
Authors: Berkman Frank , Karnopp Dean
Published: December 2011

The analysis of the effect of active control forces on distributed systems, such as elastic mechanical structures, is complicated by the complex coupling between the infinite number of degrees of freedom which may occur. Conventional truncation of the representation of the passive system to a finite-order representation may lead to erroneous conclusions about the controlled system response. In this paper, it is shown that the complete closed-loop system response may be computed without a priori truncation. An example involving an elastic body under the action of an identically located sensor and force source is given which shows that the techniques also are useful for certain passive coupled mode systems.
Lateral Stability of Road and Rail Trailers
Authors: Diboll W. B. , Hagen D. H.
Published: December 2011

The conditions for the lateral stability at a highway or rail trailer are investigated analytically and experimentally with a laboratory size trailer. The motion of the trailer is expressed in two degrees of freedom, the lateral and angular displacements of the trailer. The oscillation was found to be a self-excited vibration which is very dependent upon the lateral springing at the towing pivot point. The variables are expressed as dimensionless parameters. For conventional trailer loading, the most important variables are the damping ratio as a function of the Strouhal number, sω/V, and as a function of a dimensionless energy term, μGz/V2. As higher values of sω/V and μGz/V2 are reached (for example, lower velocity), less damping is needed for stable operation. Although the relationships have not been established precisely, there is good correlation.
Vibratory Bending of Damped Laminated Plates
Authors: Ditaranto R. A. , McGraw J. R.
Published: December 2011

The natural frequencies and associated composite loss factor have been determined for a finite-length laminated plate having alternate elastic and viscoelastic layers. Partial differential equations in terms of the variables of the plate are derived and, with the loading equation for a freely vibrating plate, a set of simultaneous partial differential equations is formed. Of two solutions considered the first is general and the second satisfies the boundary condition for a simply supported plate. In both cases, the resulting algebraic simultaneous equations are complex since the shear modulus of the viscoelastic material is a complex expression. In the first case, the expressions could not be solved directly since the value of the eigenvalues depended upon the boundary conditions, whereas the eigenvalues for the simply supported plate could be easily chosen. The simply supported case is solved and the results plotted for specific dimensionless parameters.
The Motion of a Flat-Plate Pendulum in a Viscous Fluid
Authors: Ries J. P. , Harrach W. G.
Published: December 2011

The motion of an infinite, flat plate undergoing free oscillations as a submerged pendulum in a viscous fluid is analyzed. An analytical solution has been obtained through a simultaneous solution of the equation of motion for the plate, the drag force relationship, and the boundary-layer equations for the case of laminar, incompressible, unsteady flow. Expressions for the displacement and velocity of the plate appear as the sum of a damped harmonic oscillation and a particular solution which decays asymptotically to zero with increasing time. The period and logarithmic decrement are expressed as functions of a single parameter which contains the physical properties of the fluid and dimensions of the system. Predicted values of plate displacement, plate velocity, amplitude ratio, and damped oscillation period are compared to the results of an experimental investigation performed in water and a light oil.
The Influence of Internal Friction on the Stability of High Speed Rotors With Anisotropic Supports
Authors: Gunter E. J. , Trumpler P. R.
Published: December 2011

This paper evaluates the stability of the single mass rotor with internal friction on damped, anisotropic supports. The paper shows under what conditions the rotor stability may be improved by an undamped support with anisotropic stiffness properties. A three dimensional model is presented to show the influence of rotor and support stiffness characteristics on stability. Curves are also presented on how support damping may also improve or even reduce rotor stability. An analog computer solution of the governing equations of motion is presented showing the shaft transient motion for various speed ranges, and also plots of the rotor steady state motion are given for various speeds up to and including the stability threshold. The analysis is used to explain many of the experimental observations of B. L. Newkirk concerning stability due to internal rotor friction.
Comparative Study of Optimization Techniques for Shock and Vibration Isolation
Authors: Karnopp D. C. , Trikha A. K.
Published: December 2011

Several optimum and suboptimum isolators are discussed with respect to three different criteria appropriate to shock and vibration isolation. In attempting to show the limitations of performance of a system optimized according to one criterion when considered from the point of view of another criterion, a number of advantages and disadvantages of the optimum systems are made evident. The results are presented in trade-off diagrams which allow a continuous range of choice in penalizing measures of relative displacement and the force or acceleration associated with the isolated element.
Dynamics of Beam-Type Periodic Structures
Authors: Lin Y. K. , McDaniel T. J.
Published: December 2011

An analytical technique is developed for the determination of the frequency response matrix of a one-dimensional periodic structure. The detailed analysis is carried out for a periodic Bernoulli-Euler beam on many elastic supports, a simplified version for a skin-stringer panel system commonly used in flight vehicle designs. It is shown that considerable simplification can be achieved by introducing one of several possible interior singular conditions. Finally, numerical examples are given for an undamped system and for the same system with damper units attached at periodic locations.
Nonlinear Oscillation of a Cylinder Containing a Flowing Fluid
Authors: Thurman A. L. , Mote C. D.
Published: December 2011

The fundamental and second periods of transverse oscillation of a cylinder containing a flowing fluid are theoretically determined for the approximate solution of two, coupled, nonlinear partial differential equations describing the transverse and longitudinal motion. The calculations indicate that the existence of the fluid transport velocity reduces all cylinder natural periods of oscillation and increases the relative importance of non-linear terms in the equations of motion. Accordingly, in many cases of practical interest the linear analysis is shown to be severely limited in its applicability. Curves are presented that will assist one to estimate both the accuracy of the linear period and the approximate nonlinear period in selected examples. A new approximate solution method is utilized that permits accurate and efficient calculation of the nonlinear period. This method can be applied to the period determination of additional cylindrical models not examined herein; the method appears to be semi-generally applicable to the periodic solution of weakly nonlinear systems.
Gyroscopic Systems as Vibration Absorbers
Authors: Srinivasan A. V.
Published: December 2011

Theoretical analysis of a gyroscopic system is made with a view to determine its feasibility as a synchronous vibration absorber. It is shown that antiresonance in two directions orthogonal to each other can be produced simultaneously. Thus, the total energy at antiresonance is due entirely to the angular oscillations of the gyro. Also at the null frequencies, the inertial forces induced by gyroscopic action being out of phase with the input forcing function, the latter is reacted by the former resulting in antiresonance. As the null frequencies are directly related to the angular speed of the gyro, it is possible to obtain linear synchronization so that the device can effectively be used as a synchronous vibration absorber.
A Discussion of the Effects of Sound on Jets and Flueric Devices
Authors: Roffman Gary L. , Toda Kenji
Published: December 2011

In designing fluid amplifiers it is important to know the conditions that affect a jet. These conditions generally fall into two general categories, signal and environment. Jet sensitivity to sound encompasses both categories; it therefore becomes important to understand the jet-sound relationship. This knowledge is useful in designing fluidic devices sensitive to sound signals or relatively insensitive to a noise environment. Laboratory experiments were performed which show that the spread of a bounded, two-dimensional jet increases when exposed to a sound field. From experiments conducted on smoke jets, it was concluded that for a given sound frequency the increase of the jet spread is dependent on the sound amplitude; moreover, the sound-sensitive jet has a frequency response bandwidth that contains a maximum, and both maximum and response band shift toward higher frequencies with increasing nozzle exit velocities. As the degree of turbulence of a jet increases, larger amplitude sound signals are needed to affect the jet. Using the Reynolds number as an indicator of jet turbulence and knowledge of the relationship of sound frequency to jet Reynolds number, one can then predict the sound or noise frequency that will disturb a jet in a flueric device.
On the Critical Speeds of a Continuous Rotor
Authors: Eshleman R. L. , Eubanks R. A.
Published: December 2011

An analytical investigation was made on the effect of axial torque on the critical speeds of a continuous rotor whose motion was described by a set of partial differential equations including the effects of transverse shear, rotatory inertia, and gyroscopic moments. The equations of motion and associated boundary conditions for long and short bearings were cast in nondimensional form to facilitate the study of the influence of the aforementioned effects on a torque-transmitting rotor’s critical speeds. The results of this study were compared to classical results of Bernoulli-Enter and Timoshenko to determine the relative importance of the rotor’s “secondary phenomena” in a critical speed calculation.
Vibration of Containing Structures by Sound in the Contained Fluid
Authors: Fahy F. J.
Published: December 2011

A system which consists of a rigid rectangular box with one simply supported flexible wall is analyzed by numerical and statistical methods for the internal acoustostructural mode coupling factors and the corresponding modal average radiation efficiency. It is found that for subcritical frequencies, but above a frequency which corresponds to the lower limit for maximum proximate mode coupling, the radiation efficiency is equal to that of a baffled panel radiating into a free field. At supercritical frequencies a value of radiation efficiency half that of a freely radiating panel is found. Below the limiting frequency an approximate dependence upon (f/fc)3 is found experimentally in all cases. The same type of behavior has been observed with an internally excited, partically closed cylinder. The radiation efficiency of a clamped panel is calculated to be about 3 db greater than that of the simply supported panel at low frequencies. This factor falls to zero at the critical frequency and above. Corrections to the normal statistical energy response and radiation equations are presented which take into account the fact that it may not be assumed, purely on the basis of modal density ratio considerations, that many acoustic modes couple with an individual structural mode.
An Explanation of Low-Speed Chatter Effects
Authors: Sisson T. R. , Kegg R. L.
Published: December 2011

At low machining speeds, self-excited chatter behavior is dominated by factors which have never been satisfactorily explained. By studying the forces acting on the cutting tool right behind the cutting edge, the authors have developed a physical explanation for low-speed stability. This leads to an understanding, in terms of physical quantities, of how such variables as tool edge roundness, tool clearance angles, and chatter frequency affect stability. The explanation is consistent with all published experimental observations of low-speed chatter behavior.
Theoretical and Experimental Investigation of Electrohydraulic Vibration Isolation Systems
Authors: Schubert Dale W. , Ruzicka Jerome E.
Published: December 2011

This paper presents the results of an investigation of electrohydraulic vibration isolation systems that employ multiple electronic feedback signals to control the action of a hydraulic actuator in a closed-loop servocontrol system. The theoretical basis for the operation of the isolation system is discussed, including consideration of system stability. Experimental data are provided for unidirectional single-mass isolation system configurations that provide limited-band isolation, broad-band isolation, single-notch isolation, combined notch and broad-band isolation, multiple-notch isolation, and notch isolation with automatic frequency tracking. The results emphasize the unique performance characteristics of electrohydraulic isolation systems, including isolation of ultralow-frequency vibration, zero static and steady-state relative deflections, response substantially independent of the weight of the isolated body, and the ability to tailor the frequency-response characteristics to satisfy a wide range of specific requirements.
Nonlinear Vibrations of a Beam With Pinned Ends
Authors: Ray J. D. , Bert C. W.
Published: December 2011

This paper describes theoretical and experimental investigations of the large-amplitude vibrations of a flexible beam simply supported on a nearly rigid base. The beam is designed to minimize most secondary effects, such as transverse shear flexibility, rotatory inertia, and nonlinearities in curvature and in the stress-strain curve. Detailed attention is given to quantitative verification of the assumptions made in deriving the equation of motion. Three different approaches are used to solve the equation: assumed-space mode, assumed-time mode, and Ritz-Galerkin solutions. In the experiments, the beam was base excited. The resonant frequencies and associated strain distributions, modal shapes, and waveforms were measured for various values of initial tension and amplitude ratios (ratio of maximum amplitude to beam thickness) up to 16. Within experimental accuracy, the experimental results verified all of the assumptions made in the analyses. However, no one method of solution resulted in the best predictions of all of the experimentally observed phenomena.
A Numerical Method for Estimating the Temperature Distributions in Extrusion Through Conical Dies
Authors: Altan T. , Kobayashi S.
Published: December 2011

A numerical method was developed to predict the local temperatures in the billet and in the tooling before the extrusion starts. The method was further extended for calculating the nonsteady-state temperature distributions during extrusion. The necessary velocity, strain rate, and strain fields were obtained from a visioplaslicity experiment. Heat generation and conduction were approximated in two consecutive steps taking place during equal time increments Δt. The temperature dependencies of the flow stress and of the thermal constants of the billet and the tool materials were taken into account, and the entire procedure was programmed in FORTRAN IV to facilitate its general use for analyzing extrusions with different extrusion ratios, materials, die angles, ram speeds, and friction conditions.
Stiffened Catenary Calculations in Pipeline Laying Problem
Authors: Dixon D. A. , Rutledge D. R.
Published: December 2011

According to a granted U. S. Patent, it is contemplated that deep water pipelines be laid on the sea floor from an inclined derrick on a lay barge without the aid of a stinger. Means are presented in this paper for calculation of required tension and inclination of pipeline at the lay barge. Charts giving necessary tension and inclination, taking pipeline stiffness into consideration, are presented.
Sizing Piping Networks for Incompressible Flow With a Digital Computer
Authors: Cinque A. A. , Sheridan H. C.
Published: December 2011

The computer program described in this paper will find the pipe size for each section of a complex piping network necessary for proper system performance within a given set of operating criteria for an incompressible fluid under steady, one-dimensional, isothermal flow conditions. Operating criteria are specified as flow and flow direction in each pipe section, pressures required or imposed at all end points of the network, and maximum allowable velocity of the fluid. The physical description of the network is given in the form of pipe lengths, quantities and types of components in each pipe section, and heights of all end points. Any network configuration, whether convergent, divergent, loop, parallel, or a combination of these, can be designed. Selected pipe sections may be fixed in size as input and the remaining sections of the network will have sizes chosen that are compatible. In addition to calculating pipe sizes and other related data, an option may be chosen to provide a basic list of material and a material ordering format.
The United Aircraft High Speed Train Suspension Design
Authors: Cripe A. R.
Published: December 2011

The demand for improved high speed rail transportation in our growing metropolitan corridor areas has resulted in United Aircraft’s designing and building several new turbine-powered high speed trains. This paper describes some of the unique features in the suspension design permitting significant improvements in comfort and the ability of the trains to negotiate existing curves with greater speed and safety.
Critical Review of Some Previous Work on the Mechanics of the Metal-Cutting Process
Authors: Bailey J. A. , Boothroyd G.
Published: December 2011

A review is presented concerning the mechanics of the metal-cutting process where a continuous chip is produced with the absence of a built-up edge on the tool face. It is shown that previous theories which predicted a linear relationship of the form φ = A − B (β − α) between the angle parameters cannot be used to interpret the experimental data. The apparent linear relationships observed in some previous experimental work are thought to be due partly to the method of presentation of the results. It is suggested that a more significant combination of the angle parameters is the difference between the shear angle φ and the rake angle α, that is, (φ − α). It is pointed out that two parameters which can be used to describe the frictional conditions on the tool face are the mean friction stress and the mean normal stress. Since these can vary independently, it is thought unrealistic to group them together as a single variable. It is therefore concluded that the mean angle of friction is insufficient in itself to describe the frictional conditions on the tool face.
The Control of Buildup and Diametral Growth in Shear Forming
Authors: Wells C. H.
Published: December 2011

The two major problems in shear forming cylindrical blanks are buildup of metal ahead of the tool ring and diametral growth of the part. The process variables (feed per revolution, reduction, tool ring contour) beneficial to diametral fit unfortunately enhance buildup and vice versa; the introduction of a fourth variable, roll tilt, has been found to reduce the severity of both problems, as well as frictional drag and residual stress in the part wall. The mechanisms of axial and circumferential growth are proposed, being mainly an analogy with wedge indentation. The elastic-plastic boundary about the point of contact is calculated, as is the instantaneous velocity of extrusion. The variation of buildup with feed and reduction is shown for annealed 1100 and 7075 aluminum blanks. The effect of tool ring contour on the growth of AMS 6323 and B120 VCA parts was investigated. It was found that a sharp tool ring could cause a significant reduction of diameter and that the deep feed lines could be safely eliminated by a gradual relief at the back side of the tool ring.
Evaluation of a Vibration Damping Tool and of Drill Stem Torque Requirements From Data Recorded by an Instrumented Drill Stem Member
Authors: Miller C. E. , Rollins H. M.
Published: December 2011

An instrumented drill stem member was used by Esso Production Research Company to record drill stem axial load, torsional load, bending, and rates of changing in these three values. Interpretation of these data from selected runs is used to show variation in drill stem torque at the kelly, at the top of the collars, and near the bit. Data taken near the bit demonstrate erratic bit rotation and bit loading and suggest large torsional vibrations in the drill stem. Data recorded at the kelly and near the bit indicate substantial axial and torsional vibration damping by one type of vibration damping tool. Suggestions are made for further investigations.
Viscoelastic Properties of Soft Tissue by Discrete Model Characterization
Authors: Jamison C. E. , Marangoni R. D. , Glaser A. A.
Published: December 2011

In order to study the response of the human body to acceleration and force, it is necessary to be able to relate force to deformation in various body tissues. Problems wherein this becomes essential include aerospace travel, crash injury research, and shock/vibration environments produced by mechanical systems. Since the tissues within the human body are viscoelastic in nature, it is important to apply proper viscoelastic relations when investigating the mechanics of deformation. This paper discusses on experimental technique for obtaining discrete viscoelastic models of soft biological tissues. The application of this experimental technique, using guinea pig skin as an example, is presented along with numerical results for the various viscoelastic parameters. A discussion of discrete viscoelastic modeling and the necessary mathematical equations for relating deformation to force is also included.
Bending of Circular Plates Under a Variable Symmetrical Load—Part I
Authors: Heap J. C.
Published: December 2011

The basic equations of deflection, slope, and moment for a thin, flat, circular plate, under a symmetrical variable load, for a constant force divided by the square of the radial distance, have been developed. Six cases have been derived. The first four cases cover the variable load acting over the entire plate, viz., (a) fixed, supported, outer edge and fixed, inner edge, (b) simply supported, outer edge and free, inner edge, (c) simply supported, outer edge and fixed, inner edge, (d) fixed, supported, outer edge and free, inner edge; and the final two cases are for a solid plate having the acting variable load bounded by circles of an inner radius and the outer support-load-radius; i.e., (e) fixed, supported, outer edge and (f) simply supported, outer edge.
Reducing Wear in an Electromagnetic Clutch
Authors: Kilburn R.
Published: December 2011

An analytical model of an electromagnetically operated friction-disk clutch is constructed in order to determine the wear on the clutch face. The face consists of two materials—metal rings and friction material. The pertinent differential equations, derived in the Appendexes, are solved numerically. The effects of varying such parameters as hardness, residual magnetism, and elastic constants are studied.