bluuebunny/crossref_metadata_2025 huggingface dataset:
Resonance Characteristics of Unidirectional Viscous and Coulomb-Damped Vibration Isolation Systems
Authors: Ruzicka Jerome E.
Published: December 2011

Elementary vibration theory based on transfer response analyses of single-degree-of-freedom systems indicates that an increase in isolation system damping causes a decrease in resonant transmissibility. This theory further specifies that, for viscous-damped systems, an increase in damping decreases the resonant frequency whereas, for Coulomb-damped systems, an increase in damping increases the resonant frequency. It is frequently found in practice that an increase in damping may increase the resonant transmissibility and cause a change in resonant frequency opposite to that predicted by elementary theory. This paper presents a more extensive evaluation of the resonance characteristics of unidirectional vibration isolation systems, including the effects of directly coupled and elastically coupled damping elements. Mathematical models and absolute transmissibility characteristics of viscous and Coulomb-damped vibration isolation systems are discussed and resonance characteristics are analyzed in terms of the resonant frequency ratio, the resonant transmissibility, and the rate of change of these parameters with damping. Design data are presented graphically for parametric variations of stiffness and damping which are sufficiently broad to encompass a wide range of practical engineering problems.
Calculations and Experiments on the Unbalance Response of a Flexible Rotor
Authors: Lund J. W. , Orcutt F. K.
Published: December 2011

The results of a combined analytical and experimental investigation of the unbalance vibrations of a rotor are presented. The analysis applies to a general rotor-bearing system in which the dynamic bearing forces are represented by four spring coefficients and four damping coefficients. The rotor can be represented as either a lumped or a distributed parameter system, and gyroscopic moments are included. In general, the unbalance whirl motion of the rotor will be elliptical. The analysis has been programmed for a digital computer to obtain results for comparison with the experimental data. The test rotor is a uniform, flexible shaft with heavy wheels mounted at the ends and in the middle. The rotor is supported in two silicone fluid-lubricated, tilting-pad bearings. The rotor amplitude caused by an induced unbalance has been measured over a speed range of 3000 to 24,000 rpm for three different rotor configurations, obtained by removing one or both end wheels. This speed range extends to or through the third critical speed for each of the rotor configurations. The results are compared with the theoretical values and, in general, the agreement is found to be good.
Joint Interface Layer Damping
Authors: Mentel T. J.
Published: December 2011

An experimental and theoretical study of the damping behavior of thin layers of viscoelastic material subject to different cyclic loading situations is presented. The idea of the study stems from an idealization of conditions which may be encountered at the joints and support boundaries of beams and plates if damping media, such as viscoelastic adhesive, have penetrated between structural interfaces. The damping results from viscous shear action which is generated by the coupling, through damping material incompressibility, of the vibrational, cyclic variation of the joint interface volumes into a lateral pumping action. The paper focuses on experimental studies, with only a synopsis of the current theoretical work being presented. It turns out that a comparatively elementary level of analysis accounts for most of the results observed experimentally.
The Influence of Trapped Fluids on High Speed Rotor Vibration
Authors: Ehrich F. F.
Published: December 2011

Fluids are often introduced accidentally and trapped inside of high speed rotors. This has given concern as to the possible deleterious effects of such trapped fluids on the system’s vibration characteristics. Trapped fluids will induce asynchronous vibratory motion of high speed rotors at supercritical rotational speeds. This tendency is examined in analytic detail. Assuming that the circumferential velocity of the trapped fluid varies linearly with radius, the generalized shape of the fluid film is derived. Integrating the fluid pressure on the cavity walls gives the net fluid forces and permits computation of whirl frequency and whirl amplitude as functions of rotative speed. Generalized plots are given of the film geometry, of the rotative speed at which asynchronous whirl starts, and of the induced whirl speed. General response curves are also given, showing whirl amplitude as a function of rotative speed. The detailed results indicate that whirl occurs at a rotative speed approximately double the induced whirl frequency (as happens with many rotor whirl mechanisms). Higher values of the system parameter g result in somewhat lower whirl onset speeds. The whirl velocity is approximately equal to the rotor critical speed, or slightly lower for large masses of trapped fluid. Rotor whirl amplitude increases sharply with rotative speed above onset speed until a limiting condition where the fluid film (and analytic solution) break down, at a rotative speed about 6 percent above onset speed. Trapped fluids will also influence the normal synchronous vibrations induced by rotor unbalance. Analyses of a simple model of synchronous, solid body rotation are made which give exact solutions for the condition of a fully welted cavity periphery, and give approximate solutions for a partially welted periphery. It is concluded that the trapped fluid generally reduces the critical frequency, reduces critical amplitude, and reduces high speed (supercritical) amplitude. The effect is quite small with a partially welted circumference, but is surprisingly large in the case where the periphery of the cavity stays fully welted at maximum vibration amplitude. In this case, the rotor acts as if the cavity were entirely full of fluid, even though actual trapped fluid may fill only a small fraction of the cavity volume! Significant reductions in critical frequencies and amplitude are thereby observed. In the case of systems that are partially welted in going through their resonance peak, a “rightward leaning” resonance peak is observed which results in jump phenomena and hysteresis in amplitude on accelerating and decelerating through the peak.
Study of Flow-Induced Vibrations of a Plate in Narrow Channels
Authors: Bland S. R. , Rhyne R. H. , Pierce H. B.
Published: December 2011

Vibration phenomena associated with narrow channel flow have come under study as a result of the core failure of an early nuclear rocket engine. Since the mechanism of this vibration instability was not well understood at the time of failure, an investigation of a simple system consisting of a rigid plate with two degrees of spring-restrained freedom in a two-dimensional channel has been made both experimentally and analytically. The results show a strong dependence of the flow rate required for plate oscillation on the channel width (normal to plate).
The Influence of Surface Residual Stress on Fatigue Limit of Titanium
Authors: Reed E. C. , Viens J. A.
Published: December 2011

Investigation of the effect of surface residual stress on the endurance limit of 6Al 4V titanium alloy shows that this effect is equal within experimental error to the residual stress divided by a constant. Results can be expressed by a simple equation. A value for the constant has been derived.
An Analytical Study of Drill-String Vibration
Authors: Bailey J. J. , Finnie I.
Published: December 2011

Longitudinal and torsional vibrations in a drill string consisting of drill pipe and collars, and the boundary conditions at the ends of the string, are discussed. A trial-and-error method of solution for the natural frequencies is demonstrated. Since it is very lengthy, certain useful charts are then derived, and a graphical method of solution for the natural frequencies is developed. By use of this method the natural frequencies can be quickly and easily obtained. The influences of various parameters on the natural frequencies are considered.
An Experimental Study of Drill-String Vibration
Authors: Finnie I. , Bailey J. J.
Published: December 2011

This paper describes equipment which has been developed for the measurement of axial force, torque, and axial and rotational motions at the top of a drill string. Measurements made in two wells with this equipment represent the first time these quantities have been recorded during drilling. A large number of frequencies of vibration were found in the recordings. Some of these, particularly torsional readings, correlated with predicted natural frequencies, but many did not. Several explanations have been proposed for these “extraneous” frequencies, but no completely satisfactory solution is available. In addition, some interesting interrelations between axial and torsional vibrations were observed.
The Theory of the Ideal Design of a Compound Vessel
Authors: Becker S. J. , Mollick L.
Published: December 2011

A general theory for the elastic design of a compound cylinder made by shrinking together many concentric cylinders is described. Each cylinder may have entirely different strength and operate at any temperature under any pressure, internal or external. The only assumptions, in addition to the usual homogeneity and isotropy in each member, are that they have the same Young’s modulus, although even different elastic moduli could be accommodated, and that they are not so thin that stability becomes a problem.
The Interaction of Textile Structures and High-Speed Textile Processes
Authors: Morgan H. M.
Published: December 2011

A study has been made of the interaction which takes place in certain high-speed textile processes at points of machine fiber contact. The specific actions of weaving and sewing have been analyzed.
Uniform Two-Way Orientation of Plastic Films
Authors: Longstreth M. O. , Alfrey Turner
Published: December 2011

In order for a plastic film to be stretched at equal rates in the longitudinal and the transverse direction a highly specific geometrical flow pattern must be established in the stretching zone. This flow pattern involves diverging radial flow lines; the velocity at any point is directly proportional to the distance from the convergences point of the flow lines. These geometrical facts lead to certain design requirements for a machine to be used in the production of plastic film with uniform two-way orientation. In order for new concepts to be expressed in terms of practical working designs for machinery, mechanical development is required. The reduction to practice of the foregoing concept is shown by the accompanying illustrations.
Analysis of Power Spinning of Cones
Authors: Avitzur B. , Yang C. T.
Published: December 2011

The geometry of the cone, the roller, and the spinning operation are described mathematically. A shear type of deformation is postulated, based on experimental evidence. The displacement, velocity, strain rate, and stress fields are computed for “Mises’ material,” and hence with Mises’ stress-strain rate law. The power consumed in the operation is computed from the strain rate and stress fields. The expression for the power is in a form that can scarcely be solved analytically. A numerical solution is therefore employed and results are presented in graphical forms, where the power and tangential force are plotted for a variety of the process variables. The numerical solution is compared with actual power and force measurement in experimental tests and the agreement is reasonably good.
Tube Metal Temperatures for Structural Design
Authors: Ungar Eric E. , Mekler L. A.
Published: December 2011

A simple procedure is developed for calculating the circumferential temperature distributions in tubes exposed to nonuniform radiation. Convection to the fluid in the tubes and circumferential conduction in the tube walls are accounted for, in addition to radiation. Convenient dimensionless quantities are introduced and used for the presentation of graphs which facilitate rapid calculation of metal temperatures for structural design purposes. A calculation procedure using these graphs and a sample calculation are appended.
A Photoelastic Analysis of Machining Stresses
Authors: Usui E. , Takeyama H.
Published: December 2011

Direct measurements of the distributions of normal and frictional stresses on a rake face under cutting conditions have been considered to be practically impossible. However, as reported in this paper, the stress distributions have been successfully obtained photoelastically by using a tool made of a photoelastic material. According to the authors’ experiment, the frictional stress on the rake face is distributed uniformly over a wide range of the tool-chip contact length, but it decreases rapidly near the point of chip-separation on the rake face. As to the normal stress, it has a peak near the cutting edge, being rather stationary in the middle part of the contact length and decreasing gradually toward the point of chip-separation.
Correlation of Bendability of Materials With Their Tensile Properties
Authors: Datsko J. , Yang C. T.
Published: December 2011

With the advent of high-temperature-resistant materials in the sheet-metal industry, it is becoming increasingly important to treat the subject of minimum or “critical” bend radius analytically. A simple equation is presented that correlates the minimum bend radius with the percentage reduction of area of the material. The theoretical derivation as well as experimental data are given, with very good agreement between the two. Consequently, it is possible to predict the minimum bend radius for a specific material, provided that the percentage reduction of area, as determined by a standard tensile test, is known. The relationship applies equally well to metals and nonmetals.
The Role of Friction in Metal Cutting
Authors: Kobayashi S. , Thomsen E. G.
Published: December 2011

Metal-cutting studies were made with free-cutting steel SAE 1112 and alloy steel SAE 4135 in the as-received condition with artificially controlled tool-chip contact areas and flank contact areas (artificial wear lands). The experimental results for steel SAE 1112 at a speed range of 0.083 to 1010 fpm, reveal that friction under metal-cutting conditions on the rake face can be explained satisfactorily by a junction model with possible superimposed general plastic flow above the junctions in accordance with the general rules of plastic deformation (von Mises instantaneous yield criterion). The experimental results also reveal that the friction mechanism at the controlled flank-wear contact area is essentially the same as that occurring at the tool face. The difference in behavior of the two steels was attributed to the role that manganese sulfide appears to play in free-cutting steels.
New Developments in the Theory of the Metal-Cutting Process: Part I. The Ploughing Process in Metal Cutting
Authors: Albrecht P.
Published: December 2011

Revelation of the significance of “ploughing” in the metal-cutting process, which occurs because of the finite sharpness of the cutting edge, leads to a better understanding of the mechanics of the metal-cutting process. The concept of the ploughing force on the extreme cutting edge allows the development of a more complete force diagram which separates the ploughing force from the chip-tool interface force. Components of this more detailed force diagram have been verified experimentally. In terms of the new force diagram the real value of the coefficient of friction on the chip-tool interface has been found and the paradox of variation of the coefficient of friction with variation of rake angle explained. The paper also contributes to a better understanding of such events as the effect of cutting velocity upon tool forces, built-up edge, chip curling, and residual stresses in the work surfaces.
The Measurement of Very Low Frictional Torques in Rotating Equipment
Authors: Zaid M. , Tolins I. S.
Published: December 2011

In the design of high precision, rotating equipment such as air bearings, gyroscopes, etc., it has become possible to reduce the frictional torques to “almost zero” values. The measurement and classification of the sources of these minute torques during rotation is exceedingly difficult, but very important for correct application and further design improvement. It is the purpose of this paper to present two techniques for the measurement and discrimination of the torques, and an example showing the accuracy of these techniques. Although these methods were designed specifically for the measurements of low torques, they work equally well for any magnitude and as such present a good evaluation technique. A comparison made with the values obtained by one of the better “direct” methods indicates that the direct method is inadequate.
Design by Quantitative Factor of Safety
Authors: Su Hsuan-Loh
Published: December 2011

The traditional safety factor has a qualitative meaning only. However, it can be quantitatively interpreted through the possible variations of the components in a design as well as the probability of safety. The proposed design method based on such a safety factor gives not only a more rational but also a more economic design than the conventional methods.
Inertial Effects in a Multiple-Ball Transmission
Authors: Rouverol W. S.
Published: December 2011

A new type of mechanical variable-speed transmission, which owes its improved efficiency and wear-life to the utilization of multiple point contacts in pure rolling, has a power capacity in proportion to the maximum tractive forces and rolling velocities developed by a large number of small steel balls. Designing for maximum power capacity depends on finding the point at which the components of tractive force arising from inertial effects at high speed become so large as to interfere with the proper kinematic action of the balls. Consideration is given to the influence of a number of design and operating parameters, such as ball diameter, cage diameter, cage velocities, and velocity ratio.
Some Applications of the Cycloid in Machine Design
Authors: Pollitt E. P.
Published: December 2011

Cycloidal motions have many applications in mechanical engineering. The multi-lobed epicycloid has sharply pointed cusps; therefore, a machine element performing an epicyclic motion can be utilized for performing operations requiring a corresponding action, like folding of flexible materials or feeding of components from a stack. A speed reducer, distinguished by extreme compactness, is based on the use of an epitrochoidal cam. Linkages which perform approximately straight-line motions can be designed so that they approximate the motion of the center of the generating circle of an orthocycloid.
A Discussion of the Vibration Characteristics of a Simple Mechanical Connection
Authors: Sorensen Arthur
Published: December 2011

The behavior of a simple mechanical connection over an extended frequency range is analyzed with particular reference to vibration transmission and isolation. The limitations inherent in a simplified analysis are clarified by a more refined treatment of the problem. The significance of higher critical frequencies associated with the distributed mass of the connection is pointed out, and this leads to a more generalized concept of rigidity. A qualified definition of rigidity is subsequently introduced, and the corresponding performance characteristics of a vibration transmitter and isolator are discussed. The dependency of performance criteria on the type of excitation is emphasized, and the essential ideas embodied in the paper are illustrated in an example.
Stresses in Thin-Walled Pressure Vessels With Ellipsoidal Heads
Authors: Kraus H. , Bilodeau G. G. , Langer B. F.
Published: December 2011

A finite difference approximation to the Love-Meissner equations for the ellipsoidal shell was used to calculate stresses in thin-walled pressure vessels with ellipsoidal heads. Calculations were made with a digital computer for a useful range of the shell parameters. Results are reported in the form of stress indexes and stress intensity indexes, the latter based on the maximum shear theory of failure. Comparisons are made with the available experimental and analytical work in the literature, and stresses are also given for typical heads designed in accordance with the ASME Boiler and Pressure Vessel Code.
On the Use of Clearance in Viscous Dampers to Limit High Frequency Force Transmission
Authors: Gurtin M. E.
Published: December 2011

The steady-state vibration of a single degree of freedom system with clearance in the viscous damper is investigated. The results show that the clearance damper combines the low resonant force transmission feature of the viscous damped system and the characteristic of low force transmission at high frequencies of the undamped system.
The Vibration of Shaft Ropes With Time-Variable Length, Treated by Means of Riemann’s Method
Authors: Schaffers W. J.
Published: December 2011

Longitudinal vibrations in the ropes of a mining hoist, introduced by application of the emergency brake, are complicated by the change in rope length during the braking action. The usual method of the Laplace transform cannot be applied to the governing one-dimensional wave equation ytt − a2yxx = 0, since the field of integration deviates from the semi-infinite strip 0 < x < l0, 0 < t < ∞. In this paper it will be shown how the rigorous solution can be found by using Riemann’s method of the characteristic curves. Instead of the boundary values for the deviation y certain differential relations are given which describe the dynamic conditions at the discrete masses, e.g., the cages and the Koepe pulley.
Design of Flapper Valves
Authors: Paslay P. R.
Published: December 2011

The principle of minimum potential energy is used to derive the elastic characteristics for a particular type flapper valve (Fig. 1a). The results show that to obtain adequate predictions of the deflections and stresses of the valve for all but the first increment of loading the nonlinear aspects, caused by change in configuration, must be considered. This analysis includes the nonlinear effects in the range of interest for many flapper valves.
The Free Expansion of Dry and Moist Air
Authors: Potter J. H. , Levy M. J.
Published: December 2011

If a gas is permitted to expand freely from a vessel of constant volume, the gas remaining in the vessel is generally considered to undergo reversible adiabatic expansion. For such a case, the theoretical backgrounds are developed from the points of view of thermodynamics and gas dynamics. Experiments are reported in which it is shown that, for expansions occurring over short time intervals, the temperature changes are essentially those predicted for reversible adiabatics. Some speculations are offered as to the mechanisms obtaining in the slower expansions.
A New Analytical Approach to Drill Pipe Breakage II
Authors: Bogdanoff J. L. , Goldberg J. E.
Published: December 2011

Drill pipe dynamics assuming torsional and longitudinal displacements are formulated assuming that the forces which act at the bit and the sides of the pipe are random in nature. It is shown that assuming certain criteria of failure the coupling constants may be adjusted to reduce to a minimum the probability of failure.
Engineering in Resuscitation
Authors: Smilg Benjamin
Published: December 2011

The processes of respiration are analyzed from an engineering point of view and the requirements for resuscitator design are outlined. A review of pertinent engineering considerations is presented. Several commercially successful resuscitators are described to show their principles of operation.
A New Test Method for Determination of Spinnability of Metals
Authors: Kegg Richard L.
Published: December 2011

A new test method is described whereby the spinnability, i.e., the ability to undergo shear spinning deformation, without fracture, of any material may be determined. Work done to date with this test method indicates that a good nonspinning criterion for estimating spinnability is the tensile reduction of area at fracture. Results of the spinnability test suggest that a feature of this test be adopted in the design of production cone-spinning mandrels. A qualitative discussion of the effects of deviating from the sine law is presented.
On the Mechanics of Shear Spinning
Authors: Kalpakcioglu Serope
Published: December 2011

With the use of an idealized model of the shear spinning process some of the basic quantities in the shearing mechanism have been defined and formulated, these being: shear strain, shear strain rate, specific energy, and tangential force (torque) in spinning. An experimental technique to study metal flow in shear spinning has been described. The results of analytical work have been compared with experimental data.
A Milling Torquemeter of Planetary-Gear Design
Authors: Roubik J. R.
Published: December 2011

A design of planetary-gear dynamometer or torquemeter, to measure tangential cutting forces in milling with a high degree of accuracy and sensitivity is described together with certain design considerations and limitations as well as associated force-measuring equipment. This device is a highly efficient, sensitive, and durable research tool for use in accurately determining the magnitude and manner of variation of the cutting force, energy, and power at the cutting edges of single-point or multiple-point milling cutters, as well as machine efficiency, in full-scale milling operations. Procedures and methods of determining values of tangential cutting force, specific cutting energy, and horsepower at the cutter from cutting-test data obtained with the torquemeter are given with examples.
Free Machining Steel: II—Tool-Life Characteristics of Leaded Steel
Authors: Shaw M. C. , Smith P. A. , Cook N. H.
Published: December 2011

High-speed steel tool life results are presented and discussed for a leaded and nonleaded steel from the same heat. Variables investigated include cutting speed, feed, cutting fluid, and cold work.
Use of a Centrifuge for the Precision Measurement of Accelerometer Characteristics
Authors: Sporn S. R.
Published: December 2011

The large dynamic range to which accelerometers are subjected in a space-injection application requires that precision high “g” development studies be made. The only practical way of obtaining sustained, measurable accelerations in excess of 1g is by means of a centrifugal accelerator. The purpose of this paper is to describe the techniques which have been developed at Arma Division to process and interpret accelerometer linearity data obtained on our precision centrifuge. To do this it will be necessary to formulate a basic output equation for an inertial quality accelerometer and to point out areas of correction for some size anomalies which can occur. In addition, a centrifuge acceleration formula, corrected for earth’s rate, is developed. Interpreting this formula leads to the possibility of measuring earth’s rate with an accelerometer.
On the Determination of the Influence of an Axial Preload Owing to Bolting on a Cylindrical Pressure Vessel
Authors: Paslay P. R.
Published: December 2011

An idealization of a cylindrical pressure vessel with end plates fastened by longitudinal bolts is considered. The initial axial preload is restricted to be below the load necessary to begin plastic flow and the bolting is assumed elastic throughout the application of pressure. The elastic solution is obtained and the plastic solution may be found by a numerical integration. An illustrative problem is included.
Shaft Whirling as Influenced by Stiffness Asymmetry
Authors: Hull E. H.
Published: December 2011

Using elementary apparatus and instrumentation, shaft whirling has been investigated for three cases involving round or flattened shafts in combination with uniform or asymmetric stiffness bearing supports. The type of whirl observed varies with the combination of asymmetries used. Single and double-frequency whirls have been noted, both forward and backward with respect to shaft rotation. Studies of the phase-angle changes required by the running conditions have indicated the reasons for whirl direction and frequency.
Optimum Design of Helical Compression Springs
Authors: Erisman R. J.
Published: December 2011

The most efficient spring, for a given application, is one that safely stores the required amount of energy and uses the least possible material. Springs designed to this premise are said to have minimum weight. Several analytical procedures, based on prescribed initial assumptions, are already available to the designer which permit the calculation of certain minimum-weight springs. In some instances the assumptions are not entirely relevant to the problem at hand; in which case, a true minimum spring is not obtained. This paper presents a solution to minimum-weight springs based on initial assumptions which can be more universally applied. Also, a solution is given to the ultimate condition where no design variables (outside diameter, wire diameter, spring index, load rate, solid height, or number of coils) are chosen arbitrarily.
Fifty Years of Management—A Look Back and a Look Forward
Authors: Drucker Peter F.
Published: December 2011

The decade which this report discusses, the decade of the Fifties, has been a time of fulfillment in management. It has also been a decade of conclusion for historical trends. Now we are ready for new beginnings. There has been management, the direction of people in joint effort, since time immemorial. But “managing” as a distinct kind of work, the “manager” as a distinct organ of and function in society, and “management” as a specific area of thought and study are very new. The history of management properly begins only fifty years ago.
Critical Speeds of Two Bearing Machines With Overhung Weight
Authors: Wojnowski Reyton F. , Faucett Thomas R.
Published: December 2011

The purpose of this study was to determine the general frequency expression for a rotating shaft with uniformly distributed weight, supported by two bearings, and carrying a concentrated weight at the free end. The bearing spacing and the ratio of the concentrated weight to the total distributed weight have been used as parameters. The data have thus been reduced to dimensionless form so that the results are generally applicable for this type of machine. Frequencies for the first three modes of vibration have been determined and curves plotted for rapid calculation of these frequencies.
Damping Structural Resonances Using Viscoelastic Shear-Damping Mechanisms: Part II—Experimental Results
Authors: Ruzicka Jerome E.
Published: December 2011

This paper describes the experimental dynamic response characteristics of structural design configurations employing viscoelastic shear-damping mechanisms that have been discussed in a previous paper. Experimental results are given for cantilever beams fabricated from viscoelastic-damped sheet and structural shape members; results are also given for cantilever beams damped by use of the strip damper (an additive damping technique). The effects of shock excitation, steady-state vibration excitation, vibration excitation level, structure resonant frequency, and environmental temperature on the damping properties of the structural design configurations are demonstrated. The effects of structural damping on the performance of vibration isolation systems are determined and the significance of employing highly damped structural designs in fabrications intended for use in modern dynamic environments is discussed.
A Study of Shear-Spinnability of Metals
Authors: Kalpakcioglu Serope
Published: December 2011

The deformation zone in shear-spinning is idealized for a two-dimensional process and maximum permissible thickness reduction without fracture is predicted in terms of the stress system in this zone. The effect of deviation from the sine law on the maximum reduction before fracture is shown analytically to be due to the influence of distortions of the unspun flange on the state of stress under the roller. The results of analytical work are compared with experimental data and good agreement has been obtained. The phenomenon of back extrusion in shear-spinning is shown to be the result of a compressive stress in the spun section parallel to the mandrel side and is greatly influenced by mandrel angle and deviation from the sine law.
On the Mechanics of Wire Drawing
Authors: Yang C. T.
Published: December 2011

Split-die technique was adopted to find the coefficient of friction in wire drawing directly from experiment. Simple dynamometers with wire resistance strain gages were used for measuring separating force and drawing force instead of cumbersome equipment used by former researchers. Reasonably good results were obtained. The effect of the land or parallel portion in the die on the coefficient of friction was indicated in the results. Its importance was emphasized. A theoretical equation of the drawing stress with the effect of land considered was derived. Using the coefficient of friction obtained by the split-die method, drawing stresses were calculated from the derived equation. A comparison of the theoretical and experimental drawing stresses was made. Results were tabulated and plotted. It was concluded that including the land in the analysis of wire drawing is important and further research in analyzing the shear deformation must be pursued in order to get a close agreement between theoretical analysis and experimental results.
Fundamental Machinability Research in Japan
Authors: Hitomi Katsundo
Published: December 2011

This manuscript presents a brief description of fundamental research in Japan in the field of machinability.
An Analysis of the Mechanism of Orthogonal Cutting and Its Application to Discontinuous Chip Formation
Authors: Okushima Keiji , Hitomi Katsundo
Published: December 2011

Instead of the conventional theory of the mechanics of metal cutting based on a process of shear confined to a single shear plane, the concept of flow region, a fairly large transitional deformation zone which exists between the rigid region of work and the plastic region of steady chip, was developed. The mechanics of orthogonal cutting was analyzed, theoretical equations for angles of boundary lines of the flow region and for strain in chip were deduced in the case of simple continuous chip formation and confirmed in cutting tests on lead. The concept of flow region was also applied to discontinuous chip formation, and theoretical expressions for angles of boundary lines of the flow region were ascertained to be in agreement with the experimental result for carbon steel.
New Development in the Theory of the Metal-Cutting Process: Part II—The Theory of Chip Formation
Authors: Albrecht P.
Published: December 2011

Introduction of the concept of ploughing into the metal-cutting process lead to the abandoning of the assumption of collinearity of the resultant force on tool face and on the shear plane. With this understanding the tool face force is found to produce a bending effect causing bending stresses in the shear zone. Study of the chip formation mechanism when varying cutting speed showed that increased bending action reduces the shear angle and vice versa. A set-up for the development of an analytical model of the chip formation process based on the combined effect of shear and bending stresses in the shear zone has been given. Application of the gained insight to the design of the cutting tool for maximum tool life by controlling of the chip-tool contact was suggested. Brief introduction to the study of cyclic events in chip formation and their relation to the tool life is presented.
A Graphical Analysis of Regenerative Machine Tool Instability
Authors: Gurney J. P. , Tobias S. A.
Published: December 2011

A graphical method for the investigation of regenerative machine tool chatter is presented. The method is based on the harmonic response locus of the machine tool structure and allows the determination of the stable and unstable cutting speed ranges. The chip thickness variation effect as well as the penetration rate effect are taken into consideration. The method is illustrated by a number of examples relating to drilling or spot facing chatter arising on a radial drilling machine. The effects of mode interaction and of the penetration rate on the stability and on the variation of the chatter frequency are discussed. A critical assessment of the method is presented, in comparison with other methods available.
The Superposition of Stress Concentration Factors
Authors: Paul Frank W. , Faucett Thomas R.
Published: December 2011

A photoelastic study was made of the superposition of stress raising notches. Recent investigations [1, 2] have indicated that where one stress raising notch is placed in the region of maximum influence of a second notch the resulting stress concentration factor may be determined by taking the product of the concentration factors for the individual notches. Test results presented gave general although not precise agreement with this method of combination. The tests of reference [1] were performed on specific materials for static and repeated loads, and hence combine the effects of stress concentration with the sensitivity of the particular material. The tests of reference [2] run on a brittle material indicate the same general agreement. Normal practice for applying stress concentration factors separates the two effects, i.e., the actual concentration of stress and the sensitivity of the material to such concentration. It was believed that photoelasticity might yield a better verification of the method for combining superposed stresses as photoelastic methods have shown close agreement with theoretical factors of stress concentration. Results of the present investigation indicate that the product gives the combined concentration factor with the same degree of accuracy to which the individual factors are known. A mathematical analysis was made to determine the stresses across the section.
Maximum Stresses in Beams and Plates Vibrating at Resonance
Authors: Ungar Eric E.
Published: December 2011

Expressions are derived which relate the maximum stresses encountered in simply supported beams and rectangular plates and in clamped circular plates vibrating at resonance to modal displacements and modal loadings. Computation of modal loadings from time-wise harmonic or random pressures is discussed. It is shown that the resonant maximum stress may be reasonably approximated by a simple formula suitable for conservative design calculations for all types of beams and plates.
On the Variety of Motions Generated by Mechanisms
Authors: Freudenstein Ferdinand
Published: December 2011

The nature of the curves which can be generated by points on mechanisms is described in two theorems.
Constant Diameter Cams, Their Properties and Design Characteristics
Authors: Brunell Karl
Published: December 2011

Some basic properties which govern the design of constant diameter cams and open cams with flat faced translating followers will be developed. It will be shown that the radius of cam curvature is the governing criterion and its proper use makes design of constant diameter cams for any desired dynamic characteristic possible.
Comparative Effect of Land and Crater Wear on Tool Life When Dry Cutting, Mist Cooling, and Flood Cooling
Authors: Kececioglu D. , Sorensen A. S.
Published: December 2011

Land and crater wear data, obtained when machining SAE 1045 hot-rolled steel with Kennametal type KM carbide-tipped tools and with air, flood, and mist as cutting media, are presented. The volume of workpiece material which has to be removed to attain an average land width of 0.030 in. and a maximum crater depth of 0.010 in. is plotted versus the cutting speed. From these results the conditions of cutting speed and medium at which either land or crater wear governs tool life are established, as well as the cutting medium which permits the removal of the greatest volume of workpiece material at a given cutting speed.
Metal-Cutting Analysis—I: Re-Evaluation and New Method of Presentation of Theories
Authors: Kobayashi S. , Thomsen E. G.
Published: December 2011

The orthogonal metal-cutting process was reanalyzed and the several existing theories are discussed. Alternate methods of presentation of the theories were derived in terms of energy ratios and are shown graphically in the paper.
Design of Perforated Plates
Authors: O’Donnell W. J. , Langer B. F.
Published: December 2011

This paper describes a method for calculating stresses and deflections in perforated plates with a triangular penetration pattern. The method is based partly on theory and partly on experiment. Average ligament stresses are obtained from purely theoretical considerations but effective elastic constants and peak stresses are derived from strain measurements and photoelastic tests. Acceptable limits for pressure stresses and thermal stresses in heat exchanger tube sheets are also proposed.
Stability of the High-Speed Journal Bearing Under Steady Load: 1—The Incompressible Film
Authors: Reddi M. M. , Trumpler P. R.
Published: December 2011

The phenomenon of oil-film whirl in bearings subjected to steady external loads is analyzed. The journal, assumed to be a particle mass, is subjected to the action of two forces; namely, the external load acting on the bearing and the hydrodynamic force developed in the fluid film. The resulting equations of motion for a full-film bearing and a 180-deg partial-film bearing are developed as pairs of second-order nonlinear differential equations. In evaluating the hydrodynamic force, the contribution of the shear stress on the journal surface is found to be negligible for the full-film bearing, whereas for the partial-film bearing it is found to be significant at small attitude values. The equations of motion are linearized and the coefficients of the resulting characteristic equations are studied for the stability of the static-equilibrium positions. The full-film bearing is found to have no stable static-equilibrium position, whereas the 180-deg partial-film bearing is found to have stable static-equilibrium positions under certain parametric conditions. The equations of motion for the full-film bearing are integrated numerically on a digital computer. The results show that the journal center, depending on the parametric conditions, acquired either an orbital motion or a dynamical path of increasing attitude terminating in bearing failure.
A Method for Reducing the Number of Degrees of Freedom in Mathematical Models of Damped Linear Dynamic Systems
Authors: Staffeld S. E.
Published: December 2011

A method is given for systematically operating on the equations of motion of a linear dynamic system to produce the equations of a new system of many fewer degrees of freedom. This reduced system has a multiterminal response as close as desired to the original system in a limited frequency range. The result will always be better than that obtained with the normal mode approach and application to damped systems does not result in complex coefficients.
Grinding With Abrasive Disks: Part 4—Grinding Power and Temperatures
Authors: Mohun W. A.
Published: December 2011

Variations in power during disk grinding have been explained and equations developed to represent the power in terms of the grinding variables. It has been shown that depth of cut is below the critical magnitude so that ultimate shear strength of the metal is involved for all but the initial 30 to 120 seconds of grinding. It has also been shown that the coefficient of friction is higher against stainless steel than against mild steel, and that the basic differences in performance and mechanism on these two metals originate in this property. Photomicrographs of microflats are shown. The mechanism of microdressing is explained in terms of thermal shock and mechanical impact in relation to the effect of applied load upon grinding efficiency.
Surface Effects and Residual Stresses in Electrolytically Ground Steel
Authors: Frisch J. , Cole R. R.
Published: December 2011

The effects of electrolytic grinding on surface conditions and residual stress characteristics has been experimentally investigated. Surface finish, uniformity of material removal, and corrosion resistance are found to be dependent on mechanical removal rate as determined by wheel downfeed as well as electrolyte flow rate. Downfeeds of approximately 0.002 in. in the process do not produce measurable residual stresses and therefore it was further established that electrolytic grinding with moderate downfeeds can be used in place of swab etching techniques for evaluation of residual stress distributions. The maximum residual surface stresses were found to be not more than 22,000 psi, well below the yield strength of the material and were induced during the most severe grinding conditions.
Cassinian Domes for Pressure Vessel Design
Authors: Read W. S.
Published: December 2011

The necessity for being able to choose the depth and free deflection of a pressure vessel dome independently is shown. A two-parameter equation is presented which allows the designer to choose the depth and edge deflection independently. Various physical properties of these domes are illustrated graphically.
Some Simplified Solutions for Relatively Stiff Beams on Elastic Foundations
Authors: Shaffer Bernard W.
Published: December 2011

Maximum bending moments, rotations, and deflections of beams resting on elastic foundations and subject to central forces and bending moments are computed on the basis of a linear approximation to the foundation reaction. This reaction is determined from the rigid-body motion of the beam, and is thus statically determinate. The results of these approximate analyses are compared with those obtained from the exact theory in terms of the “characteristic parameter” of the beam, which is a function of the relative stiffnesses of the beam and the foundation. It is shown that the approximate analysis introduces very little error if the beam is stiff as compared to the foundation on which it rests.
On Determining the Hardness of Grinding Wheels—II
Authors: Colwell L. V.
Published: December 2011

This second progress report on the crush grading of grinding wheels by means of force measurements takes up the question of the effect of variations in system rigidity on hardness ratings. Preliminary results with the consecutive infeed or single-pass procedure show no appreciable effect with a substantial reduction in rigidity. On the other hand, the two-pass or alternate infeed procedure is shown to be sensitive to system rigidity. This characteristic complicates the problem of devising a procedure for deriving a dimensionless hardness number. On the other hand, it offers a mechanism for isolating the effective rigidity of the grinding wheel itself.
Basic Investigation of Tool Wear
Authors: Takeyama H. , Murata R.
Published: December 2011

This paper treats a fundamental investigation of tool wear and tool life mainly from the viewpoint of flank wear. The result reveals that the mechanism of tool wear in turning can be classified into two basic types: The mechanical abrasion which is directly proportional to the cutting distance and independent of the temperature; and the other is, so to speak, a physicochemical type which is considered to be a rate process closely associated with the temperature, of course. Although it depends upon the cutting condition which type of wear plays a more important role, the latter is predominant under usual conditions. According to the analyses and the experimental results, it has been found out that the tool life from the standpoint of flank wear can be predicted to a first approximation by the initial cutting temperature.