bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic Characteristics and Design Criteria for a Class of Vibration-Producing Machines
Authors: Brickman Arthur D. , Jenks Barton L.
Published: December 2011

Many self-contained machines used in industry serve to generate a sustained mechanical vibration for performing such diverse operations as vibration testing, hammering, material conveying, impacting, and screening. A particular class of such machines having only plane motion is idealized as a dynamic “vibrator” consisting of a two-mass, spring-coupled system driven internally by an oscillatory force. A dynamic analysis of this system is presented to show that the steady-state motion has both translational and rotational components. Specific methods are given for predicting the resultant direction and amplitude of motion for any point in the vibrator system. Results of the dynamic analysis show quantitatively the effect of system resonance, mass distribution, gravity-center configuration, and internal damping on vibrator operation and these design factors are discussed in terms of typical vibrator applications.
Synthesis of Mechanical Vibration Filters With Nonlinear Characteristics
Authors: Liu Ruey-Wen , Worley Will J.
Published: December 2011

The synthesis of the desired nonlinear characteristics for the spring and damper used to isolate a single mass from a vibrating base is here investigated. The analysis is confined to the steady-state condition resulting from a sinusoidal input excitation. The purpose of this paper is to study the effect of oscillation due to nonlinear damping and the effect of the dynamic mean deflection of the nonlinear spring on the amplitude response spectrum. These factors are important in vibration isolation of equipment in space vehicles because of the variation in acceleration or in the effective weight of the isolated body. The solution for the displacement of the mass relative to its base was obtained by the harmonic balance method. The procedure has been extended to obtain the absolute displacement of the mass relative a fixed reference frame.
Response of a Free-Standing or Anchored Explosive-Forming Assembly
Authors: Penning F. A.
Published: December 2011

This investigation considers an explosive-forming assembly where an elastic base is able to take compressive loads but cannot support tension. The release of the compression without restraint may result in an undesirable rebound of the assembly. Height of rebound is found for three different pressure pulse shapes—rectangular, triangular, and exponential. Length and area of anchoring bolts to restrain an assembly may be determined for a given bolt material. Also included are explosive property curves for TNT in water.
Vector Analysis of Linkages
Authors: Chace Milton A.
Published: December 2011

Expression of vectors in spherical coordinates within an appropriately defined reference frame facilitates explicit, general solutions to a wide range of linkage problems. To demonstrate this, a position, velocity, and acceleration analysis is performed on an example of each of three linkage types: simple, complex, and spatial. Also, the mechanical advantage and the transmission criterion of a four-bar spatial linkage are determined. Solutions are obtained in a form which simplifies digital computer programming.
On the Lateral Creep of Flat Belts
Authors: Fazekas G. A. G.
Published: December 2011

Classical theory is based on one-dimensional (tangential) creep of a flat belt over the pulley. The present paper shows that in virtually every flat belt lateral creep affects performance very seriously, and explains some apparent anomalies, particularly those due to nonlinear materials.
Size and Speed Effects From Lubricant Breakdown in Plastic Compression
Authors: Pearsall G. W. , Backofen W. A.
Published: December 2011

A size dependence of the average pressure for reducing thin, geometrically similar, lubricated disks of aluminum has been associated with the development of lubricant-film breakdown at the periphery. In general, the greater amount of interface sliding (a maximum at the periphery) of larger disks led to earlier breakdown and higher stresses. However, with certain liquid lubricants the size-effect reversed with increasing reduction, the larger disks requiring the smaller stress. This reversal has been related to the presence of a lubricant reservoir, entrapped across the interface, that increases with sample size, supplying the peripheral region and eventually controlling the progress of breakdown. The effects of speed on pressure requirements were attributed to such factors as strain-rate dependence of lubricant shear strength, junction growth across the interface, and changes in the size of lubricant reservoirs.
Use of Chip Tension to Obtain a Stress-Strain Curve From Metal Cutting Tests
Authors: Finnie I. , Wolak J.
Published: December 2011

By pulling the chip at various angles during metal cutting, it has been possible to greatly decrease the shear strains and thus to obtain a wide range of shear strains with a single tool. Using this technique, stress-strain curves for commercial purity aluminum have been obtained at −320 deg F (78 deg K) and 68 deg F (293 deg K). These results lie above those obtained from compression tests on the same material and the difference is ascribed largely to strain rate. Limits are imposed on the chip-pulling technique by an instability which appears when the direction of pulling makes too great an angle with the tool face and by fracture.
A Statistical Polyhedron Model of Abrasive Grain
Authors: McAdams H. T.
Published: December 2011

A statistical polyhedron model of abrasive grain is developed and its application to the design of abrasive cutting tools indicated. The model incorporates particle geometry and orientation with respect to the workpiece into a single concept useful in the prediction of cutting performance. Projective properties of the statistical polyhedron are exploited in a proposed method for measuring axial ratios of abrasive particles.
A Contribution to Gruebler’s Theory in the Number Synthesis of Plane Mechanisms
Authors: Crossley F. R. E.
Published: December 2011

A simple algorithm is introduced to solve Gruebler’s equation for constrained kinematic chains. Use of these criteria, however, brings clearly to the fore other problems, especially for mechanisms with negative or with two or more degrees of mobility. These are the related problems of mixed mobility and of independent parts within a linkage, which need to be solved, before any systematic process of exhaustive synthesis by automatic computer can be developed. A display of X = 2 mechanisms with up to nine members is also presented which is believed to be complete. Finally, the usefulness of the collection is described by showing how it can be applied to the design of a typewriter mechanism.
A Search for New Manufacturing Processes
Authors: Rosenthal P. , McAdams H. T.
Published: December 2011

The philosophy and methodology for a systematic, general search for new manufacturing processes is presented. Some postulated processes resulting from such a search are reviewed.
The Role of Topography in the Cutting Performance of Abrasive Tools
Authors: McAdams H. T.
Published: December 2011

Correlation and related statistical techniques are used to describe the cutting surfaces of grinding belts and wheels. The relation of these statistics to cutting performance is indicated.
Machinability of Nodular Cast Irons: Part III—Tool Life of Carbide and Ceramic Cutting Tools
Authors: Hitomi K. , Thuering G. L.
Published: December 2011

Three grades of nodular cast iron (60, 80, and 100) were tested to determine the tool life of carbide and ceramic cutting tool materials. Tool life for all tools was much greater for grade 60 than for 80 and 100. Cast iron cutting grade carbide K6 was superior to steel cutting grade K3H, and at high speeds the ceramic was superior.
Superimposing Multiple Channel Data on a High-Speed Cine Record
Authors: Stall J. C. , Lang H. M.
Published: December 2011

A recording technique is described which makes possible the continuous and simultaneous photographic recording on the same film of the data displays shown on several cathode ray oscilloscopes. These data are superimposed on and synchronized with the high-speed motion picture of an event under study.
Design of High-Pressure Integral and Welding Neck Flanges With Pressure-Energized Ring Joint Gaskets
Authors: Eichenberg R.
Published: December 2011

This paper provides all necessary information to design high-pressure flanges with pressure-energized ring joint gaskets, for any pressure and made from any suitable material. These rules have been used to design the American Petroleum Institute Standard API—10,000 lb and 15,000 lb flanges.
The Theory of Plasticity Applied to Machining With Cut-Away Tools
Authors: Usui E. , Kikuchi K. , Hoshi K.
Published: December 2011

Cut-away tools have a strong tendency to produce a complicated plastic flow ahead of the restricted tool-chip contact area as far as the restriction is in effect. The paper stresses the importance of the plastic field for better understanding the machining characteristics with cut-away tools. By applying the theory of ideal plasticity, the plastic field is found to be composed of one centered fan and two straight slip-line fields. The stress and velocity fields are then calculated based upon the construction of slip lines. The plastic deformation during chip-forming process is obtained analytically as a deformed pattern of originally square grids printed on the side of workpiece. The analytical pattern is verified to be in good agreement with the pattern actually produced in experiments. A quantitative analysis for variation of coefficient of friction on rake face with the artificial reduction of tool-chip contact area is proposed, in comparison with experimental results. The experimental results appear to support the analysis.
Results of a Fifteen-Year Program of Flexural Fatigue Testing of Gear Teeth
Authors: Seabrook John B. , Dudley Darle W.
Published: December 2011

This is a report of a continuing program of testing gear teeth which had its inception in 1946. In the course of the program about 3000 gear teeth have been broken under controlled laboratory conditions. The results of tests have been incorporated into gear design work in many fields. Gears now in use by the U. S. Navy are designed for intensities of tooth loading about double that of World War II. In the aircraft field the typical propeller drive gear carries about twice the intensity of loading as in World War II. Gears of almost fantastic intensities of loading are in use in rocket engines.
On the Buckling of Columns
Authors: Paslay P. R. , Bogy D. B.
Published: December 2011

An appropriate nonlinear formulation of elasticity is reduced through the usual assumptions of bending theory. It is shown that buckling problems for uniform straight columns may be studied, to the degree of approximation in bending theory, with a strain energy function for the column given by the sum of two terms concerning (a) the column center line strain and (b) the column center line change of curvature.
Pendulation of Pipes and Cables in Water
Authors: Lampietti F. J.
Published: December 2011

A finite-difference formulation is given for the transverse motions in a fluid of a heavy, nonuniform, flexible string under variable tension. The resistance (drag) of the fluid is made proportional to the square of the string velocity. The formulation is intended for automatic computation on digital computers. Various end conditions are considered and several numerical results given for heavy pipes and cables in water more than 12,000 ft deep.
Upper-Bound Solutions of Axisymmetric Forming Problems—II
Authors: Kobayashi Shiro
Published: December 2011

The two developments in the upper-bound method are given. These are an extended treatment of the velocity field for outward flow of a cylindrical deforming region, and the introduction of a new velocity field for the flow through conical dies. The upper-bound calculation based on these velocity fields is presented in the examples of compression of a cylinder, wire-drawing, and bar-extrusion.
On the Tribomechanics of Rolling
Authors: Fazekas G. A.
Published: December 2011

Conventional kinematic concepts of rolling can be seriously in error if applied to heavily loaded contacts, particularly if traction is large. Two relevant theorems of rolling are stated, which arose from consideration of an extreme case pertaining to pneumatic tires. For a comprehensive analysis of the latter, a mechanical analog is proposed.
Some Transient Measurements in a Rarefaction Wave Tube
Authors: Levy M. J. , Potter J. H.
Published: December 2011

This paper reports upon an experimental investigation in which a heat-transfer instrument was designed, built, and applied in a rarefaction wave tube. An analysis of the heat-transfer instrument was made to evaluate the significant parameters which influence the instrument performance in the measurement of transient heat flux between the gas and wall. A mathematical analysis based upon the heat balance integral procedure, considering variable density and time-dependent free stream gas temperature, was performed to interpret the gas-to-end-wall heat transfer in a rarefaction wave tube. The heat-transfer rates predicted by the analysis com pared favorably with values measured by the calorimeter type thermistor heat-transfer instrument.
A First-Order Five-Variable Cutting-Tool Temperature Equation and Chip Equivalent
Authors: Wu S. M. , Meyer R. N.
Published: December 2011

A simple first-order five-variable cutting-tool temperature predicting equation is developed by a 25−1 fractional factorial design. Only 16 testing conditions are used in the experiment. Confirmatory tests indicate the adequacy of the first-order predicting equation. These tests also tend to confirm the physical property of chip equivalent whereby the same temperature is obtained for a constant chip equivalent at a given cutting speed.
Improving Ultrasonic Machining Rates—Some Feasibility Studies
Authors: Pentland W. , Ektermanis J. A.
Published: December 2011

Investigations are reported on the influence on removal rate of slurry liquid cavitation, low temperature, liquid metal, and stress corrosion embrittlement of the work material, tool vibration amplitude, grit size and method of application of slurry, and the influence of heat-treatment and applied stress conditions of the workpiece. From these studies it is postulated that there may be three basic mechanisms involved in the ultrasonic machining process—microchip removal and material displacement by plastic deformation, and particle removal by fracture.
Analysis of Metal Extrusion
Authors: Avitzur B.
Published: December 2011

The process of extrusion through a chamber is analyzed. Kinematically admissible velocity fields are utilized to obtain a lower upper-bound solution for the extrusion stress. Assumptions are as follows: a spherical velocity field for the early stages of direct and indirect extrusion; a radial velocity field at end of stroke; and finally maximum shear stress σ03 between billet and chamber for lower upper bound. When this maximum shear stress is then replaced by a lower friction stress, the solution obtained becomes an approximation for the actual extrusion stress. The cavity phenomena and piping effect are discussed. Conditions for inception of the cavity and development of the pipe are predicted. The inner radius of the pipe is determined. Results are given in mathematical form and plotted over a wide range of conditions. They are compared with Kudo’s [5] results.
Prestressing a Two-Layer Pressure Vessel by Plastic Deformation
Authors: Schneider R. W.
Published: December 2011

A method of prestressing two-layer pressure vessels by controlled yielding of the inner layer by internal pressure is described. The required prestressing pressure depends upon the dimensions of the vessel, the initial clearance between layers, and the properties of the material of construction. The design method takes into account the actual stress-strain curve of the material and satisfies the rules of plastic flow with work-hardening. Two-layer, cylindrical vessels are discussed in detail.
Analysis of the Motion of Deep-Water Drill Strings—Part 2: Forced Rolling Motion
Authors: Frost M. A. , Wilhoit J. C.
Published: December 2011

An equation of motion for a drill string, considering elastic, dynamic, and drag forces, was derived in a previous paper and was applied to two types of beam behavior: A beam having constant axial tension and a perfectly flexible cable. A drill string was then considered as consisting of short beam sections at the top and bottom, joined by a perfectly flexible cable. The lateral deflection of the drill string was obtained by joining the beam and cable solutions subject to boundary conditions at each junction. In this paper, the drill string is considered built-in at the ocean floor and to be experiencing a harmonic change of slope at the ocean surface imposed by roll (or pitch) of the ship, the ship remaining stationary vertically above the point of entry at the ocean floor. Examples are discussed and results are compared with experimentally measured values. The combined effects of roll and displacement are obtained by superposition of the two solutions.
Motion Control for a Series System of “N” Degrees of Freedom Using Numerically Derived and Evaluated Equations
Authors: Johnson A. R.
Published: December 2011

A numerical method of synthesizing motion considering the dynamics of a system of n degrees of freedom which is applicable to either a linear or nonlinear system is presented. The technique which uses divided differences and Newton’s Fundamental Interpolation Formula shows how interior motion requirements may be controlled, in addition to the consideration of the usual boundary conditions. The inherent problem of obtaining a negligible displacement in a disproportionate period of time at the start and end of motion when only boundary conditions are considered is eliminated. The numerical method is equally well adapted to problems in kinematic synthesis, making it a general purpose tool. It is presented in sufficient detail for computer programming, or the computer program may be obtained from the author.
The Accuracy of One Method for Mechanism Simulation by Electronic Analog Computer
Authors: Keller Robert E.
Published: December 2011

A method for the simulation of mechanisms on the electronic analog computer has been developed. In this paper a detailed discussion of the accuracy of the simulation is presented. Particular attention is given to the accuracy of the simulation of the simple kinematic link. Consideration is also made of the accuracy of the simulation when utilized in the study of complete mechanisms, for example, the accuracy to be expected of coupler curves for the four-bar linkage as generated by the simulation. Sample curves are given and their accuracy discussed. General relationships for achievement of an optimal computer system are presented.
Analysis of Errors in the Double Hooke Joint
Authors: Austin T. C. , Denavit J. , Hartenberg R. S.
Published: December 2011

A double Hooke joint consists of two properly connected single Hooke joints for the purpose of transmitting rotation with a uniform angular velocity ratio. Previous kinematic analyses [1, 2, 3] have dealt with Hooke joints of perfect or ideal configuration, viz., in which pertinent axes intersect and are perpendicular. With real Hooke joints the manufacturing errors (which include tolerances) produce axes that do not intersect and are not perpendicular. The present analysis [4] investigates the effects of such departures from the ideal for the case of the double Hooke joint. It considers their effect on the mechanism’s movability, and studies their influence on the displacement, velocity, and acceleration relations between input and output shafts. The problem is solved by matrix methods: displacement relations are derived for the ideal double Hooke joint, after which the effects of small dimensional errors are considered as perturbations from the ideal values. The analytical expressions allow the variations in velocities and accelerations to be obtained by differentiation.
A Spring-Actuated, Cam-Follower System: Design Theory and Experimental Results
Authors: Barkan P. , McGarrity R. V.
Published: December 2011

An improved technique for the design synthesis of a spring-actuated, cam-follower system is described. Long-hand calculations and a simple graphical technique suffice to design a system to meet prescribed dynamic performance characteristics. By analysis of a simplified model, the response of the system to the impact accompanying take-up of clearance is related to four dimensionless parameters. A comparison of theory and tests on one design substantiate the utility of the synthesis technique and also provide additional insights into the dynamic behavior of such systems.
Shear and Bending of the Walls of Short Cylindrical Shells
Authors: Levy S.
Published: December 2011

Equations are developed for axisymmetric distortion of cylindrical shells including the effect of shear in the walls. Numerical results are presented for determining bending moment and shear in short cylindrical shells from the slopes and radial displacements of the walls at the two ends. The range of dimensions for which numerical results are given go up to thickness/length ratios of 0.5. It is found that including the effect of shear in the walls reduces the bending moment for given displacements to less than half in some cases.
Buckling of Circular Plate on Elastic Foundation
Authors: Kline L. V. , Hancock J. O.
Published: December 2011

The buckling loads are found for the simply supported and clamped-edge conditions for a circular plate on a springy foundation under the action of edge loading in the middle surface of the plate. The small deflection theory of bending of thin elastic plates has been used.
Analytical Synthesis of Function Generators Using the Slider-Crank Inversion
Authors: McLarnan C. W.
Published: December 2011

Equations are presented which permit the synthesis of the inversion of the slider-crank mechanism for cases where three or four conditions are placed on the input and output crank rotations or their derivatives. The method of development of the equations is described, and an example problem is solved.
An Analysis of the Abrasive Machining of Plane Surfaces
Authors: Shaw M. C. , Farmer D. A.
Published: December 2011

The grinding ratio (ratio of volume of work removed to volume of wheel consumed) is found to be related to feed rate by an equation which resembles the Taylor tool life equation for single point tools. An economic analysis of the abrasive machining of plane surfaces is presented with special charts to enable the cost optimum feed rate to be easily determined in practice. The results of the analysis are used to consider the additional grinding wheel cost that is justified for a given improvement in grinding performance.
Significant Factors in Vertical Spindle Abrasive Machining Tests
Authors: Pollock Charles
Published: December 2011

This paper develops and illustrates a general procedure for accurately determining the relative effect on performance of changes in wheel variables at various feed rates in vertical-spindle rotary-table surface grinding. Present techniques are discussed and their problems outlined; a method of accurate comparison of performance, involving a plot of net power consumption versus wheel-wear rate for various wheel grades, is developed; and the use of this method is illustrated with the results of a test series showing the effect of abrasive grit size on wheel performance.
Combined Bending and Compression of a Pressurized Circular Cylindrical Membrane Column
Authors: Jahsman W. E.
Published: December 2011

Load-lateral deflection curves are developed for a pressurized tube of circular cross section under combined bending and compression. The tube walls are assumed to have negligible compressive strength so that wrinkling develops if the stress tends to become negative. It is found that for a given bending moment, the load increases monotonically with deflection until a maximum is reached beyond which the load decreases with increasing deflection. An interaction curve of the maximum load versus bending moment shows that the presence of only a small amount of bending significantly decreases the maximum compressive load below the classical Euler load. Conversely, for bending moments which produce almost complete wrinkling of the cross section, only very small amounts of compressive load can be supported.
Torsion of Inhomogeneous Elastic Prismatic Bars
Authors: Plunkett Robert
Published: December 2011

Torsion of elastic bars with prismatic inhomogeneities may be solved with a minor modification of Prandtl’s stress function and membrane analogy. This method may be used for the numerical solution of prismatic bars of any cross section with longitudinal reinforcing or for any composite section.
On Nonlinear Bending of a Plate Strip
Authors: Wilson P. E.
Published: December 2011

Ends of an initially straight plate strip are rotated 90 deg. Using nonlinear bending theory, the maximum stress is obtained as a function of the half-distance between the rotated ends of the strip. Numerical results are presented in nondimensional form, and the theoretical solution is shown to compare favorably with experimental results. Information given here has a direct application to stress states in a stress corrosion specimen.
Optimization of Step Rockets by the Discrete Maximum Principle
Authors: Fan Liang-Tseng , Hwang Ching-Lai , Wang Chiu-Sen
Published: December 2011

The general algorithm of the discrete maximum principle with information feedback is stated briefly. It is applied to obtain solutions for the optimum stage-weight distribution problems of a multistage rocket vehicle. The first problem treats the structure ratio as a constant in each stage, though it may differ stage by stage. The second problem considers the variations in structural factors with stage weight. The third problem obtains the optimum weight distribution which minimizes hardware weight. Specific examples are solved.
Application of Self-Excited Machine-Tool Chatter Theory: Contribution to Machine-Tool Chatter Research—4
Authors: Lemon J. R. , Ackermann P. C.
Published: December 2011

This paper is one of a series of four being presented simultaneously on the subject of self-excited machine-tool chatter. It deals primarily with the applications of the closed-loop chatter theory to several actual machine-tool systems. In all cases the predicted chatter performance is compared with measured data and the correlation discussed. The predicted and measured onset of chatter compare reasonably well, in each example, when the complexities of the test setups are considered. The most serious discrepancy between experiments and the simplified chatter theory is the high-stability region at low cutting speeds. Dynamic specifications to assure the chatter-free performance of a machine tool for a given set of cutting conditions are discussed. The difficulties in arriving at such specifications are also pointed out.
A New Analysis of the Forces in Orthogonal Metal Cutting
Authors: Cumming J. D. , Kobayashi S. , Thomsen E. G.
Published: December 2011

The mechanics of orthogonal cutting have been reexamined and for the shear-plane concept of metal cutting, linear and quadratic-force models were suggested. It was shown that for steel SAE-1213, investigated under variable cutting conditions, the dynamic shearing stress remained constant and the linear-force model correlated with those experimental data which were obtained under the absence of a BUE. The angle λ formed by the shear plane and the direction of the resultant force remained constant for each test condition but varied with cutting speed. Neither the Ernst and Merchant minimum energy, nor the Lee and Shaffer solutions are in agreement with experimental observations.
Report of Committee RR-6 Survey: Progress in Railway Mechanical Engineering, 1963–1964
Authors: Bateson N. E. , Lich R. L. , Baker P. H.
Published: December 2011

This paper contains the annual report of the ASME Survey Committee RR-6. Developments in Railway Mechanical Engineering from September 1, 1963–September 1, 1964, pertaining to cars and locomotives are discussed. A review is given of locomotive development activities, diesel and electric locomotives, passenger freight cars, and transit and suburban cars introduced in North America, Europe, and Asia are described and pictured.
Axisymmetric, Transverse Vibrations of a Spinning Membrane Centrally Clamped Between Collars
Authors: Bulkeley P. Z. , Savage G. H.
Published: December 2011

The axisymmetric, transverse vibrations of a spinning membrane disk, centrally clumped between collars with Coulomb friction at the disk-collar interface, are shown, by a scale factor, to be equivalent to those of a membrane fully built into a hub, or clamped between frictionless collars.
Sheet Metal Forming Research in Japan
Authors: Fukui S. , Yoshida K. , Kobayashi S.
Published: December 2011

Research activities and their results on sheet metal forming in Japan are introduced with emphasis on the mechanics of sheet metal press-forming. Based on the governing deformation mechanisms and the characteristics of forming limits, sheet metal press-forming processes are classified into deep drawing, bulging, stretch flange forming, and bending. According to this classification, formability and its testing can systematically be evaluated with the aid of the analysis of process mechanics. For the stress and strain analyses, the method of calculation is well established and the use of a computer reveals the detail stress and strain distributions in the process. A basic problem in high energy rate processes is the mechanical behavior of materials at high strain rates, and the deformation of sheet metals in high-speed tension test is discussed. There are many problems still left for the future. A few of these are the conditions of instability and fracture, the effect of anisotropy, the analysis considering the stress and strain variations in the thickness direction, formabilities, the properties of materials at high strain rates, tool wear, and tool deformations.
Effect of Water Immersion on Reduction of Die Stresses in Explosive Forming
Authors: Reismann H. , Jurney W. H.
Published: December 2011

This investigation considers the dynamic response of a thin, elastic spherical shell surrounded by a large body of fluid. The blast pressure is applied to the internal shell surface, and three distinct types of blast loading are considered: Decaying exponential, decreasing linear, and pure impulse. The problem considered is related to explosive-forming technology. By comparing shell motion in air with shell motion in water, it is shown that stresses may be substantially reduced by water immersion.
Basic Theory of Rapid-Transit Tunnel Ventilation
Authors: Brown W. G.
Published: December 2011

An analysis has been carried out for the basic mechanism of rapid-transit tunnel ventilation due to train piston action and for the temperatures resulting in the system. Theory is in general agreement with experimental results, indicating air velocities in tunnels of the order of 1/5 of the train velocity even though trains occupy only 1/4 to 1/3 of the cross-sectional area of the tunnel. Little of the heat load owing to trains, brakes, passengers, and machinery is conducted through the ground about the tunnel, but the ground serves as a heat reservoir, causing the amplitude of the diurnal subway temperature variation to be about half that of the ambient air temperature and causing a phase shift of several hours. With the help of a partly empirical theory combined with experiment, it was possible to indicate approximately the temperatures to be expected in a tunnel under differing climate conditions. The effect of train scheduling on ventilation rate is discussed, as is the possibility of using models to obtain more precise design data.
Nonlinear Bending of a Stress Corrosion Specimen
Authors: Wilson Paul E. , Spier Edward E.
Published: December 2011

This paper presents an analysis of the postbuckling behavior of an initially straight plate strip of variable flexural rigidity whose ends are subjected to opposing “axial” loads. Bending action takes place only in the center section of the strip, since the symmetric end portions are considered to be rigid. Pertinent postbuckling load-deflection curves are deduced by using the nonlinear bending theory of a plate strip, and the maximum stress is obtained as a function of the half-distance between the loaded ends. Numerical results are presented in nondimensional form, and the theoretical solution is shown to compare favorably with a major portion of the experimental stress and deflection data. Information given here has an important and direct application to the determination of bending stress states in the lateral faces of a wide class of tensile test coupons used in stress corrosion studies.
On the Vibrations of Parabolic Membranes
Authors: Fontenot L. L. , Lomen D. O.
Published: December 2011

This study is concerned with the transverse vibrations of a theoretical membrane which occupies a region bounded by two confocal parabolas. The eigenvalues and eigenfunctions for Dirichlet conditions are determined. Nodal patterns for the free vibrations of the membrane are given for various forms of symmetry. Orthogonality relations are established; initial value problems and forced vibrations also are considered.
A Study of the Normal and Shear Stresses on a Cutting Tool
Authors: Hsu T. C.
Published: December 2011

This paper contains an explanation for the variation of the “coefficient of friction” in metal cutting. The chip partly sticks to and partly slides over the tool and only in the latter region can friction occur. In the experiments, the contact area between the chip and the tool is controlled and the change in the size of the sticking region is observed. The ploughing force acting on the tool edge is taken into account and the force acting on the tool face is determined. It is found that the force on the tool face varies with the depth of cut and the contact length in a simple manner. From the variation of the normal and tangential forces the stress distribution on the tool face is deduced.
Modern Metals Machining Technology
Authors: Vaughn Robert L.
Published: December 2011

Titanium alloys such as A-110AT, B-120VCA, C-120AV, and 6-6-2AVT, which have been used to manufacture structural components for the aerospace industry, are difficult to machine when compared to aluminum and even some steel alloys. Tool wear for high-speed tool steel and carbide cutters takes place rapidly, necessitating the use of low cutting speeds and feeds to obtain a reasonable cutter life. In this study, the means used toward achieving an objective of increased producibility and reduced costs for titanium alloys was through an intensive machinability investigation of the machining characteristics. Control of pertinent machining variables, such as cutting speed, feed rate, tool material, tool geometry, machine tool setup, and cutting fluid, was rigorously maintained. Comparative cost analyses of the actual cutting operation and the attendant cutting tool costs were made concurrently with the study to obtain conditions which provided the best metal removal rate with reasonable cutter life at the lowest cost.
A Plasticity Problem Involving Plane Strain and Plane Stress Simultaneously: Groove Formation in the Machining of High-Temperature Alloys
Authors: Shaw M. C. , Thurman A. L. , Ahlgren H. J.
Published: December 2011

Although a plane strain plastic analysis represents a good approximation for the central portion of a metal-cutting chip, plane stress better approximates conditions at the free edges of the chip. Therefore the metal-cutting problem is reexamined using both plane strain and plane stress simultaneously. The analysis indicates that the material at the edges of the chip will become plastic at a lower value of stress than will be required by the central constrained region and that the energy per unit volume at the edges of the chip will be greater than at the center. The consequence of these results is discussed in terms of the wear groove frequently observed on a tool under the free edges of the chip, which is particularly troublesome when machining high-temperature alloys.
Measurement of the Stresses Set Up in a Resin Bonded Diamond Grinding Wheel While Grinding Harmet G6 Tungsten Carbide
Authors: Hughes F. H. , Richards B.
Published: December 2011

This report describes the work which has been done in measuring stresses developed during diamond grinding, and summarizes the preliminary phases of this investigation. The technical problems associated with this type of measurement are formidable, and a great deal of work has been put into developing a technique which works very well indeed. It is now possible to identify and measure four of the strains developed in a peripheral diamond grinding wheel during use. These are the radial compression, tangential drag, axial twisting, and bending strains. It is found that these strain pulses do not change shape with change in the nature of the diamond grit, or of the grinding conditions. However, their magnitude varies with the type of grit and the conditions of grinding. This suggests that strain measurements may be used to assess and thus improve grit efficiency. At the same time, wheel efficiency can also be assessed, and the influence of such factors as hub rigidity, bond hardness, and so on, can be studied. A start has been made on this, but the program will be a long and complicated one.
Vibration Analysis of Large High-Speed Rotating Equipment
Authors: Ludwig G. A.
Published: December 2011

This paper discusses the application of mobility methods to the lateral vibration analysis of coupled machinery. Some effects of bearing and/or casing structural mobility on the rotational system behavior are shown. In particular, the various types of system behavior and their interrelations are shown to be closely tied to the response of the rotor-support structure. The effect of hydrodynamic oil films are also shown. Lateral vibrational problems have been encountered when connecting drive and driven equipment produced by different manufacturers. Generally, these are caused by natural frequencies in the operating-speed range which result directly from the method of coupling. Methods of solving this problem are presented with emphasis on flexible couplings and their proper inclusion in system response calculations.
Effects of Standoff Tolerances on the Fatigue Life of a Tool-Joint Pin
Authors: Finke John
Published: December 2011

A 4 1/2-in. API full-hole, tool-joint pin is stress-analyzed photoelastically over a range of standoffs. A three-dimensional plastic model is loaded to different values of makeup torque. At each torque a range of cyclic bending loads and a range of cyclic tensile loads are simulated. The results show that makeup torques must be raised for extreme hand-tight, shoulder-gap standoffs if a given pin tension is to be maintained. Maximum static root stresses are shown to be nearly independent of standoff if a constant pin tension is maintained. Further analysis indicates that the fluctuating pin-root stresses are also nearly independent of standoff if complete relieving of the shoulder compression loads is prevented. These considerations indicate that standoff has a negligible effect on the fatigue life of a tool-joint pin if relieving of the joint shoulders under operating conditions is prevented.
The Use of Flow-Corrective Inserts in Bins
Authors: Johanson Jerry R.
Published: December 2011

A properly designed bin and hopper results in savings through better flow-rate control, larger live-storage capacity, and improved uniformity of withdrawn materials. Unfortunately, most bins are not designed for proper flow. Changes in the basic design of existing bins are difficult to justify economically. Using flow-corrective inserts can sometimes cause proper flow without costly basic design changes. The proper placement and the limitations of these inserts are discussed in this paper.
Design Requirements for MC-331 Vehicles
Authors: Webster G. R.
Published: December 2011

Hauling compressed gases on the highways has been a phenomenon of the post-World War II era. The original requirements of the late 1940’s for interstate shipments were embodied in ICC specification MC-330. The then-current ASME Unfired Pressure Vessel Codes provided a design basis, and rather generalized additional considerations for service stresses were called for. Several years ago a number of serious cargo-tank failures resulted in a questioning of integrity of the MC-330 vehicles then in service. The resulting activity by both industry and government groups culminated in the promulgation of the new ICC Specification MC-331, which took effect on September 1, 1965. This paper discusses certain of the design stress considerations and interprets the valving requirements. Sample calculations are given to guide the designer in attaining compliance.
Report of Committee RR-6 Survey: Progress in Railway Mechanical Engineering, 1964–1965
Authors: Bateson N. E. , Lich R. L. , Baker P. H.
Published: December 2011

This paper contains the annual report of the ASME Survey Committee RR-6. Developments in Railway Mechanical Engineering from September 1, 1964, to September 1, 1965, which pertain to railcars and locomotives are discussed. A review of technical achievements incorporated in locomotives, rapid transit, and freight cars introduced in North America, Europe, and Asia is described and pictured.
A Computer Program for Determining the Effect of Design Variation on Service Stresses in Railroad Wheels
Authors: Riegel Malcolm S. , Levy Samuel , Sliter John A.
Published: December 2011

Two computer analyses have been prepared relating service stresses in railroad wheels to wheel shape and dimensions. One program computes the temperature distribution and stresses due to heat input by brake shoe friction at the wheel tread. The other computes stresses due to lateral, vertical, and tractional forces between the wheel and rail. Both programs have been validated for certain known conditions using theoretical solutions and are in agreement with available design and experimental stress data to the degree that differences in wheel geometry and loading conditions permit a comparison with experimental stress data. The next step contemplated is better experimental confirmation by computations for specific wheels and loadings for which test results are available and use of the programs to study trends resulting from, changes in wheel geometry and dimensions. This work is directed toward optimization of wheel design, and elucidation of the nature and specific effects of excessive service loads. This research program is being sponsored at General Electric by the manufacturers of wrought steel wheels, through the American Iron and Steel Institute, as a service to the American railroad industry.
The Mechanism of Material Removal in the Erosive Cutting of Brittle Materials
Authors: Sheldon G. L. , Finnie I.
Published: December 2011

An analysis is presented for the erosive cutting of a brittle material by the normal impact of a stream of solid particles. The volume of material removed by a given number of particles is predicted to be: W=krf1(m)Uf2(m) In this expression, k is a quantity involving material constants, r is the average radius, and U the velocity of the impacting particles. The exponents f1(m) and f2(m) are prescribed functions of m, the flaw parameter of the Weibull fracture strength distribution. Tests on a variety of brittle materials, using both angular silicon carbide particles and spherical steel shot, show the predictions of the analysis to be applicable over a wide range of particle sizes and velocities.
The Coefficient of Friction in Cold Rolling
Authors: Inhaber H.
Published: December 2011

A derivation of a formula for computing the coefficient of friction in the cold rolling process is presented. A simplified model of the pressure distribution in the arc of contact is assumed. Since the location of the neutral point is essential in the analysis, a method is presented for determining it. Typical coefficients of friction are computed for data in the literature as well as unpublished data. Comparison is made with another derivation using analysis by Bland and Ford. In general, agreement is good between the computed coefficients and those fitting classical rolling theory.
Dynamic Stability Design of Stacks and Towers
Authors: DeGhetto Kenneth , Long William
Published: December 2011

A method is outlined for determining the critical wind velocity, natural frequency, and approximate maximum amplitude of vibration of tall heater stacks and process towers caused by vortex shedding of the wind. A plot of Strouhal number for a range of Reynolds numbers above 105 is presented for application to large-diameter stacks. Calculations for an existing stack are presented, and methods of damping vibrations are discussed.
Continuous Spectrum of the Rotordynamic Forces on a Four Bladed Inducer
Authors: Pasini Angelo , Torre Lucio , Cervone Angelo , d’Agostino Luca
Published: December 2011

The paper illustrates the results of an experimental campaign conducted in the Cavitating Pump Rotordynamic Test Facility at ALTA S.p.A., aimed at characterizing the rotordynamic forces acting on a whirling four-bladed, tapered-hub, variable-pitch inducer, designated as DAPAMITO4. The roles of the imposed whirl motion of the rotor, flow coefficient, cavitation number and liquid temperature have been investigated. A novel experimental technique, consisting in measuring the continuous spectra of the forces as functions of the whirl ratio, has been developed and validated. This technique gives the possibility of extracting valuable information from the experiments by clearly identifying the qualitative and quantitative behavior of the forces, and is therefore useful to catch the unlikely foreseeable complexity of the rotordynamic forces and their consequences on the stability of axial inducers.
Investigation of Vibration Phenomena Induced by Air Flow Over Side View Mirror
Authors: Tomac Mehmet N. , Yugulis Kevin , Gregory James W. , Loftus James , Ferrito Tony
Published: December 2011

This work develops an understanding of the flow mechanisms that induce vibrations on automotive side view mirrors. The unsteady nature of the flow over side view mirrors causes unsteady aerodynamic load distributions and flow-induced vibrations on the mirror assembly. These vibrations generate blurred rear-view images and higher noise levels, affecting the mirror functionality and passenger comfort. Certain geometrical design features of side view mirrors can exacerbate the flow-induced vibration levels of the mirror assembly significantly. This work quantifies the impact of these design features on the vibration amplitude, develops a methodology for testing mirror vibrations in a small, low-speed wind tunnel using only the mirror of interest, and delves into the interactions between the bluff body mirror geometry and its wake. Two similar side view mirror designs were investigated in this work by using laser-based vibrometry, flow visualization, particle image velocimetry, hot film anemometry, and surface stress sensitive film techniques. The magnitude of the vibrations was found to depend on the level of excursion in the dynamic location of flow separation, particularly when characteristic flow frequencies couple with the mirror housing natural frequency.