bluuebunny/crossref_metadata_2025 huggingface dataset:
Explicit Solutions for Circular Plates With Discontinuous Axisymmetric Loads and Overhung Supports
Authors: Paul B. , Sikarskie D. L.
Published: December 2011

Well-known methods exist for the solution of problems involving axisymmetric loading of thin circular plates. Unfortunately, these methods result in rather tedious algebraic and numerical work when the loads are concentrated or piecewise continuous. In such cases, the standard procedure is to divide up the plate into a number of annular regions, and to piece together a solution by matching deflections, slopes, and bending moments at points of load discontinuity. In this paper, a method of solution is presented which avoids the need to patch or match. Instead, explicit solutions are given for deflections, moments, etc., in terms of well-defined definite integrals of the prescribed loading functions (both continuous and discontinuous loading patterns are handled with equal ease). Apart from a reduction in tedium, the proposed method lends itself particularly well to the solution of statically indeterminate axisymmetric problems of circular plates and to numerical evaluation of solutions by digital computers. It is pointed out that in many cases, even if tables of influence coefficients are available, the proposed method offers greater computational conveniences than do the tables. The method is illustrated by some problems involving plates with overhung edges. This type of boundary condition, although seldom discussed in the literature, is particularly important because it is impossible to simulate, in practice, a truly simple support without providing a certain amount of overhang.
Displacement and Velocity Kinematic Synthesis
Authors: Lewis D. W. , Falkenhagen G. L.
Published: December 2011

One may wish to define the velocity transformation in addition to the displacement transformation for synthesizing a mechanism. The approach presented here is essentially that noted as the “damped least squares” that allows for successive adjustment of the parameters which define a particular type mechanism. The repetitive application of this process results in a convergence toward an optimum approximation of the displacement and velocity transformation curves which are described by a series of data points. The method has been applied to a four-bar linkage as an example of application; the approach or technique is general and is not limited in use to any specific mechanism.
The Effects of Unreinforced Circular Cutouts on the Buckling of Circular Cylindrical Shells Under Axial Compression
Authors: Tennyson R. C.
Published: December 2011

The effects of unreinforced circular cutouts on the buckling behavior of circular cylindrical shells subjected to axial compression have been investigated. In addition, the membrane stress distribution and isoclinic patterns were determined around the edge of the cutout, using photoelastic shells, and the results compared with recent theory. The membrane stress concentration factors were found to increase rapidly with increasing values in the curvature parameter β. Large reductions in the critical buckling loads occurred for relatively small cutouts (e.g., a 50 percent reduction in the collapse load was found for a/R = 0.10). As a result of the investigation, design information is provided for determining the effect of a/R on the critical buckling load of a circular cylindrical shell.
Experimental Investigation of Creep Buckling of Circular Cylindrical Shells Under Axial Compression and Bending
Authors: Samuelson Lars A˚ke
Published: December 2011

The results are presented of an experimental investigation of creep buckling of circular cylindrical shells. The test specimens, manufactured from an aluminum alloy similar to 24S, had radius to thickness ratios between 30 and 150 and length to radius ratios greater than 2. They were subjected to axial compression or bending at a temperature of 225 deg C (430 deg F) and at various stress levels. The critical time under a constant load was determined as a function of the stress level, the shell geometry, and the type of loading. It was found that the shells subjected to pure compression had a substantially shorter lifetime than those subjected to pure bending with the same maximum applied stress. The thickest test specimens failed through collapse into a “wrinkling” mode which for the pure compression case is axisymmetric, whereas the thinner cylinders buckled into a typical diamond pattern. In all cases, buckling occurred at one of the edges. The postbuckling configuration was found to depend not only on the geometry of the shell but also on the load level. For very low stress levels, even the thinner cylinders buckled in the short wave pattern (symmetric for compression). A comparison between the present experimental results and theoretical values of the critical time presented in earlier works showed that a fairly good estimate may be obtained for the case of axial compression, whereas the approximate theory for creep buckling under pure bending gives an unduly conservative result.
Short Transverse Properties of Certain High-Strength Steels
Authors: Thomson A. D. E. , Christopher P. R. , Bird J.
Published: December 2011

Attention has been paid in Naval Construction Research Establishment to the importance of problems arising from the presence of small nonmetallic inclusions in high-strength, low-alloy structural steels and, in particular, to their effect on short transverse properties. Consequences can be more marked in high yield steels since, in general, these possess a higher yield to ultimate ratio and lower ductility in tensile tests than for mild steel. The nature of these inclusions and the value of the various tests carried out to determine their effects on the properties of steel plates are discussed. The consequences of short transverse weakness in large-scale construction employing thick plates is considered. Although there is no effect on yield strength it is clear that ductility and fatigue properties of such structures may need special attention. In general, measures recently imposed to obtain adequately inclusion-free steel are endorsed for current steels, but for projected steels of higher yield more sophisticated methods of manufacture may be necessary.
On the Screw Axes and Other Special Lines Associated With Spatial Displacements of a Rigid Body
Authors: Roth B.
Published: December 2011

For a rigid body in two, three, four, and five finitely separated positions, the loci of the screw axes and other special lines are derived. It is shown that the classical planar theory is a special case of a more general theory which includes planar, spherical, and spatial displacements.
Application of Dual Quaternions to the Study of Gyrodynamics
Authors: Yang A. T.
Published: December 2011

Dual quaternions are used to derive equations of motion for an offset unsymmetrical gyroscope. From the equations, in view of the general characteristics of this six-degree-of-freedom system, dynamic equations for a variety of gyroscopic and pendulous systems may be deduced as special cases. Examples are given for illustration.
Type Synthesis of Plane Linkages
Authors: Woo L. S.
Published: December 2011

The type synthesis of plane linkages can be formulated as a systematic enumeration of linear graphs. In this study, the concepts of a “contraction map” of a graph and of enumeration technique by permutation group are introduced in order to enumerate plane kinematic chains having 13 turning joints and 10 links. In addition, an algorithm for deriving all plane kinematic chains from those of a lower number of links is introduced.
Kinematic Synthesis of Plane Curves
Authors: Lewis D. W. , Gyory C. K.
Published: December 2011

The coupler point curve of a plane mechanism is a curve that may be described by a series of paired coordinates. An extension of the method of “damped least squares” provides a means for successive adjustment of the parameters which define a particular type mechanism. Repetitive application of this process will result in a convergence toward an optimum approximation to the desired curve as described by the series of paired coordinates. The method has been applied to a four-bar linkage as an example of application.
Some Remarks on Higher Curvature Theory
Authors: Veldkamp G. R.
Published: December 2011

Freudenstein introduced the concept of generalized Burmester points using proofs involving polar coordinates. In the present paper rectangular coordinates are used; this leads to an extension and a slightly modified interpretation of the theory.
Simplified Analysis of the Bent Crank Oscillator Mechanism
Authors: Rim K.
Published: December 2011

The purpose of this paper is to introduce a simple method of analyzing the “bent” crank oscillator, a spatial mechanism often used to generate a reciprocating motion. The exact solution of this mechanism is known. However, the solution is so complicated that the physical characteristics of the kinematic behavior are completely buried under the rigor of exact analysis. In this paper it is shown how a reasonably accurate solution may be obtained through an application of series expansion and proper approximations. The final solution is so simple that the numerical results can be obtained without the use of a computer and the physical characteristics of the motion are clearly brought out in the order of significance.
Synthesis of Spherical Linkages With Use of the Displacement Matrix
Authors: Suh C. H. , Radcliffe C. W.
Published: December 2011

Equations of synthesis are derived which are based upon rigid body motion expressed as a displacement matrix. Applications are shown in spherical rigid body guidance, function generation, and path generation.
Critical Speeds of Rotating Shaft Subjected to Axial Loading and Tangential Torsion
Authors: Willems N. , Holzer S. M.
Published: December 2011

In this study the classical theory of the bending and twisting of thin rods is utilized and applied to the case of a rotating shaft subjected to axial loading and tangential torsion. The differential equation of small bending oscillations in its complex form is solved by using a three-term Galerkin approximation satisfying the boundary conditions term by term. Convergence of the solution is indicated by comparing the two-term and three-term approximations. The special cases of a stationary shaft subjected to axial load or twist are discussed briefly. Experimental results closely agree with the theoretically predicted values.
Whirling of Shafts in Geared Systems
Authors: Seireg A.
Published: December 2011

This paper presents a study on the effect of gear constraint on the whirl of simple-supported pinion shafts with and without overhung masses. A special tester capable of simulating the different conditions influencing the whirling of geared shafts is utilized. An empirical procedure is given for predicting the main resonance frequencies. The calculated values show close agreement with results from tests on several shafts supported on ball bearings.
The Analysis and Design of Hydraulic Pressure-Reducing Valves
Authors: Ma C. Y.
Published: December 2011

This paper presents the static and dynamic characteristics of single-stage pressure-reducing valves and establishes design criteria. The dynamic analysis was accomplished using frequency-response techniques. A simplified loop gain function is developed for the valve and consists of a loop gain constant and two dominant time constants. The static characteristic curve and dynamic analysis were verified experimentally. A relationship between static and dynamic performance is also given.
Creative Design of Epicyclic Gear Trains Using Number Synthesis
Authors: Johnson R. C. , Towfigh K.
Published: December 2011

The following paper applies the theory of number synthesis to the creative design of epicyclic gear trains. First, the associated linkage of an existing epicyclic gear train is derived as an initial step of analysis. Next, the requirements for an acceptable associated linkage are established. Finally, epicyclic gear trains are derived by number synthesis from acceptable associated linkages up to and including the degree of complexity of eight links.
The Effect of Experimental Error on the Determination of the Optimum Metal-Cutting Conditions
Authors: Ermer D. S. , Wu S. M.
Published: December 2011

The effect of experimental error in tool life testing on the determination of the minimum cost cutting speed (Vmin) is investigated by using the concept of statistical inference. It is shown that Vmin is not uniquely defined but lies within a probable interval of cutting speeds, and that this interval is affected by the cost and time parameters and the experimental range of feed in tool life testing. The selection of a specific speed from the Vmin confidence interval is illustrated by a decision rule based on the minimax principle.
Stator Whirl With Rotors in Bearing Clearance
Authors: Ehrich F. F. , O’Connor J. J.
Published: December 2011

In order to identify and assess the effects of stator dynamics on vibration of high speed rotating machinery, a physical model with two degrees of freedom (one for the rotor and one for the stator) has been defined. Assuming that vibratory motion, as excited by rotor unbalance, is synchronous and axisymmetric, the analysis is linear and straightforward. The calculated vibration response reveals and quantifies some new and important phenomena which are a function of the level of bearing clearance (as related to unbalance level) and of the relative values of the rotor and stator natural frequencies. In particular, the following phenomena are noted: 1. As in simpler models, bearing clearance results in a reduction in system critical speed and can result in a “rightward leaning” critical peak causing hysteresis in response on acceleration and deceleration. 2. In certain ranges of parameters, two vibration modes are possible at high supercritical rotational speeds. One, termed stator whirl, results in stator amplitudes proportional to bearing clearance which are much larger than would be expected with very tight or very loose bearings. 3. Amplitude jump phenomena are very often experienced at a rotational speed equal to stator natural frequency. 4. Hysteresis phenomena, opposite in direction to that associated with a right-leaning critical peak, can be experienced on the subcritical side of the critical peak. 5. Disconnected from the main vibration response curve, branches of stable operation are evident and are hypothesized to be realizable if the system is subjected to momentary disturbances. The results have been verified by an analog computer simulation of the same system, and the effects of component damping and friction at the bearing contact point have been evaluated. Some regimes of asynchronous nonaxisymmetric motion in the analog computer model have been sensed, even though the physical model is axisymmetric.
Estimated Roll Bite Temperatures Encountered in Cold Rolling, and Their Effect in Rolling
Authors: Inhaber H.
Published: December 2011

In modern cold rolling, strip exit velocities of the order of thousands of feet per minute are employed. Even if only moderate reductions of the strip are performed, large amounts of heat are generated due to deformation and friction. This work presents a mathematical formulation of the problem of the temperature in the roll bite as strain rate is varied (due to Cerni), as well as some calculated examples using a typical small rolling mill. The possible influence of the temperature generated on the rolling process is also considered.
Variation of Yield Stress With Strain and Strain Rate in Mild Steel
Authors: Inhaber H.
Published: December 2011

Knowledge of the yield stresses characterizing steel strip is essential to a correct discussion of the cold rolling process. Various authors have noted that yield stress rises, in general, with increasing strain rate. However, these results have been noted in compression and tension tests, and not in situations directly similar to cold rolling, though this of course does not necessarily obviate the conclusions reached. Previously, work has been done to deform steel strip in Steckel rolling, using strip of an initial thickness of 0.025 in. If we consider the work to be a function of the deformation only, we may find the yield stresses involved by differentiating with respect to strain, obtaining it as a function of strain and strain rate. The derived curves agree well with results obtained from Manjoine and others on the variation of yield stress. It can also be shown that the differential change in yield stress drops off almost exponentially with strain, showing that the effect is almost nonexistent for medium and high strains.
Effect of Idle Roll Bearing Friction on the Hot-Rolling Performance of Single-Roll Drive Mills
Authors: Holbrook R. L. , Zorowski C. F.
Published: December 2011

A study is made of the effects of idle roll drag torque on the hot-rolling performance of single-roll drive mills using two analytical models which consider the nonsymmetry of the deformation process. Predictions of roll load, torque, and exit stock curvature for a specified idle roll drag torque on a given mill setup are obtained by applying an iterative procedure of solution to a series of intermediate rolling parameter results presented in terms of the idle roll neutral point location and strip reduction. In general, it is found that the drag torque increases the stock curvature significantly, is essentially additive to the required drive torque, and decreases the roll load only slightly.
Torsional Vibration Analysis of a Hydrodynamic Split Torque Transmission
Authors: Klokkenga D. A.
Published: December 2011

The steady-state torsional vibration for one mode of an engine transmission system was analyzed, and the analysis was verified by experimental data. The engine transmission system included a diesel engine, torque divider which consisted of a fixed housing, single-stage torque converter and a planetary gear set, and a dynamometer. The equations of motion are derived by an energy method (LaGrange’s equation) and a numerical solution of these equations is obtained with the aid of a digital computer. The analytical and experimental results agree when empirical values for torque converter damping are used.
Natural Frequencies in Annuli With Induced Thermal Membrane Stresses
Authors: Mote C. D.
Published: December 2011

A number of independent studies have concluded that initial, residual membrane stresses can increase the fundamental frequency or effective stiffness of thin circular disks and annuli. The present study investigates the increase in fundamental frequency caused by purposely induced thermal membrane stresses in centrally clamped, peripherally free, rotating annuli. The principal advantage of this method over the initial stressing technique is that the state of stress is infinitely variable, allowing continuous adjustment of effective stiffness. Practical application of both these methods is limited to the cases where minimization of disk thickness is of paramount importance. The results are presented in the form of analyses of practical examples whose frequency characteristics have been adjusted by the proposed method. Optimization of the fundamental frequency and limitation of the proposed method are discussed.
The Gyroscopic Vibration Absorber
Authors: Jones Robert
Published: December 2011

The linearized equations of motion of the gyroscopic vibration absorber are derived showing that the antiresonant frequency is a linear function of the speed of the gyroscopic disk; thus the gyroscopic vibration absorber (GVA) can be easily synchronized and therefore applied to vehicles and machinery having variable frequency vibration excitation. The effects on the antiresonant frequency from elastic restraint about the pivots and flexibility in the support structure are also examined. The bandwidth of the GVA is compared to a Frahm absorber of equivalent weight. Experimental results confirm the analytical results and show the feasibility of the GVA as a synchronous absorber.
Spatial Response Concentrations in Extended Structures
Authors: Lyon R. H.
Published: December 2011

When an extended structure is excited at frequencies above the resonance of its lowest modes, spatial variations in the mean square response occur since the mode shapes are functions of the spatial coordinates. For excitation consisting of band-limited noise or a pure sinusoid, one may calculate the mean square response relatively easily. The spatial variance of the mean square temporal response can also be found and can be interpreted by application of the “central limit theorem.” Vibration modes generally are coherent to some degree. Rather large variations of response may occur at positions where coherent modes have in-phase antinodes. The probability of the occurrence of such response concentrations is studied in this paper. The probability of the occurrence of a concentration at some position on the plate is found to approach unity for some assumed statistical distribution of the resonating modes. (It is felt that the conclusions are not strongly dependent on these assumptions.)
Vibration Analysis of Shells Using Discrete Mass Techniques
Authors: McGrattan R. J. , North E. L.
Published: December 2011

A method for analyzing thin shells by a discrete mass technique is presented. The shells and stiffeners are idealized as a system of lumped masses and an elastic framework having the equivalent mass and stiffness of the actual shell. This method is most useful for shells without rotational symmetry, since classical solutions are not available for these cases. Four examples are presented and a comparison with experimental results and classical theory is made for a case of a symmetrically stiffened cylinder.
A Quantitative Evaluation of Constrained-Layer Damping
Authors: Yin T. P. , Kelly T. J. , Barry J. E.
Published: December 2011

The constrained-layer damping mechanisms on plates, beams, and tubular structures have been experimentally studied with well characterized viscoelastic materials. The Kerwin analysis [1] on plate damping has been extensively verified; important variables can now be individually controlled to achieve optimum performance. The validity of extending the plate theory to box-beams has been established; certain preferred cross-sectional geometries for highly damped beams are now defined. Experimental evidence has shown that concentric treatments are ineffective to dampen bending vibrations of tubular structures. Analyses of the strength of laminated composites have shown that structural integrity can be retained. Equations have been derived to predict the static and dynamic rigidities of such laminates.
Oil Whip Whirl Orbits of a Rotor in Sleeve Bearings
Authors: Lund J. W. , Saibel E.
Published: December 2011

An analysis of the self-excited oscillations, known as “oil whip,” of a rotor supported in fluid film bearings is presented. The source of the instability is the hydrodynamic forces of the bearing fluid film. The equations of motion are nonlinear, and they are studied to determine the limit cycles of the system, also called the whirl orbits. The nonlinear equations are solved by the method of averaging whereby the whirl orbits are obtained directly. The results are dimensionless and are given in graphical form. They show under which conditions whirl orbits can exist, and the position and the size of the orbits are also given. It is found that the orbits are only encountered in a relatively narrow speed interval around the speed at which the static equilibrium becomes unstable.
Parametric Coupling in a Nonlinear Electromechanical System
Authors: Kana D. D.
Published: December 2011

Parametric coupling that arises under certain conditions of excitation has been analyzed in an electrical R-L-C circuit that is coupled with a mechanical system through a nonlinear inductance. It is found that high frequency excitation of the electrical circuit can support low frequency oscillation of the mechanical system, the entire process arising through the existence of a low order instability in the coupled system. Approximate methods of analysis are used to show the existence of the instability as well as the form of subsequent motion, and their numerical results are compared with analog computer results. The behavior of the electromechanical system can be shown to be analogous to a similar coupling that can occur between lateral wall vibrations and free surface oscillations of liquid in a partially filled elastic cylinder.
A Ten-Step Design Method for Simulation Games in Logistics Management
Authors: Fumarola Michele , van Staalduinen Jan-Paul , Verbraeck Alexander
Published: December 2011

Simulation games have often been found useful as a method of inquiry to gain insight in complex system behavior and as aids for design, engineering simulation and visualization, and education. Designing simulation games are the result of creative thinking and planning, but often not the result of a rigorously applied design method. Design methods can be used to structure the creative process. The specific types of games we chose for studying design methods are simulation games focused on information-intensive domains, of which logistics management is an example. Our new design method takes into account the information intensiveness of the domain. The design method incorporates enterprise information management, simulation model design, and instructional design. The design method we propose uses ten steps in designing a simulation game: the first five for making a conceptual design and the final five for using the conceptual design as a basis for the simulation game. Iterative cycles are added to improve intermediate results. This paper discusses the design method and presents two different case studies. The first case study helped in developing the design method, while the second case study served for assessment and improvement.
Static Testing High-Pressure Piping Components
Authors: Moore T. G. , Opersteny E. J.
Published: December 2011

A method for testing high-pressure piping systems for service in the 20,000 to 40,000-psi range is described. Tubing systems were pressure tested and their behavior followed by means of resistance-wire strain gages mounted on the exterior surface. A method is described for graphically determining the pressure at which a tube wall becomes fully plastic. The allowable working pressure of a tube is determined by applying a safety factor to this pressure. Tubing bends and fittings, including metal gaskets, flanges, and tees, are evaluated by comparing their behavior under pressure with that of the tube with which they are to be used.
Nomographic Synthesis of Generator Linkages
Authors: Adams Douglas P.
Published: December 2011

Machines are doing more complex jobs; the need grows for simple operation and low cost of parts. The generator, or computer, linkage often fills this bill if technical requirements can be met by good methods for practical design. This article presents a graphical technique for optimizing generator-linkage design by systematic scanning of five linkage parameters. A nomograph of linkage behavior, simplified through symmetry of quadrilateral relationships, fixes the optimum linkage as a rectilinear, horizontal plot from which a measure of the error is available.
Prevention of Sulfide-Stress Cracking in Sour-Condensate Well Equipment
Authors: McGuire W. J. , Vollmer L. W.
Published: December 2011

Several case histories of equipment failures in sour-condensate wells are presented, reasons for these failures are discussed, and means for avoiding such failures are suggested.
The Twinworm Drive—A Self-Locking Worm-Gear Transmission of High Efficiency
Authors: Popper B. , Pessen D. W.
Published: December 2011

Up to the present, it has always been accepted as a proven and well-established fact that worm gears or screw threads that are self-locking are bound to have an efficiency of less than 50 per cent. An entirely different type of worm transmission has been developed which is self-locking, yet has a theoretical efficiency that can almost reach 100 per cent. Efficiencies of 90 per cent and above can easily be obtained in practice, and have, in fact, been obtained in models built by the authors. In addition, this new transmission exhibits a number of other unique and useful properties. The paper describes the transmission and develops the theory upon which its operation is based. Design equations are derived for different operating conditions, and a number of possible uses and applications are discussed.
Determination of Cutter Trajectories for Contoured Turbine Buckets
Authors: DeBiase R. G.
Published: December 2011

The advent of numerically controlled machine-tool systems introduces the serious problem of suitably employing them for part fabrication. To numerically contour the complex surface of a large turbine bucket with this type of machining system, it is necessary to determine the geometrical constraints on the motion of the cutter, which will sweep out the desired part surface as an envelope of the cutter surface. A definition of the turbine-bucket surface is given in terms of unequally spaced cross sections along the length of the part, and an interpolating procedure is employed to define the entire surface with properly faired transitions between the specified cross sections. The procedures outlined in this paper have been used to program an IBM 704 computer for the preparation of digital control tapes, which instruct the motions of the machining system.
Bending Strength of Gear Teeth by Cantilever-Plate Theory
Authors: Wellauer E. J. , Seireg A.
Published: December 2011

This paper presents a study of the bending strength of gear teeth based on a cantilever-plate approach. A semiempirical solution is given for the finite cantilever plate under transverse loads at any location on its surface. The solution which is based on the principle of superposition and a proposed moment-image method showed good agreement with results from strain-gage investigations on cantilever plates simulating the gear tooth. The effects of the position of the line load and the variation of load intensity on the stress distribution at the root are discussed.
Some Problems of Press Forging Lead and Aluminum
Authors: MacDonald A. G. , Kobayashi S. , Thomsen E. G.
Published: December 2011

Several press forgings were made and it was found that the experimental mean forging pressures were in substantial agreement with values predicted by theoretical solutions based on an approximate theory. The forging processes were axial symmetric forging of disks between flat dies and forging in closed dies with several edge effects, such as overhanging flash, with and without flash-edge restriction. The materials were commerically pure aluminum and lead and were chosen because of their respective work-hardening and strain-rate effects at room temperature. It was found further that the local pressures measured in the forging were in good agreement with the theory, but that some local plastic flow tends to equalize the pressure in the body of the forging.
Refinement of Finite Difference Calculations in Kinematic Analysis
Authors: Shaffer Bernard W. , Krause Irvin
Published: December 2011

First and second finite-difference expressions are derived for the first three derivatives of displacement with respect to time. The numerical results obtained by applying these difference expressions to a specific cam-follower mechanism are found to be in good agreement with the values obtained by successive differentiation of the displacement-time equation. Procedures for evaluating and improving the numerical results are also discussed.
Study of Critical Velocity of Stick-Slip Sliding
Authors: Singh B. R.
Published: December 2011

The motion of a body sliding under boundary friction, at a velocity slower than a particular critical velocity of the system, proceeds in a discontinuous or stick-slip form. This paper presents a theoretical analysis and an experimental study of the critical velocity of stick-slip sliding. The influence of various parameters such as friction, damping, stiffness, and sliding mass of the system on the critical velocity was studied on a mechanical model arranged on a milling machine. The arrangement was also simulated on an electric analog computer. Good correlation was observed between the theoretical values and the experimental results on the mechanical model and on the analog computer.
Free Machining Steel: I—Tool-Life Characteristics of Resulfurized Steel
Authors: Shaw M. C. , Cook N. H. , Smith P. A.
Published: December 2011

Tool-wear and tool-life characteristics of a series of five steels of different sulfur content are presented for different values of cutting speed, feed, cutting fluid, and cold work. While the presence of manganese sulfide in steel is generally found to extend tool life, certain combinations of speed and feed yield result that indicate the reverse effect. For the group of hot-rolled steels studied, sulfur was found to shorten tool life at certain cutting speeds when the feed was in the vicinity of 0.005 ipr. The hot-rolled steels of low sulfur content exhibit better tool life with high-speed steel tools than with carbide tools when the cutting speed is such as to give a tool life in the vicinity of 4 hr. A tracer device is described that is useful in exploring the nature and extent of the crater and built-up areas on the tool face.
Free Machining Steel: III—Cutting Forces; Surface Finish and Chip Formation
Authors: Shaw M. C. , Usui E. , Smith P. A.
Published: December 2011

Tests upon a variety of friction sliders reveal that, contrary to common belief, manganese sulfide is a poor solid lubricant relative to air. Lead, on the other hand, is found to be an excellent solid lubricant. An analog tool is introduced to enable surface finish studies to be made in the absence of feed marks. Cutting force results are presented for a wide variety of cutting conditions for both resulfurized and leaded steels. The built-up edge and thermal softening along the tool face lead to complex curves of cutting force versus speed. Additions of sulfur are found to promote the formation of a small built-up edge that is stable to much higher values of speed than that normally experienced with a nonresulfurized steel. Lead, on the other hand, tends to prevent built-up edge formation. Both lead and sulfur are found to produce thinner chips, promote chip curl, and to give rise to a shorter contact length between chip and tool. A discussion of the significance of the observed changes in contact length will be found in part 4 of this series.
Calibration Techniques in Ultrahigh-Pressure Apparatus
Authors: Bundy F. P.
Published: December 2011

Pressure and temperature calibration of ultrahigh-pressure apparatus is described. Pressure calibration up to 30 kilobars has been established accurately. Above this pressures are not known with sufficient absolute accuracy to compare results reliably with theoretical predictions of behavior of matter. The effect of pressure on temperature-sensing devices, like thermocouples, have been measured over temperature intervals of 100 deg C up to pressures of the order of 100 kilobars. The effect on some thermocouples is appreciable.
Balancing Flexible Rotors
Authors: Church A. H. , Plunkett R.
Published: December 2011

A method is presented for computing the size and angular location of the correction weights required in selected planes of rotation to balance a flexible shaft rotating at high speeds. It is based on mobility principles and requires a minimal number of measurements. Its application to a test rotor is described, and this indicates that the method could be developed into a practical operating procedure.
The Yielded Compound Cylinder in Generalized Plane Strain
Authors: Becker S. J.
Published: December 2011

The theory of a previous paper [1], which was designed for plane strain of a compound cylinder, is extended to generalized plane strain, where the axial strain is a constant nonzero value for every radius and depends only on the external and internal pressures and any extraneous axial load. The method is limited to incompressible elastic material and is found to be completely solvable only if an elastic zone exists in each component. The assumed Tresca yield condition is verified in the process of obtaining the complete solution.
A Theory of Shear Spinning of Cones
Authors: Kobayashi S. , Hall I. K. , Thomsen E. G.
Published: December 2011

The theoretical deformation mechanism of shear spinning of cones was re-evalued. It was found that the predicted tangential or power spinning forces for commercially pure aluminum and lead for several spinning conditions agreed well with the experimental data. In addition, the normal force and axial force components were also evaluated and fair agreement between theory and experiment was achieved.
Cyclic Processes in Closed Regenerative Gas Machines Analyzed by a Digital Computer Simulating a Differential Analyzer
Authors: Finkelstein T.
Published: December 2011

A complete thermodynamic analysis of closed, reversible, regenerative gas cycles is developed which among other refinements takes into account heat-transfer limitations, regenerator inefficiency, and flow losses. This results in a set of equations for the cyclic variations of temperatures, pressures, and flow rates in different parts of the system. A heat balance is set up for the integrated heat transfer and mechanical energy conversions per cycle and an accurate figure for the efficiency of prime movers or the Coefficient of Performance of heat pumps or refrigerators is derived from this. Special computational techniques simulating a differential analyzer on an IBM 704 electronic computer are described and the results of a typical practical case are given in graphs and figures.
On Thermal Stresses in Cylinders Subjected to γ-Ray Heating
Authors: Weil N. A.
Published: December 2011

Thermal stresses in cylinders, perfectly insulated on the outside and subjected to internal heat generation due to γ-ray radiation, are considered. Numerical values for the governing stress are presented up to q = 7 and η = 100. The asymptotic values are indicated, which permits the treatment of any problem of practical interest. Three simplified solutions, containing only elementary functions, are evaluated. These approximations are found to be surprisingly accurate, at least one of them being of sufficient engineering accuracy over the entire range of variables.
Flank Friction Studies With Carbide Tools Reveal Sublayer Plastic Flow
Authors: Thomsen E. G. , MacDonald A. G. , Kobayashi S.
Published: December 2011

Orthogonal cutting tests with artificial flank-wear lands were performed on steel SAE 1112 as-received (cold-drawn), steel SAE 4135 as-received (cold-drawn), aluminum alloy 6061-T6 (extruded), and alpha-brass as cold-drawn. Forces, workpiece temperature, average tool temperatures, and other pertinent data were taken. Each test was of short duration (approximately 10 revolutions of the workpiece or less) and the tools were reconditioned between each test run. The results show that, for steel SAE 1112, steel SAE 4135, and aluminum alloy 6061-T6, sublayer flow appears to take place when the flank wear-land clearance angle is set to a negative angle of magnitude −1 deg and the land is approximately 0.010 to 0.020 in. long. The condition for sublayer flow is predictable based on the state of plastic deformation and the stress-strain properties, at temperature and at appropriate strain rates for these materials.
Metal-Cutting Analysis—II: New Parameters
Authors: Kobayashi S. , Thomsen E. G.
Published: December 2011

The orthogonal metal-cutting process has been studied. It was found that the Ernst and Merchant solution, through the application of the limit-load theorems, appears to be a limiting solution for all cutting conditions. A new angle relationship has been developed from energy considerations and it was found that the new parameters, effectiveness η and machinability factor ξ, permit a better understanding of the machining process. It was found further that machining forces and power can now be predicted when the effectiveness η, the constant dynamic shear strength τ of the work material, and the chip ratio r or the friction angle β are known.
Strength of Thick-Walled Pressure Vessels for Materials With Directional Properties
Authors: Dapprich A. E. , Marin Joseph , Weng Tu-Lung
Published: December 2011

This paper develops a theory for the determination of the plastic pressure-deformation relation in a thick-walled cylindrical pressure vessel subjected to internal pressure and made of an anisotropic material. In this theory, large or finite strains are considered and a closed solution is found for the pressure-strain relation based on a modified log-log tensile stress-strain relation. Theory is also developed for predicting the maximum pressure which the vessel can withstand.
The Effects of External Pressure on Thin-Shell Pressure Vessel Heads
Authors: Jones Edward O.
Published: December 2011

This paper is concerned primarily with the effects of external pressure on thin-wall torispherical, toriconical, and ellipsoidal pressure vessel heads including the determination of the collapse pressures. Two test vessels, one having torispherical and 120-deg toriconical heads and the other having ellipsoidal and 90-deg toriconical heads, were used in the study. Longitudinal and circumferential stresses per psi external pressure were plotted for the regions at which the vessel heads had been welded to the cylindrical portions of the vessels. Deflection values were plotted for the torispherical and ellipsoidal heads. Both the stress values and deflection values were determined from experimental data.
Predicting Process Gas Performance of Centrifugal Compressors From Air Test Data
Authors: O’Neill Philip P. , Wickli Herbert E.
Published: December 2011

The application of centrifugal compressors to the handling of gases in the process industries is of increasing importance. The problems associated with performing tests at the manufacturer’s plant under process conditions and the lack of a universally accepted method of performance correlation are matters of concern. This paper presents a recommended correlation procedure evolved from the review of technical papers embracing aspects of the subject. A program for the free interchange of air and process test data between manufacturer and user is submitted. This recommended procedure and proposed program (1) provides designers with essential information previously unavailable to them, and (2) ultimately benefits the user by the production of higher-performance machines.
Stresses in Tapered Transition Joints in Pipelines and Pressure Vessels
Authors: Rodabaugh E. C. , Atterbury T. J.
Published: December 2011

Theoretical formulas were developed which provide a means of computing the stresses in and near a tapered transition joint when the shell is subjected to internal pressure. The theoretical equations for stresses are compared with test results in which stresses were measured at and near tapered transition joints by means of electrical-resistance strain gages. Theory and test results are in adequate agreement. Since the resulting theoretical equations are quite complex, graphs of precalculated factors are shown to enable rapid calculation of the significant stress in any tapered transition joint in the dimensional range of wall-thickness ratios from one to two; and with transition tapers from an abrupt transition to a very small slope. The theory and graphs cover joints in which (a) the transition taper is both inside and outside of the shell to produce a geometrically balanced construction; (b) taper on the inside of the shell only; (c) taper on the outside of the shell only.
Determination of the Closing Time of a Solenoid Actuated Mechanism
Authors: Baumgarten J. R.
Published: December 2011

Determination of the response time of a solenoid actuated mechanism is complicated by the fact that coil inductance varies with plunger position. In addition, the mechanical force developed by the solenoid is a function of the transient current in the circuit. The mechanism being actuated can introduce further nonlinearities in the displacement-time relationship of the plunger travel. This paper sets forth the dynamic relations governing this electromechanical system. A program utilizing the measured magnetization characteristics of the solenoid and a numerical integration technique has been mechanized on a digital computer. The effects of variation of certain design parameters on the response of the mechanisms are shown.
The Mechanics of the Coining Process
Authors: Bocharov Y. , Kobayashi S. , Thomsen E. G.
Published: December 2011

The mechanism of coining is analyzed and several approximate solutions are given. The solutions were based on the strip, slip-line, and upper-bound methods of analysis. Comparison of the solutions for the local stress distribution could only be made for the strip and slip-line methods of analysis and it was found that the particular solutions obtained agreed reasonably well with each other in predicting coining pressures as functions of degree of coining. A comparison of the strip and upper-bound method of solution revealed that the predicted average coining pressures for a single central square groove are nearly identical for blanks having thicknesses of h0 = 1/16 in. for all values of b/b0 (degree of coining) except when b/b0 approaches unity. At b/b0 = 1 (deg of coining = 100 per cent), the modified strip method of analysis, using a cylindrical state of stress in the square corner of the groove, gave the highest average coining pressures. The upper-bound solution seems to overestimate the forging pressures for h0 > 1/16 in. for all values of b/b0, except when b/b0 is unity. A comparison of experimental average pressures, for coining 1-in-diameter blanks of commercially pure lead and aluminum, with the theoretical solutions, revealed that the modified strip method appears to be the best method for predicting the pressures when the ratio of b/b0 approaches unity. However, the exact pressure at b/b0 = 1 is indeterminable by use of this method. The analyses presented in the paper and comparisons of the solutions with experimental data reveal that a lowering of the coefficient of friction has a profound influence on decreasing the required coining pressures. The analyses further show that for high friction the pressure required for getting exact definition rises rapidly as the ratio b/b0 approaches unity.
The Effect of Vibration on Plastic Flow in Coining
Authors: Bocharov Y. , Kobayashi S. , Thomsen E. G.
Published: December 2011

Coining with a superimposed vibrational load of 800 lb and with a relatively low frequency of 130 cps was investigated. The materials were commercially pure lead and aluminum which were chosen to give an indication of the coinability during hot-working and cold-working, respectively. All blanks had a constant diameter d0 = 1 in. and three initial thicknesses h0 to give ratios h0/d0, of 0.250, 0.125, and 0.0625. The definition or degree of coining and surface finish was examined when coining these materials with three punches which were provided with different grooves of equal width. The shapes of the grooves had the following cross section: square, triangular, and semicircular. It was found that superimposed vibration upon static loading reduces the peak pressure required for the same degree of coining (measure of definition) significantly for dry lead, but to a lesser degree for dry aluminum. The improvements for h0/d0 = 0.0625 were 30 to 35 per cent for lead and 5 to 7 per cent for aluminum. It was also found that unlubricated specimens give a better surface finish and that the tendency to form folds, as is observed at times with lubricated blanks, at the point of coring, apparently is eliminated.