bluuebunny/crossref_metadata_2025 huggingface dataset:
A Distortion Energy Failure Theory for Orthotropic Materials
Authors: Forman G. W.
Published: November 2010

Of the numerous methods developed to predict failure of isotropic materials exposed to a three-dimensional state of stress, experimental studies tend to confirm the validity of the distortional energy theory. To date no rational basis of predicting inelastic action in an orthotropic material exposed to principle stresses coincident with the material axes has been proposed. This study assumes that distortion energy may be used to predict failure of orthotropic materials, and a usable algebraic method of predicting failure is developed.
Shape and Flatness in Thin Strip Rolling
Authors: O’Connor H. W. , Weinstein A. S.
Published: November 2010

The paper describes measurements of lateral flow of material which took place during cold rolling thin strip. This sideways flow is shown to have a considerable influence of the final flatness of the strip. A mathematical model of a rolling mill stand is described, which includes a calculation allowing for sideways flow of material. Parameter studies are made using the mathematical model, which show the influence of crowns, tensions, back-up and work roll bending on the resultant strip shape. A comparison is made between results predicted by the model and test results obtained on a production mill.
S3—New Type of High-Performance Semisubmerged Ship
Authors: Lang T. G.
Published: November 2010

The S3 semisubmerged ship concept consists basically of two parallel torpedo-like hulls, submerged to a depth of about two diameters and attached to an above-water platform by means of four vertical struts. Horizontal fins and control surfaces attached to the hulls provide dynamic stability and permit full automatic control over pitch, heave, and roll. The anticipated advantages of the S3 over conventional ships are greatly improved seaworthiness, high-speed potential, large internal volume and deck area, controllability, and many aspects of its unusual hydrodynamic form. The S3 concept appears to be most applicable to small ships (100 to 15,000 tons) having missions associated with the use of sonar—the handling of aircraft, weapons, or submersibles—and for missions requiring a high degree of seaworthiness and stability.
Analysis of Drill Stress by Three-Dimensional Photoelasticity
Authors: Law S. S. , DeVries M. F. , Wu S. M.
Published: November 2010

An exploratory drill point stress analysis was obtained experimentally using a three-dimensional photoelastic technique. A drill model was stress-frozen under simulated drilling conditions and seven segments were sliced perpendicular to and along the cutting edge for subsequent photoelastic analysis. Isochromatic fringe patterns from slices close to the drill periphery suggest an action analogous to orthogonal cutting. Generally, stresses become more compressive as the cutting edge or the outer corner is approached. A maximum shear stress was found to exist along the cutting edge at a point about three-fourths of the distance from the chisel edge and was noted to be similar to a previously determined cutting edge temperature distribution.
Computerized Time-Temperature Parametric Analysis of C, Mo, and Cr-Mo Steel Stress-Rupture Data
Authors: Raut P. K. , Clough W. R.
Published: November 2010

Demonstrated by results obtained with highly modified or original computer programs, accomplished with 31 data sets for C, Mo, and Cr-Mo steels, is the general superiority of the new Goldhoff-Sherby and the older Manson-Haferd parameters for the correlation of stress-rupture data, as compared with the use of the Larson-Miller, Sherby-Dorn, Manson-Succop, Conrad, and Korchynsky methods. Abilities to correlate are based on values of statistical measures of scatter about master curves. Rupture-times in excess of 10,000 hr were used in separate computer runs to test the abilities of the seven parameters to extrapolate to longer times. For extrapolation the Goldhoff-Sherby and Manson-Haferd parameters are generally superior, but particular attention must be paid to the order of the polynomial used to approximate master curves.
Bin Loads—Part 2: Concepts
Authors: Jenike A. W. , Johanson J. R. , Carson J. W.
Published: November 2010

This is one of a series of papers by the authors on the loads exerted by bulk solids on containing bins. In this paper, the concepts are described. In particular, the principle of minimum recoverable strain energy is applied in the determination of pressure fields. In companion papers the concepts are developed into design formulas.
An Approximate Rigid-Plastic Analysis of Shell Intersections Loaded Dynamically
Authors: Jones Norman
Published: November 2010

An approximate rigid-plastic method of analysis which may be used in order to estimate the behavior of various shell intersections subjected to large dynamic loads is presented herein. In particular, the two common cases of cylindrical nozzles intersecting either spherical or cylindrical shells are considered in some detail. The maximum permanent radial deflections of these two structures which arise from rectangular pressure pulses are presented for various geometrical parameters.
Base Flow Characteristics of a Linear Aerospike Nozzle Segment
Authors: Mueller T. J. , Sule W. P.
Published: November 2010

The separated base flow region within a linear aerospike nozzle segment is investigated experimentally in an ejector-diffuser system. The nozzle-diffuser system and base pressure characteristics are described over the pressure ratio range from the “open wake” to the “closed wake” operation. Schlieren photographs and static pressure distributions along the test section centerline and top contour describe the transition, from “open wake” to “closed wake” flow fields. Base pressure and static pressure distributions are utilized to present the effects of a ramp diffuser. The effects of base bleed on the base pressure ratio and structure of the nozzle flow field are also presented.
Technology and the Limits to Growth
Authors: Anderson J. M.
Published: November 2010

Simulation studies performed over the past two years by a team of scientists at the Massachusetts Institute of Technology indicate that there, are physical limits to the growth of population and of capital. Technology affects the simulation of global events by raising the productivity of labor and capital. In the past, technology has pushed back the limits of growth, but technology cannot alter the physical or social delays which become increasingly important in the face of continued exponential growth. In a growth mode, technology is used to meet short-term needs, thereby deferring problems for future solution. In a steady-state mode, technology is used to select between alternatives which afford a sustainably higher standard of living.
Wear-Resistant Materials for Steelworks Plant Handling Coke and Sinter
Authors: Hocke H.
Published: November 2010

Wear tests have been carried out under works operational conditions to see how some of the currently available wear-resistant materials behave when subjected to sliding wear by coke and sliding and medium impact wear by blast furnace sinter. Results are compared with En8 (equivalent to SAE 1038), one of the commonly used wear plate materials, to estimate what savings, if any, would be achieved in practice. It is shown that by the use of better wear-resistant materials plant maintenance costs can be considerably reduced. In particular shutdown times can be reduced and output capacity increased.
Slurry Flow in Pipes and Pumps
Authors: Vocadlo J. J. , Sagoo M. S.
Published: November 2010

One of the most effective ways to transport solid material is in the form of slurries. Although the technology of solids pipelining is quite advanced the underlying principles have not yet been formulated past the semiempirical stage. In this paper new approach to slurry flow both in laminar and turbulent regimes is outlined with emphasis on the approach for turbulent slurry flow without deposits which does not rely on subdivisions of slurries into arbitrary groups and which is based on identifiable mechanisms of energy loss. Some aspects of slurry systems and pumps are discussed.
Kinematics and Statics Including Friction in Single-Loop Mechanisms by Screw Calculus and Dual Vectors
Authors: Keler M. L.
Published: November 2010

After reviewing the fundamentals of dual-complex vector algebra, a method of accounting for friction in kinematic joints is developed. The method, which is based on an iterative technique, is applicable to all single-loop mechanisms which are kinematically and statically determinate.
Analysis of Spatial RRGRR Mechanisms by the Method of Generated Surfaces
Authors: Torfason L. E. , Sharma A. K.
Published: November 2010

The motion of a spatial RRGRR mechanism can be determined by considering the intersection of two tori. In this paper the intersections of two offset skew circular tori are found, thus defining all pair variables in this class of five link mechanism.
Synthesis of an Eight-Link Mechanism for Varieties of Motion Programs
Authors: Hamid S. , Soni A. H.
Published: November 2010

Using the matrix approach, synthesis equations are derived for eight types of synthesis problems for an eight-link mechanism having five links in each of its three loops. A numerical approach due to Marquardt is applied to illustrate the synthesis technique for the varieties of motion programs.
Finite Element Analysis and Experimental Investigation of Sheet Metal Stretching
Authors: Mehta H. S. , Kobayashi S.
Published: November 2010

The finite element method was used to obtain the stress and strain distributions in sheet metal on nonaxisymmetric flat punch heads in stretching. Displacement boundary conditions were assumed. The experimental investigation was carried out by stretching securely clamped grid blanks with suitable punch heads; boundary displacements and strains were obtained from the observed deformation pattern on punch heads. A comparison with an experiment in terms of effective strain and thickness strain distributions and strains along the longitudinal axis reveals excellent agreement. The finite element method was also applied to bore expanding in a circular plate. Strain distributions were obtained for two types of materials, one isotropic and the other material having thickness anisotropy. The results showed excellent agreement with exact solution and experimental results.
Differential Pressure Extrusion Through Double Reduction Dies
Authors: Shabaik A. H.
Published: November 2010

Differential pressure extrusion using double reduction dies was examined. Axisymmetric extrusion experiments using superplastic eutectic alloy of lead-tin were carried out for both single and double reduction extrusions. The flow lines, finite strain distribution at the exit section, and the stress distribution were obtained for the single extrusion and the first stage reduction of the double extrusion. The effect of back pressure induced by the second stage extrusion on the flow behavior and the axial stress distribution was examined. The effect of the intermediate diameter and the intermediate length on the final strain distribution in double extrusion was determined.
Coastline Environmental Study: Thermocline-Sewage Field Relationships Through Microbial Population Analysis
Authors: Jackson J. D.
Published: November 2010

The City of Huntington Beach, through the Department of Harbors and Beaches, established a two year environmental coastline study in November, 1971. The study has incorporated the support of surrounding colleges and universities, as well as technical expertise from local aerospace companies. One result of the study is the mapping of sewage fields in the area of an outfall by microbial population analysis and of their dissemination according to the existence and strength of ocean thermoclines.
Thermal Control Materials and Technology in the 1970s
Authors: Gilligan J. E. , Zerlaut G. A.
Published: November 2010

IITRI’s more recent activities in the Research and Development of stable spacecraft thermal controls materials and systems are reviewed, and projections are made for the expected achievements in this and other fields. In addition to the need to solve a synergistic reaction between zinc orthotitanate and certain siloxane vehicles, an additional requirement—that such systems be non-contaminating and nonconlaminable has added an important, and difficult dimension to the development of these coalings/surfaces. In the paper the K&U of an ultrastable, low αs/ε paint consisting of zinc orthotitanate and a modified commercial silicone is described. Some of the applications and materials requirements for solar energy utilization are discussed. The special requirements of electro-conductive surfaces for reproduction and other uses are also briefly reviewed in light of applicable space thermophysics technology.
A Mathematical Programming Technique for the Evaluation of Load Distribution and Optimal Modifications for Gear Systems
Authors: Conry T. F. , Seireg A.
Published: November 2010

A generalized technique is presented in this paper for evaluation of load distribution in gear systems and automated selection of optimal modification for the best possible distribution based on any prespecified type of modification. The procedure which utilizes a simplex-type algorithm provides an efficient and effective means for the design of gears with uniform load distribution.
Elastohydrodynamic Lubrication of Involute Gears
Authors: Gu A.
Published: November 2010

A criterion is suggested for the application of the steady state elastohydrodynamic theories to the analysis of involute gear contacts. The criterion is based on a comparison of two physical time scales characterizing the system. It is found that for heavily loaded gears the unsteadiness effect may be important. A mean-viscosity method using a composite pressure-viscosity model for the lubricant is introduced for contact zone temperature calculation. An example of involute gears is given for the computation of elastohydrodynamic contact variables based on quasi-steady state assumption. It is found that the surface temperature rise in the tooth tip contact is much higher than that in the pitch line contact.
An Interdisciplinary Lubrication Theory for Gears (With Particular Emphasis on the Scuffing Mode of Failure)
Authors: Akin L. S.
Published: November 2010

A new interdisciplinary gear lubrication theory is hypothesized herein using a stepped branching technique, to consider the various technological parameters in their logical echelonic order of importance as a result of the lubrication and wear regimes that geared mechanisms may be subjected to in modern practical operational power transmission systems.
On the Cause of Regenerative Chatter Due to Workpiece Deflection
Authors: Kato S. , Marui E.
Published: November 2010

The cause and the mechanism of regenerative chatter vibrations due to the deflection of workpiece occurring in machining metals are investigated experimentally. The regenerative chatter vibration is induced by the phase lag of the undulations in successive cutting. This means that small undulations initially produced on a work surface by the transient vibration of the workpiece become larger and the undulations extend over the whole work surface because a given amount of energy is available for exciting or maintaining the vibration owing to the phase lag of successive undulations. Then, a differential equation of chatter vibration is introduced based on the experimental results, and some remarks on the properties of chatter vibration are given.
A Comparison of Numerical Optimization Methods for Engineering Design
Authors: Eason E. D. , Fenton R. G.
Published: November 2010

Seventeen numerical optimization methods are compared by plotting their convergence characteristics when applied to design problems and test functions. Several ranking schemes are used to determine the most general, efficient, inexpensive, and convenient methods. Conclusions are presented in the form of a selection guide intended for general use.
An Evaluation of Stresses and Deflection of Spur Gear Teeth Under Strain
Authors: Chabert G. , Tran T. Dang , Mathis R.
Published: November 2010

This paper aims at an evaluation of the stresses induced by a static load applied to gear teeth. For spur gears of different ratios with 20-deg pressure angle and standard addendum proportions, the stresses and deflections are computed by the finite element method. Formulas are drawn allowing a simple calculation of the maximum stresses, and the results are compared with what is given by ISO and AGMA standards related to the strength of gear teeth.
Efficiency of Gear Transmissions With Flexibly Connected Gears Subjected to Axial Vibrations
Authors: Radzimovsky E. I. , Broom W. E.
Published: November 2010

The axial vibrational motion of one of the engaged gears increases the mechanical efficiency of a gear system by reducing the frictional resistance in the plane of gear rotation. The purpose of this investigation was to determine the effect of axial vibrations on the frictional losses in gear systems which are operated under the conditions of boundary lubrication. Two basic cases were investigated: the case when all four gears were rigidly connected to the shaft, and the case in which two of the four gears in the drive were mounted to the shaft in such a manner that they had a certain degree of freedom in the axial direction. In the second case, the relative axial displacement between the engaged gears may be smaller than the amplitude of the shaft vibrations, and the effect of the axial vibrations on the frictional losses in a gear system may be reduced. The influence of the following factors upon the efficiency of the gear train were investigated: the magnitude of the force transmitted by the train, the weight of the flexibly connected gears with the masses attached to them, the frequency of the axial vibration of the shaft, and the amplitude of this vibration.
Design and Analysis of an Energy Absorbing Restraint System for Light Aircraft Crash-Impact
Authors: Hundal M. S. , McLay R. W. , Folsom L.
Published: November 2010

The application of a miniaturized energy absorbing mechanism to a light airplane occupant restraint system is presented. The mechanism absorbs energy through the continuous plastic deformation of a steel wire, closely approximating a constant force energy absorber. The design philosophy and the installation details for the aircraft are presented. A mathematical model is used for determining the occupant response during aircraft crash. The model considers plane motion of the aircraft and the human body, the latter being approximated by five rigid body segments. Occupant displacements and curves for accelerations and restraint forces are presented for a typical survivable light aircraft crash. The experimental results and the mathematical model response suggest that incorporation of the energy absorbing mechanism would produce a significant decrease in occupant injuries and fatalities. A parametric study of the occupant/restraint system is presented. Recommendations are made on steps towards improved crash protection and survival in general aviation.
Stability and Damped Critical Speeds of a Flexible Rotor in Fluid-Film Bearings
Authors: Lund J. W.
Published: November 2010

A method is described for calculating the threshold speed of instability and the damped critical speeds of a general flexible rotor in fluid-film journal bearings. It is analogous to the Myklestad-Prohl method for calculating critical speeds and is readily programmed for numerical computation. The rotor model can simulate any practical shaft geometry and support configuration. The bearings are represented by their linearized dynamic properties, also known as the stiffness and damping coefficients of the bearing, and the calculation includes hysteretic internal damping in the shaft and destabilizing aerodynamic forces. To demonstrate the application of the method, results are shown for an industrial, multistage compressor.
Vibration Characteristics of the Printed-Circuit Motor
Authors: Hu P. Y.
Published: November 2010

Since optimum damping is difficult to achieve, raising the natural frequency of the printed-circuit motor is necessary for smooth starting and stopping. Designing for this higher natural frequency also produces the minimum mechanical time constant and the optimum power dissipation. A motor with a higher natural frequency requires stiffer substrate material in the armature. The nature of the armature requires that the substrate material be a fiberglass composite, an inorganic composite or a sapphire composite. Experiments produced an armature assembly with a natural oscillation of several thousand cps outside the start/stop (exciting) bandwidth of the motor.
Stick-Slip Motion of Machine Tool Slideway
Authors: Kato S. , Yamaguchi K. , Matsubayashi T.
Published: November 2010

Stick-slip motion of a moving element on an actual machine tool slideway is investigated experimentally under various sliding conditions, and the fundamental characteristics of the stick-slip motion are clarified. Based on these experimental results, the characteristics of static friction in the period of stick and kinetic friction in the period of slip are studied concretely so as to clarify the stick-slip process. It is shown experimentally that static and kinetic frictional coefficients can be expressed with simple formulas. Using these expressions, the boundary conditions for occurrence of stick-slip motion are examined, and the relation between properties of the stick-slip motion and frictional characteristics is explained quantitatively.
Nonlinear Truck Ride Analysis
Authors: Potts G. R. , Walker H. S.
Published: November 2010

The nonlinear vibratory motions of a three-axle semitrailer truck were investigated via the use of a digital computer. The nonlinear equations of motion are presented and a method of numerical integration is discussed. The analysis allows any shape of suspension force-deflection curve (including wheel hop, suspension stops, and dry friction damping) and a similar liberality of shock absorber force-velocity characteristics. An experimental vibration study, performed on a model truck, is described and the results compare favorably with the calculated results of the numerical integration.
Towards the Efficient Vibration Analysis of Shrouded Bladed Disk Assemblies
Authors: Cottney D. J. , Ewins D. J.
Published: November 2010

Prediction of the vibration properties of turbomachine blades and disks is an essential part of turbine design. However, the complexity of modern machines and the necessity to analyze the complete assembly of disk, blades, and shroud combine to make this a lengthy task. This paper describes an investigation aimed at improving the efficiency of such prediction techniques. The assembly is analyzed by studying each component individually and then combining these together with a receptance coupling technique by matching forces and displacements at each connection point. A study is made to establish which of the 6 coordinate directions at each junction need to be included in this process. The results of this study clearly demonstrate the necessity for including certain coordinates while others may be omitted with little loss of accuracy.
The Orbital Movement and the Damping of the Fluidelastic Vibration of Tube Banks Due to Vortex Formation: Part 3—Damping Capability of the Tube Bank Against Vortex-Excited Sonic Vibration in the Fluid Column
Authors: Chen Y. N. , Young W. C.
Published: November 2010

The damping criterion previously proposed by Chen 1964/1968 is evaluated with respect to a series of existing units using various fuels. The critical value of this criterion, which was given by Chen as 600 for the ideal case with uniform velocity distribution, has been found to be about 2000 for the tube bank heat exchangers in boiler units. The reason for this difference appears to lie in the degree of uniformity of the velocity distribution over the streaming section. Since the velocity distribution in the boiler units cannot be uniform at all, the vortex streets formed in the tube bank will disturb each other. A large damping will thus arise. The damping criterion can thus be employed to design a sonic vibration-free tube bank through proper consideration of tube spacings, Reynolds number, and Strouhal number.
A Displacement Analysis of Spatial Six-Link 4R-P-C Mechanisms—Part 1: Analysis of RCRPRR Mechanism
Authors: Duffy J. , Rooney J.
Published: November 2010

The input-output displacement equation is expressed as a degree eight polynomial in the half-tangent of the output angular displacement. A procedure for determining uniquely all the linkage variables verifies the closures and in addition explains the physical significance of the closures of equivalent five-link R5 spherical mechanisms. The equation can be used to generate input-output functions of spatial five-link RCCRR and RCRCR mechanisms. The results are illustrated by numerical examples.
An Analysis of the Resonant Frequency of a Motor With a Printed-Circuit Armature
Authors: Fraser H. R. , Lammers G. B. , Baumann G. W.
Published: November 2010

This paper presents an approach that predicts the resonant frequency of a high-performance dc servomotor. The correlation between this approach and experimentally determined resonant frequencies is good. The design of the armature, the coupling shafts, and the annular couplers is discussed with regard to maximizing the resonant frequency of the motor.
Thermal Stresses in Elastic Plates With Elliptic Holes
Authors: Rao K. S. , Bapu Rao M. N. , Ariman T.
Published: November 2010

The temperature and membrane stress distributions in an elastic square plate with an insulated central elliptic hole are investigated. The temperature varies along coordinates within the plane. The temperature distribution is determined as the solution of the steady state heat conduction equation, then the membrane stresses due to the temperature are analyzed. For both steps, the free edge conditions around the insulated elliptic hole as well as the boundary conditions at the fully restrained outer edges of the plate are satisfied at selected points by the method of least square point matching. The formulation is valid for any arbitrary orientation of the major axis of the elliptic hole. The numerical results for temperature distribution and membrane stresses are presented for two orientations and compared with the corresponding results for a circular hole.
The Influence of the Interface Condition on the Plastic Deformation Zone and the Resultant Product Integrity in Extrusion
Authors: Gurney F. J. , DePierre V.
Published: November 2010

The effect of the tooling-workpiece interface condition on the metal flow in extrusions is shown to be of critical importance in the achievement of sound product. For 2:1 reduction ratio extrusions, the central burst defect is shown to occur when low fractional restraint interfaces are employed. Sound internal product is shown to occur when high frictional restraint interfaces are employed. In metal alloy powder compaction-extrusion processes, a low density core is shown to be associated with compaction at low extrusion ratios employing low frictional restraint interfaces. The experimental results are discussed in terms of recent theoretical analyses of metalworking processes which are based on the effect of the interface friction influencing the volume of the plastic deformation zone and the subsequent strain rate fields.
Analysis and Design of Thin Struts With Large Elastic Displacements: Part 1—Analysis of the Properties of the Solutions of the Nonlinear Differential Equations and the Behavior of the Strut
Authors: Na T. Y. , Kurajian G. M. , Holbert D. L.
Published: November 2010

Employing a transformation technique, an analysis is made of the properties of the solution of the differential equations resulting from the analysis of the elastic behavior of an eccentrically loaded thin strut. The thin strut is made to experience large deflections and the end supports are simultaneously pinned and restrained by torsional bar springs. The paper is divided into two parts. Part 1 deals primarily with the properties of the solution of the equations; and Part 2 deals with the practical engineering aspect where, employing Part 1, realistic values and ranges of parameters are assigned. The resulting design curves and tables, useful to the design engineer, are presented.
Configuration of Submarine Pipelines During Laying Operations
Authors: Palmer A. C. , Hutchinson G. , Ells J. W.
Published: November 2010

The stresses set up in a pipe being laid from a lay-barge over a stinger are determined by the configuration the pipe takes up. The equations governing this configuration are derived, and different techniques for solving them are examined. It is concluded that the finite-difference technique is the most attractive, and an example of its application is discussed in detail. The nondimensionalized form of the governing equation suggests a way of modeling the system physically and, at the same time, satisfying appropriate similarity conditions; the construction and use of such a model are described.
On the Effect of Track Irregularities on the Dynamic Response of Railway Vehicles
Authors: Dokainish M. A. , Siddall J. N. , Elmaraghy W.
Published: November 2010

The steady state response for models of a six-axle locomotive running on a sinusoidally irregular track has been investigated. Two mathematical models have been set up, a full model for the “stationary” vehicle in which creep between wheels and rails was neglected, and a full model for the “moving” vehicle in which creep forces, gravity stiffness effects and wheel tread profiles were considered. The use of the generalized method of complex algebra to obtain the steady state response of the railway vehicle components to varying input frequencies was used. The results given in this paper are for the case of sinusoidal lateral track irregularities only, but the method is general enough to allow also for vertical track irregularities. For the “stationary” vehicle the input frequency is increased from zero to 3 cycles per second. For the “moving” vehicle the input frequency is a function of the track wave length and the vehicle forward speed and is given in terms of the vehicle speed. The frequency response curves are computer plotted in each case. For the “moving” vehicle, responses for the cases of both new and worn wheels are obtained. The natural frequencies for the full model are also calculated. The results obtained show the effect of the creep forces and the condition of the wheels on the steady state response. It is recommended that slip and corresponding creep forces, wheel tread and rail profiles, and the gravity stiffness effect be included in the steady state response analysis of railway vehicles to track irregularities. The analysis may be used to check the response of any proposed design for a railway vehicle to economically attractive track irregularities. It may also be used to adjust geometry, spring rates and damping characteristics in order to maximize operating speeds while providing optimum damping for the trucks and body motions. This paper illustrates and describes the mathematical models used; gives generalized form for the differential equations of motion and the methods of solution. The equations of motion for the wheelsets are derived in detail including the creep forces and the wheel tread profiles.
Thermal Aspects of Grinding: Part 1—Energy Partition
Authors: Malkin S. , Anderson R. B.
Published: November 2010

An investigation of the thermal aspects of grinding is described in a two paper sequence. This first paper is concerned with the distribution of the total grinding energy among chip formation, plowing, and sliding energy components, and the portions of each of these energies which are conducted as heat to the workpiece. The results indicate that virtually all the sliding and plowing energies, and approximately 55 percent of the chip formation energy, are conducted as heat to the workpiece. In the second paper, these results are related to grinding temperatures and workpiece burn.
Thermal Analysis of the Wear of Single Abrasive Grains
Authors: Scrutton R. F. , Lal G. K.
Published: November 2010

It is shown that the wear of single abrasive grains in a simulated grinding operation (over-cut fly milling) is governed by a thermally activated mechanism. The model adopted in this theoretical treatment assumes that most of the energy expended during grinding enters the workpiece via adiabatic plastic flow. The accompanying rise in temperature at the grain-workpiece interface decreases the shear flow stress of the softer metal. This permits a greater adhesive wear rate. The predictions of the theory agree with the results of extensive experimental data.
Optimization of Tension Level and Stinger Length for Offshore Pipeline Installation
Authors: Daley G. C.
Published: November 2010

Offshore pipelines have been installed for a period of some 10 to 20 years using a variety of methods. This paper presents a new analysis method for the optimization of certain operation parameters in laying continuous pipe under tension from a barge. This method of optimization is now being used by one of the major offshore contractors. The solution is given by matching geometrical parameters through graphical overlays of network charts obtained by a computerized finite-element iterative solution. The solution is based on the requirement that the tension level be optimized with respect to either the minimum stinger length or the maximum average radius of curvature of the stinger.
Optimum Chute Profiles in Gravity Flow of Granular Materials: A Discrete Segment Solution Method
Authors: Chiarella C. , Charlton W. , Roberts A. W.
Published: November 2010

Using a single particle model and an assumed resisting force, the problem of finding the required shape of gravity flow discharge chutes to achieve minimum transit time is formulated by breaking up the path into a number of discrete segments. The method and a set of results are compared with an alternative procedure and solution obtained by use of Pontryagin’s minimum principle.
Stability of Random Vibrations With Special Reference to Machine Tool Chatter
Authors: Pandit S. M. , Subramanian T. L. , Wu S. M.
Published: November 2010

Static and dynamic stabilities of self-excited random vibrations are investigated in terms of the differential equation and time series model for the vibrational signal. Various instabilities are demarcated in the parameter space of the time series model, so that the stability of random vibrations can be ascertained by locating the parameters obtained from the vibration data. These results are applied to machine tool chatter by analyzing tool point vibrations in a turning operation under different degrees of chatter. This analysis substantiates the theoretical investigation, which is further confirmed by resonance curves obtained for the workpiece and cutting tool.
Stability Analysis of Lifting Rigs—Part 1: Necessary and Sufficient Conditions
Authors: Longman R. W. , Freudenstein F.
Published: November 2010

When heavy equipment is moved by cranes or derricks—for example, in the course of manufacturing, assembly, or installation—the rigging or hitch used should be stable, i.e., it should not dump the load in the course of its motion. A general criterion is derived which is necessary and sufficient for Liapunov stability or asymptotic stability of a hitch. The relationship between asymptotic stability and stability under persistent disturbances is discussed, and an analytical expression for the system margin of stability is obtained.
Effect of Flexibility of Driving Shaft on the Dynamic Behavior of a Cam Mechanism
Authors: Koster M. P.
Published: November 2010

The flexibility of the driving shaft affects the dynamic behavior of a cam mechanism. On the basis of a dynamic model this effect can be determined theoretically. The results of different dynamic models are then compared with test results. The drawing up of rules concerning the design of cam mechanisms makes use of a model which is sufficiently accurate as well as sufficiently simple, so that the dynamic response can be characterized by merely two dimensionless parameters, one for the follower and one for the camshaft.
Deep Submergence Spherical Shell Window Assembly With Glass or Transparent Ceramic Windows for Abyssal Depth Service
Authors: Stachiw J. D.
Published: November 2010

A total of 20 spherical shell windows with R0 = 4 in., Ri = 3 in., and 150 deg included spherical angle have been pressure tested under static and dynamic loading conditions. The tests included not only long term cyclic tests at 4500, 9000, 13,500, and 20,000 psi but also underwater shock tests at 450 psi static pressure. Two different gasket and four different transparent window materials were tested in the same metallic window flange with plane bearing surface. The transparent materials used in windows were glass ceramic CERVIT C-101, chemically surface compressed glass CERVIT SSC-201, borosilicate crown glass BK-7, and Plexiglas G acrylic plastic. The test results based on a total of over 10,000 hr of pressure testing indicate that the NUC 150 deg spherical shell window assembly design with t/Ri = 0.333 windows described in this paper can be routinely used in unmanned systems to any depth found in the ocean providing that the chemically surface compressed glass or transparent ceramic materials evaluated in this study are used in the assembly.
Steady-State Thermal Stresses in Wedge-Shaped Cutting Tools
Authors: Thomason P. F.
Published: November 2010

Closed form expressions for the steady-state thermal stresses in a π/2 wedge, subject to constant-temperature heat sources on the rake and flank contact segments, are obtained from a conformal mapping solution to the steady-state heat conduction problem. It is shown, following a theorem of Muskhelishvili, that the only nonzero thermal stress in the plane-strain wedge is that acting normal to the wedge plane. The thermal stress solutions are superimposed on a previously published isothermal cutting-load solution, to give the complete thermoelastic stress distribution at the wedge surfaces. The thermoelastic stresses are then used to determine the distribution of the equivalent stress, and this gives an indication of the regions on a cutting tool which are likely to be in the plastic state. The results are discussed in relation to the problems of flank wear and rakeface crater wear in metal cutting tools.
The Use in Probabilistic Design of Probability Curves Generated by Maximizing the Shannon Entropy Function Constrained by Moments
Authors: Siddall J. N. , Diab Y.
Published: November 2010

A general algorithm is described for obtaining the maximum entropy distribution constrained by moments in functional form. It is based on Jaynes’ principle. The distribution is proposed as a useful tool in probabilistic design. The maximum entropy distribution is generated for a large number of analytical distributions, and compared with the original. The results appear to confirm that it can represent well most populations when four or five moments are used. The maximum entropy distribution is also compared with the Johnson and Pearson empirical distributions. The results are favorable in the two examples given. The practical convenience of the method in probabilistic design is illustrated by an example in structures.
Multiplication of LNG Cold to Produce Refrigeration at 273 K
Authors: Brown G. Best
Published: November 2010

It is becoming of great importance to develop processes which can utilize the “available cold” of LNG and thus recover the energy used for its liquefaction. It is possible to evaluate the amount of refrigeration that could be produced reversibly Q1, at a temperature T1, from the amount of cold available, Q2, at a lower temperature, T2, in an environment at T0. This is:Q1Q2≤T0−T2T0−T1·T1T2 For LNG it would be obtained that: Q1Q2≤13.5 Work is being done to develop cold multiplication cycles which would approach this ideal figure. Among the systems under development is an absorption process resembling a reversal of the well-known absorption refrigerator. An ethane-neoheptane system is presented for which the multiplication factor has been around 1.8 and the efficiency of around 17 percent. The irreversibilities of the cycle and the low enthalpy of mixing of hydrocarbons are the main reasons for the relatively low cold multiplication factor and thermodynamic efficiency.
Nonlinear Stress Analysis of Vertical-Axis Wind Turbine Blades
Authors: Weingarten L. I. , Nickell R. E.
Published: November 2010

A Darrieus-type vertical-axis wind turbine has been proposed as an alternate to conventional horizontal axis, propeller-type machines. An advantage is that the blades will be primarily in tension, thus making for a more efficient design. In connection with its vertical-axis wind turbine program, Sandia Laboratories has developed the “troposkien” (Greek for turning rope) shape for the blade design. The prototype blade shape is similar to that of the troposkien, but more easily manufactured. The effect on the stress distribution of this alternate blade shape is investigated. Analytical models of the blades were constructed using a general purpose, nonlinear, dynamic finite element structural code. This code accounts for the large deflection effects of the various blade shapes through incremental applications of angular velocity.
Dynamic Behavior of Gear Systems and Variation of Coefficient of Friction and Efficiency During the Engagement Cycle
Authors: Radzimovsky E. , Mirarefi A.
Published: November 2010

In this work, the instantaneous and average efficiency and coefficient of friction of gear drives operating at low, medium, and moderately high speeds were experimentally and analytically investigated. First, using the gear testing machine specially designed for this type of investigation, the frictional losses in gearing during the engagement period were obtained experimentally. Based upon the obtained data, the values of efficiency and coefficient of friction were evaluated. A mathematical model simulating the gear testing machine was then developed and employed for the analysis of the dynamic behavior of the gear train system and analytical evaluation of gear system efficiency. The results obtained from this model were compared to those obtained directly from experiments, and a close correlation was achieved. The influence of such factors as diametral pitch, contact ratio, magnitude of transmitted load, and speed upon the efficiency of gear drives and the coefficient of friction in gearing was investigated. This investigation showed that the suggested method may be used to predict the dynamic behavior and efficiency of gear systems if a coefficient of friction is known or assumed. This investigation also gives some promise for power gear transmission design with improved capacity when scoring is the limiting criterion for capacity.
Effect of Pressurization on the Vibration Isolation Capability of Squeeze Film Bearings
Authors: Simandiri S. , Hahn E. J.
Published: November 2010

This paper investigates theoretically the effect of pressurization on the vibration isolation capability of centrally preloaded squeeze film bearings supporting a rigid rotor which in turn is mounted in rolling element bearings. Assuming the short bearing approximation, constant lubricant properties, and that steady state conditions have been reached with the journal center describing synchronous circular orbits about the bearing center, the theory is developed for the general case of arbitrary pressurization at either end of the bearing. The design data are for bearings pressurized at one end only as in circumferentially grooved bearings and conservatively assume that the saturation vapor pressure of the lubricant is atmospheric. These design curves show the effect of the relevant system parameters on the possibility of undesirable operation modes, on the unbalance force transmissibility and on rotor vibration amplitudes. Hence, the influence of lubricant viscosity, lubricant supply pressure, bearing dimensions, rotor speed, rotor mass, rotor unbalance and support flexibility may be readily determined, allowing for optimal system design. It is shown that significant unbalance force isolation is a practical possibility with consequent decrease in the vibration level of the rotor mounts and increase in rolling element bearing life, while maintaining rotor excursion amplitudes at an acceptable level, even with relatively high unbalance loading. In particular, with increased pressurization, the likelihood of bistable operation can be considerably reduced. The data suggest that by varying the supply pressure and/or the lubricant viscosity, the rotor bearing system may be gainfully controlled to run at minimum vibration level and/or with minimum unbalance transmissibility.
Brittle Fracture Under a Complex State of Stress
Authors: Shaw M. C.
Published: November 2010

A hydrostatic stress modified maximum tensile strain theory of fracture previously shown to be in good agreement with results on tungsten carbide specimens loaded to fracture under a variety of complex states of stress is discussed. This theory is applied to tests on marble involving two states of complex stress. The results suggest that the size effect in brittle fracture is smaller than usually assumed. The theory explains the difference in maximum tensile stress at fracture for torsion and uniaxial tensile tests.
Determination of Optimum Machining Conditions—Deterministic and Probabilistic Approaches
Authors: Hati S. K. , Rao S. S.
Published: November 2010

The mathematical programing techniques are applied to determine the optimum cutting parameters of machining operations. Three objectives, the cost of production per piece, the production rate, and the profit, are considered for optimization. The different constraints that arise during the machining operation are also considered. As some parameters involved in the process may not be purely deterministic, a probabilistic model is set up for the cost of production per piece and the production rate. After converting the probabilistic model into an equivalent deterministic model, the mathematical programing techniques are applied and the results obtained are compared with those of the deterministic model. A sensitivity analysis with respect to the cost parameters is carried in the case of cost of production per piece.
Investigation on the Role of Workpiece Grain Size in Electrochemical Machining Process
Authors: Kops L. , Quach V. B.
Published: November 2010

The hypothesis of grain boundaries affecting anodic dissolution as well as the concept of their interaction with the electrolyte flow on the workpiece surface subjected to ECM is presented. Scanning electron micrographs provide supporting evidence. It is shown that grain boundaries are preferentially dissolved since they are sites of higher free-energy atoms and consequently have higher rate of metal ions leaving anode surface. Due to greater fluid agitation in boundary depressions they constitute also sites of higher mass transfer, increasing the diffusion rate of dissolved ions into the mainstream of the electrolyte flow. Thus, the more grain boundaries on the surface the better the conditions for dissolution. And since the analysis shows that smaller grains provide more boundaries per unit area, the smaller the grain size the higher the metal removal rate. Tests conducted in an experimental cell designed to provide defined hydrodynamic conditions are described and discussed. Results obtained for Hastelloy-X samples of three different grain sizes confirm the hypothesis showing that for workpiece structure with smaller grain size, higher metal removal rate and current density are obtained.