bluuebunny/crossref_metadata_2025 huggingface dataset:
Pressure Resistant Bulkhead Penetrators for Fiber Optics in Deep Ocean Applications
Authors: Cowen S. J.
Published: July 2009

This paper describes results obtained at the Naval Ocean Systems Center, San Diego, under Independent Exploratory Development funding. The objective was to develop a robust, fully-demountable, high pressure penetrator design suitable for coupling light signals transmitted by optical fiber elements in an undersea cable operated at high ambient hydrostatic pressure into an electronics package or manned space. The feasibility of constructing such penetrators utilizing Graded Refractive INdex (GRIN) rod lenses as combination pressure barriers and imaging devices was demonstrated. Prototype realizations exhibited excellent optical throughput performance and readily survived in excess of 10,000 psi pressure differential as well as tolerating a wide temperature range. The design lends itself to hermetic construction for applications requiring no vapor diffusion over long mission durations. Such devices exhibit excellent potential for satisfying SUBSAFE requirements for manned submersible applications.
Low Velocity Impact of a Viscoelastic Beam
Authors: Llorens R. E. , McQuillen E. J.
Published: July 2009

A theoretical solution for the response of a viscoelastic beam to off-center low speed transverse impact is presented. The flexural model adopted for investigation consists of a uniform Bernoulli-Euler beam whose behavior has been generalized to include a linear viscoelastic constitutive relation for each element of the beam. Further, the beam and rigid impactor are assumed to remain in contact during the resulting motion and a consistent set of initial displacement and velocity distributions is adopted for the beam. The solution method utilizes two Laplace transforms, i.e., one with respect to space and the other with respect to time. Comparison of the numerical predictions of the theoretical model with central impact test results on graphite-epoxy composite laminates indicates a good agreement between theory and experiment.
Ring Forming: An Upper Bound Approach. Part 2: Process Analysis and Characteristics
Authors: Avitzur B. , Van Tyne C. J.
Published: July 2009

The generalized ring forming process has been analyzed for a Mises’ material, using an upper bound approach. This analysis allows the motivation for the process to be supplied on any surface and permits the application of external tractions on any other surface of the ring. In this second part of the series, the analytical equations for the relative forming stress and the radial flow parameter are derived for all three modes of deformation. The characteristics of these equations are shown graphically for a wide range of process parameters. The conditions that lead to the newly introduced “imaginary values” of the neutral radius (Rn) are identified.
Effects of Die Shoulder on the Prolateness and Deformation in the Bulge Test
Authors: Shang H. M. , Shim V. P. W.
Published: July 2009

In the present investigation, the prolateness and the deformation of sheet metal deformed under lateral pressure with dies of different shoulder radii are analyzed. It is found that at the beginning of deformation, the bulge shape becomes more spherical with increasing polar height. Beyond a certain stage of deformation, its shape, however, begins to deviate more and more from that of a sphere until fracture at the polar region occurs. The present results show that the die shoulder radius has little influence on the shape of the bulge, but it tends to inhibit deformation so that formability may be improved by using a die of small shoulder radius.
Product-Mix and Machine-Loading Analysis of Multistage Production Systems for Group Technology
Authors: Hitomi K. , Ham I.
Published: July 2009

An analysis of a product-mix problem of multistage production systems was performed to optimally select parts to be processed in limited amounts of time available for given production facilities, by applying the group technology concept. In addition, optimal machining speeds were determined for all parts selected so as to maximize the production rate. A solution procedure for this problem was developed and a numerical example was presented.
Belt Aggregates in High-Speed Texturing
Authors: Kang T. J. , El-Shiekh A.
Published: July 2009

In this paper the performance of the false twist texturing process is investigated. The analysis deals with false twisting systems employing belt aggregates. Theoretical analyses are compared with experimental values run at texturing speeds in the range of 800 m/min. The application of belt-twisting as an aggregate is analyzed and its feasibility as an efficient twisting element is discussed. The analysis shows the changes in yarn tension and twist level as a function of the B/Y ratios (belt to yarn speeds) and belt angle. Experimental results were found to agree fairly well with the predicted analysis.
Mechanics of Wobble Broaching. Part 2
Authors: Murty R. L. , Reddy P. Jayapal , Prasad A. Srihari
Published: July 2009

A method to calculate the cutting velocity of a point in wobble broaching of polygonal holes is presented. The results of experiments in wobble broaching of square, round, and hexagonal holes of various sizes are presented and discussed.
Fuel Consumption of Freight Trains Hauled by Diesel Electric Locomotives
Authors: Radford R. W.
Published: July 2009

The cost of railway diesel fuel has become an increasingly high proportion of railway operating expenses. The paper analyzes the generation and utilization of rail horsepower in freight train operations. The effects on fuel consumption of variations in several parameters including train consist, car weight, gradient, average speed, meet strategy, throttle control, locomotive axle arrangement, and train marshalling are examined. Estimates are made of the value, in terms of fuel cost, of weight reduction of freight cars and of selective train marshalling.
A Mathematical Model for Split Point Drill Flanks
Authors: Radhakrishnan T. , Wu S. M. , Lin C.
Published: July 2009

For consistent and accurate production of a split (crankshaft) point drill, proper mathematical models are derived. Modification of the existing, basic conical flank model yields the model for the major (primary) flank surface. An independent, planar model for splitting the point (secondary flank) is also derived. The models yield grinding parameters to set the relative positions of the drill and the grinding wheel for precise production of the split point geometry.
Brittle Fracture Initiation Under Complex Stress States
Authors: Takagi J. , Shaw M. C.
Published: July 2009

The brittle fracture locus for crack initiation in several brittle materials under biaxial states of plane stress is determined experimentally and compared with the classic theory due to Griffith. While good qualitative agreement is observed, the quantitative agreement is poor. It is found that replacing the two-dimensional hairline crack assumed by Griffith by a similar circular one leads to much better agreement between theory and experiment. The plane stress disk test is considered in terms of the new theory and some previously misunderstood aspects of this test are explained. Finally, the relation between crack initiation and crack propagation is briefly discussed.
Plane Strain Visioplasticity for Dynamic and Quasi-Static Deformation Processes
Authors: Dwivedi S. N.
Published: July 2009

The visioplasticity approach is developed to enable the complete stress history of any steady or nonsteady, quasi-static or impact, plane strain plastic deformation process to be determined from a record of the deformation pattern. The velocity field is determined experimentally, and, for dynamic conditions, high-speed photographs are taken of grid patterns marked on the end surface of the specimen. Digitization of the instantaneous grid node positions allows the velocity fields to be obtained at predetermined time intervals throughout the transient deformation period. Hence, the strain-rate, equivalent strain rate, equivalent strain, and finally stress fields can all be obtained. Plane strain upsetting tests, conducted at a speed of 0.1mm/s give results that agree closely with the well-documented “friction hill” type of normal stress distribution for quasi-static rates of strain. However, with a specimen deformed at a speed of 478.54 cm/s the normal stress distribution is radically different exhibiting a saddle-type distribution. The effect of strain rate on the interface and interior stresses will have significant bearing on a number of metal-forming operations.
Analysis on Simultaneous Double-Sided Grinding Stock Removal Distribution on a Thin Disk
Authors: Mitsuhashi M. , Yoshii S.
Published: July 2009

This paper deals with both side grinding on a thin disk used for a magnetic memory disk substrate. A grinding model was set up in which a thin disk was inserted between a pair of grinding wheels and both sides were ground simultaneously. Using this model, an attempt was made to analyze the theoretical stock removal distribution from the thin disk, when changing grinding conditions. In the analysis, a formula on thin disk rotational moment was worked out, and revolutions per minute for the thin disk were calculated using a formula about rotational moment. Calculated stock removal distribution from the thin disk were in agreement with experimental results. This meant that accurate grinding conditions for uniform stock removal could be set up, based on calculation results.
Cold Impact Extrusion-Mechanism of Formation of a Bimetallic Wall
Authors: Ciupik L. F. , Mstowski J.
Published: July 2009

Bimetallic product-cups can be manufactured by cold impact extrusion of two dissimilar metals. In these products, the cold bonding and the arrangement of layers are of a crucial role. The parameters of extrusion control the simultaneous flow of metal layers and their joining. The geometrical features of the layer can be described by a function of the type: y = axb ecx.
Erosion of Metallic Plate by Solid Particles Entrained in a Liquid Jet
Authors: Benchaita M. T. , Griffith P. , Rabinowicz E.
Published: July 2009

An experimental and theoretical study on erosion of a metallic plate by solid particles entrained in a liquid jet has been performed. The test section involved a two-phase flow jet of liquid water and silica-sand impinging on a metallic plate upon which erosion occurred. In combining the fluid mechanics of particle suspension in a liquid and a model of weight removal from the plate (by a single abrasive particle), an analytical approach is developed to determine the distribution and amount of erosion along a metallic plate. This model of erosion distribution along the metallic plate can be used as a tool to predict erosive damage in industrial equipment such as pipe bends, elbows, subsurface safety valves, and pipe contractions.
Press-Formability of Aluminum Alloy Sheets of Solution-Hardening Type
Authors: Kawai N. , Mori T. , Nozaki T.
Published: July 2009

Recently, formable metal sheets with a high strength-to-weight ratio have been developed especially to conserve energy and resources. For this purpose, two conditions are necessary: the strengthening of the sheet metal and improvement of the press-formability, which are difficult to obtain together. In the present study, the conditions necessary for this are examined using solid-solution type aluminum alloy sheets. Moreover, a new measure to assess press-formability is proposed in terms of the strain-hardening capability and plastic-anisotropy based on fracture behavior of sheet metals.
Some Observations on the Effect of Strain Paths on the Strength of Oxygen-Free Copper
Authors: Thomsen E. G.
Published: July 2009

Oxygen-free copper was extruded in the form of short solid cylinders (25 mm dia × 25 mm long) with reductions of approximately 20 percent and then followed by a compression test restoring the shape of the specimen to nearly the initial state. This process was repeated a number of times and it was found that the strength of the deformed metal did not follow the compression flow curve of the annealed metal but remained substantially lower. This procedure resulted in a temporary weakening of the metal which was attributed to a recovery process. It is thought that by a diligent selection of a forming process this temporary weakening of a metal might be utilized in practice.
Stiffness and Friction Force Measurements on a Freight Car Truck from Quasi-Static Tests
Authors: Kachadourian G. , Orth C. L. , Inskeep D. W.
Published: July 2009

A conventional three-piece truck with load sensitive friction snubbing was tested as a complete assembly with its wheels resting on a fixed section of rail and with loads applied through a fixture that duplicated the body bolster at the truck bolster interface. The purpose of the testing was to determine the stiffness and friction forces of the truck under vertical, lateral, and roll moment loading conditions. Loads were varied to cover a range of car gross weight conditions. The test was quasi-static in that load application was varied at sinusoidal rates of 0.1 or 0.2 Hertz to minimize errors in spring rate measurement caused by friction snubber forces. The desired stiffness and friction force data were obtained in terms of system rather than component properties and are consequently more directly usable in mathematical models. The roll test data were particularly useful because separate spring rates were obtained for the different conditions of center plate seated, center plate rocking, and side bearing contact. Because of the sinusoidal method of load application, it was possible to obtain system spring rates with the friction snubbers static and sliding.
Replication of Revenue Track Input Using a Vibration Test Unit for Freight Car Structure and Lading Damage Evaluation
Authors: Rajkumar B. R. , Irani F. D. , Orth C. L.
Published: July 2009

The Vibration Test Unit (VTU) of the Rail Dynamics Laboratory at Pueblo, Colorado, can be used for vibration testing of railroad vehicles with revenue track input. Until recently, the usual source of track geometry input to the VTU consisted of Plasser car digital tape recordings of track displacements as a function of distance along the track. A second track geometry input to the VTU was developed based on the Locomotive Track Hazard Dector (LTHD) concept, which produced displacement history data obtained by processing the time histories of special axle-mounted accelerometers. Tests were conducted at the Transportation Test Center, Pueblo, Colorado, to validate a suitable form of input to the VTU which closely duplicate the actual revenue track input. The results indicated that the responses of the test vehicle on the VTU, excited with input based on the LTHD concept, compared closely with the corresponding responses monitored on the actual track, while the Plasser time history input to the VTU produced responses which showed considerable variation at speeds 30 mph and above in both amplitude levels and frequency content. The close agreement between the responses during the track tests and VTU runs with the LTHD time history input has opened up a realm of testing capabilities of the VTU for freight car structure and lading damage evaluation on a given revenue track.
Process-Induced Residual Thermal Stresses in Advanced Fiber-Reinforced Composite Laminates
Authors: Stango R. J. , Wang S. S.
Published: July 2009

A study of process-induced stresses in advanced fiber-reinforced composite laminates is presented. An analysis of the residual thermal stresses is conducted on the basis of laminate thermoelasticity theory in conjunction with a quasi-three-dimensional finite element method. Formulation of the numerical method is briefly outlined in the paper. To illustrate the fundamental nature of the problem, numerical examples for a quasi-isotropic [0 deg/90 deg/ ± 45 deg]s graphite-epoxy composite system are presented. Complex three-dimensional stress states of significant magnitude are reported. Emphasis is placed on the interlaminar stress distributions along ply interfaces. Effects of laminate stacking sequence on the residual thermal stresses are examined in detail. Implications of the results on deformation and failure of composite laminates are discussed.
A Model for Bending Bimetallic Strip
Authors: DeVries W. R. , Lauderbaugh L. K.
Published: July 2009

Bending strip stock using a simple punch and die arrangement is one of the common methods of producing journal bearings. In most cases, the material formed for this purpose is bimetallic, which should be taken into consideration in analyzing the deformation process. In this paper, a model for the bending process is presented that takes into account the bimetallic and strain hardening nature of strip stock, and seeks to produce a description of the resulting strip geometry. Experimental results are included for comparison with the modeling results.
An Economic-Engineering Assessment of a Hypothetical Tuft-to-Yarn Textile Mill
Authors: Thibodeaux D. P. , Brown R. S. , Shaw D. L. , Ethridge D. E.
Published: July 2009

An economic-engineering simulation model has been developed for a hypothetical textile mill operating an integrated, continuous-flow, tuft-to-yarn (TY) system. The model was used to calculate costs of producing cotton denim yarns with two different TY configuration mills. These were compared with a similar model for a conventional open-end (OE) textile mill processing the same product at similar production rates. The models predict that the TY mills will reduce production costs by between 4.11 and 6.2 cents per pound of spun yarn which amounts to a reduction of between 18.5 and 28 percent as compared with the conventional OE mill. Considering the raw materials’ cost as constant for all the models this processing cost reduction represents a total cost savings for the TY mills of between 4.8 and 7.3 percent of the total manufactured yarn costs.
Washing Cotton to Remove Dust
Authors: Sasser P. E. , Perkins H. H.
Published: July 2009

Cottons were washed by continuous process to evaluate the effects of cleaning and washing conditions on nonlint content, dust generation during carding, and fiber properties. Washing conditions ranged in severity from a full scour and bleach to a mild water wash treatment using only a wetting agent. Differences related to washing conditions were noted in dust generation and on fiber properties. In relation to project objectives, the mild wash produced the best quality cotton. All washing treatments lowered the dust content of the fibers.
Simulation of Compression Molding for Fiber-Reinforced Thermosetting Polymers
Authors: Lee Ching-Chih , Folgar F. , Tucker C. L.
Published: July 2009

A model is presented for the flow, heat transfer, and curing that occurs during compression molding of reinforced thermoset polymers. The model applies to thin parts with slowly varying thickness and arbitrary planar geometry. Non-Newtonian fluid behavior, temperature dependent viscosity, and the heat liberated by curing are all rigorously accounted for. A finite element computer program implementing the model for isothermal Newtonian and power law fluids has been written, and some sample results are given. Unique features of the simulation allow it to run without operator interaction. Comparison with experiments shows that the isothermal models accurately predict deformations of non-Newtonian and nonisothermal materials such as sheet molding compound. Limitations of the model with regard to part thickness and the rheological properties of the molding compound are discussed.
The Practical Use of Computer Programs for the Design and Operation of Thermoplastics Screw Extruders
Authors: Cox A. P. D. , Fenner R. T.
Published: July 2009

Over the last two decades, there have been many theoretical models presented for the feeding, melting, and melt pumping of thermoplastics in the single-screw extruder. Many of the models are amenable to computer analysis, but their complexity makes them impractical for industrial applications. The various melting models are reviewed. A model allowing for a deformable solid bed and bed acceleration is presented to show the limits of screw performance and operational stability. Comparisons are made between predicted and experimental data for processing various polyolefins and polystyrene. Final melt conditions can be estimated by a two-dimensional, nonisothermal developing melt flow model, and the influence of operating conditions and material properties are presented. Effects of barrier flights on the melting and melt mixing are discussed. Examples of the combined use of both programs to design the drive requirements and screw dimensions for processing various thermoplastics are also presented.
Data-Dependent Systems Approach to Surface Generation in Grinding
Authors: Pandit S. M. , Sathyanarayanan G.
Published: July 2009

This paper initiates a new approach to the analysis of surface generation, by fitting mathematical models to wheel and work surface profiles under actual grinding conditions. Data Dependent Systems (DDS) methodology has been used to model work surface profiles in the longitudinal (across the width of cut) and transverse (along the direction of feed) directions, and the wheel profile along the longitudinal direction. A model for the “characteristic grain” consisting of the superimposition of a large and small wavelength is used to provide an indication about the grain-wear and surface roughness. The large wavelength representing the grain has been used in establishing the deflection of the grain. Due to the elastic deflection, the small wavelength representing the cutting edges cuts a smaller groove, which provides a prediction of the rms value of the ground surface in the transverse direction. From the wavelength decomposition of longitudinal profiles, the superimposition of components due to topography of the wheel and kinematic conditions have been identified. The mechanism that leads to such a superimposition is analyzed. Experimental verification of the theory and predictions is given.
Erosion of a Pipe Bend by Solid Particles Entrained in Water
Authors: Blanchard D. J. , Griffith P. , Rabinowicz E.
Published: July 2009

The erosion process in a 90-deg pipe elbow is studied to determine the magnitude and location of the maximum wear point. A two-dimensional, theoretical model of the erosion process is set up to track the particle trajectories and then calculate the wear at impingement. Erosion tests on electroplated, 1-in. I.D. elbows are made using particle sizes which vary by over an order of magnitude, but the location of maximum wear for an elbow whose R/D value is 1.5 is almost unaffected. The average angle, φ, which locates the point of maximum erosion, is determined to be 85 deg, measured from the beginning of the curve. The average wear coefficient, Ke, is found to be 0.011. Another test using a more gradual bend curvature (R/D = 5.0, and a mitre bend tested as an approximation of an elbow with R/D value of 0.5, give similar results.) There are considerable discrepancies between computed and measured values of the position of maximum wear, because the model does not account for secondary flows. Finally, a simple technique is outlined to predict the erosion depth at the maximum wear point.
Self-Excited Chatter and its Marks in Turning
Authors: Kaneko T. , Sato H. , Tani Y. , O-hori M.
Published: July 2009

Investigations were made on self-excited chatter of the work which is held at one end on a lathe machine. Analysis was carried out by a two-degrees-of-freedom system. It was verified that introduction of the multiple regenerative effect governs the finite amplitude of the vibration after it is excited. It was also shown that behavior of the work displacement rotating around the origin during the vibration could be explained by taking into account a resistive force which is inversely proportional to the cutting speed and is proportional to the velocity of the vibration. Phase difference of the vibration occurring for each turn of the work was measured by making use of a microcomputer system. Correlation of the pattern left on the work with the phase difference and with the multiple regenerative effect was studied. A slight change of the vibration frequency varies the pattern even though the phase difference is kept constant. This was also demonstrated by a simulation which generated the pattern of surface shape.
The Creep-Feed Grinding of Hard and Soft Steels
Authors: Morgan J. E. , Salter N. D.
Published: July 2009

The process of “creep-feed” grinding is briefly explained and experimental results, obtained after creep-feed grinding a number of hard and soft low alloy steels, are reported. Surface grinding and deep-form grinding results obtained by previous workers are reevaluated and the possible effect of the presence of hard carbide populations in the work-piece matrix is discussed. The results in this paper, both with and without continuous dressing, show that the bulk homogeneous hardness value of the workpiece directly affects the magnitudes of the specific energies obtained during creep-feed grinding. This hardness-related effect may not necessarily be observed during conventional surface grinding.
An Analytical Investigation of the Honing Mechanism
Authors: Ueda T. , Yamamoto A.
Published: July 2009

The cutting mechanism in the honing operation is analyzed theoretically, assuming that one stick corresponds to a single point tool with a long cutting edge. As a result, an evaluating function to present the overall severity of honing conditions and an equation to calculate the specific cutting force are derived. Moreover, some experiments are carried out to confirm the propriety of these results.
Application of Ultrasonic Forces to Remove Dust From Cotton
Authors: Ensminger D. , Montalvo J. G. , Baril A.
Published: July 2009

Previous studies have led to the determination of the forces of attachment of dust to cotton and of the forces required to remove such dust from cotton. Building on the results of the previous research, a theoretical model has been developed for predicting the intensity of a sonic or ultrasonic field that would be required to remove dust from cotton. The model takes into accout displacement amplitudes, velocities, and accelerations as functions of frequencies and intensities of sonic energy and the anticipated effects on coupling and absorption in the cotton. The theory is compared with experiment.
Space Station Technology Readiness
Authors: Carlisle R. F. , Romero J. M.
Published: July 2009

The paper discusses the meaning of “technology readiness” and how this term fits in the context of the following terms: advanced development, design maturity, risk assessment, qualification, certification, and perceived program need. The architecture of the initial module of the space station must include the provision to enable a systematic and cost-effective growth from the initial module to a space station configuration which includes two or more modules joined together in space. The paper assumes a technology readiness is required in FY 1986 to support an operational initial module of the space station in the early 1990’s. The paper defines ten disciplines/subsystems that make up the performance characteristics of a space station. Each is discussed in turn. A snapshot of the technology available in FY 1983 is used as a reference for future technology planning. A forecast of technology readiness is defined for FY 1986. The planned NASA technology and advanced development program, necessary to move the technology from the identified reference in FY 1983 to the forecast performance in FY 1986, is described including ground rules and assumptions used by NASA in the technology planning, in the use of proto-flight hardware in advanced development tests, and in the alternative techniques to be used for qualification ranging from similarity or certification through black box test or subsystem test. The paper concludes with the view that in order for the evolutionary space station to be economical, productive, and long-lived, provision for subsequent improvements and expansion in technological capability and system performance is required on the initial module. The technology options being investigated by NASA will enable the initial space station module to have provisions for reducing power costs through automated management, closing the environmental control and life support systems loops, automated subsystems, modular data network expansion, and improving human productivity. One generic technology area, automation, is pervasive in that it is an enabling technology for many of the disciplines.
Historical Review
Authors: Hook W. Ray
Published: July 2009

The National Aeronautics and Space Administration began space station studies in 1959 during its first year of existence. Since that time, numerous space station designs have been studied. A wide range of configurations and sizes that would accommodate from two to tens of crew members in space for orbital stay times from weeks to years was created. These designs were influenced by two major factors. First, the Earth launch vehicles available to place the station and logistics vehicles in orbit; and second, the intended purpose or mission of the station. Early designs were heavily influenced by the uncertainty of human performance in space, particularly zero gravity. Consequently, mission emphasis moved from research on humans to research in general and ultimately to industrial operations in space. The resultant design evolution is reviewed with emphasis on technology requirements in light of launch vehicle and mission constraints. The Skylab and Salyut programs are reviewed as a prologue to current planning. Both United States and Soviet experiences greatly influence current thinking. Finally, an overview of current plans attempts to scope the range of space station architectures under consideration in view of the ongoing space shuttle program and future mission needs.
A Stochastic Approach to the Measurement and Analysis of Leadscrew Drive Kinematic Errors
Authors: Bin Hong Zan , Yamazaki K. , DeVries M. F.
Published: July 2009

A practical way to achieve machine tool drive system accuracy is through compensation in the position control loop. Various strategies have been developed in which the compensation data are stored either in a computer or by alternative techniques. The approach described in this paper demonstrates how the dominant causes of the inaccuracies in machine tool drive systems can be determined in a simple and straightforward manner and how the compensation data can be generated using a microprocessor-based calibration technique. The proposed method was demonstrated on a Giddings & Lewis Model 10V Numericenter and consists of three major steps: 1) accuracy measurement, 2) error-map representation, and 3) error-map analysis and error cause diagnosis. Accuracy measurement was accomplished by reading both the resolver counts and the output of a laser interferometer which served as a reference (master) scale. The procedure is based on a strategy in which small 0.5 mm (0.020 in.), highly accurate ±2.5 μm ( ± 0.0001 in.) linear displacements of the machine tool table motion are taken as the measurement reference. An ARMA (Autoregressive Moving Average) model of order (16, 15) is the statistically adequate model that fit the data of the angular displacement of the resolver. The Dynamic Data System technique was used for this purpose and it can also be used to represent the error-map function. A spectral analysis of the ARMA model revealed the sources of the kinematic errors.
Implementing Spacecraft Autonomy
Authors: Dobrotin B.
Published: July 2009

Autonomy is used on spacecraft for minimizing operational cost and providing onboard failure response. System studies have been performed to provide spacecraft design criteria. This paper presents the design drivers and recommended design criteria for the Data Handling Subsystem (DHS). The impact of interfacing spacecraft subsystems, as well as alternate solutions, is discussed. The importance of establishing detail processing requirements through a Failure Modes and Effects Analysis (FMEA) is addressed and related to various spacecraft computer capabilities. A prioritized list of DHS design topics is included.
The Effect of Cutting Speed on Chip Formation Under Orthogonal Machining
Authors: Lee D.
Published: July 2009

Orthogonal machining experiments were conducted at different cutting speeds ranging from 8.5 × 10−2 cm/s (0.17 ft/min) to about 2.5 × 102 cm/s (492.1 ft/min) with 6061-T6 aluminum, 4340 steel, and Ti-6A1-4V titanium to examine the chip formation process. The most pronounced effect of the cutting speed on chip morphology was observed with the titanium alloy; the chips remained segmented at all speeds, but became continuous macroscopically at high cutting speeds. The steel chip also became continuous and oxidized, showing the effect of localized heating. The changing chip morphology that is accompanied with decreasing normal force at the high cutting speed is rationalized on the basis of localized adiabatic heating, which is dependent on the thermal-mechanical properties of each material.
Influence of Low Temperature Thermomechanical Treatment on Some Properties of High Alloy Tool Steels
Authors: Hejmej S. W. , Brown C. A.
Published: July 2009

The modification of mechanical properties (maximum bending strength and deflection, hardness and impact strength) of tool steels whose primary alloying elements are either chromium, tungsten, tungsten and molybdenum, or chromium and molybdenum by low temperature thermomechanical treatment (LTTMT) by rolling with deformations up to 20 percent and extrusion with 60 percent deformation has been investigated. The high chromium tool demonstrated the greatest consistent improvements in strength (40 percent) and deflection (55 percent) for LTTMT over conventional heat treatment. The influence of the LTTMT process on the microstructure of the chromium and tungsten steels is investigated by fractography using a scanning electron microscope. The tungsten steel and the extrusion process yielded a finer distribution of hard particles in the ductile matrix than did the chromium steel and rolling.
Studies on Temperature of Abrasive Grains in Grinding—Application of Infrared Radiation Pyrometer
Authors: Ueda Takashi , Hosokawa Akira , Yamamoto Akira
Published: July 2009

The temperature of cutting grains on wheel surface was measured by means of a new method, in which an optical fiber accepts the infrared flux radiated from the cutting grains and transmits it to an infrared detector InAs cell. This pyrometer makes it possible to observe the history of each cutting grain on the wheel surface. It was found that the temperature of cutting grains at 4.2 ms after cutting is distributed in the range of 500°C to 1400°C, and their mean temperature is 820°C.
Evaluation of a Prototype High Performance Covered Hopper Car
Authors: Arslan Ahmet V. , Kalaycioglu Semih F. , Punwani Swamidas K.
Published: July 2009

In 1980, the Track Train Dynamics (TTD) Program issued “Performance Guidelines for High Performance/High Cube Covered Hopper Cars” to stimulate new car designs and improve upon the dynamic characteristics of existing covered hopper cars. The TTD Program organized a development effort to promote better designs and to subsequently evaluate these cars. Comparative performance characteristics of a “base” car with various prototype cars submitted by car builders are to be determined by comprehensive tests and analytical studies. This paper briefly describes such a test program for the THETA-80 and summarizes the dynamic performance evaluation of this first prototype 100-ton, high-cube covered hopper car, in comparison with the base car. Test regimes consisted of rock-and-roll, pitch and bounce, hunting, curving, and curve entry/exit. The test results indicate considerable performance improvements for the prototype car compared with the base car for all test regimes.
Energy Savings Due to Wheel/Rail Lubrication—Seaboard System Test and Other Investigations
Authors: Allen R. A. , Mimis W. E. , Rownd R. C. , Singh S. P.
Published: July 2009

Following work carried out at the Transportation Test Center (TTC), a test was conducted on the Seaboard System Railroad as the first in a series designed to determine the extent of potential energy savings resulting from lubrication of the interface between the flange of a wheel and the gage face of a rail. The test was conducted on a section of track with significant grades and curvature. Energy savings of approximately 15 percent for lubricated track, as compared with dry track, were measured. The test results are described in the paper. Comparisons of predictions from a train performance simulation computer model with the test results, showed that it is probable that energy savings occurred on tangent track sections, as well as on curves. These predicted tangent track savings are of similar magnitude to those measured at TTC. Through the use of analytical models, the effects of various wheel and truck tolerances and clearances on tangent track resistance are discussed, and it is shown how lubrication can produce a dramatic reduction in this resistance.
Measurement and Prediction of Impact Loads From Worn Railroad Wheel and Rail Surface Profiles
Authors: Ahlbeck D. R. , Hadden J. A.
Published: July 2009

The effects of wheel/rail impact loads are particularly important in the design and use of modern concrete-tie track structures. The development of a computer model for predicting impact loads due to wheel or rail running-surface geometry errors is described in this paper.
Influence of Anisotropy on the Drawability of Continuously Cast Copper
Authors: Ewertz E. J. , Negroni F. D. , Thomsen E. G.
Published: July 2009

Two anisotropic copper rods 12.5 mm in diameter produced in continuous casting operations at different casting speeds were successfully drawn as cast at various reductions in area up to 60 percent. It was found also that hot rolled commercial copper showed anisotropy in shear. With the aid of Hill’s theory of anisotropy it was possible to utilize Avitzur’s model of drawing for the prediction of drawing stresses achieving moderate success. The effect of redundant deformation theoretically computed is discussed.
Some Empirical Evidence on Machine Tool Deterioration and its Use in Projecting Machine Tool Requirements
Authors: Steudel H. J.
Published: July 2009

This paper presents the results of research efforts to estimate the rate at which machine tools deteriorate. A relationship between machine tool deterioration based on component wearout “failures,” and the resulting decline in the productivity of the machine is defined and used as an aid in planning machine tool overhauls and replacements. Deterioration rates for 35 different types of machine tools are estimated via regression analysis using data obtained from a survey on the collective experiences and policies of U.S. industries on over 15,000 machine tools. The results show that different types of machine tools deteriorate at significantly different rates. This information is then embodied in a computerized planning model which incorporates product line sales forecasts, current machine utilization patterns, and machine productivity related to deterioration factors. The planning model can assist manufacturing managers by identifying machine tools which are good candidates for further detailed cost-benefit analysis concerning replacement or overhaul.
An Upper-Bound Solution for Tube Cropping
Authors: Rao R. S. , Wright P. K.
Published: July 2009

An upper-bound solution for the cropping of thin-walled tubes is developed, based on a plastic hinge approach, to predict the load-deflection behavior up to the point of shearing. A simple strain theory is used to estimate the deflection at the maximum cropping load. A deformation pattern (collapse mode) is proposed consisting of plastic hinges and then, for any given deflection, the associated plastic work is calculated. Subsequently, the cropping load is estimated by numerical differentiation with respect to the deflection. Comparisons are made with experiment.
Hydroforming Sheet Metal Into Axisymmetrical Shells With Draw-In of Flange Permitted
Authors: Shang H. M. , Chau F. S. , Tay C. J. , Toh S. L.
Published: July 2009

In this investigation, the clamped portion of copper test specimens is allowed to be drawn slightly into the die throat when hydroformed into axisymmetrical shells. Changing the blank holding load results in different draw-in characteristics. In general, the drawing-in action affects the shape of the shell and also lowers the severity of the deformation and surface area of the deformed shell. Although the nominal thickness uniformity of shells formed with draw-in permitted is improved, the actual thickness is less uniformly distributed. Experimental results also show that, at the beginning of the forming process, the infeeding material due to draw-in is unstretched; but as deformation progresses, stretching of the infeeding material becomes necessary for attaining higher polar heights. The findings of this investigation show that care should be taken in interpreting the test results when the bulge test is used as a formability test. The results also have relevance to many current studies on the “limiting dome height” test for sheet metal.
Optimal Point-to-Point Motion Control of Robots With Redundant Degrees of Freedom
Authors: Fenton R. G. , Benhabib B. , Goldenberg A. A.
Published: July 2009

Control of a kinematically redundant robot arm requires an optimization procedure to determine the motion of the end effector. The criterion for optimization can be minimum motion time, minimum joint displacement increments or a combined merit function specified according to the requirements of the user. Three different methods may be used to perform the computations and obtain the joint coordinate increments for the point-to-point motion control of the robot. The methods are the “direct,” the “pseudoinverse” and the “generalized inverse” methods. These methods are described in detail in this paper, and results obtained with the three methods are compared on the basis of performing simulated tasks. It is concluded that the generalized inverse method is the most suitable, general method for point-to-point control of robots with more than six degrees-of-freedom.
An Adaptive Pressbrake Control for Strain-Hardening Materials
Authors: Stelson K. A.
Published: July 2009

An improved adaptive pressbrake control algorithm is described. The problem is to control the punch reversal position of the press so that the final unloaded angle of the bend remains unchanged in the presence of material property and thickness variations of the sheets or plates being bent. Pressbrake control algorithms that use punch force-displacement data to identify thickness and material property variations have shown promise. However, since previous controllers have been based on an elastic-plastic material model, the parts have been overbent. In this paper, a controller based on an elastic, power-law strain-hardening model is proposed. Experiments have shown that the model eliminates the tendency to overbend the parts that is present in the elastic-plastic algorithm.
Wheel-Rail Wear and Adhesion With and Without Sand for a North American Locomotive
Authors: Kumar S. , Krishnamoorthy P. K. , Prasanna Rao D. L.
Published: July 2009

A systematic laboratory investigation, of the effect of sanding on wheel/rail wear and adhesion, is reported. The tests were conducted on the IIT-GMEMD Wheel Rail Simulation Facility, using Hertzian simulation of the conditions for a typical North American locomotive wheel. Experiments at adhesion coefficients of 0.24, 0.35 and 0.5, with and without sand application on a clean dry rail, show that ratios of terminal and average wear rates, for the two categories of tests, range approximately from 10 to 100. Archard wear coefficients for the two categories are in the range 10 × 10−5 to 50 × 10−5 for tests without sand and in the range 130 × 10−5 to 520 × 10−5 for tests with sand. The ratios of wear coefficients, for tests with and without sand, range from 5 to 30. Adhesion creepage characteristics of a locomotive wheel simulation under different contaminants, such as water, sand, diesel fuel, lubricating oil, sand after oil and oil after sand, are also reported. It was observed that the liquid contaminants decreased adhesion levels and increased creepage. Sand application reduces the high creepage due to liquid contaminants, simultaneously increasing the attainable adhesion levels. Contrary to earlier findings, it was observed that the degree of sanding does influence the adhesion creepage characteristics, low sanding rates resulting in higher adhesion levels and lower creepage as compared to medium/high sanding rates. The wear and adhesion studies indicate that the beneficial effects of sanding in improving adhesion are more than offset by the increased wear rates. This increase is one to two orders of magnitude, compared to no sanding condition, depending on levels of traction. It is concluded that application of sand should be avoided as far as possible and high adhesion should be achieved by other means in order to minimize wear and the resulting track and equipment costs.
Dynamics of High-Speed Milling
Authors: Tlusty J.
Published: July 2009

This paper is based on previous work of the author and his associates which was published in a series of papers, mainly on those given here as references [2–6], dealing with time domain simulation of chatter in milling, with cutting process damping and with stability lobes. These matters are reevaluated here from the particular point of view of high-speed milling. First, the derivation of limit of stability of chatter in the frequency domain is recapitulated, and lobes of stability explained. These lobes should lead to substantial increases of stability at high speeds of milling. Further, corrections to the results of the simple theory using time domain are presented as they are obtained by time domain simulation which takes into account, in a very realistic way, all the main aspects of milling. It is shown that still, in many instances, high gains of stability are achievable by determining and using a particular spindle speed such that the cutter tooth frequency approaches the frequency of the decisive mode of vibrations as measured on the cutter. The usual modes of vibration of a spindle with a long end mill are discussed, and it is shown how a long end mill stabilizes cutting at medium speeds but becomes a flexible element strongly involved in chatter at higher speeds. In the following section, cutting process damping is discussed which has a very strong stabilizing effect at low speeds but is also partly effective at speeds presently in use. This damping is lost in high-speed milling. Typical cases of high-speed face milling of steel and long end milling of aluminum are discussed and a need of about seven times more stiffness for spindle modes and 14 times more stiffness for the end mill mode derived. The former should be achieved by spindles with larger diameter roller bearings while simultaneously the technology for the design of these spindles running at high speeds must be developed. Present research work shows good promise for this development. For the latter, methods of maximum use of the lobing effect should be developed as well as methods of increasing the damping of the end mill mode.