bluuebunny/crossref_metadata_2025 huggingface dataset:
Surface Profile Characterization by Autoregressive-Moving Average Models
Authors: DeVor R. E. , Wu S. M.
Published: November 2010

The surface texture of a machined part is in general composed of three topographical components: waviness, roughness, and errors of form. A new technique for surface profile characterization is introduced which employs parametric stochastic models of the autoregressive-moving average (ARMA) class. The method for obtaining these models for surface profiles is shown by an example. The ARMA modeling technique for profile description is evaluated in three parts to determine its validity, workability, and descriptive power. This analysis is developed through the criteria of ergodicity, sensitivity, and describability. The ergodicity criterion tests the ability of models for physically identical profiles to convey equivalent information. The sensitivity criterion measures the level of detection of topographical differences among profiles by the ARMA model parameters. The descriptive ability of the models is examined by interpreting their parameters in light of the physical components of the profile. To implement this evaluation, ARMA models for eight different milled surfaces are determined and used.
Contributions to Synthesis of Plane Linkages by the Use of Zero Order Transmission Functions
Authors: Handra-Luca V.
Published: November 2010

A method for the dimensional synthesis of a plane mechanism with more than one degree of mobility is developed when the positions of the driven link are given in correlation with those of the driving links. The synthesis is developed both for associated relative positions and, also, for associated absolute positions. It is assumed that the number of positions given is the maximum for which, through synthesis, a single mechanism is obtained. For the solution of the problem complex numbers are used and Newton’s method is recommended for solving the nonlinear systems of equations.
Short-Time Acceptance Test for Machine Tools Based on the Random Nature of the Cutting Forces
Authors: Osman M. O. M. , Sankar T. S.
Published: November 2010

A short-time dynamic acceptance test for machine tools based on a single measurement of a coefficient of dynamic stiffness (Kd) is proposed. A feature of this test is that it takes into account the random fluctuation of the cutting forces that will be experienced by the machine tool in actual operation. Kd is defined as the inverse of the standard deviation of the steady state translational dynamic response of the machine tool under these cutting forces and is a function of the static stiffness of the machine-tool-workpiece system, the damping in the machine, and the equivalent intensity coefficient of the random cutting forces. The analytical expression for the coefficient Kd is obtained from the stationary solution of the Fokker-Planck equation that describes the probabilistic response of the machine tool. The form of excitation considered in the final results is the equivalent “white-noise” spectral density of the ensemble of the cutting forces experienced by the particular machine over the range of feed rates and cutting speeds during operations such as roughing, finishing, etc.
Stylus Tracer Resolution and Surface Damage as Determined by Scanning Electron Microscopy
Authors: Guerrero J. L. , Black J. T.
Published: November 2010

Stylus type instruments that employ needle tracers for examination of surfaces by means of translating the stylus over the surface and recording the undulations which occur during that traverse are analyzed by means of scanning electron microscopy. The scanning electron microscope (SEM) has superior resolution capabilities and can directly record the interactions of stylus with surface. The true levels of resolution of this instrument are measured and discussed in terms of finite size of the stylus, damage produced in the specimens due to stylus plowing, and stylus skipping and nonparallel tracking. The fundamental difference between magnification and resolution is examined in terms of tracer devices. Needle or stylus tracer devices are found to be dynamic microhardness testors which produce outputs which must be carefully judged as to their meaning and reliability in terms of faithfully recording the topographical nature of surfaces. The potential future of the SEM as a true nondestructive surface quality inspection tool is emphasized.
Analysis of Lateral Extrusion of 6061-0 Aluminum by Slip Line Theory Modified to Include Strain-Hardening
Authors: Quenzi P. J. , Kauppila R. W. , Weinmann K. J.
Published: November 2010

An analytical solution for the symmetrical lateral extrusion process based on slip line theory is presented. The analysis incorporates the stress equations modified for strain-hardening and the conventional First Theorem by Hencky. Material flow, material strength, and forces for extruding 6061-0 aluminum are thus analyzed. The calculated ram forces are found to be in substantial agreement with experimental results.
Enhancement of Tungsten-Carbide Tool Life by Oxide Treatment
Authors: Suh N. P. , Shyam S. , Naik S. K.
Published: November 2010

It is shown that the tool life of tungsten-carbide tools can be increased by at least 80 percent by treating the surface of carbide tools with various oxides. Among the oxides that increase the tool life are titanium dioxide, zirconium oxide, aluminum oxide, and chromium sesquioxide. The oxide treatment was done by diffusing the oxide layer, which had been coated on the tool surface, into the subsurface layer in a vacuum of 10−5 torr at various temperatures. The increase in tool life is greater at higher temperatures of the oxide treatment, the maximum temperature being the sintering temperature of the carbide tools. It is believed that the decrease in the tool wear rate is caused by the retardation of mass diffusion between the tool and work, lowering of the chip-tool interfacial friction, and by decrease in the temperature at the chip-tool interface. Other possible causes are also discussed.
Singulation—A Problem in Design
Authors: Henderson J. M. , Shawver B. M.
Published: November 2010

Singulation is formally defined, the state-of-the-art is established through study of over 2000 related patents and singulation devices are categorized into twenty-one fundamental principles of operation.
Engineering Significance of Statistical and Temperature-Induced Fracture Mechanics Toughness Variations on Fracture-Safe Assurance
Authors: Loss F. J.
Published: November 2010

An appraisal is made of linear elastic fracture mechanics (LEFM) as a method of fracture-safe assurance for carbon and low-alloy steels. The theoretical advantage of an exact flaw size-stress level relationship offered by LEFM is contrasted with the limitations posed in actual application. These limitations relate to statistical variations in KIc and KId data. The variations considered here are (a) data scatter at a given temperature, and (b) toughness variations between different heats of a given alloy. In an engineering context, LEFM is considered applicable only in the temperature region representing the initial development of the brittle-ductile transition that characterizes low-alloy steels. In this region statistical variations in the data suggest that critical flaw sizes could be significantly smaller than the values calculated on the basis of limited experimental data. The prime objective in determining fracture toughness is for use in evolving a fracture control plan that assures structural integrity under a variety of environmental and loading conditions. Often the exact flaw size is unknown, particularly if the structure has not yet been built. Since the toughness increases sharply in the transition region, a practical solution is to take advantage of this behavior and choose a minimum operation temperature that assures a high fracture toughness such that postulated flaws cannot propagate in an unstable manner. The objective of being able to define the temperature range and statistical distribution of KId curves is met equally by the use of Dynamic Tear (DT) and KId tests. The DT test, as contrasted with LEFM methods, is shown to be an effective engineering tool with which to determine the Fracture Transition Elastic (FTE) temperature; above this temperature, plane strain constraint is lost for the given thickness, and flaws cannot propagate at stress levels less than yield. The determination of a minimum structural operating temperature based on dynamic LEFM values, when modified by conservatisms necessitated by statistical variations in the data and inaccuracies in temperature measurement, is shown to be essentially equivalent to the FTE temperature.
The Stress Analysis of Heat Exchanger Expansion Joints in the Elastic Range
Authors: Wolf L. J. , Mains R. M.
Published: November 2010

Expansion joints of the style most commonly used in shell and tube heat exchangers were studied analytically and experimentally in the elastic range. A method of computing stresses and deformations for pressure and expansion loadings is demonstrated. Strain-gage tests show the analytical method to be accurate.
Investigation of Pulse Tube Refrigerator
Authors: Narayankhedkar K. G. , Mane V. D.
Published: November 2010

This paper reports a theoretical analysis and experimental investigation of pulse tube refrigerator. A concept of steps is introduced for the derivation of cold end temperature with zero heat pumping rate (Tco). This relation indicates that Tco depends not only on the length ratio, hot end temperature, and ratio of specific heats of gas used, but also on the pressure ratio employed. An empirical relation for heat pumping rate is also suggested. Experimental investigation indicates that there exists an optimum hot end length and that the optimum speed decreases with increase in the total length of pulse tube.
An Evaluation of the Jenike Bunker Design Method
Authors: Wright H.
Published: November 2010

Flow blockage in steelworks bunkers is a major source of trouble. The correct design of bunkers to ensure flow would result in reduced capital and operating costs. The Jenike method of bunker design, which claims a solution to this problem, has been critically examined for a range of iron ores using a variable-geometry wedge-shaped bunker. The main conclusion from these experiments is that the Jenike method is valid for dynamic pressure conditions and even shows some over-design. Further experiments using just one iron ore have confirmed the validity for a conical-shaped bunker under similar pressure conditions. The main limitations of the Jenike design method are as follows: (a) It does not provide a design which can accommodate impact filling. In certain cases, especially with conical bunkers, flow blockage can easily occur and (b) It does not provide a design which can be certain of eliminating arching at the transition point of a bunker with surcharge.
Bin Loads—Part 3: Mass-Flow Bins
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 the walls of containing vessels. In this paper, design formulas and charts are presented for mass-flow bins.
Singular Solutions in Burmester Theory
Authors: Kaufman R. E.
Published: November 2010

A unified complex number development of four position planar finite position theory is presented. This formulation shows that Burmester circlepoint-centerpoint theory specializes to include slider points, concurrency points, poles, and point position reduction by proper interpretation of the trivial roots of the general synthesis equations. Thus a single design technique can be used for the multiposition synthesis of most pin or slider-jointed planar mechanisms. Four position function, path, or motion generating linkages can all be designed in this manner.
Incompletely Specified Displacements: Geometry and Spatial Linkage Synthesis
Authors: Tsai Lung-Wen , Roth Bernard
Published: November 2010

The screw axis geometry associated with displacements of points and lines is studied. Analytical expressions are developed for rigid body screw displacements which have one or more free parameters. It is shown how to apply these results to the synthesis of spatial linkages. The theory is illustrated by numerical examples in which Cylindric-Cylindric cranks are designed to guide two points in a rigid body through five and then nine specified positions.
Acceleration Resolution Applied to Analog Mechanism Simulation
Authors: Fedele S. , Timm R. F.
Published: November 2010

The investigator using analog or hybrid computers in mechanism study encounters great complexity and a requirement for considerable equipment when a simulation is extended to accelerations and dynamics. This paper describes a resolver circuit which is a link analogy giving position, velocity, and acceleration terms in rectangular coordinates when driven with a voltage representing the angular acceleration of the link. It is an elaboration of former resolution methods dealing only with either position or velocity. Its utility involves a savings of computing components and it constitutes a fundamental building block when used in mechanism simulation.
Analysis of Elastic Machinery With Clearances
Authors: Winfrey R. C. , Anderson R. V. , Gnilka C. W.
Published: November 2010

Previous work on the analysis of elastic link mechanisms has been enlarged upon so as to include the effect of intermittent separation and impact between members. A cam-driven valve train is used as an example to demonstrate the methods for analyzing an elastic machine with clearances. Also demonstrated is a method for bookkeeping, or keeping track of the various configurations which the machine can assume due to the clearances. The methods presented here are sufficiently general to be applied to a variety of machinery; however, a cam-driven valve train was selected as an example because (1) it could be represented by a relatively simple elastic model, thus reducing the size of the computer program, and (2) an essentially constant geometry could be assumed, thus saving considerable computational time.
On the Surface Finish-Metal Removal Relationship in Precision Grinding
Authors: Lindsay R. P.
Published: November 2010

A semiempirical equation representing the average chip thickness existing during grinding is presented. The scatter of surface finish data obtained using high and low wheel-speeds and wheel-work conformities, fine and coarse dressing procedures and various system spring stiffnesses is greatly reduced when plotted versus average chip thickness. Two metal removal regions, ploughing and cutting, are clearly defined by the finish-chip thickness graph. Altering machine variables in order to reduce the average chip thickness greatly improves surface finish in the cutting region. In the ploughing region, the finish improvements are smaller because the degree of ploughing and grooving of the workpiece possibly affects the measured finish.
The Character of Regenerative Chatter in Cylindrical Grinding
Authors: Thompson R. A.
Published: November 2010

The steady state regenerative response of a cylindrical grinder is found. The goal of the work is to characterize chatter and find ways to monitor grinding performance. It is shown that the wheel-workpiece coupling stiffness and thus the theoretical tendency to chatter is less for a climb cut than for a normal cut. The existence and precession of both wheel and workpiece lobes is discussed. When chatter disappears the lobes become essentially equal in height. In this case a rough surface can be generated in the absence of chatter. The ratio of the lobe precession rates is indicative of the grinding ratio. The easily monitored precession therefore provides an in-process measure of grinding performance.
Cutting Fluids Performance: Part 1—Optimization of Pressure for “Hi-Jet” Method of Cutting Fluid Application
Authors: Nagpal B. K. , Sharma C. S.
Published: November 2010

The results of a series of short-run cutting tests conducted with “Hi-jet” system using four common commercially available fluids are presented. The possibility of using these tests for on-the-spot determination of optimum pressure is discussed. The dependence of the optimum pressure on the feed rate is investigated.
The Prediction of Press Loads in Deep Drawing With Various Conditions of Lubrication at Elevated Temperatures
Authors: Pope M. H. , Berry J. T.
Published: November 2010

The present work is introduced and is shown to be a logical extension of work by Chung and Swift, Ray and Berry, et al. The authors introduce the deep drawing process and analyze the stresses due to radial drawing (including friction), bending the sheet, unbending the sheet, and die profile friction. From these stresses, an expression for the total punch load is developed. The authors also describe the experimental work in which determinations are made of the work hardening exponents, the anisotropic coefficients, the friction coefficients, and the total punch load. The paper concludes by comparing the numerical evaluation of the maximum punch load with that determined from experiments.
An Insight into the Features of the OAO-C Thermal Design
Authors: Fine H. , Quadrini J. , Ollendorf S.
Published: November 2010

The Orbiting Astronomical Observatory (OAO)-C was successfully launched into 400-nautical mile circular orbit on August 21, 1972. For this spacecraft, a unique sensitivity approach to the thermal design was developed which resulted in a predictal design—the merits of which should be considered for application on future spacecra. The OAO-C is also serving as a test bed for the evaluation of thermal control hardware. To provide flight data for space program applications, experiments for a new coating and four different heat pipe designs are on this spacecraft. The data derived from OAO-C will be extremely valuable for such future programs as the Large Space Telescope (LST) and the Earth Observation Satellite (EOS). This paper will describe the detailed of the sensitivity design approach and thermal control hardware. For all aspects discussed, a comparison of pertinent analysis, ground test data, and flight data [1] will be given.
Application of Constrained-Layer Damping to Control Noise in Machine Parts
Authors: Emerson P. D.
Published: November 2010

A layer of visco-elastic material bonded between surfaces of a vibrating structure and a constraining layer produces appreciable damping of vibration. Application of the technique to textile spindles effectively reduces vibration transmitted to machine frames. When applied to circular saws the techniques is effective only when the constrained layer is subjected to shear stress.
Reliability and Economic Analyses Applied to Mechanical Equipment
Authors: Nelson N. W. , Hayashi K.
Published: November 2010

An approach is presented whereby the design and replacement of finite life equipment may be approached in a rational manner. Considering manufacturing operations large enough to give a sufficient component population, statistical methods are used to predict failure distributions and attendant cash flows. Cash flows are minimized to yield optimum replacement schedules. Component design is optimized by relating component failure probability to initial investment. By considering component replacement according to the above described optimum replacement schedules, optimum initial investment is determined. The approach is illustrated by the problem of the design and retirement of furnace tubes.
Dynamic Behavior of Heavy-Loaded Spur Gears
Authors: Ichimaru Kazunori , Hirano Fujio
Published: November 2010

In order to analyze causes of failures of heavy-loaded spur gears, the authors deal with their dynamic characteristics by considering a vibrating system composed of an effective mass of gear blanks and stiffness of meshing teeth with manufacturing errors under a given operating condition. Even in the case of gears with considerable errors the coincidence of the theoretical findings with experimental results is satisfactory. Under heavy-load conditions the plastic flow produced in the subsurface layers of gear teeth is found to affect the variation of the dynamic load considerably owing to a local change of the tooth profile. The interaction between the tooth deformation and the dynamic load is investigated experimentally and theoretically. The authors treat the conditions of initiation of the gear failures in the representative modes, e.g., pitting and scoring, in connection with the dynamic load.
Friction Induced Rotor Whirl—A Study in Stability
Authors: Begg I. C.
Published: November 2010

Of deep concern to designers of high speed, close clearance rotating machinery is that type of self-excited rotor whirl induced by rubbing friction between rotor and stator. Since the probability of transient or continuous rubbing is high, it is important to determine whether the consequent whirl will be sustained, whether it will decay, or whether it will increase destructively. This paper develops, for a simple flexible overhung rotor, an analysis showing that regimes of stability, dependent upon damping and stiffness characteristics, do indeed exist. A stability chart is computed for the selected model and this may be used to determine whether a specific disturbance deflection will decay, grow, or remain constant during the disturbance or after its removal.
A Sparse Matrix Technique for Fundamental Mode Analysis in Power Transmission Systems
Authors: McLay R. W. , Burroughs S. H.
Published: November 2010

A method is presented that allows the rapid prediction of the fundamental frequency and mode shape for a power transmission system. It is based on a programming technique taken from the chemical literature. A sparse matrix procedure is shown which allows efficient programming of this method. A technique for eliminating the rigid-body rotation is illustrated. Numerical results are discussed.
Vibration of Frame Foundation With Bilinear Hysteresis for Rotating Machinery
Authors: Karasudhi P. , Tan G. , Lee S. L.
Published: November 2010

The vibration of a single-story frame with bilinear hysteresis supporting a rotating machine is analyzed. The excitation force caused by the rotating unbalanced mass of the machine has a frequency dependent amplitude. The bilinear hysteresis of the resisting force of the frame to the motion is derived from the bilinear moment-curvature relationship of the frame columns. Solving the equation of motion of the system by the method of slowly varying parameters, the system exhibits unbounded resonance when the product of the machine unbalanced mass and its eccentricity exceeds a critical value. For the purpose of design and analysis of this type of structures, the displacement amplitude is plotted against arguments of the frequency for various values of two parameters involved.
Vibration Characteristics of Free Thin Cylindrical Shells
Authors: Cunningham F. M. , Leanhardt D. E.
Published: November 2010

This paper considers the flexural vibrations of free thin circular cylinders. A frequency equation is derived using free-free characteristic beam functions to represent the variation of mid-surface shell displacement components, u, v and w, with respect to the axial direction. Timoshenko strain-displacement relations for thin cylinders are used to determine elastic vibratory strain energy. Energy methods are applied to obtain the frequency equation and associated amplitude ratios for each of its roots. This energy solution is checked experimentally using a vibration exciter and numerically using the SABOR IV finite element program. With minor modification, the frequency equation conforms to the one obtained in a similar way by Arnold and Warburton for cylinders with clamped ends and simply supported ends. Thus the proposed form of frequency equation, by accommodating a greater variety of boundary conditions, simplifies the task of determining cylinder vibration characteristics.
Transient Response of Inelastically Constrained Rigid-Body Systems
Authors: Park K. C. , Saczalski K. J.
Published: November 2010

An energy rate balance is employed to develop the incremental equations of motion for a shock loaded, inelastically constrained rigid-body structural system. Lagrangian multipliers provide the coupling mechanism necessary to reduce the overall system of equations to a set of modified rigid-body equations which include the nonlinear geometric and structural material effects. Kinematic material hardening and a modified yield criteria are used. Examples illustrate the technique and are compared with experimental results.
The Orbital Movement and the Damping of the Fluidelastic Vibration of Tube Banks Due to Vortex Formation: Part 2—Criterion for the Fluidelastic Orbital Vibration of Tube Arrays
Authors: Chen Y. N.
Published: November 2010

The phenomenon on the tubes in a tube row, which vibrate alternately along the row in the transverse and stream-wise directions, will be explained by a vortex model. This model consists of the symmetrical vortex pair trains behind the stream-wisely vibrating tubes, and the Karman vortex streets behind the transversely vibrating tubes. It will be shown in the paper that the coupling between these two groups of vortex systems can excite the tube arrays to perform this fluidelastic vibration. A criterion for the onset of this orbital movement will be given with the expression ξ = R/Sxt. This criterion predicts a strong fluidelastic vibration for tubes with low transverse tube spacings and low natural flexible frequencies in a high speed flow. The theory leading to this criterion is based on the phenomenon of the variation in the position of the separation point for the free shear layer during the cylinder vibration. A switching of the jet for maintaining the fluidelastic vibration is then a result of this variation.
Semiclosed Cycle Internal Combustion Engine Utilizing Cryogenic Exhaust Solidification for Undersea Applications
Authors: Rathsam A. D.
Published: November 2010

The paper describes the design, hardware, testing, and performance of a breadboard semi-closed cycle power system proposed for undersea operations by the Naval Undersea Center. The work was performed to prove the feasibility of the system. The system includes a commercially available spark-ignition engine, which operates on natural gas, oxygen, and recirculated exhaust gas, and a specially designed liquid oxygen/excess exhaust gas converter. The converter utilizes heat from dry, precooled exhaust gas to vaporize liquid oxygen and provide oxygen for the engine. While providing heat for liquid oxygen vaporization, the exhaust gas becomes frozen. The well-insulated converter is designed with ample storage capacity for both liquid oxygen and solidified exhaust. Nonoptimized hardware provided reliable airbreathing and nonairbreathing operation. Tests indicate that the approach is feasible for undersea applications.
Modernization and Expansion of the Ore Handling Facilities at Sparrows Point
Authors: Keeney C. A.
Published: November 2010

A major construction program, including a computerized automatic control system, was initiated to improve the ore handling and ship docking facilities at Sparrows Point. Although the basic concept for the handling of ore has not changed, many innovations have been implemented.
On the Relation Between the Factor of Safety and Reliability
Authors: Dao-Thien My , Massoud M.
Published: November 2010

An approximate relation between the reliability of a design and the classical deterministic factor of safety, used in the design, is presented. An expression of the reliability as function of the mean value and coefficient of variation of the probability density distribution of the factor of safety, is derived. Further, the relation between the deterministic factor of safety and the statistical values of the probabilistic factor of safety, is discussed. Finally an expression for the reliability as a function of the deterministic factor of safety and the parameters determining the stress and strength distributions, is obtained. This function relationship is expressed in a design nomogram relating all the parameters involved.
Nonlinear Wheelset Dynamic Response to Random Lateral Rail Irregularities
Authors: Law E. H.
Published: November 2010

The nonlinear equations of motion for a railway vehicle wheelset having profiled wheels and contact of the wheel flange with flexible rails are presented. The effects of spin creep and gyroscopic terms are included. The rails are considered to have random lateral irregularities which are described by prescribed power spectra. The equations of motion are integrated numerically and the effects on the dynamic response of quantities such as speed, track roughness, wheel wear, flange clearance, and lateral stiffness of the rails are investigated.
On Probabilistic Design
Authors: Bury K. V.
Published: November 2010

The probabilistic approach to design is developed and contrasted with the conventional safety factor approach. A careful interpretation of random variable design inputs is given, leading to a statistical extreme-value model of loads. In addition to the “reliability” concept, the concept of “mission length” is explicitly introduced to the design process. A simple design problem, involving random variable loads and constant material properties, is solved and illustrated. Possible extensions of this design problem, and their likely difficulties, are indicated.
Air and Power Requirements for the Pneumatic Transport of Crushed Coal in Vertical Pipelines
Authors: Konchesky J. L. , George T. J. , Craig J. G.
Published: November 2010

Empirical equations were developed giving minimum air and power requirements for the vacuum and pressure transport of crushed coal through vertical pipelines. Data used in the development were obtained from transport tests in a 50-ft vertical 6-in.-dia pipeline and in a system of 2-, 4-, 6-, and 8-in.-dia horizontal pipelines, each preceded by a short vertical run. The air and power requirements are dependent upon coal rate and specific gravity, upon pipe diameter and length, and upon the ratio of cross-sectional area of the coal pickup section to the pipe. Coal size was not a variable, but the largest lumps could not exceed four-tenths of the pipe diameter. The highest throughput achieved in the 50-ft vertical pipeline was 27 tons per hr of 2-1/2- by 0-in. coal rejects of 2.9 specific gravity. In this experiment with a pickup-to-pipe area ratio of 4.6 to 1, about 1750 actual cu ft per min of air was required at the pipeline entrance to keep the coal moving without floating, and the pressure drop across the pipeline was 2.5 psi. Extrapolation of the equations can be used for designing larger and higher capacity vertical pipeline systems. For example, assuming a pressure drop of 20 psi and a pickup-to-pipe area ratio of 3 to 1, extrapolation indicates 65 tons per hour of 5- by 0-in. coal (sp. gr. 1.40) could be transported through 1000 ft of vertical 12-in.-dia pipe by 7300 actual cu ft of air per min (17,200 standard cu ft per min) at the pipeline entrance at the expense of 1080 theoretical horsepower.
Profile Characterization of Manufactured Surfaces Using Random Function Excursion Technique—Part 1: Theory
Authors: Sankar T. S. , Osman M. O. M.
Published: November 2010

This paper discusses a new approach for describing accurately the typology of manufactured surfaces. The method employs the theory of stochastic excursions to characterize the surface texture in the amplitude and lengthwise directions. The mathematical principle behind the approach is briefly explained, and it is shown that an accurate description of the roughness can be obtained from the knowledge of the intercept probabilities of the crest and valley excursions of the surface texture about any given level, say the CLA value, specified with respect to the mean line. Based on the preceding excursion probability densities, new surface texture parameters are proposed. These parameters may be computed directly from the surface roughness data obtained from commercially available measuring devices. On the basis of this investigation, it is feasible to develop a low-cost measuring device for “on-line” surface evaluation in production. It is also shown that the sampling length provides a geometrically well-defined filter characteristic similar to that of the rolling circle radius in the E-system.
Flanged Acrylic Plastic Hemispherical Shells for Undersea Application
Authors: Stachiw J. D. , Maison J. R.
Published: November 2010

The effects of an equatorial flange and a nonuniform wall thickness upon the critical pressure and stress distribution in acrylic plastic hemispheres have been investigated by experimental and analytical methods. Forty acrylic hemispheres were fabricated and tested to destruction under short term hydrostatic pressure applied on the convex surface. Dome apex displacements were obtained from each specimen and strains were obtained from a selected few. A finite element elastic analysis was performed on one window configuration for two different boundary conditions and the experimentally derived stresses were used to determine which boundary conditions was the best for analytical analysis.
Integrated Water and Waste Management System for Future Spacecraft
Authors: Ingelfinger A. L. , Murray R. W.
Published: November 2010

Over 200 days of continuous testing have been completed on an integrated waste management-water recovery system developed by General Electric under a jointly funded AEC/NASA/AF Contract. The 4 man system provides urine, feces, and trash collection; water reclamation; storage, heating and dispensing of the water; storage and disposal of the feces and urine residue and all of other nonmetallic waste material by incineration. The heat required for the 1200 deg F purification processes is provided by a single 420-w radioisotope heater. A second 836-w radioisotope heater supplemented by 720 w of electrical heat provides for distillation and water heating. Significant test results are no pre-or-post treatment, greater than 98 percent potable water recovery, approximately 95 percent reduction in solids weight and volume, all outflows are sterile with the water having no bacteria or virus, and the radioisotope capsule radiation level is only 7.9 mrem/hr unshielded at 1 m (neutrons and gamma).
Laminar Flow of Non-Newtonian Fluids in an Eccentric Annulus
Authors: Guckes T. L.
Published: November 2010

The volumetric flow rate for the steady flow of power-law and Bingham-plastic fluids in eccentric annuli is presented as a series of dimensionless plots. The plots cover a broad range of fluid properties, pipe diameters, eccentricity, and pressure drop. These relationships were obtained by numerically integrating the velocity profile resulting from a finite difference solution of the equations of continuity and motion after transformation into bipolar coordinates. The numerical procedure was verified by comparing calculations with previously published results for the special cases of Newtonian flow in an eccentric annulus and non-Newtonian flow in a concentric annulus and with limited experimental data for Bingham-plastic flow in an eccentric annulus.
Displacement Analysis of the Generalized Clemens Coupling, The R-R-S-R-R Spatial Linkage
Authors: Wallace D. M. , Freudenstein F.
Published: November 2010

The Clemens Coupling is a constant-velocity, universal-type joint for nonparallel intersecting shafts. This mechanism is a spatial linkage with five links connected by four revolute pairs, R, and one spherical pair (ball-and-socket joint), S, which is located symmetrically with respect to the input and output shafts. The Clemens Coupling is a special case of the R-R-S-R-R spatial linkage with general proportions, which will, therefore, be called the Generalized Clemens Coupling. This paper gives the algebraic derivation of the input-output equation for the general R-R-S-R-R linkage and demonstrates that it is a fourth-order polynomial in the half tangents of the crank angles. The effect of housing-error tolerances on the displacements of the Clemens Coupling has also been considered. The results demonstrate feasibility of closed-form solutions for five-link mechanisms with kinematic pairs having more than two degrees of freedom.
Geneva Mechanisms Connected in Series
Authors: Fenton R. G.
Published: November 2010

Two suitably matched Geneva-wheels driven in series are proposed to convert uniform rotary motion to intermittent rotary motion. The suggested mechanism is simple, and its kinematic characteristics are very desirable. The output motion starts and ends with zero acceleration. The acceleration increases gradually at the beginning and ends smoothly at the end of the motion cycle. The undesirable shock loadings, typical of the simple Geneva-mechanisms, are completely eliminated. A further advantage of the proposed mechanism is that the ratio of dwell to motion times can be selected from a considerable range of possible values.
Heat Exchanger Design for Ocean Thermal Difference Power Plants
Authors: McGowan J. G. , Connell J. W.
Published: November 2010

This paper discusses variations in heat exchanger design and configuration for a class of ocean thermal power plants. Details of the heat exchanger models are summarized and analytical results for component and cycle variations are presented. A heat exchanger optimization program is discussed in detail and preliminary results for this study are given.
Dynamics of High-Speed Cam-Driven Mechanisms—Part 1: Linear System Models
Authors: Chen Fan Y. , Polvanich N.
Published: November 2010

The dynamic response of the cam-driven mechanism is investigated for a variety of cam motion profiles. Based on a linear, lumped system model of single degree of freedom, the results of the response characteristics of the follower are presented in the form of nondimensional primary and residual shock response spectra. These spectra are also recasted in four-coordinate log-log grid forms. The extension of this approach to treat the system model of two degrees of freedom is delineated. Furthermore, the analysis of a two-freedom model of the cam-driven system was also undertaken to clarify the effects of many system parameters and for obtaining an optimal design. Fundamental design charts are presented.
The Use of Decelerative Metal Cutting in the Design of Energy-Management Systems
Authors: Pleck M. H. , Metz L. D. , Conry T. F.
Published: November 2010

This paper focuses on the design principles basic to the development of devices that can be used to absorb and manage energy during collisions. Design guidelines and a chart are developed for minimum-stroke energy-absorbing devices. It is shown that decelerative metal-cutting displays force–velocity characteristics that are highly efficient for the management of collision energy in the majority of practical design applications of interest. Examples of metal-cutting energy-management devices are developed.
Computer Design of a Vibration-Free Face-Milling Cutter
Authors: Doolan P. , Phadke M. S. , Wu S. M.
Published: November 2010

A method is developed to choose the blade spacing for a face-milling cutter that will minimize vibration. When the dynamic frequency response of a machine-tool-workpiece system is known, a special-purpose cutter can be designed to minimize the relative cutter-workpiece vibration for a particular cutting speed. When the dynamic system response is unknown the design method is limited to a general-purpose cutter to avoid resonant excitation over a broad frequency range. A nonlinear least-squares method is used to choose the blade angles for both cases. Experimental results using a general-purpose cutter with unequal blade spacing showed an appreciable reduction in noise and vibration compared to a similar cutter with equal blade spacing.
Effect of Stiffness on Tool Wear and New Tool Life Equation
Authors: Kuljanic´ E.
Published: November 2010

An investigation of the effect of stiffness of the machining system on tool life with different numbers of teeth in the cutter, cutting speeds, and feeds is described. A statistical analysis was used and the effects of significant factors and interactions were determined. Not only the cutting speed, feed, and number of teeth in the cutter, but also the stiffness and their interactions have a significant effect on tool life. Due to a significant effect of interactions, the effect of the stiffness of machining system depends on the number of teeth in the cutter, cutting speed and feed. A new tool life equation was developed to take this phenomenon in account. The tool life decreases with increasing the number of teeth in the cutter. The static and dynamic stiffness was measured by means of a pulse-testing method which is both simple and reliable in determining the dynamic characteristics of a machining system.
The Design of Modeled Cam Systems—Part II: Minimization of Motion Distortion Due to Modeling Errors
Authors: Matthew G. K. , Tesar D.
Published: November 2010

The dynamic synthesis procedures of Part I are reinforced by qualitative and quantitative results from analysis. The principal concern is for the motion distortion which results from off-speed operation and from errors in the model parameters. Elementary direct means for calculating errors due to transient vibrations and inertia force variations are given which eliminate the need for complex analysis procedures. Rules of thumb are developed which enable the designer to choose system parameters to minimize motion distortion and inhibit growth of wear and consequent noise.
Vibrations of a Row of Circular Cylinders in a Liquid
Authors: Chen Shoei-Sheng
Published: November 2010

The effects of interaction with surrounding liquid on the dynamic behavior of a row of circular cylinders are studied analytically. First the hydrodynamic forces associated with cylinder motions are obtained using the potential flow theory. Then a method of solution is presented for free and forced vibrations of a row of cylinders. The results of this study have important application in the modeling of crossflow-induced vibration of heat-exchanger tubes.
Substitute for the Impact Damper
Authors: Cronin D. L. , Van N. K.
Published: November 2010

A barrier to the widespread use of the impact damper is its noisy operation. Described in this paper is work related to the development of a substitute for the impact damper combining effective vibration reduction and low noise while preserving simplicity and light weight. The device is a vibration-driven, free-piston pump which dissipates energy by forcing air through throttling valves at either end of its container during operation. Equations of motion are developed for a single-degree-of-freedom oscillator and attached free-piston damper. The thermodynamic cycle assumed for the damper involves polytropic compression, expulsion at constant pressure, polytropic expansion, and intake at constant volume. The resulting nonlinear formulation is analyzed approximately using the method described by Kryloff and Bogoliuboff. Ranges of system parameters providing nonimpacting steady symmetric operation are developed, and stability is explored. A digital model is formulated to investigate transient response and to establish the ranges of stable operation possible when the system is started from rest. It is established by comparing approximate and simulated results that when steady symmetric operation without impact is achieved, the approximate analysis provides a good prediction of system response amplitude. The relative efficacy of an impact damper and a free-piston damper of comparable weight is examined, and it is established that the free-piston damper may prove a suitable substitute for particular applications.
The Application of Impact Dampers to Continuous Systems
Authors: Roy Ranjit K. , Rocke Richard D. , Foster J. Earl
Published: November 2010

A study has been made of the application of impact dampers to two types of continuous systems, a simply supported and a clamped beam. Experimental models were tested in the laboratory and computer programs were developed to calculate response by two separate approaches. Results from calculations agreed favorably with experimental tests. Curves presented show the response to be expected for values of significant system parameters and enable the user to apply impact dampers to these types of continuous systems.
Destructive Vibration of Trashracks due to Fluid-Structure Interaction
Authors: Crandall S. H. , Vigander S. , March P. A.
Published: November 2010

Trashracks in pumped storage systems with high flow rates can develop fatigue failures due to excessive vibration excited by the flow past the rods in the rack. An experimental study of trashrack vibration was made on a half-scale model of a prototype rack design for the TVA Raccoon Mountain pumped storage system. The natural frequencies and loss factors of the first dozen natural modes of the rack were determined in air before placing the rack in a water channel. Under normal flow rates the rack developed “locked-in” pure tone vibrations of sufficient amplitude to cause early fatigue failure. Unexpectedly, the frequency of the vibration was not close to the vortex-shedding frequency and the motion of the rods was not transverse to the flow. The “locked-in” modes were identified as modes in which the bending displacements of the rods were parallel to the flow. Further investigation showed that the excitation mechanism involved synchronization between the fluctuating drag involved in vortex shedding and the fore-and-aft motion of the rods in sharply resonant modes. Modifications of the original design were introduced to defeat the identified mechanism. In order to completely eliminate the “lock-in” phenomenon it was necessary to change the bar cross-sectional shape and to introduce additional damping into the rack structure. A half-scale model of the modified design was built and tested to verify the absence of destructive vibrations.
Squeeze Film Dampers: Amplitude Effects at Low Squeeze Numbers
Authors: Sadd Martin H. , Stiffler A. Kent
Published: November 2010

Gaseous squeeze film dampers are analyzed to determine the effect of periodic disturbance amplitude on the dynamic performance. Both circular and rectangular parallel surfaces are investigated. A solution of the nonlinear Reynolds equation is obtained by expanding the pressure in powers of the squeeze number σ, retaining up to and including terms 0(σ2). The time dependent load characteristics are found. The effect of disturbance amplitude on the film stiffness and damping is given.
An Evaluation of Grinding Performance for Single and Polycrystal Grit Aluminum-Oxide Grinding Wheels
Authors: Kirk James A.
Published: November 2010

Dry surface grinding tests have shown a large difference in the number of passes to workpiece burn between structurally identical single and polycrystal Al2O3 vitrified grinding wheels. Special composite grinding wheels were designed and built to observe sequentially wear flat development in the scanning electron microscope. No difference in wear mechanisms was found for the two types of wheels. The difference in grinding performance is explained in terms of the number active cutting points per unit area and the dislodgment of dressing damage.
Experiments on Adaptive Control of a Milling Machine
Authors: Bedini R. , Lisini G. G. , Pinotti P. C.
Published: November 2010

The paper describes a theoretical and experimental research on adaptive control of the metal-cutting process. Results of experiments performed in various cutting conditions on a milling machine connected to a process computer acting as adaptive controller are reported. The behavior of the adaptive control system in stationary and transient conditions and in presence of air gaps has been tested and the results are discussed.