bluuebunny/crossref_metadata_2025 huggingface dataset:
Radiation and Temper Embrittlement Processes in Advanced Reactor Weld Metals
Authors: Hawthorne J. R. , Fortner E.
Published: November 2010

Experimental weld filler metals having high resistance to radiation embrittlement at ≃550 F (288 C) have been developed for quenched and tempered A543 and A542 steel. The filler metals are from a special 2-1/4 Cr-1 Mo-0.40Si-0.10C composition series formulated to study the effects of variable copper, nickel, and manganese contents on weld performance. This report presents an advanced evaluation of weld deposit performance based on new Charpy-V (Cv) and tension data and an analysis of temper embrittlement and radiation embrittlement processes. High fluence assessments confirm the high resistance to radiation embrittlement of the low copper content filler metal group. A 530 F (277 C) irradiation of one typical submerged arc weld deposit to a fluence of 3.8 × 1020 n/cm2 > 1 MeV did not elevate its Cv 30 ft-lb transition temperature to above 275 F (135 C) or reduce its Cv shelf energy level to below 50 ft-lb. Radiation embrittlement saturation was not evident. Temper embrittlement and radiation embrittlement development and the probable mechanisms of copper and phosphorus influences on radiation embrittlement sensitivity are analyzed with the aid of experimental data for the weld metals and A543 plate. Temper embrittlement and radiation embrittlement are shown to be additive effects which can occur simultaneously or sequentially. A separate component of irradiation effects, manifested as a strength increase without embrittlement, is revealed. The enhancement of radiation sensitivity by high copper content (≧0.16–0.27 percent Cu) is related to a copper influence on the radiation elevation of yield strength; the enhancement of radiation sensitivity of phosphorus is ascribed to a detrimental effect similar to that of temper embrittlement. It is proposed that copper acts to pin radiation-induced defect aggregates and dislocation arrays in the matrix and that phosphorus segregates during irradiation to weaken the interface of ferrite platelets and carbides.
On the Use of the Nodal Elastica for the Analysis of Flexible Link Devices
Authors: Shoup T. E.
Published: November 2010

The equations of the nodal elastica describing the static behavior of an end-loaded flexible strip include forces, elastic properties, dimensions, and some parameters which are not physically measurable. This paper presents a technique whereby the designer can determine reasonable first approximations to the parameters contained in the equations of the nodal elastica. These first approximations are particularly useful for the iterative solution required for the analysis of flexible link devices. An example of the use of this technique is presented.
Analysis of Piping With Flexible Joints
Authors: Lind N. C. , Fung P. K.
Published: November 2010

A method is described for the analysis of structural systems containing flexible joints. The formalism of mechanical systems theory is employed to show that there always exists at least one rigid-jointed system equivalent to a system with flexible joints. In practice, the flexibility components of a joint are obtained experimentally; the prerequisite transformations are described. The analysis is illustrated by an example, showing that joint flexibility may be a significant factor in the stress analysis of a piping network. It is also shown that the equivalent rigid-jointed system cannot be given a physical representation. Finally, the best physically realizable approximation is given for a tee or a wye joint.
A Probabilistic Approach to the Determination of the Optimum Cutting Conditions
Authors: Iwata K. , Murotsu Y. , Iwatsubo T. , Fujii S.
Published: November 2010

An analytical method applying a chance-constrained programming concept is proposed to determine the optimum cutting conditions considering the probabilistic nature of the objective function and constraints. The proposed analytical method is illustrated through an application to an example. It is shown that the optimum cutting conditions are significantly affected by the probabilistic nature of coefficients in the constraints. The effect of the uncertainty of the predicted tool life in the production cost function on the optimum cutting conditions is also considered. The study further investigates the effects of the cost-time parameter and allowable maximum force on the optimum conditions and the resulting production cost.
Mathematical Model of Vehicle Safety Deformation Under Impact—Design for Safety
Authors: Gross L.
Published: November 2010

Under impact, when the velocity is reduced from its initial value vo to zero over a very short period of time, the deceleration a and its rate of increase a˙ (the principal parameters determining the survival of the occupants) are dictated by the length x of the vehicle deformation and by its dynamic process. The model equation suggested by the author is a = Ktn with 0 < n < 1. The constants K and n depend on the design of the vehicle and on deformation conditions. Alternative mathematical expressions of safety deformation requirements are considered with a view to improved design in the future and to speed restrictions on designs currently in use. Analysis of the formula reveals the conflict between the requirements for low a and a˙, as well as the problem of high initial a˙. An acceptable compromise can be recommended. Using suitable n values, a more satisfactory dynamic process can be achieved and the time of deformation tt can be increased considerably at a given length xt. The optimal value for n seems to be around 1/4. The concepts of deformation coefficient and deformation factor are included in the discussion.
Conical Shell Inversion—An Approximate Energy Analysis
Authors: Jones J. W. , Wagner J. G.
Published: November 2010

The plastic inversion of a simply supported conical shell is considered. The shell is loaded through a rigid central collar. The material is assumed to be elastic-perfectly plastic and to obey the Tresca yield criterion. Upper and lower bound calculations are presented for the collapse load of the inverted configuration. The steady state load-deflection behavior for the large deflection inversion process is determined through a continuous application of the upper bound calculation. Minimization of the upper bound serves not only to determine an accurate characterization of the load-deflection curve but also provides a realistic measure of the bend radius associated with the mode of deformation assumed. Experimental results are presented and compared with the theory.
Measurement of Powder Properties for Hopper Design
Authors: Schwedes J.
Published: November 2010

It is common practice in powder technology to run shear tests for characterizing the flowability of powders. To measure these shear properties the flow factor tester of Jenike is mainly used. In this apparatus the state of stress cannot be determined completely and assumptions regarding the position of slip planes are necessary to evaluate the test results. Therefore this apparatus is less applicable in research work to get more information on the stress-strain behaviour of powders. In order to make such work possible a new apparatus, based on the ideas of Roscoe, has been developed, in which the states of stress and strain can be determined completely. Test results from measurements with both apparatuses will be compared and it will be shown, how the different results influence the design of hoppers.
Constant-Velocity Shaft Couplings: A General Theory
Authors: Hunt K. H.
Published: November 2010

The theory here expounded reveals certain inescapable geometrical conditions with which all couplings must comply when they are required to reproduce at the output shaft, simultaneously and precisely, all angular input shaft displacements. Plunging-type linkage couplings, whose geometrical forms follow very simply from the theory, are fully listed for both intersecting and parallel shafts. Many, particularly those for parallel shafts, are entirely new, and it is believed that there could be useful precision-engineering applications.
Application of Linear and Nonlinear Graphs in Structural Synthesis of Kinematic Chains
Authors: Huang M. , Soni A. H.
Published: November 2010

Using graph theory and Polya’s theory of counting, the present paper performs structural synthesis and analysis of planar and three-dimensional kinematic chains. The Section 2 of the paper develops a mathematical model that permits one to perform structural analysis and synthesis of planar kinematic chains with kinematic elements such as revolute pairs, cam pairs, springs, belt-pulley, piston-cylinder, and gears. The theory developed is applied to enumerate eight-link kinematic chains with these kinematic elements. The Section 3 of the paper develops a mathematical model that permits one to perform structural analysis and synthesis of multi-loop spatial kinematic chains with higher and lower kinematic pairs. The theory developed is applied to enumerate all possible two-loop kinematic chains with or without general constraints.
A Lumped Parameter Approach to Vibration and Stress Analysis of Elastic Linkages
Authors: Sadler J. P. , Sandor G. N.
Published: November 2010

A method of kineto-elastodynamic analysis is developed employing lumped parameter models for simulating moving mechanism components considered as simply-supported beams subject to in-plane bending. Application of finite difference approximations to Euler’s beam theory leads to a system of nonlinear, ordinary differential equations of motion, and numerical solution of these equations is illustrated for specific examples. Variable as well as uniform cross-section members are analyzed for elastic vibration and stresses. By means of a general optimization procedure presented, nonuniform beam contours are obtained which provide a substantial stress reduction relative to the uniform case, without a corresponding increase in total mass.
Guidance of a Rigid Body in a Fixed Track
Authors: Freudenstein F. , McLarnan C. W.
Published: November 2010

A rigid body in plane motion can be guided by specifying the paths or tracks of two of its points. In general these tracks are distinct. One may, however, ask for the guidance of the plane by the motion of two of its points along a single track. In this paper, we describe the kinematic synthesis of the single-track guidance of a rigid body, finite plane displacements of which are prescribed.
A Simplified Approach to Two-Freedom Linkages
Authors: Laksminarayana K.
Published: November 2010

The use of what are known as identical swing positions (identische Schwingenlagen) is shown to simplify considerably the synthesis of the plane seven-link mechanism to generate functions of two variables. The mechanism with a fixed double joint, suitably achieved, has a four-link loop and can be easily synthesized for the largest number of precision points (11) by the foregoing method without any restriction in principle on the nature of the function to be generated. Application of the method to mechanisms without a four-link loop is possible under certain restrictions on the nature of the function.
Analysis and Synthesis of Mechanical Error in Linkages—A Stochastic Approach
Authors: Dhande S. G. , Chakraborty J.
Published: November 2010

A stochastic model of the four-bar linkage considering tolerances and clearances is made. The mechanical error is analyzed for the three-sigma band of confidence level. The effectiveness of the dynamic programming procedure to optimally allocate tolerances and clearance to different members of the linkage for a specified maximum allowable mechanical error is shown.
Closed Form Synthesis of Spatial Function Generating Mechanism for the Maximum Number of Precision Points
Authors: Rao A. V. Mohan , Sandor George N. , Kohli D. , Soni A. H.
Published: November 2010

A general closed form method of planar kinematic synthesis is applied to spatial function generating mechanism for up to the maximum number of precision positions. Computer programs are written for the computation of five, seven and eight design parameters of four-revolute spherical, RCCC and RCRP and of spatial RSSR function generators, respectively. Structural error of these four-link spatial function generators is compared to that of Freudenstein’s optimized five-point planar four-bar function generators.
Necessary and Sufficient Existence Criteria of Overconstrained Five-Link Spatial Mechanisms With Helical, Cylinder, Revolute, and Prism Pairs
Authors: Pamidi P. R. , Soni A. H. , Dukkipati R. V.
Published: November 2010

Dimentberg’s approach of passive coupling is extended to develop necessary and sufficient conditions for the existence of five-link spatial mechanisms with helical, cylinder, revolute, and prism pairs. The developed conditions are examined to describe the geometry for the existence of 36 five-link spatial mechanisms with one and two passive constraints.
Evaluation of 165 deg F Reverse Osmosis Modules for Washwater Purification
Authors: Hossain S. , Goldsmith R. L. , Tan M. , Wydeven T. , Leban M. I.
Published: November 2010

Three membrane systems have been evaluated for concentration at 165 deg F of wash-water contaminants. Membranes tested are polybenzimidazole (hollow fibers), cellulose acetate blend (spiral wound), and sulfonated polyphenylene oxide (plate-and-frame). Detailed membrane flux and rejection data are presented for 200-hr life tests with synthetic washwater, at two concentrations, and real washwater, at one concentration. Advantages and limitations of the membranes, and membrane configurations, are discussed.
Development of a Direct Condensing Radiator for Use in a Spacecraft Vapor Compression Refrigeration System
Authors: Williams J. L. , Keshock E. G. , Wiggins C. L.
Published: November 2010

The development and feasibility testing of a hybrid spacecraft heat rejection system that incorporates a single radiator capable of functioning as either a conventional space radiator or as a condenser in a refrigeration cycle is described. Emphasis is placed on development of the radiator/condenser (RC), which is considered to be the most critical component of the hybrid system. The selection, design and fabrication of candidate RC configurations are described together with preliminary parametric analyses necessary to establish pressure drop, heat transfer and flow stability characteristics. Verification testing in one-g and zero-g environments is described; the latter condition being obtained by means of a C-135 aircraft. The testing included flow visualization (i.e., high-speed photography) of the condensation processes in a parallel channel quartz tube system modeling the RC. Representative qualitative photographs are presented. Results indicate stable flow conditions prevail for both one-g and zero-g operation.
Advanced Techniques for Rolling Mill Gearing
Authors: Henriot G.
Published: November 2010

This paper explains some of the problems arising from the increased speed and horsepower being applied to modern steel rolling mills. To deal with these problems techniques have been adopted which have already been used in cement mill and marine propulsion gearing. The use of harder materials, including case carburized steels is the primary recommendation. A modern steel mill operating in Holland is used as a basis for comparing the “advanced technique” gearing with conventional steel mill gearing. The paper also includes a brief description of some of the manufacturing operations which are unique to this type of gearing.
Reduction of Vibration and Noise Generated by Planetary Ring Gears in Helicopter Aircraft Transmissions
Authors: Chiang Thomas , Badgley R. H.
Published: November 2010

Rotor-drive gearboxes are major noise sources in helicopter aircraft. Narrow-band examination of this noise often indicates the presence of several or more very high, narrow noise peaks, which are located at gearbox mesh frequencies or their multiples. Important exceptions are sideband noise components, located so near the main signal component as to be indistinguishable except by very narrow band reduction. Noise of this type is most effectively treated through a systematic study of the flow of high-frequency vibration energy in the drive train. Such studies should examine the mechanism by which gear meshes generate vibrations, and the vibration response of the gearbox components which support the gears. Results of such calculations are presented for the planetary reduction ring-gear casing elements in the Boeing-Vertol CH-47 forward rotor-drive gearbox and the Bell UH-1D main rotor-drive gearbox. The calculations indicate logical reasons why noise is generated. Typical ring-gear casing design changes are examined for noise reduction.
Exact Stress Distribution in Standard Gear Teeth and Geometry Factors
Authors: Baronet C. N. , Tordion G. V.
Published: November 2010

Using the two-dimensional theory of elasticity and an appropriate transform function, the stress distribution in a gear tooth acted on by a concentrated load has been obtained. Computations were carried out for the 20 and 25-deg pressure angle, standard full-depth system, for numbers of teeth ranging from 20 to 150. The intensities of the maximum static surface stresses along the root fillets are given for different loading positions on the tooth profile. Some of the results are compared with others found in the literature.
Automated Design of Bonded Joints
Authors: Sainsbury-Carter J. B.
Published: November 2010

In bonded lap joints it is well known that the shear stress within the adhesive peaks at points of discontinuity of the adherends. In order to control these stress concentrations to a satisfactory level, in linear elastic adhesives, tapered adherends are necessary. This paper presents the development of linear analytical procedure for the analysis and design of flat bonded joints with tapered homogeneous isotropic adherends. The geometry of this taper is calculated to minimize the shear stress concentrations in the adhesive. Reducing the shear stress peaks in the adhesive by tapering the adherends from the nominal thickness often creates a secondary tensile stress concentration in the adherends. Satisfactory shear stress concentrations in the adhesive and tensile or shear stress concentrations in the adherends can be achieved simultaneously by careful geometric design of the adherends.
The Optimum Design of Mechanical Systems With Competing Design Objectives
Authors: Bartel D. L. , Marks R. W.
Published: November 2010

A general method is developed for analyzing optimum design problems with multiple, competing objective junctions. Methods are presented for generating trade-off curves for problems with competing objectives. The usefulness of these methods is demonstrated by applying them to the optimum design of hydrodynamic journal bearings.
Design of Multi-Recess Hydrostatic Journal Bearings for Minimum Total Power Loss
Authors: Cusano C. , Conry T. F.
Published: November 2010

The design problem is formulated for multi-recess hydrostatic journal bearings with a design criterion of minimum total power loss. The design is subject to the constraints of constant ratio of the recess area to the total bearing area and maximum load capacity for a given recess geometry. The L/D ratio, eccentricity ratio, ratio of recess area to total bearing area, and shaft rotational speed are considered as parameters. The analysis is based on the bearing model of Raimondi and Boyd [1]. This model is generally valid for low-to-moderate speeds and a ratio of recess area-to-total bearing area of approximately 0.5 or greater. Design charts are presented for bearings having a ratio of recess area-to-total bearing area of 0.6 and employing capillary and orifice restrictors, these being the most common types of compensating elements. A design example is given to illustrate the use of the design charts.
An Experimental Investigation of the Dynamic Response of an Elastic Mechanism
Authors: Alexander R. M. , Lawrence K. L.
Published: November 2010

Interest in the dynamic response of elastic mechanisms has recently prompted several analytical investigations. To date however, experimental data on the response of such mechanisms has been lacking. In this paper the experimentally determined steady state elastic response of a planar four bar, quick return mechanism is presented. Strain data are given for points on the coupler and output links for several different input rotation speeds. Structural damping of the links was also determined experimentally. Excitation of the link bending modes by the quick return impulse is clearly evident in the recorded strain data. The experimentally determined bending strains are compared with analytical results obtained using a digital computer program which employs a matrix structural analysis representation of the mechanism at a discrete set of crank angle positions. Agreement between calculated and measured strain data is good.
Influence of Profile Modification and Lubricant Viscosity on Scoring of Helical Gears
Authors: Matsunaga T.
Published: November 2010

Scoring limit of helical gears made of carburized steel is investigated experimentally. Gear testing machine used for the tests is a closed power circuit type and designed for operation up to 23,000 rpm. All tests are made with pairs of 14 and 141-tooth gears of 3-module, 20-deg normal pressure angle, 29.066-deg helix angle, and 30-mm face width. The effect of profile modification on the scoring limit is investigated, and the effects of lubricant viscosity and location of oil supply nozzle are investigated in connection with the effect of profile modification. Three kinds of lubricants of various viscosity ordinarily used in a gear system are tested (lubricant viscosity: 32, 53, 70 cSt at 40 C). Load carrying capacity of the lubricant of the highest viscosity is higher by 25 percent than that of the lowest one. But the effect of modification is much larger than that of lubricant viscosity.
On the Dynamic Accuracy of Machine-Tool Hydraulic Copying Systems
Authors: Sankar S. , Osman M. O. M.
Published: November 2010

The mathematical model of a hydraulic copying system, utilizing a fourway, critical centered spool valve and a symmetrical volume power cylinder under the action of dynamic cutting forces is developed. The model takes into account the following features: (a) dynamic behavior of the control valve and the action of the flow forces, (b) dry-friction between the copying system and its mountings, (c) dynamic behavior of the stylus, (d) time domain model of the kinematic input due to the template configuration, and (e) dynamic input that accounts for the cutting force fluctuations and its interaction with the velocity response of the system. A dynamic accuracy criterion which includes static, kinematic, and transient errors is formulated. The dynamic accuracy criterion is a function of the specified manufacturing tolerance of the produced workpiece and can be directly evaluated from the system analysis. Analog computer simulations are carried out to study the effects of various influencing parameters on the dynamic accuracy of copying systems. Plots are developed to be used as a guide for the design and operation of hydraulic copying systems. The dynamic accuracy is calculated for commercial copying systems using the methods developed and found that the results are in close agreement with the data supplied by the manufacturers.
Modal Response of a Flexible Rotor in Fluid-Film Bearings
Authors: Lund J. W.
Published: November 2010

An analysis is presented for calculating the response of a general flexible rotor in fluid-film bearings to forced and transient excitation. It is a modal method where the governing system equations are transformed by means of normal coordinates into a set of decoupled, first-order equations which can be solved in closed form. The transformation is based on the orthogonal complex modal functions (“mode shapes”) associated with the eigenvalues of the system. The method has been applied to an industrial multistage compressor. Numerical results are given for the response to selected unbalance distributions and, also, the transient response to a shock pulse.
Elasticity Solutions for Thick-Wall Submersible Spheres
Authors: Dzialo F. J.
Published: November 2010

Elasticity solutions utilizing the classical Boussinesq potential functions for thick-wall submersible spheres are developed. The solutions provide field stresses and strains, which consider the effect of gravity body forces, and arbitrary boundary loadings. The boundary loadings may be due to a nonuniform hydrostatic pressure, hull equipment, ballast, and can be expressed as an infinite series of Legendre polynomials. A numerical example which considers a nonuniform hydrostatic pressure and an arbitrary counter-buoyancy force applied at the inner boundary is given. Field stresses and strains are presented for various shell thicknesses and hydrostatic pressures.
Thermal Aspects of Grinding: Part 2—Surface Temperatures and Workpiece Burn
Authors: Malkin S.
Published: November 2010

Energy partition results from the previous paper are used to calculate the surface temperature distribution during grinding. The grinding temperature is calculated as the sum of a local temperature in the vicinity of an abrasive grain and a grinding zone temperature over the apparent area of contact between the grinding wheel and the workpiece. The peak local temperature at the cutting edge of an abrasive grain is found to be close to the melting point of the workpiece. By assuming that workpiece burn occurs at a critical grinding zone temperature, the energy flux at the onset of burn is related to the grinding conditions.
Early Wire Drawing Through Dies
Authors: Thomsen E. G. , Thomsen H. H.
Published: November 2010

The history of wire drawing through dies is reviewed and the description of the process by Theophilus, dating from about 1100 A.D., is discussed. It can be assumed that the fact that this early metal worker did not mention a die angle was due to his lack of knowledge of its function. It is suggested that deburred holes, or holes in which the boring operation inherently produced conical surfaces possibly were sufficient to make the wire drawing process successful without the operator knowing the reasons for his success. The recent data presented by Okolo and Wistreich seem to confirm that wire drawing is possible over a wide range of operating conditions and die angles.
Free Machining Steels—The Behavior of Type I MnS Inclusions in Machining
Authors: Hazra J. , Caffarrelli D. , Ramalingam S.
Published: November 2010

Experimental results obtained by in situ machining within a Scanning Electron Microscope of a resulphurized steel containing Type I manganese sulphide inclusions are presented. The data obtained from slow speed machining tests show that chip formation in these steels involves decohesion and cavitation at the sulphide-matrix interface as well as fracture of sulphide inclusions. While these processes promote fracture in the shearing region during chip formation (confirming an earlier hypothesis due to Tipnis and Cook), it is argued that these phenomena cannot be responsible for better tool life, surface finish, and lowered power requirements usually encountered with free machining alloys under typical industrial cutting conditions. The role of thermal dissipation during machining and its effect in altering the chip formation through thermally induced changes in plastic flow behavior of Type I sulphide inclusions are discussed.
Determination of Geometric Properties of Coated Abrasive Cutting Edges
Authors: Friedman M. Y. , Wu S. M. , Suratkar P. T.
Published: November 2010

The surface topography of a coated abrasive was measured by a special designed profilometer with an oscillating stylus, revealing very detailed geometric features of the peaks. The criterion for a peak to be a dynamic active cutting edge is analyzed and the results are applied for the identification of active cutting edges of the measured profiles. The distributions of some geometric properties of the active cutting edges as heights, distances, rake-angles and wear-lands are evaluated for six grades of coated abrasives.
The Fracture Strength of Abrasive Grains
Authors: Brecker J. N.
Published: November 2010

The diametral compression test is developed as a means of relating abrasive grain fracture characteristics to grinding forces. The effective stress required to fracture a variety of abrasive materials was measured using both static and roll crushing techniques. Grain strength was found to depend strongly on particle size and some shape effects were also observed. The manner in which the grain fractures, as observed from oscillographic force recordings, can be used to characterize the mode of fracture.
The Formation of Oxycarbides During the Oxide Treatment of Cemented Carbide Tools
Authors: Naik S. K. , Suh N. P.
Published: November 2010

Reactions between oxides and carbides were investigated in order to establish enhancement mechanisms occurring during the oxide treatment of cemented carbide tools. TiO powder was compacted around solid WC and TiC specimens, which were then heated to 1400 deg C in a vacuum of 10−4 to 10−5 torr. The reactions of Al2O3 with these carbides was similarly investigated. X-ray diffraction analysis show that oxycarbides formed on the carbide surface during the oxide treatment. Discussions are given with regard to how these oxycarbides may enhance the metal cutting properties of cemented carbide tools.
On Chatter Vibrations of Machine Tool or Work Due to Regenerative Effect and Time Lag
Authors: O¯ta H. , Ko¯no K.
Published: November 2010

This paper treats the most general chatter vibrations of machine tool or work originating by regenerative effect having an arbitrary overlap factor, by wave cutting effect (time lag of thrust force upon chip thickness fluctuation as varied by relative motion between tool and work), and by wave removing effect (time lead of shearing area upon chip thickness fluctuation through a previous cut). The new concept of “equivalent time lag of thrust force,” containing both any overlap factor and time lag of thrust force, is introduced, and by it, the cutting limit of absolute stability free from chatter can be obtained very easily. Moreover, this concept is verified to be very effective as a stability criterion for regenerative chatter with an unsymmetrical boring bar.
Advanced Technology for Reducing Aircraft Engine Pollution
Authors: Jones R. E.
Published: November 2010

The proposed EPA regulations covering emissions of gas turbine engines will require extensive combustor development. The NASA is working to develop technology to meet these goals through a wide variety of combustor research programs conducted in-house, by contract, and by university grant. In-house efforts using the swirl-can modular combustor have demonstrated sizable reduction in NOx emission levels. Testing to reduce idle pollutants has included the modification of duplex fuel nozzles to air-assisted nozzles and an exploration of the potential improvements possible with combustors using fuel staging and variable geometry. The Experimental Clean Combustor Program, a large contracted effort, is devoted to the testing and development of combustor concepts designed to achieve a large reduction in the levels of all emissions. This effort is planned to be conducted in three phases with the final phase to be an engine demonstration of the best reduced emission concepts.
Dynamic Acceptance Tests Applied to a Center-Type Lathe
Authors: Sadek M. M. , Knight W. A.
Published: November 2010

Dynamic acceptance tests based upon forced vibration tests employing electromagnetic exciters are applied to a center-type lathe. The stability is assessed in terms of the coefficient of merit (c.o.m.), which is determined from the harmonic responses of the machine. The influence of the following on the harmonic responses, modes of vibration, and limit of stability of the machine have been determined: Position of excitation along the axis of the lathe; Weight of testpiece; Support of the workpiece with or without a center; and Variation of the thrust between the workpiece and the center.
Optimum Synthesis of Path-Generating Four-Bar Mechanisms
Authors: Bakthavachalam N. , Kimbrell J. T.
Published: November 2010

Synthesis of path-generating four-bar mechanisms is considered as an optimization problem under inequality constraints. The penalty function approach is used. The effects of clearances and tolerances in manufacture are considered in order to make sure that the inequality constraints are within the acceptable tolerance during the required motion. Modifications are introduced in the gradient method, and sequential unconstrained minimization techniques are used in the process of minimization. A typical example under various conditions is presented in order to study the effectiveness of the technique.
Optimum Synthesis of Plane Mechanisms for the Generation of Paths and Rigid-Body Positions via the Linear Superposition Technique
Authors: Bagci C. , Lee In-Ping Jack
Published: November 2010

A method of optimum synthesis of plane mechanisms for the generation of paths and rigid-body positions is presented. The method is developed for the four-bar plane mechanism with six and eight unknown dimensions. Dimensions of the optimum mechanism are determined by minimizing the error in the loop-closure equations for N design points on the path, along with the loop-closure equation of the linkage, where N is not limited by the number of the unknown dimensions of the system. Design equations are linearized by the method of linear superposition. Solution of design equations requires no iterations, and it leads to a series of optimum mechanisms of different efficiency of approximation. Numerical examples are given.
An Analysis of the Picking Mechanism of a Textile Loom
Authors: Lord P. R. , Mohamed M. H.
Published: November 2010

A shuttle loom runs irregularly, noisily, and sometimes inefficiently due, in part, to the nature of the conventional picking mechanism. The fact has been demonstrated by measuring the instantaneous speed and power values over a number of loom cycles. The probable reasons for the behavior are discussed from a theoretical viewpoint and some supporting data are presented to show that the simple classical theories do not hold good under actual dynamic conditions.
On the Analytical Lumped-Mass Model of an Elastic Four-Bar Mechanism
Authors: Sadler J. P.
Published: November 2010

The lumped-parameter method for the elastodynamic analysis of mechanisms is applied to a particular case for which existing experimental evidence is available. The mechanism analyzed is a planar four-bar linkage, and the calculated results include steady-state deflection and stress and strain responses associated with the bending vibration of the three moving links. The analytical model is based on nonlinear differential equations derived by way of Euler-Bernoulli beam theory, and numerical solution is obtained through the use of a digital computer. Comparison of the analytical and experimental results shows very good agreement, supporting the use of the lumped-parameter approach in analyses of this type.
High-Speed Mechanism Design—A General Analytical Approach
Authors: Imam Imdad , Sandor George N.
Published: November 2010

A general method of kineto-elastodynamic design is developed and illustrated with examples. With this method, mechanisms with elastic links can be designed in a systematic way for a desired performance at high speeds. This is achieved by first performing the kinematic synthesis of the mechanism considering its links to be rigid, and then proportioning the areas of cross section of the links optimally to account for kineto-elastodynamic effects. Design optimization with respect to stress level, mass distribution and elastic deflections is performed by imposing constraints on dynamic stresses in every link and on the deflections of the path or function generating links throughout the range of motion. The optimization problem is formulated in terms of nonlinear programming techniques. Numerical examples are presented. The KED design procedure, which is developed and demonstrated here by way of several examples, is believed to be the first method of this kind for a completely elastic mechanism.
An Analysis of a Stationary Pneumatic Wave-Energy Converter
Authors: McCormick Michael E.
Published: November 2010

A theoretical analysis of a stationary pneumatic wave-energy conversion device is presented. Results obtained from the analysis show that the power converted is proportional to the cube of the wave height, producing a maximum time-averaged power per wave period of 25 kw for a 20-ft (6.096 m) diameter unit located in a 3-ft (0.9144 m) sea. The device can be adjusted for purposes of efficiency in any sea spectrum by simply changing the draft (length of the centerpipe) of the unit. The peak power output of the device occurs at a period similar to the resonant period of a surge chamber.
Thermal Energy Storage and Control
Authors: Schro¨der J.
Published: November 2010

Eutectic fluoride mixtures of alkali and alkaline earth metals posses extremely high thermal storage capacities, and are therefore suitable for space heating as well as for powering heat engines. Their melting points ranging from 449 to 832° C are well adapted to any high level heat supply. The compounds are of high chemical stability and show no corrosive action with stainless steel. In order to make efficient use of the stored heat, good thermal insulation and controllable heat transfer are achieved by a multifoil insulation jacket with a controllable hydrogen filling. For powering engines energy transfer is realized by heat pipes.
A Foundation for a Unified Theory of Analysis of Spatial Mechanisms
Authors: Duffy J. , Rooney J.
Published: November 2010

In analogy with a spherical (spatial) triangle there are only three fundamental loop equations for any spherical (spatial) polygon, namely the real (dual) sine, sine-cosine, and cosine laws. All other loop equations which fall naturally into groups of subsidiary sine, sine-cosine, and cosine laws can be derived from the three basic laws. Novel half-tangent laws are derived which are expressions for the common root of pairs of sine and sine-cosine laws.
An Experimental and Analytical Study of Connection Forces in High-Speed Mechanisms
Authors: Dubowsky S. , Young S. C.
Published: November 2010

The increases in the dynamic forces within the connections of high-speed mechanical systems due to connection clearances and mechanism elasticity are of great interest to design engineers. These forces, which can play a dominant role in the performance and life of these systems, are experimentally studied in this investigation, and the observed experimental behavior is correlated with the results of analytical predictions. The experiments performed confirm the importance of clearances in machine joints on the amplification of connection forces. The effects of connection friction and mechanism elasticity on the connection forces are also investigated.
Reduction of Harmonic Response of Cylindrical Shells
Authors: Warburton G. B.
Published: November 2010

The normal mode method is used to investigate the reduction in the steady-state response of a simply supported cylindrical shell when conventional absorbers are attached to the shell. Two types of excitation are considered: (a) a single radial harmonic force, and (b) a harmonic pressure distributed over the shell surface. The effect upon response of varying the absorber parameters is studied. Optimum conditions for specific cases are obtained and compared with those required to minimize response when absorbers are added to cantilever beams and to the classical single degree of freedom system.
The Vortex Induced Oscillation of Elastic Structural Elements
Authors: Iwan W. D.
Published: November 2010

A technique is presented whereby certain mathematical models for the vortex shedding induced response of a rigid elastically supported cylindrical element can be applied to internally elastic structural elements such as beams, cables, etc. The formulation is used to generate an analytic relationship which predicts the maximum amplitude of response of a variety of elastic elements. The analytic results are compared with experimental observations using a particular vortex shedding model.
The Design of Variable Antidive Vehicle Suspension Systems
Authors: Metz D. , Carlson A. , Golden L. , Owen R.
Published: November 2010

Variable antidive suspension characteristics represent an excellent design compromise between 100 percent dive compensation and ride harshness. This paper develops a simple suspension modification which permits wide flexibility in the choice of variable antidive to be used by a vehicle designer. A sample suspension design is presented for which variable antidive characteristics are developed.
A Simulation Method of Establishing Fatigue Life Distribution
Authors: Elmaraghy H. A. , Siddall J. N.
Published: November 2010

This paper presents a Monte Carlo simulation method for fatigue failure, by which the randomness of two material properties as well as that of the applied load can be incorporated into a stochastic model using an appropriate failure criterion to predict the statistical characteristics of fatigue life under constant and random amplitude cyclic loading conditions. In this technique, both the endurance limit Se and the fatigue strength coefficient Sf′ are treated as stochastic variables. The combined effect of the randomness of Se, Sf′, and the applied stress on the statistical characteristics of fatigue lives is predicted analytically using digital simulation of fatique tests. The life distributions and their statistical characteristics are found to be in good agreement with those obtained from analyzing the experimental results, indicating that the proposed technique and the underlying assumptions and hypotheses are adequate. The suggested method is believed to be an effective, fast, and easy-to-use design tool which is suitable for use on electronic computers. It is ideal for parametric studies compared with the costly and time-consuming laboratory fatigue tests. Minimum experimental data are needed as a basis for the analysis. New results are presented which show the effect of the randomness of the loads and material properties on the randomness of fatigue life distribution.
Drawing Solid Wires Through Soft Dies in Antiquity
Authors: Thomsen E. G. , Thomsen H. H.
Published: November 2010

It has been shown on theoretical as well as experimental grounds that it is possible to draw solid wires of gold or silver to diameters of the order of 0.3 mm (0.012 in.) or smaller by the use of soft dies of the same metal. It is argued that solid wire of these metals could have been drawn in antiquity by the use of such dies even though no such dies have been found (or recognized) in archaeological excavations. One explanation for this lack of archaeological evidence may be ascribed to the possibility that the ancient goldsmith did not leave such artifacts since he may have remelted the precious metals for other uses in his craft.
An Analysis of Tool Life Based on Flank-Face Wear—Part 1: Theory
Authors: Rubenstein C.
Published: November 2010

The wear mechanisms to which a cutting tool is subject may be separated into those causing acute failure, e.g., edge breakage due to cracking, and those causing gradual loss of material, e.g., crater wear or continuous flank-face wear. In the present paper only continuous flank-face wear is considered and an analysis is given in which wear is attributed to adhesion between tool and workpiece materials while acknowledging that other wear mechanisms could, and on occasion undoubtedly do, produce continuous flank-face wear. The fundamental basis on which the analysis rests is the realization that in a continuous cutting operation the temperature of the subsurface layer of the workpiece increases much less than that of the subsurface layer of the tool. The analysis leads to the Taylor tool-life equation, the extended Taylor tool-life equation, the Schallbroch-Schaumann equation, the relation between the Taylor and the Schallbroch-Shaumann indices and the factors influencing the life of a cutting tool.
Metal Cutting Dynamics With Reference to Primary Chatter
Authors: Szakovits Richard J. , D’Souza A. F.
Published: November 2010

Identification of metal cutting dynamics is important for predicting the occurrence of chatter. An experimental investigation was conducted to study the relationship between the oscillations in the undeformed chip thickness and the oscillations in the thrust and cutting forces in orthogonal cutting during wave producing or a simulation of primary chatter. The relationship exhibits hysterisis which changes from passive to active as the frequency is increased; it is also a function of the amplitude of oscillations in the undeformed chip thickness. The objective was to relate the experimental results to the development of a nonlinear theory of analysis of chatter as a limit cycle oscillation by the describing function method.
Curvature Analysis of Surfaces in Higher Pair Contact—Part 1: An Analytical Investigation
Authors: Dhande S. G. , Chakraborty J.
Published: November 2010

In this paper, the analytical investigation is done to evaluate the normal and principal curvatures of contacting surfaces in higher pair contact. The velocity ratio of the members connected with the higher-pair-contact surfaces is assumed to be variable. The principal curvatures of the generated or driven surface are expressed in terms of those of the generating or driving surface.
The Interaction of Collinear Arrays of Griffith Cracks on Two Radial Lines
Authors: Aksogan O.
Published: November 2010

The elastostatic plane problem of an isotropic homogeneous infinite plane with a number of Griffith cracks lying along two radial lines is considered. The analytical technique consists of the joint use of the Mellin transform and the Green’s function. The system of singular integral equations, thus obtained, is solved numerically taking advantage of the fact that the fundamental function is the weight function of the Chebyshev polynomials. The results for several cases are compared with those of previous authors. Stress intensity factors and probable directions of cleavage, which are important from the viewpoint of fracture mechanics, are studied in detail and illustrative numerical results for selected cases of geometry and loading are presented in graphical form.
Epicyclic Gear Vibrations
Authors: Botman M.
Published: November 2010

The natural frequenices of in-plane vibration of a single planetary gear stage are analyzed. The gear tooth stiffnesses are approximated as linear springs. The effect of planet pin stiffness on the natural frequencies is evaluated. Rotation of the carrier gives rise to a system with periodic coefficients which is solved by means of Floquet’s theory. The rotation of the carrier appears to suppress the nonaxisymmetric modes which are present in the system with nonrotating carrier.
Instrumental Procedures for Analysis of Nonlint Particles in Cotton
Authors: Barker R. L. , Lyons D. W.
Published: November 2010

Universal grade standard samples supplied by the United States Department of Agriculture were used as the basis for a study of the operation of electronic scanning instrumentation adapted to measure the number and physical features of nonlint particles found on the surface of cotton. A series of tests was carried out to provide a preliminary evaluation of this instrumentation in the comparative classification of cotton by grade. Results of these tests forecast the potential utility of image analysis for use in the quantitative categorization of cotton based on automatic optical-electronic assessment of nonlint particulate levels.