bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis and Temperature Control of Hybrid Microcircuits
Authors: Pogson J. T. , Franklin J. L.
Published: November 2010

The results of a study on thermal modeling and analysis of hybrid microcircuits are presented. Parametric studies covering typical component mounting methods, bonding agent materials, and component spacing are described. Temperature profiles of substrates, component temperatures, and thermal resistances are presented. It is shown that the use of moly tabs can significantly reduce component temperature levels. Additionally, it is shown that thermal modeling can greatly aid the circuit designer in the layout and preliminary design phases.
Instantaneous Efficiency and Coefficient of Friction of an Involute Gear Drive
Authors: Radzimovsky E. I. , Mirarefi A. , Broom W. E.
Published: November 2010

In this work the authors, using a testing machine designed for this investigation, determined experimentally the variation in the friction losses in gearing during an individual tooth engagement period. Based upon the obtained data “instantaneous efficiency” of various gear drives and the variation of “apparent coefficient of friction” during the engagement period were evaluated. This “apparent” or “effective” coefficient of friction is a coefficient which represents the effect of the friction due to rolling or a combination of rolling and sliding motion between the engaged teeth in the gear drives. The instantaneous coefficients of friction in the gearing during the engagement cycle were obtained for a large number of different operational conditions. The following factors were used as variable parameters: the torque transmitted by the gears, the speed of gear rotation, the diametral pitch, and the contact ratio of the gearing.
Optimum Torque for Drill Collar Makeup
Authors: Weiner P. D. , True M. E.
Published: November 2010

Drill collar connection failure frequency increases when wells are drilled deeper and when directional holes are drilled. These failures, which materially increase the cost of operations, prompted a study to find the best way to make up drill collar connections for achieving maximum joint life. This paper discusses the results of an investigation conducted by Texas A&M University Research Foundation to (1) determine from laboratory tests the optimum makeup torque for a select number of typical drill collar connections, (2) develop an analytical method of calculating optimum makeup torques for all sizes and types of drill collar joints, and (3) compare the laboratory derived torque makeup with those predicted by the analytical method. The close correspondence of the laboratory and analytical values supports the use of the analytical method for predicting torque makeup for those sizes and types of drill collar joints not tested in the laboratory.
Optimum Design and Control of Underwater Gliders
Authors: Baz A. , Seireg A.
Published: November 2010

This study deals with the optimum design of an underwater glider that utilizes buoyancy control as a means of propulsion. The glider’s hydrodynamic lifting surfaces are designed for maximum forward velocity. Optimum travel paths of the system are developed for missions in clear waters and around obstacles. Energy consumption at different operating depth are discussed and compared with other propulsion systems. The system can be utilized for moving scuba divers, small submersibles and instrument packages underwater with minimum effort in conditions where the propulsion speed is not critical.
Dynamic Response of Surface-Moored Vertical Barrier to Wave Action by Analog and Digital Simulation
Authors: Fowler J. R. , Bailey E. I.
Published: November 2010

The two-dimensional dynamics of an oil containment barrier, which was designed to have very low tensile loads due to current and waves, were simulated with a theoretical model. The model was solved on both analog and digital computers, and a lab test program conducted to verify the model. For nonlinear problems such as this, for which “exact” solutions do not exist, the analog computer has many advantages, principally rapid parameter studies and convenient plotting output, plus giving the engineer a real time “feel” for the problem. The problem treated here was especially well-suited to analog simulation. Charts and graphs present maximum force and amplitude data, and experimental verification of the solution was obtained from wave tank studies.
Surface Temperature and Scoring Resistance of Heavy-Duty Gears
Authors: Ishikawa Jiro , Hayashi Kunikazu , Yokoyama Masaaki
Published: November 2010

The surface temperature on spur gear teeth is measured by the newly developed dynamic thermocouple method. From a large number of the results an experimental equation for the surface temperature is obtained. The effect of tip relief on the surface tempera-perature rise is also studied.
Experimental Investigation of a Simple Squeeze Film Damper
Authors: Thomsen K. K. , Andersen H.
Published: November 2010

This paper describes an experimental investigation of a squeeze film damper for the control of rotor amplitudes. From direct measurements of the transmitted force and the velocity of the damper sleeve, the damping coefficient of the squeeze film is obtained over a range of frequencies and for several values of film thickness and oil viscosity. The results are compared with the theoretical formula, based on assumptions of linearity, and from a practical application point of view the correlation is satisfactory.
Analysis of a Multi-Layered Spherical Head Impact Model
Authors: Gordon S. L. , Moskowitz G. D. , Byers R.
Published: November 2010

The development of adequate protection against head injury requires a thorough knowledge of the mechanics of trauma to an unprotected head. Impact to multi-layered spherical head models are analyzed with an elastic skull, elastic tables and elastic-plastic diploe skull, and elastic tables and crushable foam diploe skull. All models have a hydrodynamic brain model. The energy absorbing skull models yield highly attenuated and smoothed tensile pressure peaks in the brain as compared to the elastic skull model. The generality of the solution technique would readily permit extension of the analyses to investigate impact to a head protected by a multi-layered helmet.
On Sparse Matrices in Finite Element Wave Propagation
Authors: Buturla E. M. , McLay R. W.
Published: November 2010

The finite element method has been extensively applied to the solution of static and dynamic problems. Some work has been done in finite element wave propagation but matrix techniques typically employed require vast amounts of computer main memory and peripheral storage devices. In this work, a method is presented which utilizes the sparse nature of the coefficient matrix. The method enables problem execution in a smaller main memory space than standard techniques. A comparison is made on memory requirements and run times for both standard methods utilizing conventional assembly techniques, some sparse matrix techniques and the proposed scheme.
The Use of Vibration for Material Handling
Authors: Paz M. , Morris J. M.
Published: November 2010

In this paper a general survey of material handling by vibrating equipment is presented with a discussion on applications and basic design considerations. Attention is given to the need of designing vibrating equipment properly in order not to produce unacceptable environmental pollution in the form of noise and structural vibrations. It is also shown in this paper that the stiffness method of structural analysis may be applied effectively in the design and analysis of vibrating conveyors to give accurately the motion and the forces along a vibrating conveyor. The effect of the vibrating material is considered in the analysis as mass effect and equivalent frictional factors. Experiments conducted for the determination of these factors are reported. Also, a computer program outline for the analysis of vibrating conveyors under load is presented and numerical examples are given to illustrate the method.
Metering of Solid Materials With Reaction Devices
Authors: Nolte C. B.
Published: November 2010

The three types of reaction devices used for mass flow measurement of solid materials are described and compared as to function. These, as a class, are compared with weighing type devices. The incorporation of mass flow reaction devices into instrument system loops is considered with recommendations and suggestions for handling, flow control, proportioning solid to solid, solid to liquid, totalizing and batching.
Dynamic Analysis of Multi-Rigid-Body Systems
Authors: Gupta V. K.
Published: November 2010

A method is presented for formulating and solving the Newton-Euler equations of motion of a system of interconnected rigid bodies. The digital simulation may involve numerical integration of the kinematic equations as well as the dynamic equations. The reaction forces and torques resulting from rigid constraints imposed at the connecting joints are also determined. The derivation of kinematic expressions for first and higher derivatives is demonstrated based on direct differentiation of the rotation matrix in the spirit of the classical vector approach. A representative problem in spatial mechanism analysis is solved and illustrated with numerical results.
Gross-Motion Dynamic Response Analysis of Indeterminate Mechanisms by Matrix Displacement Method
Authors: Brasfield R. L. , Bagci Cemil
Published: November 2010

A method of gross-motion dynamic response analysis of indeterminate space mechanisms, as well as indeterminate plane mechanisms with offsets of links, to specified input forces or torques, such as in mechanisms of automated systems, mechanical robots, and switching mechanisms, is presented. The method uses joint force analysis along with the matrix displacement-direct element method. Unknown motion of the mechanism as function of time is determined by the solution of equations of gross-motion as an initial value problem. The effect of small oscillations of a link about an equilibrium position is neglected. An indeterminate plane four-bar and the indeterminate Bennett mechanisms are analyzed as switching mechanisms in the numerical examples.
Monte Carlo Simulation of the Machining Economics Problem
Authors: Groover M. P.
Published: November 2010

A mathematical model of the machining operation is developed from experimental cutting data. The model considers two aspects of the machining process: tool wear and surface finish. The tool wear model includes the variability inherent in the tool wear mechanism and represents the wear as a tool wear profile rather than a single measure of wear. The surface finish on the machined surface is determined to be functionally related to tool wear and also contains variability. The model is used with Monte Carlo simulation to study the machining economics problem. The economics problem is first defined as a speed-only problem and the effect of tool wear variability is investigated. The speed and feed problem is also studied with surface finish constraints imposed on the optimization procedure.
The Design of Modeled Cam Systems—Part I: Dynamic Synthesis and Chart Design For the Two-Degree-of-Freedom Model
Authors: Matthew G. K. , Tesar D.
Published: November 2010

An extension of the dynamic synthesis philosophy given earlier [1] for cam follower systems is made in terms of a two-degree-of-freedom model. Three additional dimensionless parameters η, λ, γ for the distribution of mass, spring, and dashpot content are sufficient to describe this more complex system relative to the single degree-of-freedom coefficients. Charts in terms of η, λ, γ are presented to assist in choosing the best set of these values. Finally, “rules of thumb” are given which are applicable to a wide range of mechanical systems.
Combined Axial Stress Fatigue Reliability for AISI 4130 and 4340 Steels
Authors: Kececioglu D. B. , Chester L. B.
Published: November 2010

The failure-governing strength distributions of round specimens are determined. These are subjected to a mean tensile axial stress onto which alternating tensile and compressive axial stresses are superimposed. The AISI 4340 steel specimens are tested for a life of 106 cycles and the AISI 4130 steel specimens for 2 × 106 cycles. Distributional Goodman diagrams are developed and various combined-stress theories are compared with the experimental results. The application of the probabilistic “Design-for-Reliability” methodology utilizing these design data is illustrated by two examples. This methodology leads to improved design and to the determination of the reliability of mechanical parts and components subjected to such combined axial fatigue loads.
Metal Oxycarbides as Cutting Tool Materials
Authors: Carson W. W. , Leung C. L. , Suh N. P.
Published: November 2010

The role of chemical stability of cutting tool materials in tool wear was investigated by studying the wear characteristics of titanium oxycarbides. The oxycarbides TiC0.25O0.75, TiC0.5O0.5, TiC0.6O0.4, and TiC0.75O0.25 were produced by solid state interdiffusion of TiO and TiC. Their hardnesses and lattice spacings were determined as functions of their chemical composition. The chemical interaction of these oxycarbides with steel was investigated by diffusion couple experiments. Then commercially available cemented carbide tools were coated with TiC0.5O0.5 and TiC0.75O0.25 by RF diode sputtering. The wear resistance of these coated tools was determined by cutting tests. The wear rate of these oxycarbide coated tools was comparable to that of a TiC coated tool, although the free energies of formation of oxycarbides were lower and their hardnesses comparable. It is, therefore, concluded that while the data on free energy of formation and hardness can be useful in the initial screening steps of tool materials, the kinetics of the wear process needs to be more fully understood to define the chemical stability of tool materials in a cutting environment.
Effects of Built-Up Edge in Drilling
Authors: Dolodarenko A. G. , Ham I.
Published: November 2010

Experimental tests were performed to study the effects of built-up edge in drilling four different work materials with a twist drill, at different cutting speeds and feeds. The tests were made dry to facilitate observation. Chip-flow angles, normal rake angles, and web angles with built-up edge were measured and correlated with inclination angles and effective rake angles. Comparison of the angles with and without built-up edge showed that the built-up edge significantly affects the basic mechanics of drilling.
In-Process Analysis of Machine Tool Structure Dynamics and Prediction of Machining Chatter
Authors: Moriwaki Toshimichi , Iwata Kazuaki
Published: November 2010

Theoretical and experimental investigations were carried out to identify the dynamics of a machine tool structure during cutting to predict the borderline of stability against the self-excited regenerative chatter. The validity of theoretical analyses in calculating the stability limit for conventional machining was confirmed by cutting experiments using a structural model. The model dynamics were identified during cutting under stable (non-chattering) cutting conditions by applying a technique of system identification based on time series analysis of the small random cutting force variations measured by a specially designed tool dynamometer and the corresponding minute vibrations. The experimentally obtained borderline of stability had a fairly good agreement with that calculated from the identified dynamics of the structure and the cutting dynamics, the latter being estimated from the static cutting data based on the so-called shear plane model.
Optimization of a Ribbed Table for Minimum Weight and Minimum Deflection
Authors: Brown M. L.
Published: November 2010

This paper demonstrates a method for the optimization of a ribbed table, such as a machine tool base. Although the particular structure considered has been idealized so that the shapes of only five members are developed, the method is applicable to very complex structures. This technique utilizes energy methods to synthesize mathematical models and the Euler-Lagrange Equation to find the best shape. In this way the optimization of each individual member is separated from the rest of the problem causing great simplification in the mathematics involved.
A Modal Transient Simulation Model for Flexible Asymmetric Rotors
Authors: Childs D. W.
Published: November 2010

A simulation model is developed which accounts for an orthotropic as opposed to an axisymmetric rotor, i.e., rotors are considered whose stiffness and inertial properties in two mutually orthogonal planes are different. A rotor-fixed formulation is employed to define the rotor’s elastic deflections. Favorable characteristics of this formulation are that (a) the rotor’s inertial and stiffness properties are constant, and (b) the modal coordinates are nonoscillatory during synchronous motion. The validity of the formulation is verified by conducting transient simulations for a rotor having the approximate physical dimensions of a two-pole 500 MW alternator. The simulation model correctly simulates the rotor’s theoretically predicted dynamic behavior.
Spin-Decoupled Projectiles: Relationship of Spin to Muzzle Velocity
Authors: Soper William G.
Published: November 2010

A rationale is presented to explain the decrease in spin rate which frequently accompanies an increase in muzzle velocity for gun projectiles fitted with plastic sealing bands.
Selection of Operating Parameters in Surface Grinding of Steels
Authors: Malkin S.
Published: November 2010

This investigation is concerned with the selection of operating parameters for surface grinding of steels, when the grinding wheel tool life is limited by workpiece burn. Relationships are developed to show the effect of operating parameters on the volume removed per wheel dressing and the production time to grind away a unit volume of material. The results indicate that it is best to use the maximum allowable workpiece velocity with a corresponding optimum downfeed which is larger for slower workpiece velocities. It is also demonstrated that there are severe restrictions associated with high-speed grinding of steels.
An Analysis of Heat Transfer and Fade in Disk Brakes
Authors: Secrist D. A. , Hornbeck R. W.
Published: November 2010

The heat transfer and fade characteristics of automotive disk brakes are studied. A distributed model for the disk is employed, with convection from the sides and edge of the disk and conduction to the hub included. Available expimental data for friction coefficient as a function of temperature for two different lining materials is included in the analysis. The heat transfer equations and dynamic equations of the vehicle are solved numerically. Results presented include the effects on brake pad pressure required and on stopping distance of a sequence of repeated stops with cooling perds between each stop. Also included are deceleration versus time curves, sample temperature distributions in the disk, and a study of the manner in which the heat generated in braking is distributed to storage in the disk, conduction to the hub, and convection to the air.
The Abrasive Cut-off Operation With Oscillation
Authors: Murata R. , Shaw M. C.
Published: November 2010

In the abrasive cut-off operation in which a thin rotating disk is plunged through a workpiece, chips must be stored as a grain traverses the entire width of work being ground. Also, heat flows radially inward from the wheel surface for a longer time the wider the workpiece, thus increasing the tendency to overheat the polymeric bond posts that hold the abrasive grains in place. Oscillation of the workpiece in a tangential direction tends to reduce the length of continuous contact between abrasive grain and work and significantly improves grinding performance when relatively wide workpieces are ground. This paper discusses the more important aspects of the abrasive cut-off operation with oscillation.
On Eccentrically Loaded Fasteners
Authors: Fazekas G. A.
Published: November 2010

Use of the pole concept allows an easy evaluation and optimization of fastener geometry. When used on joints with unequal fasteners, it leads to the concept of Equivalent Area, and shows that optimal disposition of a given fastener geometry depends on load eccentricity.
On Optimal Bolt Preload
Authors: Fazekas G. A.
Published: November 2010

A linear model of a bolted joint subject to alternating tension is directly correlated with a modified Goodman diagram. It is shown that bolt preload can have a beneficial or adverse effect. The optimal value is determined by the minimal clamping force. The rigid flange plus elastic bolt is shown to be of advantage in all circumstances.
A Generalized Return Vector for Projection Methods in Optimization With Nonlinear Constraints
Authors: Ho K. T. A. , Townsend M. A.
Published: November 2010

Variable metric methods can be adapted to constrained nonlinear optimization by incorporating projection methods and a return vector when the indicated next step leaves the feasible region. A generalized return vector is developed here which yields a superior return to the feasible region in terms of the metric associated with the objective function. It is shown that a better point results and faster convergence is expected. A numerical example is given.
A General Method for Simulating the Flow Dependent Nonlinear Vibrations of Compressor Reed Valves
Authors: Elson J. P. , Soedel W. , Cohen R.
Published: November 2010

A mathematical model is developed for the nonlinear vibrations of automatic reed valves in high-speed refrigeration compressors. Specifically considered are a general class of values which wrap about curved backer plates. Two simple experiments are described which allow the nonlinearities of the valve system to be defined by a single nonlinear second order differential equation. Valve oscillation frequencies inside an operating compressor are predicted through a linearization of the valve equation. Comparisons with experiment are included.
Dynamics of a Drifting Buoy-Cable-Array Assembly Used in Submarine Detection
Authors: Modi V. J. , Misra A. K.
Published: November 2010

The paper investigates the dynamics of a drifting buoy-cable-array assembly used in submarine detection. The steady-state configurations of the three-dimensional cable and flexible legs are determined. A perturbation analysis around the steady state is carried out, and the frequencies for both lateral and longitudinal motions of the system obtained by analyzing the resulting eigenvalue problem. A study of the decay of the disturbances applied to the system suggests the use of an optimum arm diameter for given cable and arm lengths.
Dynamic Stability of Timoshenko Beams by Finite Element Method
Authors: Thomas J. , Abbas B. A. H.
Published: November 2010

A Finite Element model is developed for the stability analysis of Timoshenko beam subjected to periodic axial loads. The effect of the shear deformation on the static buckling loads is studied by finite element method. The results obtained show excellent agreement with those obtained by other analytical methods for the first three buckling loads. The effect of shear deformation and for the first time the effect of rotary inertia on the regions of dynamic instability are investigated. The elastic stiffness, geometric stiffness, and inertia matrices are developed and presented in this paper for a Timoshenko beam. The matrix equation for the dynamic stability analysis is derived and solved for hinged-hinged and cantilevered Timoshenko beams and the results are presented. Values of critical loads for beams with various shear parameters are presented in a graphical form. First four regions of dynamic instability for different values of rotary inertia parameters are presented. As the rotary inertia parameter increases the regions of instability get closer to each other and the width of the regions increases thus making the beam more sensitive to periodic forces.
Instabilities of an Asymmetric Rotor With Asymmetric Shaft Mounted on Symmetric Elastic Supports
Authors: Ardayfio D. , Frohrib D. A.
Published: November 2010

Instabilities of an asymmetric rotor with asymmetric shaft mounted on symmetric elastic supports are considered. The periodic coefficients which appear in the system equations are eliminated by transformation to a rotating coordinate system rotating at the constant angular speed of the rotor. The unstable speed regions are identified by studying the nature of the roots of the characteristic equation. The combined effects of the inertia and shaft asymmetry and the flexible supports are appreciated by representative numerical examples. The results are presented in three-dimensional diagrams to show how the asymmetry parameters affect the unstable speed regions for known values of support stiffness.
Product Design Implications of New High-Speed Milling Techniques
Authors: King R. I. , McDonald J. G.
Published: November 2010

The results of recent research into ultra high-speed milling production will revolutionize machine tool design concepts and associated technical-economic study parameters. Testing demonstrated major improvements in productivity, part stability, and process selection. Several specific production problems are analyzed to emphasize changes in design and manufacturing concepts. A forecast of process limitation is given which reflects the strength of machine tool materials as the only constraint to future mechanical design improvements.
The Application of the Double Ligament Tensile Test in Deformation Processing
Authors: Kumble R. G. , Berry J. T.
Published: November 2010

The foundation of the double ligament tensile test for determining mechanical properties of wrought as well as cast materials has been established. With the aid of the finite element stress analysis the design geometry of the double ligament specimen has been improved and correction factors for three design geometries have been calculated. Tensile properties of two low-carbon, very low-alloy steel plate materials and a high-strength wrought aluminum alloy have been determined by the double ligament tensile test. The corrected yield strength values and percent elongation data compare favorably with those obtained by conventional test methods where geometry considerations allow the sampling of full-size test bars. The test bar size is such that random sampling of multiple specimens (8) is quite permissible and desirable to determine representative tensile properties of a material. The test has been found to be particularly suitable in evaluating tensile properties in the short transverse direction of wrought plate and across cross sections of complex-shaped forgings or castings less than 1 in. (2.5 cm) in thickness.
Optimum Synthesis of Multiloop Planar Mechanisms for the Generation of Paths and Rigid-Body Positions by the Linear Partition of Design Equations
Authors: Bhatia D. H. , Bagci C.
Published: November 2010

The optimum synthesis of multiloop planar mechanisms for the generation of paths and rigid-body positions employing the linear partition of the design equations is presented. Design equations and their applications for the optimum synthesis of the three distinct types of the Stephenson’s six-bar mechanism for the generation of paths and rigid-body positions are presented. The optimum sets of dimensions of a mechanism are determined by minimizing the error in the loop-closure equation of the path dyad and of the loops of the mechanism. Design equations having nine to twelve unknown dimensions are presented. Industrial applications of the design equations are illustrated with design examples.
Influence of Nonlinear Wheel/Rail Contact Geometry on Stability of Rail Vehicles
Authors: Hull R. , Cooperrider N. K.
Published: November 2010

Nonlinear behavior caused by wheel flanges, worn wheel treads, and dry friction can have an important effect on rail-vehicle stability. In this paper the influence of such nonlinearities on the stability of rail freight vehicles is investigated using quasi-linearization techniques. Nonlinear equations of motion are presented that describe the lateral behavior of a 9-degree-of-freedom representation of a complete freight car with three-piece trucks. The nonlinear wheel/rail geometric constraint functions for the rolling radii, angle of wheel/rail contact, and wheelset roll angle are found by a numerical technique. The suspension description includes dry friction where appropriate. The hunting stability of the freight car is studied by employing describing-function techniques. Results are presented for a typical freight car with three different wheel profiles. The stability results illustrate the dependence of behavior on the amplitudes of vehicle motions. Application of the results in realistic situations and suggestions for future quasi-linear studies are discussed.
An Investigation of Factors Contributing to Wide Gage on Tangent Railroad Track
Authors: Ahlbeck D. R. , Harrison H. D. , Noble S. L.
Published: November 2010

Wide gage—a fatigue failure of the track to maintain the nominal lateral distance between rail heads—is one of several modes of track failure on which the AAR-FRA-RPI-TDA Track Train Dynamics Program has focused attention. To investigate the generation of wide gage on tangent track, experiments were conducted to measure track dynamic response and long-term fatigue life of track sections on the Union Pacific Rail-road in Idaho. Results of these experiments have defined the important factors in this mode of track fatigue.
On Some Problems Associated With Vibration Isolation of Ship Machinery
Authors: Golinski J. A.
Published: November 2010

Vibration isolators of machines installed on ships are subject to both dynamic forces involved with the working of these machines and inertia forces resulting from the rolling of the ship. In order to illustrate this better, a solution of the vibration equation of a single mass system has been analyzed, the system being excited simultaneously by a dynamic force and a motion of foundation. It has been found that the larger the ratio of rotation speed is to natural frequency of vibration, the larger is the relative displacement of a machine mounted on vibration isolators. To obtain as small as possible a value of this ratio it might be necessary to use “hard” isolators, but such a solution is not one of the best, because forces transmitted to the foundation would then be larger than the dynamic forces causing the vibration of this machine. Thus the author recommends employing “soft” isolators, on condition, however, that the frequency ratio mentioned previously be chosen such that the elastic deformation of the isolators be within allowable limits.
A Unique Cotton Sliver Drafting System
Authors: DeLuca L. B. , Mayer M.
Published: November 2010

A unique method of drafting textile fibers makes use of a discontinuously surfaced or segmental drafting roll. In segmental drafting, more complete force relaxation occurs between each maximum buildup of force, and an intermittent strand attenuation occurs. This action minimizes the mean drafting force. The technique described is an improvement over conventional drafting because it uses only two drafting zones instead of three or four to produce similar or equal quality sliver.
Synthesis of Spring Parameters to Balance General Forcing Functions in Planar Mechanisms
Authors: Matthew G. K. , Tesar D.
Published: November 2010

The analytical formulation from a companion paper is extended to allow the concept of multiply separated positions to be applied to the spring-energy problem. A major change in perspective for mechanisms is accomplished by the ability to presume that the mechanism pre-exists. Heretofore it has always been necessary to deal with mechanisms on a positional basis where higher-order motion could not be considered without also including the location of the mechanism. The set of analytics applied to springs is not affected by ignoring positional information. Utilization of the mechanism-spring system in the proposed manner creates a dynamic tool for the enhancement of machine operations.
An Optical Scanning Technique for Measuring Fiber Size
Authors: Barker R. L. , Brown M. H. , Lyons D. W.
Published: November 2010

An optical scanning system was used to obtain considerable information related to the fineness and fiber to fiber fineness variability of various samples of natural and man-made staple fibers. The adaptation and use of this system is described as various techniques for presenting an assembly of fibers for automatic optical analysis are considered. Frequency distribution curves of the diameters distribution of several different fibers were defined by using the image analyzer to scan the magnified images of fibers. These data are discussed as the fineness variability of the different staple fibers are analyzed and compared.
A New Hooked Needle Device For Forming Fiber Beards For Length and Strength Measurement
Authors: Barker R. L. , Poole H. W. , Lyons D. W.
Published: November 2010

Research was conducted in the design, development, and evaluation of a new hooked needle device for obtaining from a sample of cotton a parallelized beard of fiber suitable for instrumented length and strength testing. Through systematic definition of critical design parameters, needle combs were developed capable of forming thin profile fiber beards of exceptional uniformity and visual appearance. The acceptability of a hooked needle method for preparing beards of cotton fiber for automated analysis was demonstrated as this device was compared with conventional clamp and comb arrangements of fiber sampling.
On an Axiomatic Approach to Manufacturing and Manufacturing Systems
Authors: Suh N. P. , Bell A. C. , Gossard D. C.
Published: November 2010

A manufacturing system consists of the following processes; design, materials selection and processing, assembly, and quality control. Maximum productivity of a given manufacturing system can be obtained only through optimization of the entire system rather than through optimization of its components individually. A system can be optimized through either a thorough understanding of the entire system and the interactions between its components, i.e., an algorithmic approach; or through the application of axioms to each decision-making step. This paper discusses an axiomatic approach to manufacturing and a methodology for developing axioms. Several hypothetical axioms and some of their corollaries are presented with examples to illustrate the basic concepts.
Identification of Machining System Dynamics by Equation Error Minimization
Authors: Srinivasan K. , Nachtigal C. L.
Published: November 2010

The application of a sequential equation error minimization method to the identification of the dynamics of machining systems is described here. The development of the identification method was motivated by the need for models of machining system dynamics for the design of active chatter controllers. The dynamic cutting force parameters as well as the machine structure transfer function parameters are required for this task. This identification method is novel in the machine tool area in that it identifies both cutting force parameters and structure parameters with the same experimental data. A convenient excitation of the system dynamics is chosen. The system response is prefiltered before being processed and the equation error minimization scheme is refined to insure the validity of the results obtained. The correctness of the identification scheme is verified by using it to identify parameters in analog computer simulations of practical maching systems. The results of structural identification for experimental plunge cutting operations are also presented here.
Aspects of Job Scheduling
Authors: Phillips K.
Published: November 2010

A mathematical model for job scheduling in a specified context is presented. The model uses both linear programming and combinatorial methods. While designed with a view toward optimization of scheduling of facility and plant operations at the Deep Space Network (DSN) Station at Goldstone, the context is sufficiently general to be widely applicable. The general scheduling problem including options for scheduling objectives is discussed and fundamental parameters identified. Mathematical algorithms for partitioning problems germaine to scheduling are presented. A more detailed description of algorithms and of operational aspects of the model is planned for a later report.
A Mathematical Model for Drill Point Design and Grinding
Authors: Tsai W. D. , Wu S. M.
Published: November 2010

The performance of a drill is affected by the geometry of its point. The available mathematical representations of drill point geometry are inadequate to describe the variation of the drill point design. This paper develops a comprehensive mathematical model that describes the drill point geometry including the conical, the hyperboloidal, and the ellipsoidal drills. The model developed also enables one to precisely predict and control the drill point geometry and the process of grinding.
Technique for Efficient Time-Domain Analysis of Complete Buoy-Cable Systems
Authors: Wang H. T.
Published: November 2010

A brief description is given of a computer program for the time domain analysis of the two-dimensional dynamic behavior of general ocean buoy-cable-body systems. Several sample problems are given to illustrate the versatility of the program. The concept of using the results for a cable with reduced elastic modulus, adjusted so that the cable does not stretch, to predict the dynamic behavior of a nearly inextensible cable with much higher elastic modulus is discussed in detail. Except for the transient phase, it is shown that this technique generally predicts tensions and motions with errors of only a few percent for nearly inextensible cables which would otherwise require substantially longer computer times.
Torsional Strength of Glass Under Hydrostatic Pressure
Authors: Sakata M. , Aoki S.
Published: November 2010

Solid and hollow cylinders of Pyrex glass were twisted under hydrostatic pressure up to 1000 kg/cm2. The torsional strength of specimens coated with thin rubber films was increased by superposed hydrostatic pressure, while that of naked specimens remained constant. It is shown that rupture commences at a surface flaw and that the effect of hydrostatic pressure on the torsional strength of glass may be explained on the basis that fracture occurs when a critical stress-intensity factor is reached at a part-through surface crack.
The Effect of Hydrostatic Pressure Environment on the Low Cycle Fatigue Properties of a Maraging Steel
Authors: Lunsford G. , Pense A. W. , Venkatesan P. S. , McIntosh M. J.
Published: November 2010

To investigate the low cycle fatigue properties of an 18 percent nickel maraging steel, a high pressure fatigue testing machine including the high pressure chamber and associated hydraulic controls was designed and developed to apply simultaneously to the specimen (1) constant fluid pressure up to 100,000 psi, (2) mean uniaxial tensile or compressive stress, and (3) alternating push-pull load at a selected rate. Using this machine, notched and unnotched specimens were tested. Results indicated a definite increase in fatigue life of the material in the high pressure environment.
The Influence of Simulated Service Exposure on the Rupture Strengths of Grade 11, Grade 22, and Type 304 Steels
Authors: Wilson D. J.
Published: November 2010

High temperature exposures were carried out to simulate long-time service. Rupture curves for exposed Grade 11 and Grade 22 steels did not exhibit the instabilities characteristic of the unused materials so that straight-line extrapolation gave good predictions of long-time strengths. Possibly due to a C-type reaction, strength predictions were poorer for Type 304 steel. Similar strengths were obtained using parameter tests of the unused materials. At the present stage of development, simulated service exposures offer an alternative, but not a superior, technique for extrapolating rupture characteristics.
A Numerical Method for Stress Concentration Problems of Infinite Plates With Many Circular Holes Subjected to Uniaxial Tension
Authors: Hamada M. , Mizushima I. , Hamamoto M. , Masuda T.
Published: November 2010

The boundary collocation method using the general form of the stress function is proved to be available for the problems of stress concentration in infinite plates with many circular holes. As numerical examples, the problems treated are of infinite plates with two circular holes of unequal diameters, those of infinite plates with four circular holes of equal diameters and of symmetric arrangement, and those with a row of infinite circular holes, all of which are subjected to uniaxial tension. Also the problem of an infinite plate with a row of infinite circular holes subjected to shear is solved. The numerical results are summarized in some diagrams.
An Interpretation of the Yoder-Griffis-Crooker Observations of Sustained-Load Cracking in Ti-6Al-4V
Authors: Krafft J. M.
Published: November 2010

Their recent NRL report documents a substantial degradation in load carrying capability of partially cracked specimens of annealed Ti-6 Al-4V plate in a room air environment. In this paper, the effect is analyzed as a special case of tensile ligament instability model, set up to permit integration of crack growth rate over the path to KIc. Results show that the time dependence and magnitude of the load carrying capability and of the sustained load crack growth SLC are predictable from plastic flow characteristics, including the transient stress relaxation rate, and from a slight environmental effect. A simplified diagram for engineering assessment of SLC is presented. Importance is attached to the persistence of stress relaxation, as much as to its rate, in inducing SLC. Little effect is expected from the level of fracture toughness to the extent that it is controlled by the process zone size dT.
Effects of Cold Work and Mechanical Equation of State in 1100 Aluminum Alloy
Authors: Ellis F. V. , Wire G. L. , Li Che-Yu
Published: November 2010

The concept of mechanical equation of state is reviewed based on experimental results on 1100 aluminum alloy. It is applied to describe the effects of cold work on creep and creep rupture properties of this material.
Optimum Design for a Corrugated Diaphragm Clamped to a Shaft Undergoing Axial or Angular Displacement
Authors: Rubin C.
Published: November 2010

The bending of a circular corrugated diaphragm which is clamped along its outer edge and clamped to a shaft at its geometric center is analyzed. The shaft may undergo small axial displacements or small angular displacements in a plane perpendicular to the plane of the original plate surface. The diaphragm is treated as a polar-orthotropic plate and closed form solutions are obtained for the deflection and stresses at any point for cases with and without a uniform load acting on the diaphragm surface. Maximum deflections and stresses are located and optimum inner-to-outer diameter ratios are determined.
Crack Initiation In Grain Boundaries Under Conditions of Steady-State and Cyclic Creep
Authors: Raj R.
Published: November 2010

Nucleation of intergranular cracks during steady-state and cyclic creep is analyzed in detail. The basis of the analysis is that grain boundary sliding produces stress concentrations at inclusions, ledges and triple-line junctions which leads to nucleation of cracks. The analysis is built upon different facets of the mechanical behavior of grain boundaries such as: sliding with elastic accommodation, diffusional and power law creep accommodation, and the contribution of sliding to the strain rate under power law creep conditions. Inclusions play an important role in fracture since the energy of the inclusion-matrix interface is usually high and since sliding produces stress concentration at inclusions. Triple line fracture is shown to be important during transient creep conditions. Crack initiation is calculated as a function of the following engineering parameters: temperature, strain rate, grain size, inclusions, cyclic frequency and hold time. The results are in broad agreement with experimental observations.
Initial Crack Extension in Two Intermediate-Strength Aluminum Alloys
Authors: Griffis C. A. , Yoder G. R.
Published: November 2010

Three-point bend tests were conducted to examine the geometry dependence of JIc in two intermediate-strength aluminum alloys, 2024-T351 and 7005-T6351. The amounts of crack growth at selected points on the load-versus-deflection curves were delineated using a heat tinting technique. Resistance curves of J-versus-crack extension were constructed to facilitate determination of JIc at incipient crack movement. The through-thickness variation in fracture toughness of a 7.6-cm-thick plate of 7005 aluminum was determined and correlated with fractographic and metallographic observations. The current JIc measurements from subsized specimens of 7005 aluminum are compared with previous KIc characterizations using linear-elastic, full-thickness specimens.
A Fracture Criterion for Porous Materials and Its Application to the Shape of Sintered Preforms in Forging
Authors: Tabata T. , Masaki S.
Published: November 2010

Ductile fracture of porous metals during forging was studied. The effect of the shape of sintered copper preforms on the forming limit is examined in upsetting with flat dies at room temperature. Cylindrical preforms with concave ends were found to show less barrelling during deformation and had a larger upsetting limit compared to those with flat ends. A fracture criterion for porous materials was proposed as a function of the history of the hydrostatic component of the stress. The criterion was applied to upsetting of sintered copper preforms. For calculation of the forming limit, the histories of the stress components at the equatorial free surface were obtained applying the plasticity equations for porous materials. The change in the density distribution during upsetting was measured.
The Use of Classification Zones for Fatigue Behavior in Steels
Authors: Weiss M. P.
Published: November 2010

Numerous studies on fatigue damage and fatigue crack propagation in the past dealt with these problems, either by a cumulative damage approach, or using crack propagation equations based on linear elastic fracture mechanics. Although these two approaches are not compatible, each is useful for predicting fatigue behavior correctly, but only within defined limits. This study introduces the “fatigue phase diagram”, which classifies different combinations of stresses and crack lengths in a given specimen, as zones in which different fatigue evaluation criteria, and possibly different fatigue mechanisms govern. Furthermore, a definition of the “threshold crack length” is proposed for consideration as the end of the crack initiation stage. It is suggested that most stress-intensity-range-threshold studies in the literature, were performed with stress range under the fatigue limit of the material, and therefore no crack initiation or propagation could have been measured. Any additional study should specify the zone of the tests on the fatigue phase diagram, so that correlations between different tests could be done with the proper data only.