bluuebunny/crossref_metadata_2025 huggingface dataset:
The Choking Pressure Ratio of a Critical Flow Venturi
Authors: Hillbrath H. S. , Dill W. P. , Wacker W. A.
Published: November 2010

The critical flow venturi has many important applications in the measurement and control of gas flow. In many of these applications, it is desirable to minimize the pressure loss required to maintain critical flow conditions. The performance of the venturi may be characterized by the ratio of outlet static pressure to inlet total pressure just sufficiently small to produce critical flow. This ratio is called choking pressure ratio (CPR). The optimization of diffusers for critical flow Venturis is discussed and suggestions for designs practice are presented. Test results are given for six different diffuser configurations, and a comparison is made with data on 11 configurations from other investigators. This work was done under contract to the National Aeronautics and Space Administration—Marshall Space Flight Center. It is shown that, for the small divergence angles considered, a simply defined diffuser effectiveness parameter is approximately independent of flow conditions and may be used to predict choking pressure ratio. Even very short diffusers greatly improve performance, and, for longer diffusers, critical flow can be maintained at total pressure losses of 5 percent.
Vibration of a Loosely Held Tube
Authors: Blevins R. D.
Published: November 2010

The results of a series of over 700 measurements of the tube damping and natural frequency of heat exchanger tubes are presented. The damping and frequency measurements of the loosely held tube show considerable scatter. Damping increased slightly with increasing excitation force or decreasing preload applied to the tube. Increasing the proportion of the tube length held in the support strongly increased damping. Third mode vibrations were more lightly damped than first mode vibrations. The resonance frequency increased with static preload applied to the tube.
Stability and Damped Critical Speeds of Rotor-Bearing Systems
Authors: Bansal P. N. , Kirk R. G.
Published: November 2010

This paper describes an analytical technique to calculate the damped critical speeds and the instability threshold speed of multimass rotor-bearing systems. Necessary equations are developed to study the effect of bearing as well as bearing support flexibility and damping on the system stability, thereby enhancing the current state of the art. Included in the analysis are the effects of linearized disk gyroscopic moments, shear deformation, and speed dependent bearing characteristics. The method of solution is based on the Transfer Matrix approach and uses complex variable notation to develop the overall system matrix. Mutter’s quadratic interpolation technique is employed to extract the complex eigenvalues of the rotor system and the corresponding mode shapes are found by back substitution. The analysis has been programmed for digital computer solution. Computational time is saved by eliminating from the polynomial the complex conjugates of the roots already found. Numerical overflow/underflow is controlled via scale factors. In addition to calculating the damped critical speeds, the computer program also provides information about the undamped frequencies, peak response frequencies, response amplification factors, and logarithmic decrements of the system. The accuracy of the predictions of the program has been verified and is shown to be acceptable for typical rotor systems. The results of an extensive investigation of an intershaft journal bearing instability in a dual rotor system are summarized. The stability map for this system is presented and clearly indicates the effect of rotor radial misalignment on system stability.
The Bond Graph as a Unified Data Base for Engineering System Design
Authors: Rosenberg R. C.
Published: November 2010

In developing a unified data base for support of engineering systems design there are several important factors to consider, such as efficiency of model description, ease of modifying models, and characteristics of assembling device models into systems. The multipart model and its associated bond graph representation can serve very effectively as a unified data base, especially when devices and systems involve several energy domains simultaneously (e.g., electromechanical or hydromechanical transduction). In addition to providing a succinct, flexible data base for linear and nonlinear, static and dynamic models, bond graphs can be processed causally to reveal important information about alternative input-output choices and device-level coupling factors when submodels are assembled into systems. Particularly for large-scale nonlinear systems this is an important feature in aiding the formulation of state equations. Illustrations of the bond graph data base approach are given.
Design of a Squeeze-Film Damper for a Multi-Mass Flexible Rotor
Authors: Cunningham Robert E. , Fleming David P. , Gunter Edgar J.
Published: November 2010

A single mass flexible rotor analysis was used to optimize the stiffness and damping of a flexible support for a symmetric five-mass rotor. The flexible support attenuates the rotor motions and forces transmitted to the support bearings when the rotor operates through and above its first bending critical speed. An oil squeeze-film damper was designed based on short bearing lubrication theory. The damper design was verified by an unbalance response computer program. Rotor amplitudes were reduced by a factor of 16 and loads reduced by a factor of 36 compared with the same rotor on rigid bearing supports.
The Order Problem of Burmester Linkage Synthesis
Authors: Waldron K. J.
Published: November 2010

A modification to Modler’s solution to the problem of obtaining a crank to drive the synthesized linkage through the design positions in a specified order is suggested. This permits location of such cranks by inspection of the circle-point curve and the image poles alone.
The Rupture Strength of Fully Annealed, Metallic Spherical-Cap Diaphragms
Authors: Beese J. G.
Published: November 2010

Equations are developed which predict the maximum hydrostatic pressure that an initially dished, and subsequently annealed, circular safety rupture diaphragm can withstand. Diagrams based on the equations show the range of bursting pressure that can be obtained by suitably treating one particular sized disk of one specific material.
Vibration of an Asymmetrically Mounted Rotor With Gyroscopic Effects
Authors: Ardayfio D. , Frohrib D. A.
Published: November 2010

The equations of motion for the asymmetrically mounted rotor with gyroscopic effects contain periodic coefficients. These periodic coefficients which arise from the system asymmetries cannot be eliminated by transformation into rotating coordinates. The parametrically excited vibrations are studied by referring to the natural frequencies of a generating system consisting of a symmetric rotor on asymmetric supports. First the equations of motion are transformed into normal coordinates of the generating system by application of the Bulgakov normalization technique. The assumed small inertia asymmetry introduces coupling terms with periodic coefficients which are evaluated as generalized forces acting on the generating system. Then the final equations are solved by the approximate perturbation—variation method of Hsu. Formulae for parametric instability speed ranges are derived for the assumed small inertia asymmetry.
Approximation for Determining Harmonically Excited Response of Nonclassically Damped Systems
Authors: Cronin D. L.
Published: November 2010

The straightforward task of generating response plots for harmonically excited, nonclassically damped systems involves substantial computation. A current approximate approach based on classical analysis reduces computation but is shown to perform poorly in resonance regions when resonances are closely spaced. An improved approximation also based on classical analysis is developed and is shown to behave well in these regions for a numerical example. An inquiry concerning a “best” diagonalizable damping representation leads to a frequency dependent, load distribution dependent damping matrix that may in some cases aid computation and support visualization.
The Formation and Properties of Machining Burrs
Authors: Gillespie L. K. , Blotter P. T.
Published: November 2010

The mechanisms causing machining burrs and four analytical models that predict burr properties are presented. The study indicates that three basic mechanisms are involved. They are lateral deformation, chip rollover, and material tearing. Both the theory and experimental results indicate that machining burrs cannot be prevented by changing machining parameters alone.
Cutting Rate-Tool Life Characteristic Functions for Material Removal Processes—Part 2: Verification and Applications
Authors: Tipnis V. A. , Friedman M. Y.
Published: November 2010

The experimental verification, interpretations, and applications of the concept of cutting rate-tool life (R-T) characteristic functions are presented in this paper. Two statistically designed experiments, one on sawing and the other on milling, verifying the concept are described. The analytical and geometrical interpretations of the concept, including the existence of optima in the R-T domain, are presented. The applications discussed include economic selection of machining conditions, economic tool life determinations, comparison of machining response, objective function for adaptive control, and maximization of material removal at a desired level of surface integrity. The concept can be applied to other machining responses of conventional as well as nontraditional material removal processes.
The Dynamics of Rotor-Bearing Systems Using Finite Elements
Authors: Nelson H. D. , McVaugh J. M.
Published: November 2010

A procedure is presented for dynamic modeling of rotor-bearing systems which consist of rigid disks, distributed parameter finite rotor elements, and discrete bearings. The formulation is presented in both a fixed and rotating frame of reference. A finite element model including the effects of rotatory inertia, gyroscopic moments, and axial load is developed using the consistent matrix approach. A reduction of coordinates procedure is utilized to model elements with variable cross-section properties. The bearings may be nonlinear, however, only the linear stiffness and viscous damping case is considered. The natural whirl speeds and unbalance response of a typical overhung system is presented for two sets of bearing parameters: (i) undamped isotropic, (ii) undamped orthotropic. A comparison of results is made with an independent lumped mass analysis.
Collection Efficiency and Pressure Drop of Needle Punched Filters
Authors: Afify E. M. , Mohamed M. H.
Published: November 2010

Although needle punched fabrics have been used in filtration with increasing success, only meager information is available on their performance characteristics in relation to their unique structure. In this paper an experimental investigation on the performance of needle punched filters is presented. A testing apparatus designed and constructed for this study is described. The pressure drop characteristics of needle punched filters were investigated. The effects of flow rate, packing density, and needling intensity were studied. Experiments were also performed to determine the collection efficiency of needle punched filters using flyash. The effect of flyash concentration, time duration of test, and needling intensity were considered. The role played by the structure in utilizing the mechanisms of collection and reducing the time rate of pressure rise during filtration is discussed. A new scale for measuring the quality of performance of filters using dust and relating, in a dimensionless form, the dust penetration, the pressure drop, and the filter weight per unit area was also developed. Comparison between the performance of commercial woven and needle punched filters demonstrated the superiority of needle punched fabrics over woven fabrics in filtration.
A Linear Programming Approach for Balancing Flexible Rotors
Authors: Little R. M. , Pilkey W. D.
Published: November 2010

The feasibility of a new flexible rotor balancing method is demonstrated. Discrete “effective” unbalance components which produce the same observed response as the actual rotor unbalance are identified, and subsequently removed, using linear programming. In addition to satisfying rotor runout observations, the unbalance may be identified such that it is potentially harmful to response at a speed above the level at which the shaft can safely run without balancing. The potentially harmful response corresponds to the linear programming objective function, while the observations become constraints. In addition, further constraints can be included to assure that the size of the calculated balance weights are within practical limits. The versatility of the new approach is demonstrated with example problems using a rotor model for which the response is obtained with a computer code.
Analytical and Experimental Investigation of a High-Speed Elastic-Membered Linkage
Authors: Sutherland G. H.
Published: November 2010

The paper presents the derivation of the equations of motion of a fully elastic four-bar linkage using the assumed mode analysis approach. The form of the solution for the member deflections is discussed and the governing nondimensional parameters are identified. Numerical results are then obtained in a nondimensional form in order to provide a broad interpretation and use of the results. The validity of the mathematical model is then confirmed by the results of physical experimentation.
Workability of Aluminum Alloy 7075-T6 in Upsetting and Rolling
Authors: Oh S. I. , Kobayashi Shiro
Published: November 2010

The workability of aluminum alloy 7075-T6 was investigated in upsetting and rolling at room temperature with reference to occurrence of free-surface cracks. The fracture criterion was established by a plane-strain sheet tension test and an upset test. An improved version of the matrix method was used to obtain the complete solution in upsetting. Then a workability chart was constructed by combining the fracture criterion and the complete solution for various friction conditions and several specimen dimensions. In rolling, a theory for the analysis of spread was utilized to compute the strain history at a point on the free edge surface. With this theory it was possible to predict workability in multipass rolling with reference to edge cracking. The limiting reductions in thickness were given as functions of workpiece dimensions for various friction values. Experimental results demonstrated that the predictions were very good.
Computer Design of a Minimum Vibration Face Milling Cutter Using an Improved Cutting Force Model
Authors: Doolan P. , Phadke M. S. , Wu S. M.
Published: November 2010

An improved cutting force model is integrated in the design of a minimum vibration face milling cutter. The cutting force of a blade is approximated by a rectangular pulse whose height is governed by the blade spacing. Specific examples of a special purpose and a general purpose cutter are given and their performances are evaluated.
Axisymmetrical Vibrations of Underwater Hemispherical Shells
Authors: Chen F. C. , Huang T. C.
Published: November 2010

Free vibrations of an underwater elastic hemispherical thin shell with fixed edge have been investigated based on the bending theory. The solution of this fluid-solid interaction problem involves the differential equations of motion of underwater spherical shells, the velocity potential of the water field, the hydrodynamic pressure, and the continuity and boundary conditions. A transcedental frequency equation in terms of Legendre functions is derived and the normal and tangential mode shapes are found. Examples are given and results are plotted for natural frequencies and modes shapes.
Attritious Wear of Silicon Carbide
Authors: Komanduri R. , Shaw M. C.
Published: November 2010

Attritious wear of silicon carbide in simulated grinding tests against a cobalt base superalloy at high speed and extremely small feed rate was studied using a scanning electron microscope (SEM) and an auger electron spectroscope (AES). In many cases the wear area of silicon carbide was found to be concave rather than planar in shape. Several microcracks and grain boundary fracture were also observed. No evidence of metal build-up was observed on silicon carbide which was not the case with aluminum oxide. AES study of the rubbed surface on the work material and transmission electron microscope (TEM) investigation of the wear debris suggest that attritious wear of silicon carbide is due to one or more of the following mechanisms: 1 – Preferential removal of surface atoms on the abrasive, layer by layer, by oxidation under high temperature and a favorably directed shear stress; 2 – disassociation of silicon carbide at high temperature and (a) diffusion of silicon into the work material and formation of metal silicides and (b) diffusion of carbon into the work material and formation of unstable metal carbides (in the present case Ni3C and Co3C) which decompose during cooling to metal and carbon atoms; 3 – pinocoidal cleavage fracture of silicon carbide on basal planes c(0001) resulting in the removal of many micron-sized crystallites.
Mechanism Design Using Animation
Authors: Ladd H. E.
Published: November 2010

Modern mechanism synthesis techniques provide powerful tools for satisfying path constraints. However, for industrial applications there are often equally important constraints on space available for the mechanism and on how it can be driven. Two examples clarify the problem. A computer graphics procedure is outlined as a workable solution.
Identification of Structures Through Records Obtained During Strong Earthquake Ground Motion
Authors: Udwadia F. E. , Shah P. C.
Published: November 2010

The problem of estimating a space dependent coefficient in a forced linear hyperbolic differential equation from the knowledge of the solution at one or more isolated points is dealt with. The continuous model of a structural system by a shear beam is used to study the utility of earthquake records in determining structural models. Starting with an initial “guess,” a systematic method of iteratively improving the estimate of the structural stiffness using the information contained in the measured response to a known ground excitation is developed. A highly efficient and automatic numerical algorithm for this purpose, based on an optimal control formulation of the problem of history matching is developed. Numerical examples are presented showing the dependence of the estimate on the initial guess. The nonunicity of the estimate is demonstrated, pointing to the fact that though history matching at one or more points in a structure may be a necessary condition for arriving at an adequate model, it may not be a sufficient one.
Stiffness of Machine Tool Joints: A Random-Process Approach
Authors: Thomas T. R. , Sayles R. S.
Published: November 2010

A random-process surface model of elastically yielding asperities with a gaussian height distribution is proposed to represent the deflection of a machine tool joint. A passband of surface wavelengths taking part in the interaction is derived in terms of workpiece dimensions, material properties, and a plasticity criterion. The necessary moments of the surface power spectrum are computed from profile measurements on a lathe bed, and hence the stiffness of the joint between it and the saddle is calculated. Finally, theoretical predictions of the variation of stiffness with load are compared with published measurements on bolted joints. Good agreement is found for a rectangular planform; for other planforms agreement is reasonable at low preloads.
Power Input to Weaving Looms Driving Motors
Authors: Mohamed M. H. , Lord P. R.
Published: November 2010

In this article a method for measuring the instantaneous power input to a motor is described. The wattmeter developed was used to estimate the characteristics of a particular loom motor. Also the fluctuation of the power input to the loom driving motor and the effect of the different loom mechanisms on the power consumed was investigated.
Mechanical Couplings—A General Geometrical Theory, Part 2: Examples and Applications of the Theorems
Authors: Fichter E. F. , Hunt K. H.
Published: November 2010

Having established “feather” as an invariant property of algebraic couplings with connectivity 1, and of some with 2, many examples of its use are now given, in both planar and spatial motion, to predict order of point-loci, class of plane-loci, and degree of line-loci. Apparent exceptions are explained and interpreted, thereby strengthening the general theory. Some theorems on line-loci attributable to Cayley are shown to be important keys to the determination of “feather” in a number of instances.
On the Design of Bolted Connections With Gaskets Subjected to Fatigue Loading
Authors: Osman M. O. M. , Mansour W. M. , Dukkipati R. V.
Published: November 2010

Bolted connections subjected to fatigue loading are usually considered to be the “weak point” in a design. They usually are highly preloaded to increase their resistance to external dynamic loading resulting in selecting large bolt diameters. This paper presents a design method for calculating an optimal bolt diameter required for a specific fatigue-loading situation. When load is applied to the bolted connection, the bolt tensile stress increases and the members undergo a decrease in compression. Based on the fact that the decrease in the deformation of the connected members must be equal to the increase in the deformation of the bolt, expressions are derived for maximum and minimum forces and stresses on the bolt. Using Soderberg’s failure line, an expression is developed for bolt diameter. It implies that there exists an optimal safe bolt diameter satisfying the loading conditions. Using a lower-bound value of bolt preloading produced an expression for the critical diameter of the bolt in terms of maximum and minimum dynamic force applied, the yield strength of bolt material, the factor of safety, and the stiffness constant. Examples are given to illustrate the design procedure.
Effect of Thickness on the Stresses in a Plate With an Elliptic Hole
Authors: Bapu Rao M. N.
Published: November 2010

A three-dimensional analysis is presented for the stresses around an elliptic hole in an infinitely long thick plate subjected to uniform tension and shear. The maximum stress is found to depend on the ratio of plate thickness to the length of the semimajor axis of the hole, as well as on Poisson’s ratio. In the limiting cases the solution reduces to that of the circular-hole problem and the two-dimensional solution of the elliptic-hole problem.
Vibrations and Dynamic Response of Viscoelastic Plates on Nonperiodic Elastic Supports
Authors: Nagaya K.
Published: November 2010

This paper discusses the vibration and transient response problems of nonperiodically elastic supported viscoelastic continuous plate. The three-element viscoelastic model is adopted in the analysis. The solution for the plate is obtained from the correspondence principle by applying the Laplace transform to the constitutive equation and the equation of motion for the elastic plate. Expressions of displacements and bending moments for an impact load are obtained, and the results for the viscoelastic plate are compared with those for the elastic plate.
Average Life of Equipment Subject to Compound Failures
Authors: Malik M. A. K.
Published: November 2010

When systems are subjected to both chance and wear-out failures, the mean of the failure distribution—which would be the average life of the system—does not exist in closed form. In this article, such a distribution is developed from basic engineering phenomena; its general mean is developed in nonclosed form; a particular solution easier to evaluate is derived, and the attention of the researchers in “equipment life”, “reliability”, and “maintenance” as well as in statistics and mathematics is drawn toward developing the relevant integral transform for this function. Some related distributions depicting various combinations of chance failures, wear-out failures, and aging and standby processes are also discussed.
An Approximate Method for the Dynamic Analysis of Elastic Linkages
Authors: Midha A. , Erdman A. G. , Frohrib D. A.
Published: November 2010

A new numerical procedure based on an iterative technique is progressively developed in this paper for obtaining an approximate particular solution from the equations of motion of an elastic linkage with small damping and at subresonant speeds. The method is introduced by employing a simple vibrating system, a single degree-of-freedom mass-dashpot-spring model under both harmonic forcing and periodic forcing. A harmonically excited two degree-of-freedom model is also solved by the suggested approach. Error functions are developed for each case to give an estimation of the order of error between the exact analytical solution and the approximate technique. The suggested technique is then extended to solve an elastic linkage problem where the uncoupled equations of motion are treated as a series of single degree-of-freedom problems and solved. These are retransformed into the physical coordinate system to obtain the particular solution. The first and second derivatives of the forcing functions (involving rigid-body inertia) are approximated utilizing the finite difference method.
A Two-Path Variable-Ratio Transmission With an Extended Range of Ratios
Authors: White G.
Published: November 2010

The range of speed ratios available from a simple two-path, variable-ratio transmission is increased by adding a two-speed gear train and a pair of clutches. Two phases of operation minimize the torque demand on the variable ratio elements; transfer between these phases is effected by clutches engaged when unloaded and at a synchronous speed. In consequence, no speed or torque discontinuity occurs when engaging or freeing a clutch. Dimensionless analytical relations describing the transmission are developed.
Investigation of Surface Temperature in Electro-Discharge Machining
Authors: Marty C. C.
Published: November 2010

In the E.D.M. process one can correlate on the basis of a heat conduction model the material surface temperature with adimensional parameters. A mathematical formulation is proposed. For a given heat input and a maximum surface temperature it is demonstrated that crater depth and radii of the heat source are correlated by an universal function. Experimental data give, for many materials, a surface temperature of the same magnitude as the boiling point.
Dynamic Data System: A New Modeling Approach
Authors: Wu S. M.
Published: November 2010

The dynamic data system (DDS) is a modeling technique that uses dynamic data in the form of a time series to develop physically meaningful stochastic difference/differential equations. The general mathematical formulation and background of the DDS methodology are given, and the modeling procedure evolved in this approach is illustrated by an example pertaining to neutron flux data. An example of a machine tool system analysis is presented to show the physical interpretation and the subsequent exploitation of the mathematical models. Various applications of the technique are also described, and the future development of DDS is envisaged.
Analysis of Plane-Strain Extrusion Through Arbitrarily Shaped Dies Using Flow Function
Authors: Nagpal V.
Published: November 2010

Plane-strain extrusion of a nonworkhardening material through a die with arbitrarily defined profile is analyzed using extremum principles. General kinematically admissible flow models for the extrusion process are obtained using the flow function approach. A closed-form expression for the rate of energy dissipated is derived with a special class of the flow models. For given process conditions, an approximate solution of extrusion pressure and metal flow is obtained by minimizing the rate of energy dissipated. Results obtained with the wedge-shaped dies, cosine dies, elliptic dies, and hyperbolic dies are presented. Optimal shapes of the dies for different frictional conditions at the die-material interface are derived from the solution.
A Sparsity-Oriented Approach to the Dynamic Analysis and Design of Mechanical Systems—Part 2
Authors: Orlandea N. , Calahan D. A. , Chace M. A.
Published: November 2010

The work described herein is an extension of sparse matrix and stiff integrated numerical algorithms used for the simulation of electrical circuits and three-dimensional mechanical dynamic systems. By applying these algorithms, big sets of sparse linear equations can be solved efficiently, and the numerical instability associated with widely split eigenvalues can be avoided. The new numerical methods affect even the initial formulation for these problems. In this paper, the equations of motion and constraints (Part 1) and the force function of springs and dampers (Part 2) are set up, and the numerical solutions for static, transient, and linearized types of analysis as well as the model optimization algorithms are implemented in the ADAMS (automatic dynamic analysis of mechanical systems) computer program for simulation of three-dimensional mechanical systems (Part 2). The paper concludes with two examples: computer simulation of the front suspension of a 1973 Chevrolet Malibu and computer simulation of the landing gear of a Boeing 747 airplane. The efficiency of simulation and comparison with experimental results are given in tabular form.
Digital Simulation of Impact Phenomenon in Spur Gear Systems
Authors: Azar R. C. , Crossley F. R. E.
Published: November 2010

A digital simulation model is developed to represent a lightly loaded geared torsional system consisting of a drive unit, spur gear pair and load connected by flexible shafts. A clearance model called an Impact Pair [13] is used to represent the gear pair and includes the effects of backlash, time-varying stiffness and damping of the gear teeth and tooth-form error. Experimentally determined frequency spectra of the torsional oscillations of a gear-driven shaft have been plotted and reported on earlier [1]. Similar frequency plots are obtained from the simulation study, and data from these plots are compared with the experimental results for a variety of parameter changes including shaft speed, backlash and load. Results indicate that the simulation model portrays reasonably well the torsional behavior of the output shaft.
Loss Factor for a Rectangular Plate of Parabolic Thickness Variation
Authors: Nigam S. P. , Grover G. K. , Lal S.
Published: November 2010

The importance of the internal damping and of the evaluation of the fundamental mode loss factor of structural members subjected to multiaxial stress system is well known. A good amount of work is available on the elastic vibrations of ectangular plates of uniform thickness but it appears that little work has been done on vibrations of rectangular plates of variable thickness, though such cases are of interest in the aeronautical field since they approximate to wing sections. In the present work, the fundamental mode loss factors for a simply supported rectangular plate with parabolic thickness variation in X direction have been evaluated for different combinations of the aspect ratios and the taper parameters. An approximate relationship has been obtained which correlates the loss factor for the plate of variable thickness with that of a plate of uniform thickness.
Flank Wear Model of Cutting Tools Using Control Theory
Authors: Koren Y.
Published: November 2010

A model of the flank wear of cutting tools is developed by using linear control theory. The flank wear is assumed to consist of a mechanically activated and a thermally activated component. The wear process is mathematically treated as a feedback process, whereby the progressive wear raises the cutting forces and temperature thereby increasing the thermally activated wear-rate, and contributes to the mechanically activated wear. A mathematical expression for the flank wear growth is derived and shown to be consistent with experimental results. The experimental data is fitted to the wear model for calculating the mechanical wear coefficient and activation energy for the thermally activated wear. The model yielded a new tool-life equation which is valid over a wider range of speed than Taylor tool-life equation.
The Characteristics of Blended Polyester/Cotton Yarns Made by Ring and Open-End Spinning
Authors: Lord P. R. , Mohamed M. H. , Egambaram T. R.
Published: November 2010

A blended polyester/cotton yarn has a higher breaking elongation than a cotton yarn because of the rupture of cotton fibers which allows inelastic extension of the yarn. However, the polyester is not able to absorb as much of the load as it could because of its lower stiffness. Also, OE yarns have a structure different from ring yarns; this affects both the elongation and tenacity. The paper suggests theories to account for the characteristics demonstrated by experiment on both ring and OE yarns.
Mechanics of Rotary Dressing of Grinding Wheels
Authors: Malkin S. , Murray T.
Published: November 2010

An investigation is reported on the mechanics of the rotary dressing process for grinding wheels. Dressing forces were measured over a wide range of conditions, and SEM observations were made of the dressed wheel surfaces. It was found that the rotary dressing process is mainly controlled by the magnitude of the interference angle between the paths of the abrasive grains and the diamonds on the dresser surface. With a larger interference angle, there is a greater tendency for the abrasive to fracture rather than to plastically deform, thereby reducing the specific dressing energy and providing a sharper wheel with less flattened area on the grain tips.
Correlation of Tempering Effects With Temperature Distribution in Steel Cutting Tools
Authors: Wright P. K.
Published: November 2010

Experimental methods are described for determining the temperature distribution in steel cutting tools over the range 150 C to 1000 C. The techniques correlate temperature with changes in microstructure and hardness that arise due to the heat conducted into the tool. Results are presented for the machining of low carbon iron and commercially pure copper, and the effectiveness of cutting coolant is evaluated for a range of cutting speeds and for two different methods of application. Simple models for the heat sources in chip formation are derived and used to verify the experimental work by calculating the temperatures on the rake face.
Tool Life Distributions—Part 4: Minor Phases in Work Material and Multiple-Injury Tool Failure
Authors: Ramalingam S. , Watson J. D.
Published: November 2010

Distributed tool life under production machining conditions results in the need for unplanned tool changes. In the case of large volume or automated production systems, such production interruptions invariably lead to higher manufacturing costs. When the distribution in tool life is known, logical operating strategies can be devised to minimize the costs associated with unforeseen production interruptions. To facilitate this, analytical models for tool life have been developed and presented in the first two parts of this paper. These stochastic models portray tool failure as resulting from injuries due to damage producing encounters in the course of machining. In Part 3 of this paper, a physically consistent model for damage producing encounters which result in tool fracture has been identified and validated for single-injury tool failure. The case of multiple-injury failure is considered here with emphasis on the tool life scatter due to the variations in minor phase content of the work material (nonsulphide, nonmetallic inclusion content). The role and significance of the oxygen-rich nonmetallics to tool wear and machinability in unalloyed carbon steels is examined. It is shown that given a steel, the chemistry and volume fraction of oxygen-rich nonmetallics in it may well determine the tool life (machinability) and tool life scatter. If this be the case, details of the steel making process can be varied to limit and control the detrimental effects of the oxygen-rich, nonmetallic phases to the tool life. Some such techniques that allow machinability enhancement by steel making process modifications are discussed to illustrate the validity of the concepts postulated here. The analysis suggests that the tool life (or machinability) can be improved by limiting the frequency of damaging encounters. But since the minor phase is dispersed and the encounters are stochastic, the tool life improvement will have to be accompanied by an increase in scatter in agreement with previously reported results.
Structural Performance of Acrylic Plastic Plane Disk Windows With Twin Conical Bearing Surfaces
Authors: Stachiw J. D. , Smith N. E. , Burnside O. H.
Published: November 2010

Exploratory investigation into the structural performance of acrylic plastic plane disk windows with twin conical bearing surfaces has shown that such windows behave under hydrostatic loading similarly to plane disk windows with a single conical bearing surface. This conclusion is based both on experimental data from a test program and on findings from a finite element stress analysis. The test program encompassed short term and cyclic pressure testing of plane disk windows with twin conical bearing surfaces in the 0.21 ≤ t/Di ≤ 0.423 and 60 deg ≤ α ≤ 120 deg ranges. The finite element stress analysis addressed itself only to plane disk windows with 90 deg twin conical bearing surfaces in the 0.23 ≤ t/Di ≤ 1 range. On the basis of findings reached in this investigation it is recommended that the existing criteria (ANSI/ASME PVHO-1) for the design of plane disk windows with a single bearing surface be applied also in the design of plane disk windows with twin conical bearing surfaces since their structural performance under external hydrostatic loading appears to be very similar.
Effects of Rotary Dressing on Grinding Wheel Performance
Authors: Murray T. , Malkin S.
Published: November 2010

An investigation is described of the effects of rotary dressing on grinding wheel performance. Grinding performance is evaluated mainly in terms of the grinding forces and surface finish. It is demonstrated that the magnitudes of the grinding forces can be attributed to differences in the size of the wear flat area obtained by the various rotary dressing conditions. For finer dresser infeeds and greater differences between the peripheral velocities of the dresser and the grinding wheel, bigger grinding forces and smoother surfaces are obtained. A direct relationship is obtained between the grinding performance and the dressing interference angle, a larger angle resulting in smaller grinding forces and rougher surfaces. This leads to a trade-off relationship between grinding forces and surface roughness which characterizes the rotary dressing process.
Limit Analysis of Hollow Disk Forging—Part 1: Upper Bound
Authors: Avitzur B. , Sauerwine F.
Published: November 2010

An upper bound analysis for hollow disk forging is presented. Flow is described by a kinematically admissible velocity field which accounts for bulging of the inner and outer surfaces. The friction stress is assumed to be constant across the entire platen-hollow disk interface. Analytical predictions include the relative neutral radius, a bulge parameter and the relative average pressure all in terms of friction and hollow disk geometry. An improvement is observed over previous parallel velocity field solutions.
Thermal Damage and Rail Load Stresses in a 33-Inch Railroad Car Wheel
Authors: Wetenkamp H. R. , Kipp R. M.
Published: November 2010

Stresses in a 33-inch (.840 m) railroad car wheel in response to static rail loadings are presented on the basis of experimental work and theoretical predictions. In regions away from the contact area, the theoretical predictions are verified by experiment. The rail load stresses are compared to theoretically damaging thermal loads, and a possible method of analysis of fatigue damage from the combined loading is discussed.
Disk and Strip Forging with Side Surface Foldover—Part 2: Evaluation of the Upper-Bound Solutions
Authors: Kohser R. A. , Avitzur B.
Published: November 2010

The upper-bound solutions developed in Part 1 are evaluated with regard to their ability to produce a lower value for required power (load, pressure, or work). Comparisons made with existing solutions such as the triangular field solution and one-zone bulge solution show that for strip, each solution has a domain of geometry and friction in which it is superior. The new solution produces a lower upper-bound for conditions of high interface friction and relatively thin specimen, the area where foldover is the observed mode of flow. For solid cylindrical disks, the solution fails to improve upon existing analyses, but comes sufficiently close to warrant additional study. After evaluation, these solutions were then used in an incremental technique to model the geometry and flow as a function of reduction in height. Results appear most encouraging, and the relative simplicity of the technique when compared with present alternatives is quite attractive.
Lateral Stability of Freight Cars With Axles Having Different Wheel Profiles and Asymmetric Loading
Authors: Tuten J. M. , Law E. H. , Cooperrider N. K.
Published: November 2010

The majority of studies of rail vehicle lateral dynamic response have utilized models wherein it is assumed that the loading and geometry of the vehicles are symmetrical left and right and fore and aft. It has been observed that with use North American rail freight vehicles develop transverse wheel profiles that may be different for wheels on a given axle and that may also differ from axle to axle on a given vehicle. As the transverse wheel profiles exert a strong influence on lateral dynamic response by affecting the effective conicity and gravitational stiffness of the wheelset, models capable of having different wheel profiles on the same axle as well as on different axles were developed to investigate the stability behavior. Additionally, these models were formulated so that the effects on stability of asymmetric fore and aft loading conditions, as manifested through gravitational stiffness effects and creep coefficients, could be examined. Results of studies using these models are presented that display characteristics markedly different from those of completely symmetric models. A particularly interesting result is that, in most cases, the lateral stability of vehicles with different wheel profiles on the various axles is strongly sensitive to the direction of motion with results for each direction of motion which may differ radically from symmetric cases.
Electrical Stimulation of Fabric Filtration (ESFF) for Cotton Dust Control
Authors: Costanza P. A. , Lamb G. E. R. , Dunbar J. B.
Published: November 2010

ESFF is a technique which promises to give improved performance in the filtration of flyash from the effluent gas of coal combustion. The present studies were made to assess the feasibility of the same technique in the removal of cotton dust from the air of a cotton processing plant. Particle size analysis of cotton dust generated from various sources indicates that trash from a mill filter can be used to generate a suitable test aerosol. None of the distributions measured were found to contain particles smaller than 0.5 μm. Experiments with such aerosols showed that ESFF reduced penetration significantly over the entire particle size range.
A Scheme to Assist in the Evaluation of Tenter Frame Dryer Performance
Authors: Beckwith W. F. , Beard J. N.
Published: November 2010

One of the textile industry’s largest consumers of energy is the tenter frame dryer. To assist the industry in operating these dryers efficiently, a mathematical model which simulates the drying process and a scheme to solve for the parameters in the differential equations of the model have been developed and are presented in this paper. Temperature profiles predicted from the model are compared with profiles measured on commercial dryers. Also dryer simulation studies to elucidate optimal operating conditions are discussed.
Performance Prediction for an Axial Flow Hydraulic Transmission
Authors: Sheets H. E. , Corriveau P. J. , Skeels H. B.
Published: November 2010

An axial flow hydraulic transmission is being investigated when using such a transmission in conjunction with ship propulsion driving a propeller. The investigation covers the procedure to discern the theoretical and predicted operating points for an axial flow hydraulic transmission. Theoretical performance characteristics of the primary and secondary units are determined and actual performance is predicted based on design and fluid losses. The performance curves of each component are then overlayed, and the intersection of these curves represents the transmissions’ operating point. Since actual performance curves are highly non-linear, graphic representations provide the best way to predict actual operating points.
Some Implications of Noncoaxiality in Finite Deformations
Authors: Hsu T. C.
Published: November 2010

Two-dimensional finite deformations are analyzed by factoring and multiplying the matrices of the linear transformations representing them. A general linear transformation consists of a pure shear, a uniform dilation, and a rigid-body rotation. Coaxiality is defined for finite deformations and its effect on the resultant distortion discussed. Tests for coaxiality are devised for use on rectangular grids which are often employed in metal forming research. Formulas are derived for the initial and final directions of the resultant major principal axis in both equal and unequal noncoaxial pure shears and, in particular, conditions are found for the constancy of distortion in the second deformation.
Correlation of Flow Stress With Strain Rate and Temperature During Machining
Authors: Bailey J. A. , Bhanvadia D. G.
Published: November 2010

An idealized model of the orthogonal metal cutting process is used to determine the stresses, strain rates, and temperatures at the tool rake face for the machining of several materials under dry, unlubricated conditions, where a continuous chip is produced with an absence of a built-up edge. An attempt is made to correlate stress with strain rate and temperature using a temperature compensated strain rate parameter, and velocity modified temperature.
Fatigue and Corrosion-Fatigue Crack Propagation in Intermediate-Strength Aluminum Alloys
Authors: Crooker T. W.
Published: November 2010

Fatigue crack propagation studies were conducted on a variety of intermediate-strength aluminum alloys under high stress-intensity range cycling (ΔK > 10 ksiin.). Tests were conducted in ambient room air and in 3.5-percent NaCl saltwater environments. Data are presented on log-log coordinates in terms of fatigue crack growth rate (da/dN) as a function of the stress-intensity factor range (ΔK). Comparisons are made among similar crack propagation data for steel and titanium alloys.
Fatigue Crack Growth Resistance of Several Neutron Irradiated Pressure Vessel Steels and Welds
Authors: Shahinian P. , Watson H. E. , Hawthorne J. R.
Published: November 2010

Pre and postirradiation fatigue crack growth rates in A302-B, A533-B, and A543 steel plate and in two A543 welds (submerged arc and electroslag) were determined at 550 deg F (288 deg C) in air. The fracture mechanics approach was used to analyze the experimental data. Neutron irradiation at 585 deg F (307 deg C) to 2.5 × 1019 n/cm2, > 1 MeV produced no significant effect on resistance to crack growth in A302-B steel and caused only a slight decrease in crack growth resistance of A533-B and A543 steels. Also, the resistance to crack growth of the submerged arc weld was unaffected by the irradiation, but that of the electroslag weld was substantially improved. The crack growth rate versus stress intensity factor range curve for the A302-B steel represents an upper bound for the pre and postirradiation data for the steels and welds of this study.