bluuebunny/crossref_metadata_2025 huggingface dataset:
Some Elementary Projective Properties of the Four-Bar Linkage
Authors: Marquez J. S. , Adams D. P.
Published: November 2010

The four-bar linkage defines a complete quadrilateral—a figure with extensive elementary projective properties. The undertaking is to search out and discover evidences or indicia of projective interrelationships in the geometry of the four-bar, such as concurrencies of lines, collineations of points, constancies of cross-ratios, harmonic divisions, tangencies of lines and curves, and others, toward the practical application of such properties in four-bar motion. Several of these have indeed been discovered and proved, each worth-while in its own right and each expressible as an instantaneous projective relationship between members of a simply-defined family of linkages. The most startling and applicable of the properties is the collineation of the centers of the inflection circles of the connecting-rod motions of the defined family.
Dynamic Response of Pressurized Thin Cylindrical Shells Subjected to Torsional Loads
Authors: Kessel P. G. , Liao N. K.
Published: November 2010

This paper presents a theoretical analysis of the transient and steady-state response of a thin cylindrical shell of finite length, simply supported at both ends, under a uniform initial biaxial stress and subjected to either a circumferentially tangential harmonic point force of a sinusoidally distributed harmonic line load acting in the circumferential direction. The analyses are based on both Flugge’s and Donnell’s theories. Numerical results of the steady-state response are presented for both theories to illustrate the effects of various relevant parameters on the dynamic deflection, and to provide a direct comparison between Donnell’s and Flugge’s theories for dynamic loadings. This paper establishes the range of shell geometry for which Donnell’s equations give satisfactory results in predicting the steady-state response. The dynamic behavior after the first resonant frequency and the effect of initial stress on the dynamic response are also pointed out.
Inhomogeneous Shearing During Continuous Chip Formation
Authors: Cooke W. B. H. , Rice W. B.
Published: November 2010

Metallographic examination of chips cut from a directionally solidified eutectic provided direct evidence of discontinuous shearing in continuous chip formation. The built-in grid of the eutectic was deformed into the chevron type pattern associated with a double shearing process, but certain differences indicate that a plastic wave phenomena was involved rather than simple shearing. Observation of the shear zone during the chip formation process provided no evidence of the discontinuous process occurring inside the chip.
New Solutions to Rigid-Plastic Deformation Problems Using a Matrix Method
Authors: Lee C. H. , Kobayashi S.
Published: November 2010

The matrix method for the analysis of rigid-plastic deformation problems was described and applied to simple compression of cylinders and plane-stress bore expanding and flange drawing. In cylinder compression new solutions were obtained with regard to the effect of specimen dimensions on the contact stress distributions, the effect of friction on the relative slip at the tool-workpiece interface, and bulging and “folding”. In plane-stress problems the planar anisotropy was taken into account and the application of the matrix method resulted in new solutions for nonaxisymmetric hole expansion and “earing” in flange drawing.
A Theoretical Model for High Rate Electrochemical Machining
Authors: Loutrel S. P. , Cook N. H.
Published: November 2010

A theoretical model for the process occurring in the cutting zone is developed. A computer solution to apply the model to an actual ECM situation is outlined. A simplified model and computer solution is described which can be used to predict machining parameters for complex geometries. For both models good correlation of experimental results is found in most cases. The application of classical electrochemistry to conditions where extreme current densities (5800 amps/cm2) are encountered is discussed.
Computer Simulation of Dynamic Stress, Deformation, and Fracture of Gear Teeth
Authors: Wallace D. B. , Seireg A.
Published: November 2010

This paper presents results from a computer based technique for the evaluation and graphic display of stress, deformation, and fracture patterns in gear teeth when subjected to dynamic loading. The method is illustrated for conditions of impulsive loads applied at different points on the tooth surface and moving loads normal to the tooth profile. The technique incorporates a viscoelastic model for the material properties and prespecified failure criteria. The accuracy of the simulation is investigated by applying a Hertzian impact on a cantilever beam and comparing the analytical results with those obtained by strain gages placed at the root. The simulation procedure provides a versatile and powerful means for the analysis and design of gears subjected to dynamic loading.
A Multi-Purpose Planetary Gear Testing Machine for Studies of Gear Drive Dynamics, Efficiency, and Lubrication
Authors: Kasuba R. , Radzimovsky E. I.
Published: November 2010

Feasibility of a multi-purpose testing machine for research studies in gearing has been demonstrated with construction of a unique gear testing machine with a differential planetary gear drive. This machine was used in such interdependent studies as determination of instantaneous gear tooth engagement loads, minimum film thicknesses, and gear efficiencies. With minimal structural and mechanical modifications, this gear research machine can be used for studies of surface durability, thermal distribution in gear meshing zones, and effects of variable torques and torsional oscillations on performance of gearing. Most of these studies could be conducted simultaneously. Upon selection of appropriate gear ratios, this machine was operated either with one or two stationary gears. Presence of stationary gears simplified greatly the measurement techniques and increased the reliability of tests. This machine can accommodate spur, helical or any special type of gearing. Design and operational characteristics of this machine, as well as a short summary of research projects performed on this machine, are presented in this paper.
Study of the Electro-Erosion Phenomenon of Fe and Zn
Authors: Guerrero-Alvarez J. L. , Greene J. E. , von Turkovich B. F.
Published: November 2010

Single electrical discharges were produced on Fe and Zn electrodes under conditions similar to Electro-Discharge Machining (EDM). Crater morphology and surface texture were studied by means of Scanning Electron Microscopy (SEM) and a method was developed to measure the volume of metal removed per unit of applied energy. In all cases the volume of metal removed from the cathode was found to be larger than that from the anode. The efficiency of metal removal was also obtained and shown to decrease as the applied electrical energy of the discharge is increased. In addition, Energy Dispersive Spectroscopy (EDS) studies indicate that the existence of cross metal deposition from dissimilar electrodes is independent of the energy of the discharge, of the polarity, and of the electrode material (Fe or Zn). The combination of observations from SEM and EDS provided information on the mechanism of electro-erosion.
High Rate Electrochemical Machining
Authors: Loutrel S. P. , Cook N. H.
Published: November 2010

This is the first of three papers on high rate Electrochemical Machining. Feed rate limiting mechanisms are discussed along with qualitative predictions. Methods of increasing feed rates are studied theoretically and experimentally. The use of high supply voltages (118 volts) high electrolyte pressures (330 bars (4800 psi)) and high flow velocities (192 M/sec) when machining iron in aqueous sodium chloride electrolyte led to feed rates of 10.8 cm/min (4.25 in/min). The following two papers will discuss a theoretical model of the ECM process and present high temperature and pressure electrolyte conductivity and ion mobility.
Sodium Chloride Electrolyte Data at High Temperatures and Pressures
Authors: Loutrel S. P. , Cook N. H.
Published: November 2010

Electrolyte conductivities were measured and ion mobilities were calculated for use in applying the theoretical model for high rate Electrochemical Machining which was described in two other papers. The ions treated are Na+, Cl−, Fe++, and OH−. Mathematical models are derived to allow simple calculation of ion mobilities including the case where mixtures of ions are present. The effect of high temperatures (on the order of 200 deg C) and high pressures (on the order of 220 bars) is emphasized. The experimental apparatus used in making these measurements is also described.
Guidelines for Textile Industry Noise Control
Authors: Bailey J. R. , Brown C. M.
Published: November 2010

A systems approach is developed for defining compliance with the noise criteria of the Occupational Safety and Health Act of 1970. The result is a flow diagram which can be used as a “road map” for determining progress toward compliance. A flow diagram is also developed as a guideline for evaluating the feasibility of engineering noise control. General suggestions are made for controlling the noise produced by air sources, oscillating bodies, frictional sources, impact, and gears. Absorption, enclosures, and barriers have also been considered as means of interrupting the path between the source and the receiver. Noise exposure has been included as an important factor with economic feasibility as a final consideration in the flow diagram.
Fling-Off Cooling of Gear Teeth
Authors: DeWinter A. , Blok H.
Published: November 2010

An exploratory theory shows even moderate rates of supply of the gear oil to the tooth faces to suffice for attaining the limiting coolant capacity that proves to be inherent in the conventional centrifugal fling-off process. However, in heavy-duty gears beyond a certain size and speed the conventional “intermittent” fling-off cooling can no longer take a substantial share in the withdrawal of the frictional heat generated in the meshing zone. Much greater cooling capacities are then realizable by the less known “continuous” fling-off process, to be dealt with in a followup paper.
An Improved Determination of the Elastic Compliance of a Spur Gear Tooth Acted on by a Concentrated Load
Authors: Premilhat A. , Tordion G. V. , Baronet C. N.
Published: November 2010

The elastic compliance of a spur gear tooth acted on by a concentrated load is determined through the use of appropriate stress functions resulting from the complex transformation of the tooth profile. Comparisons with previously published results indicate a slightly greater flexibility of the tooth resulting from this analysis.
Gearbox Noise Reduction: Prediction and Measurement of Mesh-Frequency Vibrations Within an Operating Helicopter Rotor-Drive Gearbox
Authors: Badgley R. H. , Hartman R. M.
Published: November 2010

This paper presents correlations between analysis and test results for a complex mechanical system. While the paper is specificially concerned with a helicopter rotor-drive gearbox, the results and methods employed are general enough to be broadly applicable to gearboxes of all kinds. The development of gearbox noise reduction technology has been the objective of an extensive U. S. Army-supported program over the past five years. The gearbox noise problem has been recast as a mechanical vibrations problem, and detailed analytical methods have been developed to treat it. Gear excitation analyses, drive-train response analyses, and empirically-based acoustic spectrum prediction methods have been developed and published in considerable detail. Rolling-element bearing stiffness prediction methods and thin-shell vibration response prediction techniques have been shown to be essential elements in the procedure. In order to verify the analytical methods, a detailed and comprehensive test program was undertaken on a complete CH-47 forward-rotor-drive gearbox, operating under normal torque conditions in a test-cell environment. At the same time, predictions were made of quantities to be measured using the previously published analytical methods. Comparisons between predicted and measured quantities show reasonably good correlation, indicating that the analytical procedures are suitable for careful use in gearbox design or redesign efforts directed at vibration and noise reduction. Areas in which the analytical methods can be improved were also identified.
Synthesis of Solid Elastic Horns
Authors: Coy J. J. , Tse F. S.
Published: November 2010

Synthesis of the profile of a solid elastic horn from its matrix of transfer functions is examined. Two methods of synthesis are developed. The first method makes use of the Inverse Sturm-Liouville theory. A second design method is provided by a computer program.
Experimental Evaluation of the Exact Point-Speed and Least-Squares Procedures for Flexible Rotor Balancing by the Influence Coefficient Method
Authors: Tessarzik J. M. , Badgley R. H.
Published: November 2010

An experimental test program was conducted to extend the verified operating region of the Influence Coefficient Method’s Exact Point-Speed procedure for balancing of flexible rotating machinery. Also, the Least-Squares procedure (of which the Exact Point-Speed procedure is a particular case) was applied to several test cases which were identical to those investigated by the Exact Point-Speed procedure. A comparison of the effectiveness of both balancing procedures under identical test conditions was thus obtained. The practical aspects of balancing real, flexible rotors were investigated through inclusion of rotor out-of-roundness data at the measurement probe locations. The computer program was demonstrated to be fully capable of handling out-of-roundness data in the investigation. Testing was performed predominantly with a machine having a 41-in. (104 cm) long, 126-lb (57 kg) rotor. This rotor was operated over a speed range encompassing three rotor-bearing system critical speeds. Both balancing procedures were evaluated for several different conditions of initial rotor unbalance. Safe (and slow) passage through all the critical speeds was obtained after two or three balancing runs in most cases. The Least-Squares procedure was found to be generally equivalent in capability to the Exact Point-Speed procedure for the configurations studied.
Vibration Analysis of Rotating Compressor Blades
Authors: Henry R. , Lalanne M.
Published: November 2010

Calculation of the total potential energy of a system is performed in the case of thin rotating plates. The structure is divided into plane triangular elements with three nodes and eighteen degrees of freedom. The mass and stiffness matrices in which the rotation effects have been introduced are derived using area coordinates. First, the initial stresses due to the rotation are calculated; next, frequencies and modes are determined by a simultaneous iterative technique. The method is then applied to an existing compressor blade. The correlation with experimental results is good for the first ten frequencies and the first five modes. A calculation process for machine designers based on the methods introduced by Petricone-Sisto and Rawtani-Dokainish and the finite element method is then presented.
A Similarity Parameter for Scaling Dynamic Inlet Distortion
Authors: Moore M. T. , Lueke J. E.
Published: November 2010

A similarity parameter suitable for use in both analog and digital analyses of time-dependent inlet pressure distortion data has been developed. This parameter, when used in conjunction with the recently developed Method D distortion methodology, facilitates prediction of full scale instantaneous pressure distortion levels from scale model inlet dynamic data. The similarity parameter was developed by relating the inlet size to the data frequency bandwidth by simple acoustic wave theory. This parameter is shown not only to collapse data from different scale sizes of the same inlet but also to produce similar ratios of dynamic to steady-state distortion levels for inlets of different types and sizes operating at or near engine matched conditions. When operating supercritical the increase in dynamic distortion relative to steady-state distortion is seen to be consistent for the various sizes of inlets at constant values of the similarity parameter. Along with the development of the inlet dynamic distortion similarity parameter, this paper treats the subject of analog filtering and digital averaging of the time-dependent pressure data prior to computation of the Method D parameters. Under certain conditions analog filtering and digital averaging are shown to be equivalent. Furthermore, by use of the similarity parameter, consistent selection of either analog filter bandwidth or digital average time can be made for comparison of trends in inlet dynamic distortion between inlets of different types and sizes.
Characterization of the Mechanical Properties of Spring Materials
Authors: Weissmann G. F. , Wonsiewicz B. C.
Published: November 2010

Spring materials are purchased under specifications which impose limits on the tensile strength but do not control the crucial properties, i.e., resistance to plastic flow and stiffness. Present techniques for characterizing spring material are discussed in detail. A novel test is described which is quick, inexpensive, and reliable and holds promise for both research and quality control applications. The test is based on a dynamic determination of energy dissipation in a sample stressed in bending or torsion, the usual modes of deformation for most springs. Stiffness and permissible deformations are determined directly and the elastic modulus and yield strength can be calculated easily. The results obtained in this way compare favorably with those determined by tensile testing. An example is given which illustrates the operation of the test and the calculation of results. Since the entire test from sample preparation to calculation of results requires about five minutes, and since the apparatus should be relatively inexpensive, the test ought to find application in many areas where testing is not practical at the present time.
Lateral Vibrations of a Damped Laminated Hollow Circular Cross-Section Beam
Authors: Ditaranto R. A.
Published: November 2010

The free lateral bending vibrations of an “infinitely” long or simply-supported thin-walled circular cross-section beams having elastic-viscoelastic-elastic layers are investigated to determine the natural frequencies and associated composite loss factors. The analysis considers the inner and outer beams to behave as elastic beams in which the mass and mass-moment of inertia are both considered along with the interaction of the two elastic beams through the viscoelastic material. The results indicate that there are two natural frequencies. The lower one associated with the two elastic beams moving together so that little damping is obtained in this mode of vibration; the higher mode in which the two elastic beams vibrate in opposite directions so that there is an amount of damping comparable to the material loss factor of the viscoelastic material. A simplified model analysis is performed which is used to corroborate the trends obtained in the computer solutions of the more rigorous analysis. A series of curves are obtained for equal thickness elastic layers which can be used to obtain natural frequencies and composite loss-factors for a realistic range of geometrical and physical properties of a laminated circular cross-section simply supported beam.
Analysis of a Thin Elastic Ring Under Arbitrary Loading
Authors: Liu J. Y. , Chiu Y. P.
Published: November 2010

This paper presents a general solution for a thin ring under a self-equilibrating loading system comprising any combination of radial, tangential, and moment loads. The formulations are applicable to concentrated loads as well as to distributed load functions. Closed-form solutions are obtained for each case for engineering applications. Comparisons with recent published results for some special cases are demonstrated in some of the sample problems.
Power Loss and Optimum Tensioning of V-Belt Drives
Authors: Gerbert B. G.
Published: November 2010

In a previous report [2] the author presents a new theory for V-belt drives. In that work special attention is directed to the motion of the belt. Stress variation in the cord of the belt is treated in another report (3). In the present report the earlier theory is extended and the main interest here is how the power loss is influenced by different belt and drive properties. The contribution to the power loss can be divided into two main parts viz: losses due to external friction (sliding between belt and pulley) and internal friction (sliding between molecules-hysteresis). The former losses are treated theoretically and the latter experimentally. A further separation is also made and power losses due to external friction arising when the belt enters and leaves the pulley are specially treated. Different types of contribution to the power loss are calculated by Gervas and Pronin (4) and in another paper (5) Gervas measures the internal friction losses caused by the bending (flexure) of the belt. However, the experimental method used didn’t separate the losses due to external and internal friction. In a chapter on optimum tensioning of a belt drive, different types of losses are combined and the efficiency reaches a maximum for a certain combination of transmitted power and pretension.
An Analytical Solution for the Tapered Arbor Spring Slip Clutch
Authors: Robe T. R. , Jones S. E.
Published: November 2010

An analytical solution is developed for the tapered arbor spring slip clutch by introducing approximations that do not appreciably affect the accuracy of the important clutch quantities. In addition, the influence of the coefficient of friction on the output torque, the axial force on the spring coil, and the radial contact forces alongthe tapered arbor are shown.
The Engineering Characteristics of Snow Skis—Part 1: Static Bending and Torsional Characteristics
Authors: Deak A. , Jorgensen J. , Vagners J.
Published: November 2010

This paper presents the results of analytical and experimental studies of static bending and torsional characteristics of snow skis. The purpose of the work is to develop analytical and experimental techniques that would be useful to the ski designer who must continually explore the applicability of new materials and geometric arrangements to snow ski construction. A brief review of composite shallow beam theory is presented in a form directly applicable to ski analysis. The experimental setup to verify the analytical results is described.
Design of Springs Made of Flat Material
Authors: Dore´ R. , Deslauriers S.
Published: November 2010

A technique is presented for the analysis of deflection and stresses in helical compression or tension springs of rectangular cross-section. The technique consists in analyzing the deflection and stresses in a circular plate cut radially. Using the theory of elastic dislocations, a stress system is determined which gives as the resultant over any terminal cross-section, a single force acting along the axis of the plate. If the pitch angle of the spring is neglected, the stresses in a helical spring are obtained. The deflection and stresses are evaluated in terms of the dimensions of the spring and compared with the results of other theories.
NS-100 Membranes for Reverse Osmosis Applications
Authors: Rozelle L. T. , Kopp C. V. , Cadotte J. E. , Cobian K. E.
Published: November 2010

The structure of the new NS-100 nonpolysaccharide reverse osmosis membranes and additional separation properties relating to removal of impurities from water has been investigated. Infrared spectrophotometric evidence has indicated that the urea linkages are formed before the heat cure step. The heat curing process was found to cross-link the polymer further by elimination of ammonia and formation of additional secondary and tertiary amine linkages. Long-term tests under seawater conditions have indicated water fluxes of 18 gfd at 99.5 percent salt rejection. The NS-100 membranes have exhibited high rejections toward organic compounds; for example, phenol is rejected up to 90 percent. All experimental data indicate that the NS-100 membranes are more resistant to varying environments with higher reverse osmosis performance than any current commercial membrane.
Dynamic Synthesis of Cams Using Finite Trigonometric Series
Authors: Wiederrich J. L. , Roth B.
Published: November 2010

New methods are presented for the design of high-speed cam profiles. These methods have the advantage of assuring the accuracy of the assumed mathematical model while at the same time providing for good dynamic performance. These methods do not rely on rules of thumb. In fact, it is shown that at high speeds low vibration motions exist which violate heretofore commonly accepted empirical design rules.
On the Motion of a Class of Five-Link, R-C-R-C-R, Spatial Mechanisms
Authors: Pamidi P. R. , Freudenstein F.
Published: November 2010

Algebraic conditions have been derived for determining the complete or partial rotatability of the input and output links of a class of five-link, R-C-R-C-R, spatial mechanisms with zero offset at the floating turning pair. The results, which can be regarded as a spatial counterpart of Grashof’s rule, are illustrated by numerical examples.
Computer Program to Generate Dimensional and Inertial Properties of the Human Body
Authors: Bartz J. A. , Gianotti C. R.
Published: November 2010

A digital computer program has been developed to calculate dimensional and inertial properties of the human body. The program has been designed so that the user may either select a data set from a program library, or compute a data set from a geometric man-model. From primary program inputs of sex, standing height, seated height, and weight, the routines compute body segment link lengths, contact surface dimensions, masses, and moments of inertia from inputted sets of anthropometric data. Overall validity of the formulation and techniques has been established by comparing computed results with measurements on the human body reported by various investigators.
Influence of Neutral Axial Stress on Yield and Collapse of Pipe
Authors: Lubinski A.
Published: November 2010

Axial stress with zero stress as datum is conventionally used in calculating the influence of tension or compression on yield or collapse of pipe. In this paper, zero stress datum is replaced by “neutral” stress datum. This results in a simpler curve of plasticity, namely a circle, instead of the conventional skewed ellipse. Although equations based on neutral axial stress datum are simpler than equations based on zero axial stress datum, the results of the two methods are equivalent for yielding. On the other hand, the results are different for collapse. Experimental collapse pressures are closer to those calculated on the basis of neutral axial stress datum. Means for making allowance for pressures both inside and outside the pipe are given in the paper. Radial stress is taken into consideration, and, therefore, the treatment is triaxial.
Determination of the Accuracy of Segmented Representations of Cable Shape
Authors: Wang H. T.
Published: November 2010

The results of a comprehensive investigation of the accuracy of representing a continuous cable by a finite number of segments are presented. The results are limited to the two-dimensional static case. The accuracy of three different finite-segment models is evaluated for a number of segments ranging from 1 to 40. The difference between the three models lies in the manner in which the inclination of each segment is obtained. The results basically show that relatively few segments are required to accurately obtain the overall geometry and resultant tension of the cable.
Plasticity of Ice and Sand-Ice Systems
Authors: Smith Leonard L. , Cheatham J. B.
Published: November 2010

The experimental deformation of ice and sand-ice systems is compared with predictions based upon plasticity theory. Properties of the materials were determined under various temperatures, confining pressures, and loading rates using conventional triaxial compression tests. Samples were indented at atmospheric pressure using flat punches and sharp wedges at two loading rates and calculated force-displacement relationships were determined for the von Mises, coulomb, and parabolic yield conditions. Comparison of the results of the experiments with the computations indicates that the force-displacement relationships for ice and sand-ice samples can be approximated using plasticity theory.
Optimum Mechanism Design Combining Kinematic and Dynamic-Force Considerations
Authors: Conte F. L. , George G. R. , Mayne R. W. , Sadler J. P.
Published: November 2010

A general computer-aided procedure is presented which combines the kinematic synthesis and dynamic design of four-bar mechanisms. This procedure utilizes nonlinear programming techniques, adjusting the arbitrary parameters in a kinematic synthesis to include performance criteria related to dynamic forces, as well as kinematics. In a particular example, optimum crank-rocker path generating mechanisms with prescribed timing are found based on objective functions related to shaking force, shaking moment, input torque fluctuation and bearing reactions. The optimization procedure results in a significant improvement in these dynamic characteristics.
Matrix-Displacement–Direct-Element Method for Force and Torque Analysis of Determinate and Indeterminate Space Mechanisms With Arbitrary Skew Angles
Authors: Brasfield R. L. , Bagci Cemil
Published: November 2010

A matrix-displacement-direct-element method (a finite-element method with spatial line elements) for elastic analysis of determinate and indeterminate space mechanisms with arbitrary skew angles is presented, wherein each member experiences flexural deformations in two orthogonal planes, torsional deformation about its axis, and axial deformation. A generalized-member external-stiffness matrix is developed that is used in forming the global external-stiffness matrix for the mechanism member by member. The method permits different freedoms of elastic deformation for the ends of links at pair locations about the axes of pair freedoms. It is also for the elastic analysis of space frames having arbitrarily oriented spatial members. Force and torque analyses of the indeterminate 4R Bennett and 4P space mechanisms are performed in the numerical examples; force distributions, deformed geometries, bearing forces, and mechanical advantages are given.
Adjustable Mechanisms for Exact Path Generation
Authors: Kay F. J. , Haws R. E.
Published: November 2010

The generalized design equations for a path generating cam-link mechanism are developed. A cam-link provides a continually adjustable link that provides accuracy over a range of motion not available with coventional linkages. The design equations are used with an optimization scheme to satisfy a merit function based on cam pressure angle and drift angle. Examples are included that illustrate the capabilities of this synthesis technique.
The Analytical Synthesis of Complex Mechanisms for Combinations of Specified Geometric or Time Derivatives up to the Fourth Order
Authors: Myklebust A. , Tesar D.
Published: November 2010

Past work in mechanisms synthesis has been primarily position-dependent. Here, the problem of coordinating time and geometric states up to the fourth order simultaneously for several functions is accomplished with all classes of multiply separated specifications. The previous algebraic formulation for geometric Burmester theory based on a set of Amt coefficients is now transformed into a time-dependent Burmester theory by using an expanded set of tabulated coefficients Dmt. New problems of complex geometric coordination of three functions relative to some position parameter are now solvable, and it is shown that geometric synthesis is a special case of time synthesis. This generalized theory vastly increases the range of solvable problems for industrial application in terms of the 4-, 5-, and 6-bar mechanisms.
Kinematic Synthesis of Geared Spherical Five Bar Mechanisms for Function Generation
Authors: Riddle D. L. , Tesar D. , Duffy J.
Published: November 2010

The synthesis of geared spherical five-bar mechanisms with application to the function generation problem is considered for multiply separated position specifications. Special gear train values reduce the geared five-bar to the elementary spherical four-bar. The planar four- and five-bar become a design subset to the spherical five-bar. Design procedures with complete formulation are outlined in detail.
The Role of Grain Tip Radius in Fine Grinding
Authors: Lal G. K. , Shaw M. C.
Published: November 2010

The scratches produced by single abrasive grains in overcut fly milling show that the transverse shape of a grain is closely approximated by an arc of a circle. This radius of curvature is found to be independent of grain type and grinding conditions but varies with the grain size. The equation for undeformed chip thickness for surface grinding is rederived in terms of this radius. The important role that the transverse curvature of the grain plays relative to surface finish is also discussed.
Dynamics of High-Speed Cam-Driven Mechanisms—Part 2: Nonlinear System Models
Authors: Chen F. Y. , Polvanich N.
Published: November 2010

The dynamic responses of the cam-driven mechanism are investigated, based on a non-linear lumped system model. The nonlinearity is an energy-dissipating element which consists of viscous, quadratic, Coulomb and static frictions combined. The nonlinear equation of motion of a single degree of freedom is first analyzed using a numerical method and the results of time responses are presented and characterized in the phase-plane. The primary and residual shock response spectra in nondimensional form for a number of typical cam input excitations are presented and compared with those of the associated linear cases.
Experimentally Determined Dynamic Strains in an Elastic Mechanism
Authors: Alexander R. M. , Lawrence K. L.
Published: November 2010

Measured dynamic bending strains in the links of a model four bar mechanism are presented. Cyclic strain variation and frequency response data are given, and comparison is made between calculated and measured values for one of the mechanism configurations.
Multiple Impacts of a Ball Between Two Plates—Part 2: Mathematical Modelling
Authors: Veluswami M. A. , Crossley F. R. E. , Horvay G.
Published: November 2010

A mathematical model is developed to portray the vibroimpacts of a steel sphere which is trapped between two flat steel plates with clearance, while the plates are oscillated by an electromagnetic shaker. Data from a long series of experimental observations are reported in Part 1 of this paper [53]. The aim is to determine a law of motion by which a computer simulation can satisfactorily reproduce the major characteristics of the observed movement. During each impact the motion of the ball is taken to be a brief half wave, due to the highly nonlinear forces of surface compliance and surface damping. Modelling is by analog simulation. It was found first that linearization of the surface stiffness does not reproduce the observed phenomena. The mathematical model formulated is that the motion of the ball during contact is governed by the equation mx¨ + cx1.5 x˙ + kx1.5 = 0, where x is the penetration, c is a damping constant, and kx1.5 is the Hertzian force of compliance. The results of experiments can be corroborated only on the basis of a variable damping coefficient cxn with n = 3/2.
A Weighted Flexible Tolerance Algorithm for Constrained Minimization
Authors: Townsend M. A. , Lam F. Y.
Published: November 2010

A direct search algorithm based upon the flexible tolerance method developed by Paviani and Himmelblau [1] for minimization of a functional subject to nonlinear equality and inequality constraints is proposed and evaluated. The modification incorporates a weighting on the direction of search in which the flexible polyhedron formed orients itself toward the gradient of the objective function (and clings to all active constraints). This is accomplished by weighting the centroid, in the sense of minimization, of the polyhedron with respect to the objective function. A number of problems have been solved satisfactorily by this algorithm, generally with more rapid convergence.
The Effect of Viscosity on the Dynamics of a Submerged Spherical Shell
Authors: Su Tsung-Chow , Lou Y. K.
Published: November 2010

In order to clarify the effect of fluid viscosity on the vibrations of submerged elastic shells, the axisymmetric vibrations of a spherical shell immersed in a compressible, viscous fluid medium are studied. The dynamic response of the shell is determined by the classical normal mode method while a boundary layer approximation is employed for the fluid medium. The study of free oscillations reveals that fluid viscosity may produce noticeable effects on the damping components of the complex natural frequencies and is particularly important for the nonradiating modes. For forced vibrations, the present study concluded that the contribution of viscous effect is of small order, except possibly in the vicinity of the peak shell responses when the forcing frequency is near to one of the real components of the natural frequencies.
Plastic Failure of Ductile Beams Loaded Dynamically
Authors: Jones Norman
Published: November 2010

It is shown herein how simple rigid-plastic methods may be used to predict the large inelastic deformations of fully clamped beams loaded impulsively, and to estimate the threshold velocities at which failure due to either tensile tearing or shearing occurs at the supports of beams. The approximate theoretical methods give surprisingly reasonable agreement with the recent experimental tests of Menkes and Opat [1] on aluminum 6061 T6 beams.
Review of Materials Processing Literature 1971–72—Part 1: Material Removal Practice
Authors: Boothroyd G.
Published: November 2010

In this set of papers, the ASME Production Engineering Division presents results of its continuing efforts to provide a condensed survey of significant contributions to the understanding of materials processing, as they appear in literature. This work is intended to be of use to engineers engaged in research and practice alike. Two new contributors are welcomed to this effort: Professor G. Boothroyd, University of Massachusetts, who has agreed to take over the review of Material Removal Practice, and Professor C. H. Kahng, Michigan Technological University, who will review the literature published in the Japanese language starting with this series. Reviews of Grinding and the German Language Literature complete the set of papers presented here. The reviews of Plastic Working of Metals and Metal Cutting Analysis will appear at a later date.
Analytical Investigation of the Effect of Tool Wear on the Temperature Variations in a Metal Cutting Tool
Authors: Levy E. K. , Tsai C. L. , Groover M. P.
Published: November 2010

An analytical study of the effect of crater wear on the response of a remote thermocouple sensor is described. The remote thermocouple sensor is at present being developed as a device for the on-line measurement of tool wear. This technique depends for its operation on the strong influence of wear on the transient temperature variations in the tool. The two-dimensional transient temperature variations in the chip and tool regions are determined using a numerical finite-difference technique. Results are obtained under idealized cutting conditions with a zero wear rate, a normal wear rate, and an accelerated wear rate. Comparisons are made between the three cases to develop relationships for the effect of wear on the temperature at the remote thermocouple location.
Analysis of the Radial Forging Process for Manufacturing Rods and Tubes
Authors: Lahoti G. D. , Altan T.
Published: November 2010

The slab method of analysis was applied to study the mechanics of radial forging of rods and tubes. The analysis has been computerized by taking into account the effects of strain, strain rate, and temperature upon the flow stress of the material being forged. Forging loads were predicted for selected conditions in radial forging of rods at room temperature. The predictions were compared with experimental data, published by another investigator. The results indicate that the analysis developed in the present study is sufficiently accurate for practical purposes. A parametric study was conducted to determine the relations between various process variables in hot radial forging of tubes.
Stress Concentration Factors From Overlapping Stress Fields in Uniaxial Tension
Authors: Gencsoy H. T. , Hamilton J. F. , Yang C. C.
Published: November 2010

Standard transmission photoelastic techniques were used to determine the resultant stress concentration factors produced by multiple stress raisers in flat, rectangular bars under uniaxial tension. Observations were made on the overlapping stress fields due to various combinations and orientations of holes and semicircular grooves. Two cases of directly superposed discontinuities were also investigated. The results of this investigation indicate that the sizes and relative positions of the discontinuities had a substantial effect on the resultant stress concentration factor. In some cases the stress concentration factor would be decreased while in other cases it would be increased. In the case of superposed stress raisers considered in this investigation, the resultant stress concentration factor can be taken as the product of the individual stress concentration factors; this is in agreement with the results of other investigators. However, for other cases, much judgment and experience will be required to decide when this can be done. And even then this product should be considered only as the probable upper limit of the actual stress concentration factor.
A Linear Least Squares Method for Describing and Comparing Gently Curved Three-Dimensional Surfaces
Authors: Dietz H. K. , Manning J. R.
Published: November 2010

A simple method is developed for fully describing gently curved surfaces with the aid of a computer, using a finite number of point measurements as input data. By means of this method, cut sections through a surface in various directions may be computed and graphically displayed. Similar surfaces, corresponding to a workpiece and its desired shape, may then be compared along a cut section on a command from an operator, resulting in the visual display of the section curves. This technique should prove useful in iterative forming of shallow panels (e.g., aircraft wing sections) and other applications involving gently curved surfaces.
Hot Spot Heating by Composition Shoes
Authors: Wetenkamp H. R. , Kipp R. M.
Published: November 2010

It is generally understood that uneven heating of the tread of a wheel during braking is possible. A method has been devised to measure the intensity and frequency of hot spots on the wheel tread surface. After a description of the measurement apparatus and technique, results of a study of hot spots during constant speed brake applications with single composition shoes are presented. Possible lowering of the hot spot level by increasing the conformability of the brake shoe is studied by cutting one slot across each pad of a brake shoe. This method of hot spot study may be useful for future analysis and improvement of brake shoes.
A Stochastic Approach to Characterization of Machine Tool System Dynamics Under Actual Working Conditions
Authors: Burney F. A. , Pandit S. M. , Wu S. M.
Published: November 2010

The machine tool dynamics is evaluated under actual working conditions by using a time series technique. This technique develops mathematical models from only one signal, viz., the relative displacement between the cutter and the workpiece. Analysis of the experimental data collected on a vertical milling machine indicates that the new methodology is capable of characterizing the machine tool structure and the cutting process dynamics separately. Furthermore, it can also detect and quantify the interaction between these two subsystems.
Application of EHD Oil Film Theory to Industrial Gear Drives
Authors: Wellauer E. J. , Holloway G. A.
Published: November 2010

The method and assumptions used for the application of EHD theory to the calculation of gear tooth oil film thicknesses for the design and analysis of industrial gear drives is presented. A nomograph, utilizing readily available gear geometry, operational, and lubricant parameters, is illustrated which allows rapid determination of calculated gear tooth oil film thicknesses for a wide range of gear drive conditions. Gear tooth surface distress is related to the specific film thickness, λ, the ratio of calculated oil film thickness to the magnitude of the composite surface texture. The term “surface texture” is introduced for gear contacts to indicate that surface attributes coarser than roughness importantly relate to tooth surface distress, but a sophisticated method for its quantitative assessment has not been developed. Data from several hundred petroleum lubricated laboratory tests and closely followed field applications which include through hardened gears of 1 in. to 15 ft in diameter are used to correlate specific film thickness and gear tooth surface distress. Curves are given to predict the probability of occurrence of such distress over the range of pitch line velocities of 4–35,000 ft/min.
Theoretical Model for Predicting Steam-Ejector Performance
Authors: Kurtz E. F.
Published: November 2010

A simple theoretical model has been developed as an aid to designing steam ejectors. The ejector flow is modeled as comprising a number of continuum components such as potential flows and shear flows. Velocity profiles are approximated by stepped profiles, each flow component having a uniform velocity. Compressibility effects are accounted for by assuming isothermal flow in the mixing section. The differential equations governing momentum and mass transfers are integrated numerically, yielding pressure distribution predictions in the ejector mixing section, as a function of primary- and secondary-steam inlet states, and of mixing-section shape, in good agreement with published steam-ejector data. The model exhibits compound choking and compound supersonic flow in agreement with the data. While the isothermal-flow model has been tested only with steam-ejector data, it should be applicable for designing any ejector wherein the primary stream is a two-phase liquid-vapor mixture with the liquid fraction in small droplets occupying a negligible volume fraction. The model has been implemented via a FORTRAN computer program.
Passive Refrigeration for Arctic Pile Supports
Authors: Galate J. W.
Published: November 2010

This paper demonstrates the feasibility of passive refrigeration for maintaining soil stability near pile supports in permafrost. Laboratory tests for Alyeska pipeline pile supports have evaluated the heat removal capabilities and operational limitations of two passive refrigeration schemes—the air convection pile, a single-phase open system driven by natural convection of cold air, and the heat pipe, a closed system natural convection, two-phase, heat transfer loop which depends on an internal vaporization and condensation cycle. The laboratory tests show that heat removal rates are high enough from either refrigeration scheme to effectively “freeze-in” pile supports and thereby substantially increase their load-carrying capacity in many permafrost regions. While the paper concentrates on laboratory results, reference is made to field tests and computer calculations which confirm laboratory predictions and suggest their usefulness as design data for other Arctic applications of passive refrigeration schemes. The use of heat pipes in piles supporting elevated portions of the Trans-Alaska Pipeline is one example of successful application of passive refrigeration. Other potential applications include protection of permafrost near Arctic construction sites and near oil producing and processing operations.