bluuebunny/crossref_metadata_2025 huggingface dataset:
Nonlinear Deflection Analysis for Coupled Tubular Structures
Authors: Barinka L. L.
Published: November 2010

An analysis is presented for determining the large, transverse deflections of tubular structures that are mechanically coupled at discrete locations along their length. The nonlinearities treated are characteristic of the limiting nature of frictional and spring-type coupling. Tubular structures are analyzed by considering the assembly of tubes to be subdivided into axial segments between adjacent coupling locations. The governing relationships are developed for tubular structures consisting of any number of different types of tubes. The end product is a well-behaved linear system of equations, which is solved under iteration of applied loading for the nonlinear, transverse deflections of each tubular segment. Reactor fuel assemblies are considered for specific examples of coupled tubular structures, and numerical results are compared with experimental measurements of actual assemblies to demonstrate the accuracy of the analysis.
An Isothermal Analogy for Thermal Stress in Shells
Authors: Hannon B. M.
Published: November 2010

For a shell which is subjected to temperature gradients, this paper provides the theory for a set of analogous surface loads for an isothermal model shell. These loads produce deflections in the isothermal model proportional to those in the heated prototype. Model stresses are determined by experiment and translated into prototype stresses. The complete set of model boundary condition equations is presented for orthogonal coordinate boundaries. Examples of a heated plate and cylindrical shell with various boundary conditions demonstrate the theory.
The Effective Utilization of Yield Strength
Authors: Gross J. H.
Published: November 2010

In many structural and constructional applications (such as pressure vessels), steels, particularly high-yield-strength steels, are not being utilized as effectively as may be possible. This occurs because the design stress permitted by many specifications and codes is effectively based only on the tensile strength. Thus, the increase in yield-to-tensile-strength ratio with increasing tensile strength is not recognized, and no design-stress credit is given for the proportionately higher yield strength of high-strength steels. Because increased utilization of yield strength will probably require demonstration of the satisfactory fabricability and service performance of high-yield-strength steels, the present paper summarizes the general effects of increased yield strength on formability and weldability and on resistance to failure by stress-dependent modes—overload, brittle fracture, fatigue, and stress corrosion. The present state of knowledge indicates that fabrication does not significantly limit the use of high-strength steels. Although high-yield-strength steels are more difficult to form and weld than lower-strength steels, appropriate forming and welding practices that are not unduly restrictive are in common use for such steels. If design stress is based directly on yield strength, the safety factor against failure by simple overload or by unstable propagation of a crack decreases with increasing yield strength. However, increasing fracture toughness can significantly reduce susceptibility to failure by unstable crack propagation that is the result of low shear energy absorption or the growth of cracks to critical size by fatigue or stress corrosion. In recent years, the fracture toughness of steel has been continuously rising because control of metallurgical factors is continuously improving. For this and other reasons that suggest beneficial effects of yield strength, the possibility of more effectively utilizing the yield strength of steel should be reexamined.
Flexible Rotor Balancing by the Exact Point-Speed Influence Coefficient Method
Authors: Tessarzik J. M. , Badgley R. H. , Anderson W. J.
Published: November 2010

A test program was conducted to confirm experimentally the validity of the exact point-speed influence coefficient method for balancing rotating machinery, and to assess the practical aspects of applying the method to flexible rotors. Testing was performed with a machine having a 41-in. long, 126-lb rotor. The rotor was operated over a speed range encompassing three rotor-bearing system critical speeds: two “rigid-body” criticals and one flexural critical. Rotor damping at the flexural critical was very low due to the journal bearings being located at the nodal points of the shaft. The balancing method was evaluated for three different conditions of initial rotor unbalance. The method was found to be effective and practical. Safe passage through all the critical speeds was obtained after a reasonable number of balancing runs. Success of the balancing method was, in large part, due to the accuracy of the instrumentation system used to obtain phase-angle measurements during the balancing procedure.
Resonance Response Criteria of a Damped Three-Layered Beam
Authors: Mead D. J. , Di Taranto R. A.
Published: November 2010

The vibration damping ability of a laminated elastic-viscoelastic-elastic layered simply-supported beam is analytically investigated. The criteria for damping ability of this beam, at resonance, is determined for displacement, velocity, acceleration, and stress. Curves are obtained relating the variation of the four criteria for varying ratios of elastic layer thicknesses and other geometrical and physical properties of the laminated beam.
Aerodynamic Approximations for Unsteady Supersonic Flow Through Ducts of Revolution
Authors: Skop R. A. , Kaplan R. E.
Published: November 2010

Supersonic flow of a perfect, inviscid gas through a finite, flexible duct of revolution is considered. Internal equivalents to Lighthill’s piston theory and Ackeret’s strip theory are derived and compared. The comparison shows that for low reduced frequencies of the duct wall the two internal theories coincide. Using “internal strip theory”, the flutter bounds for a circular cylindrical duct are calculated. The results demonstrate that, as the effective duct aspect ratio becomes large, the flutter bounds are asymptotic to those predicted by using classical strip theory for internal flow.
Techniques of Optimization
Authors: Mangasrian O. L.
Published: November 2010

This paper describes computational algorithms for solving unconstrained and constrained optimization problems.
A Hybrid Electromechanical Analog Computer Technique for Optimizing Vibration Systems
Authors: Masri S. F. , Ibrahim A. M.
Published: November 2010

A simple and efficient real-time simulation method is presented for investigating certain classes of vibration problems by employing a hybrid electro-mechanical analog computer. This approach combines the efficiency of electric-analog techniques with the advantages of using actual mechanical components to generate “genuine” functions that are not known or not well defined analytically. The response of a two-deg-of-freedom system equipped with an impact damper was investigated by using this approach and the effects of mode shape, frequency ratio, mass ratio, coefficient of restitution, and damper clearance ratio on the response of the system were determined. This simulation method, which is useful in automated design processes, was used to determine the optimum design parameters of the impact damper.
Analysis of Nonlinear Transient Motion of Cables Using Bond Graph Method
Authors: Tsai Nien-Tszr
Published: November 2010

The dynamic motion of underwater cable systems under hydrodynamic load is investigated using the system formulation of bond graph technique. The cable system can be a single mooring line or a multimooring system with nonuniform cables. The dynamic behavior of the cable systems due to fluid flow excitations, such as strumming force and surface waves, is calculated in this paper by using digital simulation programs. The result shows that the complicated transient motion of underwater cable systems can be treated successfully with this technique.
Transient Torsional Vibration Due to Suddenly Applied Torque
Authors: Pollard E. I.
Published: November 2010

Several instances of gear, coupling, or turbine-bucket failures in systems in which the compressors were subjected to extensive periods of heavy surge suggested the possibility that the transient torsional vibration caused by the surge could have contributed to the failures, and led to this investigation. Calculations of transient torsional vibration during acceleration through resonance and for motor or generator sudden short-circuit is treated in reference [1]. The current paper extends this work to the solution of transient vibration resulting from a suddenly applied aperiodic torque. The suddenly applied torque can be a step function representing motor or generator trip-out and compressor surge, or any other aperiodic function of exponential form. Transfer functions for shaft torques due to a sudden change in torque at any point in the system are given for systems with four degrees of freedom. Rules are given for the relatively easy conversion of the transfer functions from the frequency to the time domain. An approximate method of calculating more complex systems is suggested.
Thin Elastic Rings Subjected to Radial Load Sets
Authors: Kurajian G. M. , Na T. Y.
Published: November 2010

General equations are developed for determining internal loads in thin elastic circular rings, simultaneously subjected to a number of sets of radial loads. All sets are not necessarily of the same nature, but within each set the loads are equally spaced and of equal magnitude and radial sense. The formulations are applicable to distributed load functions as well. Applications of the method, embracing sometimes necessary computer solutions, are included in sample problems.
A Self-Starting Hydrodynamic Gas Bearing
Authors: Molnar D. , Ranov T.
Published: November 2010

An experimental self-starting hydrodynamic gas bearing was designed, built, and tested. This bearing operates on the principle that the bearing is started and stopped hydrostatically by means of an air supply which is generated by the bearing itself. For this purpose, a portion of the self-starting bearing is executed as a herringbone grooved bearing, which performs as a pump, charging a reservoir during hydrodynamic operation of the bearing. The reservoir air supply generated by the herringbone bearing is used for hydrostatic operation of the bearing during starts and stops. Starting and stopping of the experimental bearing was demonstrated using the air supply generated by the herringbone bearing. An equation was derived for the mass flow rate of the herringbone bearing pump.
Oval Ring With Stiffeners
Authors: Vafakos W. P. , Housner J. , Brodsky W. L.
Published: November 2010

The behavior of a doubly symmetric oval ring, with a pair of stiffeners parallel to either the major or minor axis, subjected to a uniform radial load is investigated. It is shown that there exists an optimum placement of the stiffeners which minimizes the maximum bending stress. Also, it is shown that the common assumption of inextensional deformations leads to gross physical errors, especially when applied to those cases in which stiffeners are placed near the extremities of the oval. In such cases, the extensional deformations in both ring and stiffener play a crucial role which cannot be neglected.
Design of a Flash Stage for a Multistage Flash Evaporator
Authors: Best T. R.
Published: November 2010

Two correlations are developed (for which there is precedent in the literature) interrelating the many process variables for adequate design of a flash stage. Both correlations are based on the Colburn factor, jm, for mass transfer. These correlations were determined from experimental data obtained from American Machine and Foundry Co. (AMF) in Connecticut and another model by Baldwin-Lima Hamilton (BLH) in Wrightsville Beach, North Carolina.
Derivation of Stress Intensification Factors for a Special, Contoured, Integrally Reinforced Branch Connection
Authors: Schneider R. W. , Rodabaugh E. C.
Published: November 2010

The results of an extensive experimental investigation of a contoured, integrally reinforced branch connection in a cylindrical pressure vessel (or run pipe) have been reported [1]. One size model, specifically a 12 in. (0.375) × 6 in. (0.280) standard weight header was studied by three-dimensional photoelasticity using the stress-freezing and slicing technique. Loads applied were internal pressure, plus in-plane and out-of-plane bending moments on the branch; one model was used for each mode of loading. In addition, carbon steel headers were fatigue tested by longitudinal and transverse moments cyclically applied to the branch pipes. A model was required for each mode of loading for each level of amplitude of applied nominal stress. Stress concentration factors (stress indices) were derived from the photoelastic tests, whereas, the fatigue tests produced stress intensification factors. The stress indices and stress intensification factors derived from the tests apply only to 12 × 6 standard weight headers, or geometrically identical headers, with the particular type of branch connection. This paper describes how generalized stress intensification factor equations were derived to cover a broad range of sizes and thicknesses of headers incorporating the same type of branch fitting. In this paper the term “header” applies to a single branch connection in a pipe remote from all other discontinuities.
Pressure Ratio Effects on Rarefied Flow Through Square Tubes
Authors: Milligan M. W. , Wilkerson H. J.
Published: November 2010

Experimental data are presented for the flow of argon gas through a 0.0985 in. sq tube 12 in. long. Data were obtained for pressure ratios varying between 0.943 and 0.0027. The range of Knudsen number variation was from 0.0025 (continuum) to 2.0 (near free molecular). These data are compared to existing theoretical model predictions. A simple semiempirical model is presented and compared with the data.
Industrial Use of Renovated Municipal Wastewater
Authors: Weddle C. L. , Masri H. N.
Published: November 2010

A survey of industries in the United States revealed that twenty-two plants are presently using renovated municipal wastewater. Eleven industries have discontinued the usage, one because of the recent availablity of a fresh water source of high quality, two because of operational difficulties, and the remaining eight due to business relocation or closure or inadequate wastewater availability. One industry was identified which is planning to start using renovated wastewater in 1972. The vast majority of the industries are receiving municipal effluent after secondary wastewater treatment. Of the twenty-two industries using the renovated wastewater, fourteen provide additional inplant treatment, besides chlorination. Pilot plant investigations at Contra Costa County, California, indicated that renovated municipal wastewater used for industrial cooling purposes compares favorably with the Contra Costa Canal water presently being used by local industry.
On a Set of Displacements in Space
Authors: Bottema O.
Published: November 2010

In this paper we study sets of screw displacements in three-dimensional space when the displacements are not uniquely specified. The two cases considered are displacements which transform a row of points onto a congruent row of points, and displacements which transform a line onto a line. In the first case the locus of all screw axes is shown to be a regulus which is either cubic (a cylindroid) or quadratic (a hyperbolic paraboloid), depending upon, respectively, if the displacement is direct or indirect (a reflection). In the second case the locus of screw axes is shown to be a line congruence of order 3 and class 1.
Mechanics of Epicyclic Bevel-Gear Trains
Authors: Yang A. T. , Freudenstein F.
Published: November 2010

The kinematics, statics, and inertia-force analysis of epicyclic bevel-gear trains have been described. Beginning with the general case of nonparallel, nonintersecting axes, the results are specialized to planetary bevel-gear trains. Dual (3 × 3) matrices have been found useful in the analysis, which is an outgrowth of earlier work on spur-gear trains.
The Study of Adjustable Oscillating Mechanisms
Authors: Handra-Luca V.
Published: November 2010

The basic principles of linkages with adjustable output oscillations are discussed. It is then shown how to design six-bar linkages with adjustable output-oscillation angles. The kinematic analysis of the output motion is given in terms of transmission functions.
Tensile Strength of Composite Materials—Part 1: Upper Bound Analysis
Authors: Avitzur B.
Published: November 2010

The upper bound approach is applied to a simple model for a composite material and an expression for relative strength of a composite is developed. Relative strength of the reinforcing particle, bond strength between particle and matrix, deformation of particles, void formation, and geometrical factors are all considered in the analysis. It is shown that the general expression for composite strength contains the familiar rule of mixtures as a special case. Further examination of predicted behavior shows that strengths equal or very close to the simple rule of mixtures may be expected in some cases; however, for other ranges of the parameters, the strength will never reach the value predicted by the rule of mixtures.
Simulation Study of the Grinding Process
Authors: Law S. S. , Wu S. M.
Published: November 2010

A model in terms of grain distributions and kinematic conditions has been recently developed [8] for a specified grinding process. Using this model, an exploratory attempt was made to study the grinding process with respect to the surface topography and nature of surface interactions by simulation on a digital computer. Fundamental grinding parameters, such as the effective grain density, grain spacings, chip depths, and chip areas, are employed to describe the grain-workpiece interactions. The grinding process is studied under a systematic variation of table speed, wheel depth of cut, and grain apex angle. The physical significance of the Z-distribution and stochastic nature of the grinding process is also discussed.
Minimum Error Synthesis of Multiloop Plane Mechanisms for Rigid Body Guidance
Authors: Prasad K. N. , Bagci C.
Published: November 2010

A variational method of synthesizing single-degree of freedom, single or multiloop plane mechanisms to guide rigid bodies through specified planar positions is presented. The optimum set of dimensions of a mechanism is determined by minimizing an objective function, which is the sum of the squared errors in the generated coordinates of two body points. The design equations are solved either by matrix iteration or Gaussian relaxation methods. By introducing constraints necessary to coincide the two body points, the problem is reduced to that of optimizing a plane mechanism to generate a planar path. Stephenson six-bar mechanism of Type I and the 4R plane mechanism are synthesized for rigid body guidance and path generation. Numerical examples are given, where all the geometric inversions of a mechanism are synthesized as distinct mechanisms, thereby eliminating the mixing of the geometric inversions at the design positions, thus assuring the mobility of the resulting mechanisms within the design interval.
A New Approach to Gear Tooth Root Stresses
Authors: Shotter B. A.
Published: November 2010

Observed root stresses and crack initiation points on high strength toothforms were found to be inconsistent with the predictions of conventional bending beam theory. Alternative stressing methods have been used and a new simple model offers a better understanding of the observed results. However, high strength toothforms require a greater knowledge of the material fatigue properties than has hitherto been considered necessary; failures are not always associated with maximum tensile stresses.
Efficient Design of Axisymmetric Elastic Plates
Authors: Paul B. , Singh B.
Published: November 2010

Machine design is an iterative procedure which is greatly aided by the use of rapid and efficient computer programs for commonly occurring structural components. The method of load integrals is developed and applied to the implementation of such a special purpose computer program for thin circular plates with multiple ring supports, overhanging edges, and axisymmetric but otherwise arbitrary surface loads, both distributed and concentrated. The simplicity of the input and the great efficiency of the program is demonstrated in design examples.
Automated Design of Aerospace Structures
Authors: Fulton R. E. , McComb H. G.
Published: November 2010

The current state-of-the-art in structural analysis of aerospace vehicles is characterized, automated design technology is discussed, and an indication is given of the future direction of research in analysis and automated design. Representative computer programs for analysis typical of those in routine use in vehicle design activities are described, and results are shown for some selected analysis problems. Recent and planned advances in analysis capability are indicated. Techniques used to automate the more routine aspects of structural design are discussed, and some recently developed automated design computer programs are described. Finally, discussion is presented of early accomplishments in interdisciplinary automated design systems, and some indication of the future thrust of research in this field is given.
On Predicting the Dynamic Effects of Clearances in Planar Mechanisms
Authors: Dubowsky S.
Published: November 2010

The presence of clearances in mechanisms can result in the degradation of the performance of these devices. This question is investigated analytically with particular attention paid to the response of a slider-crank with clearances. The use of a simple model to predict the effects of clearances in planar mechanisms without the need for complex and exhaustive analysis is considered. It is shown that such a model, called an impact pair, will provide adequate design information for considering the effects of clearances.
Surface Durability of Spur Gears at Hertzian Stresses Over Shakedown Limit
Authors: Ishibashi Akira , Ueno Taku , Tanaka Shigetada
Published: November 2010

Using a new type of gear-load testing machine and a disk-type rolling fatigue testing machine designed and made by the authors, the upper limits of Hertzian contact stress allowable on rolling contact surfaces were investigated. It was shown conclusively that gears and rollers made of soft carbon steels could be rotated beyond 108 revolutions at Hertzian stresses over shakedown limit (≈ 0.4 HB). In the case of gears, pits having a pitting area ratio of 0.04 percent occurred during 1.16 × 108 rotations at a Hertzian stress of 0.50 HB. However, no pitting occurred on the roller rotated through 1.20 × 108 revolutions at a Hertzian stress of 0.71 HB, although appreciable changes in texture were observed at the subsurface. In order to rotate gears or rollers at Hertzian stresses over shakedown limit, their surface must either be very smooth initially or after a short period of running, and an oil film must be formed between contacting surfaces.
Electromechanical Simulation of Helicopter Blade Responses to Random Excitation During Forward Flight
Authors: Kana D. D. , Chu Wen-Hwa
Published: November 2010

The response of a model helicopter rotor blade to random excitation while in simulated forward flight is studied analytically and experimentally by means of an electromechanical apparatus. Generalized transfer functions are defined which relate steady-state responses in bending, flapping, and torsion modes to a sine input. Responses occur at the input and side-band frequencies. These transfer functions are then used along with excitation power spectra to predict the nonstationary time-averaged power spectrum of the response. Validity of the transfer function analysis is investigated by means of the electromechanical model which includes analog computer simulation of the interaction of blade deflections and aerodynamic load. Generalized transfer functions are measured for sinusoidal excitation. They are then used with measured excitation power spectra to predict the response, and the result is compared with measured response power spectra. Agreement is generally good for low advance ratio, but discrepancies diverge with increasing advance ratio.
Free Vibrations of Fluid-Conveying Cylindrical Shells
Authors: Chen S. S. , Rosenberg G. S.
Published: November 2010

This paper treats the free vibrations of cylindrical shells conveying fluid. The shell motion is described by the Flu¨gge’s equations, whereas the hydrodynamic forces are described by the linearized potential flow theory. Frequency spectra are presented for symmetric and asymmetric modes and the effects of flow velocity and other parameters are discussed. In the low-frequency range, a modified water-hammer theory and an approximate bending frequency equation including the effect of the flowing fluid are developed.
Torsional Response of Internal Combustion Engines
Authors: Eshleman R. L.
Published: November 2010

A digital simulation technique for determining the torsional response of internal combustion engines subject to constant and pulsating end item torques is described herein. A refined mathematical model of the engine and end item power shafts is utilized to determine their natural frequencies, mode shapes, torsional motions and stresses using a digital computer. The mathematical model is composed of a finite number of elements which simulate lengths of continuous, massive, elastic shaft with end attached lumped masses and springs. Forcing functions, obtained by Fourier series expansion of the engine pressure-crank angle curve, are applied at the lumped masses. The technique is applied to a small gasoline engine attached to a reciprocating compressor and to a large Diesel engine with a constant torque end item.
Vibration Analysis of a Damped Machinery Foundation Structure Using the Dynamic Stiffness Coupling Technique
Authors: Sainsbury M. G. , Ewins D. J.
Published: November 2010

A detailed dynamic analysis is made of a heavily damped foundation structure designed for the multidirectional isolation of machinery vibrations. The principal components of the structure are damped sandwich beams and complex-shaped rubber blocks. In order to study the complete structure, each component was analyzed for its mechanical impedance data. Where possible, these were obtained theoretically, but in some cases it was necessary to resort to experimental measurement. The individual components were then connected together using the dynamic stiffness coupling technique in order to predict the vibration characteristics of the complete structure. The accuracy of the final results testifies to the feasibility of combining measured and theoretical data in this way in order to analyze a complex mechanical structure.
A Displacement Analysis of Spatial Six-Link 4-R-P-C Mechanisms—Part 2: Derivation of Input-Output Displacement Equation for RCRRPR Mechanism
Authors: Duffy J. , Rooney J.
Published: November 2010

The input-output displacement equation is expressed as a degree eight polynomial in the half-tangent of the output angular displacement. The equation can be used to generate input-output functions of spatial five-link RCRCR and RCRRC mechanisms. The results are illustrated by numerical examples.
A Comprehensive Study of the Small Deflections of Thin Rectangular Cantilever Plates Under Point Loading
Authors: Hageniers O. L. , North W. P. T.
Published: November 2010

An experimental program was carried out to determine the effect of aspect ratio on cantilever plate deflections under point loadings. These results were compared to deflection information obtained using the theoretical technique outlined by Szmelter, Sulikowski and Lipinski [1]. The theory and experiment gave good agreement over the range of aspect ratio studied. A series of curves giving the maximum deflection of a cantilever plate as a function of aspect ratio and load position are presented. These curves show the transition of plate deflections from the cantilever beam case to the infinitely wide cantilever plate case.
The Rating of Abrasive Cutoff Wheels
Authors: Shaw M. C.
Published: November 2010

A rational approach to cutoff wheel selection is presented based on the most important criterion for this operation—minimum cost per cut. New parameters are identified which play a more significant role than the conventional quantities grain size, grade (hardness), and structure number normally used to characterize a wheel. The new quantities are: a) the effective number of cutting points per square inch on the wheel periphery (substitute for grain size); b) the volume that may be accommodated between successsive grains under cost optimum conditions (substitute for structure number); c) a chip flexibility parameter (no counterpart in conventional wheel signature); d) the downfeed corresponding to a grinding ratio of unity (this reflects wheel grade and resistance to wear). A number of experimental examples are presented to illustrate the application of the procedures proposed.
Waste-Treatment Applications of Reverse Osmosis
Authors: Cruver J. E.
Published: November 2010

Reverse osmosis has come of age as a unit operation and is finding increasing usage in water and waste treatment. Large-scale (100–1000 gpm) units are currently operating throughout the world on a wide variety of feed streams. This paper summarizes the status of development of reverse-osmosis processing of municipal and industrial waste streams. Plants are described which process secondary effluent, metal-finishing wastes, and textile dye wastes. Capital and operating costs are also presented for reverse osmosis and compared with those of other desalting methods.
Damping at Metallic Interfaces Subjected to Oscillating Tangential Loads
Authors: Rogers P. F. , Boothroyd G.
Published: November 2010

The results of experiments are described where the energy loss per cycle occurring at a flat metallic interface subjected to oscillating tangential loads is measured. The effects of the magnitudes of the normal and oscillating tangential loads on this energy loss are observed for various materials. The results presented should be useful to those interested in machine tools or similar structures where the damping occurring in bolted joints is important.
Helices Under Load
Authors: Durelli A. J. , Parks V. J. , Hasseem H. M.
Published: November 2010

Previous solutions for the case of close-coiled helical springs and for helices made of thin bars are extended to cover all the range of geometric parameters. The complete solution is presented in simple graphs convenient for use by designers. The theoretical development is corroborated with new experiments.
On the Equivalent Diameter Approach to Prediction of Rarefied Gas Flow in Noncircular Tubes
Authors: Rieder W. G.
Published: November 2010

The feasibility of using a new characteristic dimension (equivalent diameter) is explored for predicting rarefied flows in noncircular tubes. A conclusion is that a single characteristic dimension is not necessarily appropriate. However, a normalized equivalent diameter does appear to give good relative descriptions of noncircular passages. In addition, a simplified equation based on the Weber equation is proposed. Coefficients in this equation include the variability of the characteristic dimension, and are determined by matching with three analytical solutions spanning the rarefied regimes. Significant computer time is saved and predictions are as accurate as the matching values. The classical hydraulic diameter appears to be the best characteristic dimension to use for correlating the predicted data.
Stress Concentration in Crowned Rollers
Authors: Singh K. P. , Paul B.
Published: November 2010

The edges of rollers in needle and roller bearings are crowned (i.e., rounded) in order to prevent large stress concentrations. At present, the crowning radius is determined empirically. In this paper, a numerical solution for the stress concentration in crowned elastic rollers is found. Using this method the true contact region, the load-vs.-compliance relationship, and the peak normal pressure can be determined for any roller geometry. The influence of crown radius on stress concentration is illustrated through numerical examples. This method may profitably be used in the stress analysis and design of a variety of machine elements such as gears, cams, and toothed couplings.
Response Spectra for Nonlinear Oscillators
Authors: Manning J. E.
Published: November 2010

Methods are presented for calculating the response spectrum of a nonlinear oscillator with broadband random excitation. A perturbation approach is used for oscillators with slightly nonlinear spring elements to show that the effect of the nonlinearity is a slight shift in the spectrum peak. A new heuristic approach is used for oscillators with large nonlinearities and small damping to show that in addition to a shift in the peak an increase in spectral bandwidth also occurs. The Duffing oscillator is studied as a specific example.
Dynamic Behavior of an Inherently Compensated Air Squeeze Film Damper
Authors: Cunningham R. E.
Published: November 2010

Experimental values of damping and stiffness were determined for an externally pressurized, inherently compensated, compressible squeeze-film damper up to excitation frequencies of 36,000 cycles/min. Experimental values of damping were higher than predicted by a small pressure perturbation theory at low squeeze numbers and less than predicted at high squeeze numbers. Experimental values of air film stiffness were less than the theory predicted at low squeeze numbers and much greater at higher squeeze numbers.
Some Considerations on the Formability Parameter in Sheet-Metal Forming
Authors: Kawai N. , Gotoh M. , Kurosaki Y.
Published: November 2010

The applicability of the relative load-carrying capacity as a formability parameter is examined for deep-drawing, combined-forming, and pure stretch-forming tests, using various kinds of sheet metals. High correlations are observed between this parameter and the forming depth throughout these forming tests with all of the sheet metals used. In combined-forming the correlations are grouped according to the fracture mode, which are classified into three types: punch profile, intermediate, and wall fracture. The experimental results can be confirmed also by a simple theoretical analysis. Moreover, it is found that the parameters measured in each forming test are markedly correlative.
Necessary Conditions for Ductile Flow of a Tensile Composite Rod
Authors: Iscovici S. , Avitzur B.
Published: November 2010

The upper bound approach is applied to the problem of deriving the conditions which promote ductile flow (i.e., flow which incurs no void formation) in a composite rod undergoing a tensile test. The conditions for homogeneous deformation and for nonhomogeneous deformation without void formation, including the case of nondeforming particles, are obtained as particular cases of ductile flow. The composite material under study is a homogeneous soft matrix with hard inclusions. The relative strength of the reinforcing particles, the geometrical parameters, and the possibility of testing under pressure are all included in the analysis. These factors appear in the equations expressing the necessary conditions for ductile flow and the expression for the composite strength. A detailed algorithm is provided for translating in graphical form the necessary conditions for ductile flow. The calculation of the flow pattern parameters is also simpler when the graphs are used. Two typical graphs are presented showing the dependency of the expected strength on such factors as external pressure and particle strength.
Equivalent One-Dimensional System for Analysis of Taper Leaf Springs
Authors: Nigro N. J. , Bhatia S. P.
Published: November 2010

In this paper an equivalent one-dimensional system for taper leaf springs (similar to those used in vehicle suspension systems) is developed so that results obtained from it are in good agreement with those obtained from the distributed parameter system. Curves which simplify the calculation of the parameters of the equivalent system are also provided.
The Stabilizing Capacity of Bearings for Flexible Rotors With Hysteresis
Authors: Black H. F.
Published: November 2010

The paper deals with the stability of a rotor subject to hysteretic forces and externally damped only through the shaft supports. Bearings with negligible cross-coupling are assumed, but asymmetry of support stiffness and damping is considered. The mechanism of internal friction is not defined specifically in the analysis; viscous Coulomb and standard linear hysteretic forces are considered as specific examples derived from a common general solution. It is concluded that stability limits may vary considerably with different hysteresis mechanisms and that irrespective of this, optima in bearing damping can be specified.
Curvature Analysis of Surfaces in Higher Pair Contact—Part 2: Application to Spatial Cam Mechanisms
Authors: Dhande S. G. , Chakraborty J.
Published: November 2010

In this paper curvature analysis is performed for different three-dimensional cam mechanisms. In every case the expressions for principal curvatures of the cam surface are given in closed forms for ready use. A numerical example is given to show the usefulness of the proposed procedure.
Cutting Rate-Tool Life Characteristic Functions for Material Removal Processes—Part 1: Theory
Authors: Friedman M. Y. , Tipnis V. A.
Published: November 2010

The existence of cutting rate-tool life (R-T) characteristic functions for material removal operations is introduced in this paper. This new concept enables a comprehensive development of a theory for economic optimization encompassing commonly used criteria of cost, production rate, and profit rate in machining when more than one cutting variable is involved. The theory provides conditions for the existence of economic optima, all of which must lie on the R-T characteristic curve for a given operation. The analysis of the theory is carried out for one and two independent cutting variables. For these two cases, it is proven that the locus of the tangent points of constant cutting rate and constant tool life curves describes the R-T characteristic curve, and also that the tool life is maximum along a given constant cutting rate curve at the point of tangency and vice versa. This geometric interpretation provides useful application of the concept as shown in Part 2.
Current Profile Energy and Ocean Moorings
Authors: Hartman P. J. , Nash C. D.
Published: November 2010

Thirty-five deep ocean current profiles obtained by direct current meter measurements have been studied to determine their influence on buoy mooring systems. The total kinetic energy of each current profile has been calculated and the observed maximum determined to be 1 075 200 joules (1075.2 kJ) as contained in the Gulf Stream Current profile at 37 deg 12 min N, 67 deg W. A single graph is presented which delineates the observed natural bounds on shape, kinetic energy, and current speed of these profiles. Single point nylon moorings in 3000 meters of water are shown to be nearly insensitive to current profile shape when the total kinetic energy is concentrated in the upper 1/6 of the water column. Well developed, high energy profiles do exhibit this concentration. As a result, mooring analysis in the survival environment can be greatly simplified. Comparisons between real and idealized current profiles are provided to demonstrate this phenomenon.
Casing Collapse Performance
Authors: Mehdizadeh P.
Published: November 2010

Laboratory collapse tests and data available in literature have been used to assess the effect of such manufacturing parameters as slack quenching, rotary, and gag straightening on the collapse performance of oil-well casings. The detrimental effect of slack quenching and residual stresses due to slack quenching and straightening is established. The use of hardness testing and slit-ring tests as quality control methods for monitoring these parameters is discussed, and a new method of collapse testing is proposed.
Velocity Fluctuation in Four-Bar Linkages and Slider-Crank Mechanisms
Authors: Freudenstein F. , Primrose E. J. F. , Ray S. , Laks B.
Published: November 2010

Velocity fluctuations have been recognized as important in the dynamics and statics of mechanisms with time-varying angular velocities as long ago as the classical transmission-angle problem [1, 2]. The analysis of velocity fluctuations represents a more difficult problem, primarily in view of greater nonlinearity. The present investigation represents an algebraic solution of the velocity-fluctuation optimization problem. This leads to numerically efficient optimization procedures and sheds some light also on other problems, such as certain dwell-type intermittent-motion mechanisms and the synthesis of “constant-velocity” linkages.
A Derivation of a Minimal Set of Multilinear Loop Equations for Spatial Mechanisms
Authors: Potts P. D.
Published: November 2010

The relationship between skew-symmetric and rotation matrices due to Cayley is associated with the quaternion representation of finite rotations. Novel rotation parameters yield three real (dual) equations of simple form for spherical (spatial) polygons which are multilinear in half-tangents. This new form of the equations implies that all mechanisms (with the exception of geared linkages) are multilinear systems. Solution strategies for these equations are discussed for simple spatial structures.
Dynamic Simulation of Planar Mechanical Systems With Lubricated Bearing Clearances Using Vector-Network Methods
Authors: Rogers R. J. , Andrews G. C.
Published: November 2010

This paper describes the use of a “self-formulating” computer program, PLANET II, in the simulation of mechanisms with clearances in the revolute connections. The PLANET II program is based on the vector-network method, which is discussed briefly, and requires only the mechanism description to generate the dynamic response. Mathematical models of bearing elements which take into account the effects of clearance, surface compliance, and lubricant have been developed and are included in the program. The various bearing models are described and the results of the simulations of two planar mechanisms are presented. The PLANET II program appears to be a convenient and accurate means of simulating dynamic planar systems.
Acoustodynamics of the Longitudinal Collinear Impact of Finite Elastic Cylinders
Authors: Matsumoto G. Y. , Simpson W. J.
Published: November 2010

The acoustodynamics of finite elastic cylinders is examined both experimentally and theoretically to investigate the sources of noise generation associated with longitudinal, collinear impact. Analytical predictions are based on the assumption that the acoustic radiation is predominately derived from the acceleration response of the free, plane-end surfaces of the colliding bodies and consists of rigid-body deceleration and vibration “ringing” components. Those predictions are in excellent agreement with structural acceleration and acoustic pressure measurements obtained experimentally from two separate cylinder impact configurations, except for the presence of a single dominant noise pattern originating from the proximity of the impact surfaces. This unexpected noise consists of damped pressure oscillations at a frequency unrelated to any natural frequencies of the test apparatus. Its source can be traced to the injection of air into the region between the impact surfaces just following impact separation.
Performance Characteristics of Freight-Car Trucks Determined Through Road Testing
Authors: Byrne R. , Andresen J. A.
Published: November 2010

The behavior of railroad freight-car trucks is described in relation to response modes developed within the truck structure and the freight car. A 70-ton-capacity mechanical refrigerator car equipped with conventional-style, friction-snubbed three-piece trucks was tested under a variety of conditions to develop performance behavior over the speed range of 10-79 mph. Testing was conducted on tangent track and curved track. Response behavior is described in graphs showing frequencies and amplitudes of significant descriptors.
On Optimal Arch Design
Authors: Na T. Y. , Kurajian G. M.
Published: November 2010

This paper connects a very useful theory in the area of optimal arches with a presentation of an outlined and demonstrated procedure for use by the design engineer. The eigenvalue problem presented in the work of Budiansky, Frauenthal, and Hutchinson [1] is first verified and extended. The theory, which considers buckling as the criteria for failure, is then applied to categories of cross sections. A complete design example is included to illustrate the procedure.
Sensing of Drill Wear and Prediction of Drill Life
Authors: Subramanian K. , Cook N. H.
Published: November 2010

High-speed steel drill life is found to be a strong function of the work material hardness (Tl α HB−16) when drilling cast iron. This strong dependence may account for the large variation in the life of the drills, which is observed in industrial conditions. Torque, thrust, and power are observed to be functions of drill wear. In the drilling of cast iron using H.S.S. drills of 10.32 mm (13/32 in.) dia at 690 rpm or 22.25 M/min (73 ft/min) maximum, the following relations were observed: torque(M)=0.125HBd2f+0.289HBd2r+0.0487HBd2w(3)thrust(T)=0.325HBdf+0.1242HBdw+0.755HBdr+0.0022HBd2(7) where HB = Brinell hardness of work material, d = diameter of the drill, f = feed per revolution, w = average flank wear, and r = radius at the cutting edge (0.01 mm or 0.0004 in.) all in consistent units. Flank wear of a drill increases rapidly at the end of its life. Torque and thrust reflect this change but are also influenced by workpiece hardness. Therefore, torque and thrust can be used as variables for drill wear sensing only when there is a close tolerance on the workpiece hardness, of the order of ±5 percent.
Tool Life Variation and Its Influence on the Development of Tool Life Models
Authors: DeVor R. E. , Anderson D. L. , Zdeblick W. J.
Published: November 2010

An investigation into the nature of the inherent variation of tool life over a range of cutting conditions for a finish turning process is presented. In this study, tool life is based upon a fixed amount of wear on the clearance face of the tool. The nature of tool life variation as a function of the prespecified wear level is also examined. It was found that the inherent variation of tool life increased as the wear level increased, to the point where an optimum wear level should be definable through an economic optimization of the process. Statistical tests showed that the variance of logarithmically transformed tool life data is not homogeneous over the range of cutting conditions examined. To account for this behavior, the method of weighted least squares is employed in developing tool-life-predicting equations. A comparison between the weighted least-squares method and the ordinary (unweighted) least-squares method is presented. More realistic predicting capabilities resulted by using the weighted method given the inherent behavior of the tool life variation.
Dynamic Response of a Cam-Actuated Mechanism With Pneumatic Coupling
Authors: Chen F. Y.
Published: November 2010

The dynamic characteristics of a cam-actuated system whose follower mass is coupled with a nonlinear pneumatic mechanism of hysteretic type are investigated using a lumped-parameter model. The dynamic response of the cam follower is obtained from the solution of the formulated system equation by the Krylov-Bogoliubov method of variation of parameters. The stability of the system is also investigated.