bluuebunny/crossref_metadata_2025 huggingface dataset:
A General Method for Kineto-Elastodynamic Analysis and Synthesis of Mechanisms
Authors: Erdman A. G. , Sandor G. N. , Oakberg R. G.
Published: November 2010

Kineto-elastodynamics is the study of the motion of mechanisms consisting of elements which may deflect due to external loads or internal body forces. This paper describes the initial phases in the development of a general method of kineto-elastodynamic analysis and synthesis based on the flexibility approach of structural analysis, which may be applied to any planar or spatial mechanism. Dynamic error is investigated due to flexural, longitudinal, and torsional element strain, and system inertia fluctuations; the treatment of Coulomb and viscous friction is indicated. Kineto-Elastodynamic Stretch Rotation Operators are derived which will rotate and stretch both planar and spatial link vectors reflecting rigid body motion plus elastic deformations of the link. A numerical example is presented to demonstrate the elastodynamic analysis technique.
An Experimental Study of Thermal Aspects of Cylindrical Plunge Grinding
Authors: Lee D. G. , Zerkle R. D. , DesRuisseaux N. R.
Published: November 2010

The workpiece temperature in cylindrical plunge grinding is considered as a superposition of a base temperature and an interference zone temperature. A solution for the transient base temperature distribution is derived. A two-part experiment for determining thermal effects is described. The heat transfer coefficient at the workpiece surface is measured in the first part, and specific grinding energy and workpiece temperature are measured in the second part. The energy entering the workpiece during grinding is determined from the base temperature solution and experimental data. Results obtained with several grinding fluids and application systems are presented. The energy entering the workpiece was found to be 75 to 85 percent of the total grinding energy during dry grinding and 25 to 35 percent during wet grinding.
An Evaluation of Finite Element Methods for the Computation of Elastic Stress Intensity Factors
Authors: Oglesby J. J. , Lomacky O.
Published: November 2010

Since theoretical solutions for stress intensity factors are limited to very simple configurations, numerical approaches must be utilized. However such approximate procedures must first be verified on many simple configurations before they can be applied with confidence to complex structural details. This paper discusses the merits of several computational techniques based on the utilization of finite element direct stiffness method of analysis. Examples of the application of such methods to several simple axisymmetric and two-dimensional plane strain problems are presented.
Inelastic Buckling of Shallow Spherical Shells Under External Pressure
Authors: Sureshwara B. , Lee L. H. N. , Ariman T.
Published: November 2010

In this paper the inelastic effect on the axisymmetric buckling load of a clamped shallow spherical shell subjected to an external pressure is investigated. A variational principle derived from a set of rate equilibrium equations and expressed in terms of Lagrangian variables is introduced. Then, the variational principle is employed with a step-by-step numerical process based on a Rayleigh-Ritz technique to determine the initial pressure. The spherical shell is idealized as a structure composed of four thin load-carrying layers of equal thickness and made of a work hardening material. The numerical results of the present analysis compare favorably with those of available experimental work.
Analysis of Temperature Field in Chip
Authors: Friedman M. Y. , Lenz E.
Published: November 2010

A solution is presented for the temperature field in the chip under experimental edge conditions in the contact zone and at the upper chip face. The pattern of the temperature gradient in the chip normal to the tool face while turning steel with hard-metal tools is analyzed.
State Space Characterization of Complex Rigid Body Systems Subject to Control
Authors: Townsend M. A.
Published: November 2010

The dynamic equations of systems of rigid bodies are developed as nonlinear, muti-variable control systems in state-space representations. This provides a unified treatment in terms of the general problem and indicates specific characteristics of coupled-body system equations which may be later exploited. A purpose of this paper is to provide a formulation for treating the optimal dynamic synthesis problems of general rigid and nonrigid body systems.
Reaction Force Analysis in Generalized Machine Systems
Authors: Smith D. A.
Published: November 2010

A method is developed which reduces the calculation of reaction forces for multi-degree-of-freedom, constrained, mechanical, dynamic systems to a process of accumulating a sum of terms representing inertial forces, applied forces, and Lagrange multiplier forces. This method results in an approach to reaction force calculations which is computationally more efficient than either virtual work or equilibrium when these methods are applied in conventional ways. The method is based on selecting a tree for the network being simulated in which the chords of the network correspond to revolute pairs (for two-dimensional systems). When such a tree is determined, Lagrange’s equation with constraint is used to represent the mechanical system. If the paths to the centers of mass and the paths associated with applied forces are developed from tree branches, the Lagrange multipliers are directly interpretable in terms of the total reaction forces at the chords of the network. These multipliers are obtained in the process of determining the system motion. The remaining reaction forces and torques are determined by a sequence of additions.
Optimization Technology as Applied to Mechanism Design
Authors: Fox R. L. , Gupta K. C.
Published: November 2010

The purpose of this paper is to provide a review and summary of the relationship between optimization methods (mathematical programming) and mechanism synthesis. These applications are discussed and existing work reviewed. An outline of the more developed mathematical programming areas is given and a bibliography is provided.
On the Mechanics of Micro-Thin Foil Production
Authors: Thomsen E. G. , Thomsen H. H.
Published: November 2010

The mechanics of micro-thin foil or leaf production by hammering has been analyzed. It was found that the metal foil cannot be reduced by a compression process alone because of the large impact loads that would be required, due to interfacial friction between the foil and the separating paper sheets. It is demonstrated that a likely mechanism is a plastic stretching process of the metal combined with relatively large elastic stretching of the paper due to the Poisson effect when a blow is struck. The actual mechanism is probably a combination of stretching and slipping of the metal.
Process Applications and Design of Single and Two Shaft Hot Gas Expander Compression Systems
Authors: Linhardt H. D.
Published: November 2010

Single and two shaft hot gas expander compression systems will soon replace conventional multitrain, low speed equipment due to significant economic and process advantages. The single train concept is a direct result of the recent advances in high pressure ratio compressor, high performance radial inflow turbine and high performance steam turbine technology. The application and custom engineering of single train compression systems is discussed, whereby emphasis is placed on performance and reliability.
Prediction of Wellbore Temperatures During Mud Circulation and Cementing Operations
Authors: Sump G. D. , Williams B. B.
Published: November 2010

An improved method predicts mud circulation temperatures and accounts for heat evolution in cementing operations more accurately than presently used API correlations or other numerical techniques. This method is based on an existing mathematical model of the wellbore and the formation near the wellbore. This model has been improved by using heat transfer coefficients and formation thermal conductivities determined by simultaneously fitting 28 unsteady-state circulating temperature measurements made on nine wells. Data used in this analysis were obtained from wells ranging in depth from 9225 ft to 22,725 ft, with static bottom-hole temperatures ranging from 230 to 410 deg F. The effect of heat evolution on cement pumping time is compensated for by a modified cement testing procedure. This procedure is based on experiments to determine the timing of heat evolution during the cement hydration. The experimental procedure used to simultaneously measure cement consistency and quantity of heat evolution is described.
Application of Finite Elements to the Analysis of Gear Tooth Stresses
Authors: Wilcox L. , Coleman W.
Published: November 2010

This paper explains the application of the analytical method of finite elements to the analysis of gear tooth stresses. The details necessary for simulating a two-dimensional tooth shape with finite elements are outlined and a technique for determining stress values at the tooth surface in the root fillet is given. The remainder of the paper uses the finite element method to analyze tensile fillet stress in generated tooth shapes incorporating either symmetric or asymmetric profiles. Special attention has been given to the asymmetric profiles (used in Hypoid gears) since no reliable formulas are available. Stress data thus obtained are used to develop a new simplified stress formula that gives tensile fillet stress as a function of geometric tooth shape and general loading conditions. The accuracy and wide range of applicability of the new stress formula is shown by comparing the new formula to other previously accepted formulas for a variety of tooth shapes and loading conditions.
Kinematics and Evaluation of Flat-Toothed Hypoid Gears
Authors: Dareing D. W. , Chen Chung-Moon
Published: November 2010

This paper presents kinematic equations which can be used to mathematically generate and evaluate novel gear tooth systems. The equations apply to spur, bevel, and hypoid gearing but are used specifically to generate surfaces which engage flat-toothed hypoid gears. Curvatures of these surfaces are then used to determine and compare the maximum Hertz contact pressure corresponding to various parameters. The analysis shows that Hertz contact pressure is the smallest for surfaces having line contact perpendicular to the plane contain the common unit normal vector and unit, tangent (to the path of contact) vector.
Dynamic Shear Stress—Analysis of Single Crystal Machining Studies
Authors: Ramalingam S. , Hazra J.
Published: November 2010

Experimental results obtained when single crystals of aluminum of known orientation are machined under identical cutting conditions are presented. Analysis of the data obtained shows that the dynamic shear stress remains constant for all orientations tested and is in good agreement with the calculated value for polycrystalline aluminum. The implications of these results to metal cutting theory and the metal physical foundations on which the concept of dynamic shear stress, as a true material property, rests are discussed. The possible role that the dynamic shear stress may play in determining the geometry of the metal cutting problem, a problem in partially constrained plastic flow of metals, is discussed.
Experimental Studies in Electro-Machining
Authors: Cook N. H. , Foote G. B. , Jordan P. , Kalyani B. N.
Published: November 2010

Three separate studies are discussed: (a) The effect of operating voltage, on electrochemical machining of tungsten carbide, was found to be very important, determining whether machining occurred or not. Best results were obtained in the 50–60 region. (6) “Discharge machining of glass” was studied in a system in which discharges between a tool and an electrolyte cause erosion of the glass. While the mechanism of erosion has not been identified, drilling rates up to 0.1 in/min. have been obtained. (c) Bubbles, formed by electrochemical machining (H2), behave as though positively charged. Interaction between the “charged” bubbles and an a-c field produce a desirable dispersion of the bubbles.
Analysis of Force Components in Bar Turning
Authors: Husein A. B. , DeVries M. F. , Wu S. M.
Published: November 2010

This paper presents the development of equilibrium equations permitting the determination of the force components at each of the chip-tool-workpiece contact surfaces in bar turning. The analysis is an extension of the force separation method developed for the oblique cutting of tubes. The solution presented is applicable to both bar and tube cutting and was experimentally evaluated. The bar turning data produced solutions that compared favorably with tube turning data obtained.
A Theory of Nonlinear Regenerative Chatter
Authors: Hanna N. H. , Tobias S. A.
Published: November 2010

A mathematical theory of nonlinear chatter is developed. In this, the structure is represented by an equivalent single degree of freedom system with nonlinear stiffness characteristics and the cutting force by a third degree polynomial of the chip thickness. This model leads to a second order differential equation with nonlinear stiffness and nonlinear time delay terms from which the conditions of steady state chatter are derived. These are then discussed by applying them to an equivalent system derived from experimental data pertaining to a face milling process. The theory provides an explanation for the stages in which chatter develops and also for the “finite amplitude instability” phenomenon.
An Investigation on Secondary Action on Skew Gears
Authors: Sakai Takao , Maki Minoru
Published: November 2010

There may be certain points on a gear tooth surface which contact twice with its mating gear tooth surface. This phenomenon is called “secondary action” and has been indicated relating to several kinds of worm gearings [1, 2, 3]. This secondary action may play an important role in skew gears, especially in worm gears. But its character has been scarcely investigated. The authors tried to reveal the general character of the secondary action and got some interesting results. In this paper, the authors lay emphasis on the basic character of the secondary action and omit the procedure of the numerical works.
Dynamic Characteristics of Rotating and Nonrotating Machine Tool Spindles
Authors: Allemang R. J. , Graef H. Thomas , Powell C. D.
Published: November 2010

The initial concern of this paper is to establish the general relationships between vibration testing using a static machine tool, and vibration testing using a machine tool under dynamic conditions, obtaining the frequency response by a pulse technique. The application of pulse testing to determine the dynamic characteristics of a rotating machine tool spindle is investigated. The characteristics of a static spindle are contrasted with the characteristics at different rotational speeds of the same spindle while also noting any effect of table feed. The capabilities, advantages, and limitations of the testing method are discussed with respect to mounting conditions and physical aspects of the machine tools examined.
A Study on Flash Temperatures on the Spur Gear Teeth
Authors: Tobe Toshimi , Kato Masana
Published: November 2010

Detailed analysis of the flash temperature and the partition of heat between gear teeth has been made. The problem is treated as an unsteady one where the intensity and the moving velocity of heat source changes momentarily as mesh proceeds. Making a comparison between the results and Blok’s simple solution, the latter shows too high values of flash temperature at a few specific points; for example, it gives over 15 percent higher temperature at the starting point of mesh, but the difference between these solutions becomes smaller as the meshing point moves toward the ending point of mesh. The effects of tooth load, number of revolutions, module, shifting and profile modification are illustrated and discussed. For the most part, their effects are larger than Blok’s. Some experiments are performed, and using measured dynamic load, flash temperature is calculated and compared with measured one.
Further Experiments on Balancing of a High-Speed Flexible Rotor
Authors: Tonnesen J.
Published: November 2010

The accuracy of the influence coefficient method is experimentally investigated. The influence of the number of measurement transducers, their location, and type is demonstrated on a flexible rotor where simultaneous balancing is performed in up to five planes and passing through three critical speeds. The correction weights are calculated by means of a computer program, based on a least-squares minimizing procedure. The method itself is shown to be accurate and uses only a minimum of balancing runs to reduce the vibrations to a true minimum level. The overall accuracy in determining the unbalance weights is found to be 4.5 percent. The method’s effectiveness is demonstrated on a rotor with four balancing planes and with unbalance distributed at random in six and seven planes. The absolute level of residual vibrations is found to be in the ISO 0.4 quality class [5].
The Response of Rotating Machinery to External Random Vibration
Authors: Tessarzik J. M. , Chiang T. , Badgley R. H.
Published: November 2010

A high-speed turbogenerator employing gas-lubricated hydrodynamic journal and thrust bearings was subjected to external random vibrations for the purpose of assessing bearing performance in a dynamic environment. The pivoted-pad type journal bearings and the step-sector thrust bearing supported a turbine-driven rotor weighing approximately twenty-one pounds at a nominal operating speed of 36,000 rpm. The response amplitudes of both the rigid-supported and flexible-supported bearing pads, the gimballed thrust bearing, and the rotor relative to the machine casing were measured with capacitance type displacement probes. Random vibrations were applied by means of a large electrodynamic shaker at input levels ranging between 0.5 g (rms) and 1.5 g (rms). Vibrations were applied both along and perpendicular to the rotor axis. Response measurements were analyzed for amplitude distribution and power spectral density. Experimental results compare well with calculations of amplitude power spectral density made for the case where the vibrations were applied along the rotor axis. In this case, the rotor-bearing system was treated as a linear, three-mass model.
Vibration of Cylindrical Structures Induced by Axial Flow
Authors: Paidoussis M. P.
Published: November 2010

In this paper we consider the vibration of flexible cylinders, isolated or in clusters, induced by axial flow. It has been shown that for the range of flow velocities and other parameters pertaining to industrial systems, the effect of purely axial, steady, and uniform flow is to damp free motions of the cylinders. Nevertheless, departures from such ideal flow conditions induce small-amplitude vibration, which is the subject of this paper. The underlying mechanism of the vibration is examined, as well as the means for its prediction. These latter are either empirical or analytical (generally semiempirical); the analytical methods are further classified into three categories accordingly as they postulate the vibration to be forced, parametric, or self-excited. The measure of success achieved in predicting the vibration amplitude is discussed, and possible reasons to account for its being generally poor.
Vibration Control Using Semi-Active Force Generators
Authors: Karnopp D. , Crosby M. J. , Harwood R. A.
Published: November 2010

A type of force generator which can respond to general feedback signals from a vibrating system in order to control the vibration but which does not require the power supply of a servomechanism is described. Computer simulation studies show that performance comparable to that of fully active vibration control systems can be achieved with the semi-active type of device. Physical embodiments of the concept are discussed and compared to hardware used in active and passive vibration control systems.
Dynamic Response of Three-Dimensional Framed Structures
Authors: Lee C. L. , Huang T. C.
Published: November 2010

The orthogonality condition for vibrating three-dimensional framed structures has been directly applied to solve initial value problems. In solving the dynamic response problems due to force and displacement excitations by using the mode expansion method it is necessary to use the same orthogonality condition.
The Orbital Movement and the Damping of the Fluidelastic Vibration of Tube Banks Due to Vortex Formation: Part 1—The Interplay Between the Self-Excited Vibration of the Single Circular Cylinder and the Karman Vortex
Authors: Chen Y. N.
Published: November 2010

In the present paper a series of experimental results obtained by several authors on the phenomena of the vortex street behind a vibrating cylinder are analysed. From this we can establish a flow model for the relationship between the vortex shedding, the cylinder movement, the vortex lift and the variation in the position of the separation point. This relationship reveals that a close synchronization of the vortex shedding and the lift generated by it will arise when the flow velocity enters the lock-in region. Furthermore, the flow model will enable us to predict the narrowing of the vortex street shed by a vibrating cylinder for certain Reynolds number ranges. The theory can thus qualitatively explain the corresponding phenomena observed by Koopmann, Griffin and Votaw.
Determination of Underwater Plate Dynamics Using Laser Beams
Authors: Croteau Rudolph E. , Sheets Herman E.
Published: November 2010

Underwater plate vibration and its associated noise are of interest for the analysis of ship structures, propeller blades, and other areas of underwater acoustics. In order to analyze the relationship between a plate vibrating underwater and the acoustic pressure in the near-field, optical interferometric holography, using a blue-green laser beam, was used to determine surface displacement for the vibrating plate, which was excited through a fluid-coupled system. Acoustic measurements of the same source were made in a water tower concurrently with the holography and later at a precision acoustic testing facility. This method permits prediction of underwater plate modal frequencies and shapes with high accuracy.
Critical Reynolds Number Estimates by Thermo-Dynamic (Stochastic) Methods
Authors: Hrycak P. , Levy M. J.
Published: November 2010

Methods based on fundamental thermodynamic principles and the notion of statistical probability have been used to estimate the point of instability and the lower critical Reynolds number for a round pipe and an infinite channel. It is also shown that order of magnitude estimates of the ratio of the average shear stresses for each regime allow one to draw definite conclusions about the lower and the upper critical Reynolds number in a variety of geometries.
Conform—A New Concept for the Continuous Extrusion Forming of Metals
Authors: Etherington C.
Published: November 2010

The paper describes a new continuous extrusion forming process, for metals, which is particularly applicable in the wire, section, and tube manufacturing fields. The principle of the process is based on the mechanical friction which exists between a billet and its container in conventional extrusion. If the container is rectangular in cross section and three sides are formed as a groove in a rotating wheel, with the fourth side forming a stationary shoe fitting against the outside of the wheel, then rotation of the wheel will carry the billet along with it. If a stop with die orifice is sized to fit the groove and is fixed to the shoe, then as the billet is forced against the die, extrusion can occur. The development of the process from a laboratory bench top model for lead wire, to a powered experimental machine capable of continuously extruding aluminium wire through ratios of 40:1 is described in the paper. The possibilities for future development are discussed and some guide is given to the possible size and capacities of projected machines.
Analysis of Soil Penetration by a Whirl-Excited Probe
Authors: Harker R. J. , Shah R. M.
Published: November 2010

The vertical penetration of sedimentary materials is of importance for many scientific and engineering purposes, including soil sampling and pile driving. One approach to this problem is to achieve orbital motion of a probe in a horizontal plane, thereby displacing the soil radially, with excitation produced by a rotating unbalance. The probe thus reacts with the soil, resulting in radial and tangential forces. The former produce hole enlargement, and the latter are in the nature of frictional drag related to orbital motion. The analysis indicates that such a system is bistable, with radial probe amplitudes dependent upon whirl frequency, soil friction, soil compressive resistance, probe mass, and exciter unbalance. Such a device exhibits several desirable operational characteristics, tending to enlarge the hole at increased radial resistance, and to decrease amplitude at reduced resistance, thus being somewhat self-regulating. A prototype has been built and tested experimentally; however, this paper is primarily a study of the steady-state vibratory behavior of a whirl-excited probe, with basic design equations presented.
Design of Squeeze Film Damper Supports for Rigid Rotors
Authors: Mohan S. , Hahn E. J.
Published: November 2010

This paper investigates squeeze film bearings supporting a centrally preloaded rigid rotor mounted in antifriction bearings. Assuming the short bearing approximation and isothermal, incompressible lubrication, design data are presented for such a system over a wide range of operating conditions. Design considerations include the possibility of undesirable operation modes, the maximum unbalance for which the squeeze film support is superior to the rigid mount, the transmissibility at design speed and the forces transmitted during start-up. It is shown that unbalance force attenuations by factors of three or more are a practical possibility with a consequent increase in antifriction bearing life. A numerical example is included.
Experimental Synchronization Study of the Gyroscopic Vibration Absorber
Authors: Sneckenberger J. E. , Butler H. W. , Neou In-Meei
Published: November 2010

Analysis of the Gyroscopic Vibration Absorber (GVA) is made with a view to improve its effectiveness as a linear synchronous absorber. Theoretical consideration reveals that much of the nonlinearity of the governing equations of motion of the structure-absorber system involves terms containing an absorber parameter IE. The experimental development of a GVA for which this parameter is made to vanish by appropriate proportionment of certain absorber moments of inertia is shown to be feasible. Laboratory tests examining the nulling potential of this experimental GVA show that linear synchronization of the antiresonant frequency to the speed of the GVA rotor can be obtained for a wider range of excitation frequencies than when the absorber parameter is not equal to zero. Comparison of the experimental results with analytical predictions is also favorable.
Harmonic Response of Cylindrical Shells
Authors: Warburton G. B.
Published: November 2010

The normal mode method is used to determine the steady state response of a simply supported, uniform thin cylindrical shell to a radical harmonic force with hysteretic damping included in the analysis. Numerical results are given for the variation with excitation frequency of the radial component of amplitude at different points along the shell for three levels of damping. The response at the resonances, corresponding to the first few modes of each shell, and their convergence, as the number of modes included in the solution is increased, are considered in detail. Novozhilov’s thin shell theory is used in the analysis, but the effects upon resonant response of using other shell theories are discussed.
Ocean Thermal Difference Power-Plant Design
Authors: McGowan J. G. , Heronemus W. E. , Connell J. W. , Cloutier P. D.
Published: November 2010

This paper discusses the preliminary design of a closed Rankine cycle power system using the ocean temperature difference as an energy source. A thermal cycle analysis and hull design factors for the system are presented. Graphical and tabular results which illustrate the importance of various cycle and design parameters are included as well as the outline of the digital-computer-based cycle analytical model. In addition, one design for a 400-mw power plant is shown.
Dynamic Stability of Cars in Long Freight Trains
Authors: Blader F. B. , Kurtz E. F.
Published: November 2010

A method is described for investigating the lateral response and hunting tendency of cars in long trains. A linear model is developed representative of North American freight-car design with parameters descriptive of wheel wear and truck flexibility. Included is a simple model of the couplers assumed under tension. Transfer matrices are used to examine the behavior of groups of cars. Results are given showing that the behavior of a group of such cars under tension is no less stable than that of the single uncoupled car. The effects of variation in certain parameters on the natural response are described. Truck stiffness is shown to have a primary effect on the lateral stability of the car.
General Kinematically Admissible Velocity Fields for Some Axisymmetric Metal Forming Problems
Authors: Nagpal V.
Published: November 2010

An approach for selecting general kinematically admissible velocity fields for an incompressible material from assumed shape of streamlines is outlined. Velocity field and generalized boundaries of plastic zone are obtained for axisymmetric extrusion of a rod through arbitrarily shaped die. For special case of conical die, the velocity field reduces to that presented by Stepanskii and Avitzur. General velocity field and boundary of dead zone, if assumed, for the problem of axisymmetric forging of cylindrical work-pieces are obtained. Other problems which can be treated are briefly discussed.
A Study of the Drilling Process
Authors: Williams R. A.
Published: November 2010

Drilling is a complex three dimensional cutting process yet it is possible to simulate the action of a two flute twist drill with two dimensional models provided consideration is given to the influence of the feed velocity on the cutting geometry at the drill point. Two models of chip formation and an indentation model are developed to simulate the action of the drill point. From these models equations are derived for the prediction of total torque and thrust given the cutting conditions, drill geometry, and an empirical factor which is related to the work material. Computed values of torque and thrust are shown to compare favorably with those obtained from drilling tests on an 0.45 percent C steel. The shape and magnitude of the wear zone about the chisel edge is estimated and it is shown that the observed finite thrust force as the feed rate approaches zero can be attributed to the “cutting” action of the chisel edge.
Buckling of Circular Cylindrical Shells Using a Displacement Function
Authors: Cheng Shun , Chang C. K.
Published: November 2010

The buckling problem of circular cylindrical shells under axial compression, external pressure, and torsion is investigated using a displacement function φ. A governing differential equation for the stability of thin cylindrical shells under combined loading of axial compression, external pressure, and torsion is derived. A method for the solutions of this equation is also presented. The advantage in using the present equation over the customary three differential equations for displacements is that only one trial solution is needed in solving the buckling problems as shown in the paper. Four possible combinations of boundary conditions for a simply supported edge are treated. The case of a cylinder under axial compression is carried out in detail. For two types of simple supported boundary conditions, SS1 and SS2, the minimum critical axial buckling stress is found to be 43.5 percent of the well-known classical value Eh/R3(1−ν2) against the 50 percent of the classical value presently known.
Methods of Analysis for Very Thick-Walled Cylindrical Shells
Authors: Vinson J. R.
Published: November 2010

Methods of analysis are presented for very thick-walled cylindrical, isotropic shells subjected to axially symmetric lateral and in-plane loads. These methods are developed for shells with ratios of wall thickness to mean radius as large as 0.5, as well as being applicable for thin classical shells which involve Love’s First Approximation. The present methods are elasticity solutions and employ no shell theory assumptions. Explicit solutions are presented for the shell subject to in-plane loads and laterally distributed loads which are constant or varying linearly axially for various boundary conditions at the ends.
Vibrations of an Intermediately Supported U-Bend Tube
Authors: Lee L. S. S.
Published: November 2010

Vibrations of an intermediately supported U-bend tube fall into two independent classes as an incomplete ring of single span does, namely, the in-plane vibration and the coupled twist-bending out-of-plane vibration. Natural frequencies may be expressed in terms of a coefficient p which depends on the stiffness ratio k, the ratio of lengths of spans, and the supporting conditions. The effect of the torsional flexibility of a curved bar acts to release the bending stiffness of a straight beam and hence decrease the natural frequency. Some conclusions for an incomplete ring of single span may not be equally well applicable to the U-tube case due to the effects of intermediate supports and the presence of the supporting straight segments. Results of the analytical predictions and the experimental tests of an intermediately supported U-tube are in good agreement.
An Analytical Study of Controlled Buoyancy in Laying Deep-Sea Pipelines
Authors: Hall J. E. , Healey A. J.
Published: November 2010

The application of active and passive buoyance control as an aid to deep marine pipelines has been quantitatively investigated. The use of buoys yields a substantial reduction of barge thrust and pipe tension. A systematic method is used to calculate buoy forces from a desired stress distribution. An efficient numerical solution procedure has been developed for predicting static marine pipeline geometries during laying operations. The iterative procedure is well suited for solving the two-point boundary value problem over a wide range of ocean depths.
Mechanism Design: Accounting for Manufacturing Tolerances and Costs in Function Generating Problems
Authors: Sutherland G. H. , Roth B.
Published: November 2010

Theory and design algorithms, which account for the manufacturing cost and statistical manufacturing tolerance effects as well as the structural error, are presented for the synthesis of function generating mechanisms. The algorithms are illustrated in a planar, four-bar synthesis problem. The theory and associated algorithms may be applied to the synthesis of any planar or spatial function generating linkage.
A Unified Approach to the Analytical Design of Three-Dimensional Cam Mechanisms
Authors: Dhande S. G. , Bhadoria B. S. , Chakraborty J.
Published: November 2010

The paper presents a unified approach for the analytical design of three-dimensional cam follower systems. Generalized expressions for various cam parameters, such as the equation of the conjugate cam profile, the pressure angle at the point of contact and locations of the cutter and the grinding wheel axes are derived. The effectiveness of the proposed method is illustrated by applying it to camoids, three-dimensional cylindrical cams with translating and oscillating followers, globoidal cams with oscillating followers and two-dimensional disk cams with translating and oscillating roller followers.
Impact Spectra and Intensities for High-Speed Mechanisms
Authors: Mansour W. M. , Townsend M. A.
Published: November 2010

The local and path-spectra of the impacts between the socket and pin are obtained. It is shown that the dominant impacts occur at only one of the dead points. The other shows a profusion of impacts at a lower intensity-level. An index for measuring the severity of the impacts in the socket is introduced. The effects of the variation of clearance, driving speed, and friction are studied. Resonant-impact-driving speeds and tuned operating points are discussed. Design recommendations are included throughout.
The Disk Test for Brittle Materials
Authors: Shaw M. C. , Braiden P. M. , DeSalvo G. J.
Published: November 2010

The test in which a simple penny shaped disk is loaded along a diameter until it splits is a simple one to perform on brittle materials. However, the interpretation of the results obtained relative to uniaxial tensile strength is far from simple because of the biaxial state of stress at the center of the disk where cracks initiate. Results on relatively brittle tungsten carbide disks and uniaxial tensile specimens are brought into good agreement by adopting a maximum tensile strain criterion for strength, a hydrostatic stress effect on fracture strain, and a small size effect. Weibull extreme value statistics are employed to handle the dispersion of results common to all brittle fracture studies. It is clearly demonstrated that tensile strength is not a material properly for a brittle material but depends upon the state of stress at the critical point of fracture.
Computerized Casing Design Considerations
Authors: Smith H. Irvin
Published: November 2010

Casing design via computer is accurate, inexpensive, quick, and versatile. This paper discusses some of the factors which must be considered when specifying a computer solution. Methods of constraining the design to select only from available stock are shown.
The Experimental Measurement of Casing Wear Due to Tripping—Part 1: Drill Pipe Wear
Authors: Fontenot J. E. , McEver J. W.
Published: November 2010

An experimental investigation was undertaken to explore the effects of various factors on casing wear due to tripping drill pipe. Wear tests were run using full-size samples of casing and drill pipe at various contact loads in water, a gel mud containing sand, and in a 14-lb/gal water base mud containing various quantities of simulated drill solids. The wear results were compared with field data. The major conclusion is that tripping drill pipe is generally not a major cause of casing wear.
Experimental Determination of Casing Wear by Drill String Rotation
Authors: Bradley W. B.
Published: November 2010

With the trend toward deeper objectives, the time spent drilling through casing has increased with a consequent increase in casing wear. As a result of the expanded importance of casing wear, a research program was undertaken to investigate means to predict the rate of casing wear and means to reduce this wear rate. This paper presents experimental results on the effectiveness of drill pipe rubbers in reducing rotational casing wear and measurements of the rate of casing wear by rotating tool joints and drill pipe rubbers under simulated drilling conditions. The results from this paper and the results from reference [1] have been used to develop techniques for predicting casing wear under field conditions. These techniques are reported in reference [2].
Optimal Synthesis of Flexible Link Mechanisms with Large Static Deflections
Authors: Sevak N. M. , McLarnan C. W.
Published: November 2010

Flexible link mechanisms (commonly referred to as flexural mechanisms) subjected to large static deflections are analyzed and synthesized for function generation. The large deflections present nonlinear problems. The nonlinear analysis is performed by the finite element method with aid of Martin’s linear incremental procedure and the synthesis problems are solved by the optimization techniques of Fletcher and Powell’s variable metric method. The techniques are demonstrated on mechanisms in which one or two links are flexible. The obtained analytical results are verified experimentally.
Stability Analysis of Lifting Rigs—Part 2: Sufficient Stability Criteria and Design Guidelines
Authors: Longman R. W. , Freudenstein F.
Published: November 2010

When heavy equipment is moved by cranes or derricks the rigging used must be stable. Based on the results in Part I, various sufficient stability criteria are derived which can be used to make rapid determinations of stability. A set of guidelines are developed as an aid in the loading or designing of a lifting rig in order to avoid unstable configurations, and stability boundary plots are presented which express the necessary and sufficient stability criterion in a readily usable chart form.
Dynamic Motion Analysis of Plane Mechanisms With Coulomb and Viscous Damping via the Joint Force Analysis
Authors: Bagci Cemil
Published: November 2010

Analysis of response of determinate plane mechanisms to known driving input force, or input torque, via the joint force analysis is presented. Coulomb damping and viscous damping forces in the pair bearings are included. Equations of dynamic equilibrium are solved for the components of the normal joint forces and for the motion of the mechanism as initial-value problems. The rotation of the resultant joint force, due to the fact that the pair member on a link is the inner member or the outer member of the pair, is considered by defining a generalized Coulomb damping force. Links of the mechanisms are considered rigid. The plane 4R and slider-crank switch mechanisms are investigated. Explicit solutions and numerical examples are given.
Dynamic Interactions of Link Elasticity and Clearance Connections in Planar Mechanical Systems
Authors: Dubowsky S. , Gardner T. N.
Published: November 2010

This study is an investigation of the effects of clearances and link flexibility on the stresses in joints of high speed mechanisms. A general large angular motion mathematical model is developed using an efficient mathematical formulation based on displacement functions. Numerical solution of the model reveals that over a wide operating range, link flexibility consistently reduces joint bearing stresses. The possibility of developing simple design procedures for quantitative prediction of joint bearing stresses is discussed.
Kinematic Properties of Tripode (Tri-pot) Joints
Authors: Durum Metin M.
Published: November 2010

The geometry of tripode (also called tri-pot) joints or shaft couplings is simplified by folding one side onto the other, and the kinematic properties are obtained. Due to a built-in orbital motion, a tripode joint cannot be used alone between two shafts of fixed axes; therefore it cannot directly be compared with a typical CV (constant-velocity) joint. Yet it is shown that: (a) if its shafts are kept parallel to a fixed plane a tripode joint transmits equal rotations as other CV joints do; (b) if one shaft axis is fixed and the other shaft axis has a fixed point, input and output angular velocities slightly differ, with a cycle of three times shaft speed; (c) to transmit rotation between two shafts of fixed axes, a tripode joint must be incorporated with another tripode or CV joint or a mechanism. In this case deviation between input and output angular velocities can be made very small or even nil.
Combined Bending-Torsion Fatigue Reliability of AISI 4340 Steel Shafting With Kt = 2.34
Authors: Kececioglu Dimitri , Chester Louie B. , Dodge Thomas M.
Published: November 2010

Results generated by three, unique fatigue reliability research machines which can apply reversed bending loads combined with steady torque are presented. Six-inch long, AISI 4340 steel, grooved specimens with a stress concentration factor of 2.34 and RC 35/40 hardness were subjected to various combinations of these loads and cycled to failure. The generated cycles-to-failure and stress-to-failure data are statistically analyzed to develop distributional S-N and Goodman diagrams. Various failure theories are investigated to determine which one represents the data best. The effect of the groove and of the various combined bending-torsion loads on the S-N and Goodman diagrams are determined. Three design applications are presented. The third one illustrates the weight savings that may be achieved by designing for reliability.
The Anisotropic Cutting Behavior of Free-Machining Steels
Authors: Poirier D. R. , Kieras A. P.
Published: November 2010

A determination of the anisotropy in the shear strength during machining of a group of free-machining steels including 1117, 11L17, and 1215 and a plain steel, 1018, is presented. The three free-machining steels are anisotropic in the as-received condition, but the nonfree-machining steel is not anisotropic. In terms of the extremes, 1018 steel has a shear strength of about 34,000 psi when cut in both the longitudinal and transverse directions, whereas 1215 has a shear strength of about 40,000 psi when cut in the longitudinal direction but only 24,000 psi when cut in the transverse direction. By fully annealing the free-machining steels, the anisotropy is reduced in 11L17 and 1215 and is eliminated in 1117. Examinations of the shear zones in stopped-chip specimens show that the free-machining additives form inclusions and that, in the shear zone during machining, long sharp cracks emanate from the tips of the deformed inclusions or there is a separation of material at the matrix-inclusion interface. No such voids or microcracks form in the plain steel containing only impurity levels of sulfur (1018). Since tensile ductility depends on inclusion content and the orientation of inclusions relative to the specimen axis, and the same is true for the shear strength during machining, then, as expected, there is a relationship between the two for all the steels at the same strength level of 50,000 psi; the effective shear strength during machining decreases with decreasing tensile ductility.
Multiple Impacts of a Ball Between Two Plates—Part 1: Some Experimental Observations
Authors: Veluswami M. A. , Crossley F. R. E.
Published: November 2010

This paper is a report on a series of physical experiments made with a steel sphere vibrating while trapped between and impinging against two end plates, as in an impact damping device, while the plates are shaken by an electromagnetic shaker. Three materials were used for the end plates. It was found that, for the range of frequencies (0–60 Hz) and amplitudes (0–5 mm) investigated, the ball generally hits several times on one boundary before passing over to strike the other, per cycle of the shaker. Observed data are presented on these modes of vibration and on the duration of the contacts. Objective of the tests is to provide a datum for a mathematical model of a single impact. This is pursued further in a sequel paper [18] in which certain hypotheses are tested by simulation and one is found to match the character of these observed phenomena.
Some Considerations on Tool-Life Scatter and Its Implications
Authors: Levi R. , Rossetto S.
Published: November 2010

The effect of tool-life scatter on the uncertainty of parameters of a typical tool-life model is analyzed using the joint confidence region approach. Some apparent contradictions concerning tool-life test data are explained in terms of their information content in the light of personal probability concepts.