bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimum Design of Four-Bar Crank Mechanisms With Prescribed Extreme Velocity Ratios
Authors: Savage M. , Suchora D. H.
Published: November 2010

The design of four-bar crank mechanisms to have prescribed maximum and minimum angular velocity ratios is treated. The mechanisms are optimized by minimizing their maximum pressure angles. Two design procedures, based on the collineation axis theorem are presented: one uses the computer, the other graphical constructions. Worked out examples using both techniques are included. The paper also presents property charts for the four-bar crank mechanism which aid in the practical selection of this device.
Steels for Seamless Hydrogen Pressure Vessels
Authors: Loginow A. W. , Phelps E. H.
Published: November 2010

To provide engineering data useful in the design, manufacture, and operation of seamless pressure vessels, extensive tests have been conducted in hydrogen at pressures ranging from 3000 to 14,000 psi (21–97 MN/m2) with precracked specimens of steels having a wide range of mechanical properties. The critical stress-intensity level at which crack propagation spontaneously arrests, KH, was determined. The values of KH were used in an illustrative calculation to estimate the critical flaw size at which hydrogen crack propagation would be expected in thick members loaded in bending. In general, the susceptibility of steels tested increased with yield strength. For the steels with intermediate yield strengths (85–113 ksi or 586–779 MN/m2), KH tended to decrease as pressure was increased from 3000 to 14,000 psi (21–97 MN/m2). The crack path was analyzed, and a sequence of events is described involving the initiation, growth, and arrest of cracking induced by gaseous hydrogen.
The Displacement Synthesis of Four-Bar Straight-Line Mechanisms
Authors: Mitchiner R. G. , Mabie H. H.
Published: November 2010

This paper presents an analytical method for synthesizing a four-bar linkage from a slider-crank mechanism using the cubic of stationary curvature of the slider crank. A coupler point on the resulting linkage will generate an approximate straight line, and the functional relationship between the displacement of the coupler point and the crank angle will be the same as the relation of slider displacement to crank angle of the original slider crank.
A Pendulating Model for Mechanisms With Clearances in the Revolutes
Authors: Townsend M. A. , Mansour W. M.
Published: November 2010

A model is developed for evaluating impulsive forces and torques in mechanisms with clearances. It is built around the momentum-exchanges during impacts rather than following the traditional path of simulating the contacting surfaces by springs and dashpots. The spectrum of the impulses for a four bar mechanism is obtained for a number of cycles of the crank rotation. The model provides a proper design tool for investigating wear, life-expectancy, and noise characteristics of high-speed mechanisms with clearances.
Fatigue Reliability With Notch Effects for AISI 4130 and 1038 Steels
Authors: Kececioglu D. , Stultz J. D. , Chester L. B. , Nolf C. F.
Published: November 2010

Methodologies for developing distributional theoretical stress concentration factors, fatigue stress concentration factors, and notch sensitivity factors for circumferentially grooved, rotating AISI 4130 and AISI 1038, 3/8-in.-dia rods subjected to reversed bending are developed and the results are presented. The groove radii vary from 0.031 in. to 1.870 in., and the base diameters at the groove vary from 0.0937 in. to 0.2700 in. Two illustrative cases for designing such components to a specified life and reliability are given.
Air and Power Requirements for the Pneumatic Transport of Crushed Coal in Horizontal Pipelines
Authors: Konchesky J. L. , George T. J. , Craig J. G.
Published: November 2010

Empirical equations were developed giving minimum air and power requirements for the vacuum and pressure transport of crushed coal through horizontal pipelines. The test system included 2-, 4-, 6-, and 8-in.-dia pipelines, each with a 200-ft straight section followed by three shorter runs connected by 90-deg bends of different radii. Air requirements were found to be a function of coal rate and specific gravity, pipe diameter and length, and the ratio of the cross-sectional area of the pickup section to that of the pipe. Although coal size was not a significant variable, the maximum size cannot exceed four-tenths the diameter of the pipe. The highest coal rate—55 tons per hr—was achieved in pressure operation with 1.35 specific, gravity coal transported through the 8-in.-dia pipeline. In this experiment with a pickup to pipe area ratio of 3 to 1, about 2200 actual cu ft per min of air at the pipeline entrance was required to keep the coal moving in full suspension with a 7.5-psi drop in pressure. The equations can be used to design horizontal pipeline systems operated under either vacuum or pressure with different types of pick-up devices and varying conditions of coal gravity and rate and pipe diameter and length. For example, assuming a pressure drop of 20 psi and a pickup to pipe area ratio of 3 to 1, 380 tons per hr of 5- by 0-in. coal (sp. gr. 1.40) could be transported through 1000 ft of straight 12-in.-dia pipe by 7300 actual cu ft per min (17,300 standard cu ft per min) at the pipeline entrance at the expense of 1080 theoretical horsepower.
Mechanical Properties of Simulated Deep Permafrost
Authors: Goodman M. A.
Published: November 2010

Creep tests were performed on frozen and unfrozen 20–40 mesh sand to evaluate the viscoelastic and yield properties of simulated deep permafrost. Overburden pressure associated with permafrost depth was imposed on samples by freezing under constant confining pressure and maintaining the pressure during the tests. The data showed that both thawed and frozen simulated permafrost behaved as a delayed elastic material before yield and as a coulomb plastic material after yield. The appropriate viscoelastic material constants were determined by correlating the test data with a mathematical model for the delayed elastic material. The results, together with Prudhoe Bay field test data, indicate that the creep response of deep permafrost, subject to loadings caused by thawing and refreezing, is negligible in comparison to the elastic and yield response.
Wellbore Gyp-Scale Control
Authors: Knowles T. L.
Published: November 2010

Gyp-scale deposition in producing wellbores is a recognized problem in many West Texas oil fields. The results of gyp-scale formation are usually reduced producing rates, premature well abandonment, and high operating expenses. An effective gyp removal and inhibition program is necessary for successful operation where gyp-scaling problems exist. Development of the gyp-control program presently in effect in the Means (San Andres) Unit began in 1969 when gyp was originally detected in the Grayburg-San Andres reservoir of the Means Field in Andrews County, Texas. Prior to that time, a great deal of progress had been made in the area of gyp-scale control in the Means (Queen) reservoir which overlies the Grayburg-San Andres. This paper presents a description of the Means (San Andres) Unit Gyp Scale Control Program and the results achieved with that program.
Dynamic Response of a High-Speed Slider-Crank Mechanism With an Elastic Connecting Rod
Authors: Chu S.-C. , Pan K. C.
Published: November 2010

To achieve the performance of a mechanism to a higher degree of accuracy requires that the elastic deformations of a member in a mechanism under dynamic loading conditions be taken into account. Coupled nonlinear governing partial differential equations have been derived for transverse and longitudinal vibrations of an elastic connecting rod in a slider-crank mechanism operating at high speed conditions. The derived coupled governing nonlinear partial differential equations of motion were transformed into ordinary differential equations by use of the Kantorovich method and the method of weighted residuals. The resulting coupled ordinary differential equations were solved numerically by use of the piecewise polynomial method and the fourth-order Runge-Kutta method. The dynamic response of the system has been investigated on the basis of natural frequencies of the first mode free vibrations, the ratios of the length of crank to the length of connecting rod, viscous damping, and rotating speeds of crank. These parameters can be used by the designer to predict the vibrations of an elastic mechanism under high-speed conditions.
A Parameter Identification Study of Kinematic Errors in Planar Mechanisms
Authors: Dubowsky S. , Maatuk J. , Perreira N. D.
Published: November 2010

The performance of machines and mechanical systems based on an evaluation of their theoretical design is often less than is optimally expected due to manufacturing errors, clearance, play in the machanism connections, wear, thermal gradients and unstable material properties. Yet the problem of identifying the sources of the poor performance based on available measured data has been treated essentially by trial and error methods. This study applies mathematical methods drawn from recently developed computer optimization techniques to identify the sources of this poor performance based on an examination of the system response.
Effects of Variable Thermal Properties on Moving-Band-Source Temperatures
Authors: Isenberg J. , Malkin S.
Published: November 2010

Temperatures calculated by moving-heat-source theory for machining and sliding processes are often sufficiently large that the assumption of temperature-independent thermal properties is invalid. In the present paper results of a numerical analysis are presented that consider the effects of variable thermal properties on the temperatures due to a moving-band source. Compared with the constant-property model, the maximum surface temperatures are found to be significantly higher with small Peclet numbers and strong heat sources, but the average surface temperatures within the band are much less affected by the variations of thermal properties with temperature. The variable-property model also indicates significantly larger transverse temperature gradients, a phenomenon that should cause greater thermal stresses.
Confirmation of the Critical Speed Stability Theory for Symmetrical Circular Saws
Authors: Mote C. D. , Holoyen S.
Published: November 2010

The critical speed theory for circular saws predicts conditions of stability when a saw remains plane and cuts a straight path, and conditions of instability when the saw is no longer plane and no longer produces accurate cuts. This paper presents results of an experimental program on a production process which shows near perfect correspondence between the theoretical critical speed prediction and the measured product accuracy. The critical speed computation required measurement of the production blade temperature with a radiation thermometer and the product accuracy was independently evaluated as the standard deviation of the product thickness. The critical speed theory has direct application to both optimal design and optimal operation of circular saws.
The Slack in a Stretched Thin Foil Bent Against Two Parallel Cylinders
Authors: Eshel A.
Published: November 2010

A stretched finite stiffness foil bent against two parallel cylinders is approximately analyzed. The difference between its length and that of a perfectly flexible foil under similar conditions, termed “slack,” is computed. Changes in wrap angle and in frictional slip forces due to the finite tape stiffness are evaluated. Pertinent results are graphically presented as a function of a stiffness parameter and radii ratio.
Kinematic Analysis of Mechanisms by the Complex Conjugate Exponential Method
Authors: Smith J. A.
Published: November 2010

Generalized closed-form expressions are presented for the analysis of angular and path position and dynamic state properties of an n link mechanism with single or multiple prescribed input specifications. The complex conjugate concept is extensively used to formulate these explicit expressions. A numerical example of a six-bar mechanism is presented, and the closed-form expressions are used to calculate—without graphical, numerical, or iterative techniques—the angular position, angular velocity, and angular acceleration of each link.
The Impact Damper as a Method of Improving Cantilever Boring Bars
Authors: Thomas M. D. , Knight W. A. , Sadek M. M.
Published: November 2010

The dynamic behavior of three different designs of a cantilever boring bar are compared by means of forced vibration tests. These are a bar with diametrically opposed flats machined along its length, a bar fabricated from laminates of steel and a damping compound, and a bar fitted with an impact damper. The impact damper boring bar is found to be the most effective, and an improved design, giving increases in stable metal removal rates of more than 100 percent, is outlined and tested. A theoretical analysis is presented for predicting the effectiveness of the impact damper with a spring supported impacting mass. This analysis enables the optimum mass ratio and gap setting of the damper to be selected for specified characteristics of the vibrating systems to which the damper is fitted.
Optimal Linear Dampers for Flexible Plates
Authors: Van de Vegte J. , Wu Y. L.
Published: November 2010

Modern optimal control techniques are applied to minimize the transient vibrations of uniform plates by means of one or more linear dampers. Both damper rates and locations are optimized, and guides are provided as to the number of dampers to be used. The design technique readily generates optimal designs with a range of dynamic characteristics, to satisy different requirements.
Railway Truck Response to Random Rail Irregularities
Authors: Cooperrider Neil K.
Published: November 2010

This paper discusses the random response of a seven degree of freedom, passenger truck model to lateral rail irregularities. Power spectral densities and root mean square levels of component displacements and contact forces are reported. The truck model used in the study allows lateral and yaw degrees of freedom for each wheelset, and lateral, yaw and roll freedoms for the truck frame. Linear creep relations are utilized for the rail-wheel contact forces. The lateral rail irregularities enter the analysis through the creep expressions. The results described in the paper were obtained using frequency domain techniques to solve the equations of motion. The reported results demonstrate that the guidance force needed when traveling over irregular rail at high speed utilizes a significant portion of the total available tangential force between wheel and rail.
Design Synthesis of Safety Devices on a Logging Trailer: Part 1
Authors: Bhushan Bharat , Feder K. R.
Published: November 2010

A safety device is proposed which enables the driver to dump the loaded trailer in case of emergency. The proposed device is supposed to perform the following operations in sequence. (1) It will disconnect the cup and saucer assembly. (2) It will apply the emergency brakes to stop the decoupled trailer. (3) It will drop the scotch block skid-plates in front of the duals of the trailer in order to avoid any skidding on a slippery road. The device is inoperative at speeds over 45 mph (72 km/hr) to insure that the driver cannot use it on highways. A thermodynamic analysis, for propagation of a real gas from a high pressure gas tank to two variable volume cylinders with movable pistons, is proposed to calculate the time required to perform these operations.
A Least Weight Circular Cooling Fin
Authors: Gu¨c¸eri S. , Maday C. J.
Published: November 2010

The design of the least weight circular cooling fin is obtained through an application of the Minimum Principle. The fin temperature, thickness, and heat flux are considered to be functions only of the radius. Solutions are obtained for the exact one-dimensional representation and also for the approximate case where the profile curvature is neglected in the convection calculation. A regularization technique is used to avoid computational difficulties, especially near the tip where the fin thickness becomes vanishingly small. In the exact case, an additional degree of freedom allows the selection of the fin root dimension. This flexibility suggests the possibility of optimization in a parameter, the root dimension; this was done by using a pattern search technique. Closed form results are given for the approximate case. For kθo/qo = 100, the fin design obtained in the exact case is about 20 percent shorter and contains about 1 percent to 2 percent less material than the fin obtained in the approximate case.
Effect of a Biphase Lubricant on Half Frequency Whirl in a Full Journal Bearing
Authors: Tolle G. C. , Muster D.
Published: November 2010

It is shown that a liquid–solid biphase lubricant can stabilize the motion of a rigid rotor in a full-journal bearing. The biphase lubricant is a uniform dispersion of Teflon particles in an SAE 20 lubricating oil. The stabilizing effect of nine combinations of particles and oil at two rotor speeds are investigated (particles of 25, 32, and 40 micron dia in concentrations of 5, 10, and 15 percent by weight, respectively, at rotor speeds of 1200 and 1800 rpm). These results are compared with the computed and measured orbits of the journal center relative to the bearing center when the same lubricating oil is used alone. In the analysis account is taken of the forces associated with the crushing of the Teflon particles and the usual inertia and fluid-film forces. A rigid-rotor, full-journal bearing apparatus was used to measure the orbits described. Agreement between computed and measured results was generally good. Both support the conclusion that a liquid-solid biphase lubricant can, in fact, stabilize the motion of rotors in full-journal bearings.
An Analysis of Epitrochoidal Profiles With Constant Difference Modification Suitable for Rotary Expanders and Pumps
Authors: Robinson F. J. , Lyon J. R.
Published: November 2010

Epitrochoidal curves modified by constant difference increments and their associated inner and outer envelopes may be defined in terms of four parametric equations in Cartesian coordinates. Four basic constants are required to specify a given epitrochoid and its envelope; use is made of a digital computer program to plot examples. Curves which are useful as profiles for rotary expanders and pumps are discussed, together with the limits of the constant difference modification that can be applied. Some apparently unrelated machine profiles may be defined in terms of the basic constants discussed using the parametric equations. Examples of such machines are illustrated.
Effect of Nonuniform Residual Bending Stresses on Postleveled Sheet Flatness
Authors: Hsu Y. W.
Published: November 2010

The relationships between sheet unflatness and nonuniform residual longitudinal bending stresses are investigated. Mathematical analysis shows that edge and center waviness of a short sheet sample may be caused by nonuniform residual bending stresses instead of differential longitudinal strains across the width of the sheet. The latter has often been thought as the only reason for edge and center waviness in sheets. In an infinitely long sheet, or in the inspection zone of a continuous leveling line, the nonuniform residual bending stresses manifest themselves as nonuniform transverse curvatures. There is no longitudinal waviness associated with the residual bending stresses. Nonuniform residual bending stresses may exist in any leveled sheet, to a certain degree, due to initial unflatness and to the strain hardening properties of the alloy. The present study, therefore, may provide a guideline for determining the flattening capability of a leveler in leveling any given alloy with given initial unflatness.
Loss Factors and Resonant Frequencies of Periodic Damped Sandwich Plates
Authors: Mead D. J.
Published: November 2010

This paper describes a method of determining loss factors and resonant frequencies of three-layer, damped sandwich plates with regularly spaced stiffeners spanning the plate in one direction. Periodic structure theory is used in conjunction with the theory of damped forced normal modes. Computed results are presented which show how loss factors and resonant frequencies are affected by the presence of the stiffeners and their attachment rivets, by the stiffener spacing, and by the shear stiffness of the sandwich core.
Analysis of Combined Backward-Forward Extrusion
Authors: Avitzur B. , Hahn W. C. , Mori M.
Published: November 2010

The upper bound approach is used to analyze combined backward-forward extrusion. The deformation region is divided into five zones separated by planer and cylindrical surfaces of velocity discontinuities. The internal power of deformation and shear and friction losses are computed individually and summed. The pseudo-independent process parameter is the backward rate of flow with respect to which the total power of deformation is optimized. The optimal backward rate of flow is assumed to be the actual one. Thus, the backward rate of flow becomes a dependent parameter to be studied through this analysis. Conditions covering backward rates of flow from zero to maximum are demonstrated graphically. Examples are given for which combined flow results and for which either only forward flow or only backward flow occur.
A Comparison of Charpy V-Notch, Dynamic Tear, and Precracked Charpy Impact Transition-Temperature Curves for AAR Grades of Cast Steel
Authors: Sharkey R. L. , Stone D. H.
Published: November 2010

Impact tests using Charpy V-notch, Dynamic Tear and Precracked Charpy samples were conducted on AAR-B, AAR-C (several compositions and heat treatments), and AAR-E cast grades of steel and on a high-strength, alloy cast steel. Graphical presentations of the transition-temperature data are given. Differences in the relative shapes of the curves and the locations of the NDT temperatures with respect to the transition temperatures are discussed. Fracture toughness, KId, values are also presented.
On the Development of Multi-Edge Cutting Tools for BTA Deep-Hole Machining
Authors: Osman M. O. M. , Latinovic V.
Published: November 2010

The design concept and the analysis of multi-edge BTA deep-hole machining tools are presented. The main feature of the design is that the tool cutting edges are unsymmetrically located on the boring head. This provides a stabilizing cutting force resultant necessary for self-guidance of the boring tool. The role of this stabilizing force for machining accurate holes of high length-to-diameter ratio is explained and demonstrated by examples. The principles of tool self-guidance and the range of application for various drilling methods are discussed and examples are given. The results show that, besides achieving higher material removal rate, the use of unsymmetrical multi-edge cutting tools provides similar performance to that of single cutting-edge boring tools in terms of tool stability and bore accuracy. Results also show that by controlling the cutting force resultant at a predetermined value based on feed rate, cutting conditions and tool geometry, a full-film lubrication at wear-pads of the boring head can be insured during the boring operation.
Spherical Shell Sector Acrylic Plastic Windows with 12,000 ft Operational Depth for Submersible Alvin
Authors: Stachiw J. D. , Sletten R.
Published: November 2010

It has been found that the 90-deg plane conical frustum windows with t/Di = 0.7 ratio in ALVIN submersible can be replaced with 90-deg t/Di = 1 spherical shell sector windows without any modification of window seat flanges. The 90-deg spherical shell sector windows with t/Di = 1.0 possess not only a higher short term critical pressure but also develop more uniform stress distribution during a typical dive to 12,000 ft than the t/Di = 0.7 acrylic conical frustum windows that they replace. The 90-deg t/Di = 1.0 spherical shell sector windows (1) withstood, without catastrophic failure, 100 hr sustained loading to 20,000 psi, (2) 33 pressure cycles of 7-hr duration to 13,500 ft depth without any signs of fatigue, and (3) experienced less than 15,000 μin. strain during a simulated typical prooftest dive to 13,500 ft depth. The 90-deg t/Di = 1 spherical shell sector window presents a 50 percent larger view in water than a 90-deg t/Di = 0.7 conical frustum window that it replaces. This permits the observer inside the submersible to cover visually more ocean bottom during a single pass along the bottom and thus decreases the cost of a typical bottom search mission for a submersible.
Optimum Design of Automatic Depth Control System for Underwater Divers
Authors: Baz A. , Seireg A.
Published: November 2010

This study deals with the development of an automatically controlled depth-seeking system that enables the scuba diver to reach and maintain a predetermined depth. The system utilizes an inflatable life vest as a buoyancy-compensating element. The buoyancy of the vest is regulated by two on-off solenoid values that are controlled by depth and depth rate signals to improve stability. The valves and the depth-sensing pressure transducer are enclosed in a pneumatic control box that can be easily strapped to the diver’s waist and is controlled by an electronic control console carried by the diver. The system is operated by constant pressure air tapped from the diver’s air regulator. A theoretical model is developed to select the system design parameters which optimize its overall performance. Several tests of the device showed its excellent potential as a practical tool for the working divers. Besides its capability of maintaining a predetermined depth, it can be used in conjunction with a decompression meter to control the depth of the diver during the different decompression stages. The optimum design formulation with the selected parameters and merit criterion have provided an effective rational procedure for the design of this type of system.
On The Use of The Extreme Value Distribution in Reliability Analysis and Design
Authors: Wirsching P. H. , Jones L. H.
Published: November 2010

Use of the Type 1 Extreme Value Distribution of Maxima to design engineering problems is reviewed. Results of a Monte Carlo study of the statistical behavior of the distribution parameter estimators are summarized. The study compares behavior of the method of moment and maximum likelihood estimators, and the results suggest that the method of moment estimators, a simpler algorithm, is but slightly less efficient than the maximum likelihood estimators. An example is given to illustrate how a design engineer uses these results to translate observations into an estimate of “reliability” or “risk”. Moreover, a scheme for obtaining approximate confidence intervals on reliability is presented.
A Modal Transient Rotordynamic Model for Dual-Rotor Jet Engine Systems
Authors: Childs D. W.
Published: November 2010

A transient modal simulation model is developed for a “typical” two-spool jet engine configuration, consisting of a low-speed rotor, a high-speed rotor, and the supporting case structure. The formulation cited permits bearing connections from a rotor to the support structure and between rotors. A conventional Jeffcott-Green flexible rotor formulation is used to model each rotor as a collection of rigid bodies connected by a mass-less elastic structure. The case structure is similarly modeled as a collection of axisymmetric elastically connected rigid bodies. The transient modal simulation model development is based on eigendata for the complete structural dynamics model (elastically coupled rotors and case structure) at zero running speed. The completed model readily accounts for gyroscopic effects, bearing damping and nonlinearities, structural modal damping, concentrated damping due to oil-film dampers, etc. The applicability and utility of the model is demonstrated by the simulation of a turbine-wheel blade loss.
Guide Vane Vibrations Caused by Wakes and Blower Noise—Part 2: Transferability From the Model to the Prototype
Authors: Chen Y. N. , Baylac G. , Walther R.
Published: November 2010

Model tests were carried out on vibrations of guide vanes induced by wakes and noise. The results will be compared with the measurements on the prototype. It will be shown that the modeling law applies well for the wake-induced vibration. But for the noise-excited vibration, the model test with the loudspeaker noise gave too high a level of the dynamic stress compared with that in the prototype excited by the blower noise. This deviation can be attributed to the unsteady phase relationship of the noise generated by the turbomachinery. The acoustic resonances in the channels will be investigated both theoretically and experimentally. A damping of these resonances can be achieved by inserting cross plates into a part of the channel. The mechanical vibration of a turning blade can only be severely excited by the noise, as long as an acoustic resonance prevails in a neighboring channel near the corresponding frequency.
On Extreme Velocity Ratios in Spherical Four-Link Mechanisms
Authors: Pamidi P. R.
Published: November 2010

The conditions for the existence of extreme velocity ratios in spherical four-link mechanisms have been investigated by algebraic means. It is shown that, in the general case, all such extreme velocity ratios must be among the real roots of a 10th-degree algebraic polynomial. The results make it possible to obtain the extreme velocity ratios of any given spherical four-link mechanism. The method of the paper has been illustrated by several numerical examples. Special formulations of the general case have also been considered and applications to some practical spherical mechanisms have been discussed. The results can also be used for synthesizing spherical four-link mechanisms with prescribed extreme velocity ratios.
A Variational Principle for the Elastodynamic Motion of Planar Linkages
Authors: Thompson B. S. , Barr A. D. S.
Published: November 2010

A variational principle is presented that may be used for setting up the equations describing the elastodynamic motion of planar linkages in which all the members are considered to be flexible. These systems are modeled as a set of continua in which elastic deformations are superimposed on gross rigid-body motions. Displacement continuity at pin joints, or any other special constraints that are peculiar to the linkage being analyzed, are incorporated by the use of Lagrange multipliers. By permitting independent variations of the stress, strain, displacement, and velocity parameters for each link approximate equations of motion, boundary and compatibility conditions for the complete mechanism may be systematically constructed. As an illustrative example, the derivation of the problem definition for a flexible slider-crank mechanism is given.
Optimal Cantilever Dynamic Vibration Absorbers
Authors: Jacquot R. G. , Foster J. E.
Published: November 2010

This work considers the use of a double-ended cantilever beam as a distributed parameter dynamic vibration absorber applied to a single-degree-of-freedom system in the presence of sinusoidal forces. The problem is analyzed exactly and by an energy approach using a single mode approximation for the cantilever beam. The results for both techniques compare favorably and damping is introduced in the form of a complex beam modulus. Optimal tuning and optimal damping parameters are found for a given ratio of absorber mass to main mass.
Influence of Axle Load, Track Gage, and Wheel Profile on Rail-Vehicle Hunting
Authors: Hannebrink D. N. , Lee H. S. H. , Weinstock H. , Hedrick J. K.
Published: November 2010

Analyses have been conducted on the influence of axle load, track gage, and wheel contour on the hunting behavior of simplified models of wheelsets for typical freight- and passenger-car suspensions. The capability of the wheel flange to limit hunting oscillations is found to increase with wheel axle load. The use of worn wheel contours or excessively tight gage is found to increase the susceptibility of the wheelset to excessive and unstable hunting oscillations. For freight-car applications, coulomb friction in the suspension (e.g., constant-contact side bearings) may act to increase the range of speeds over which hunting will not occur and may permit operation at higher speeds for extremely straight track. However, if track irregularities are sufficient to cause a breakout of the friction, drastic hunting oscillations leading to derailment can occur. Regions of stable limit-cycle hunting and unstable operating conditions are defined. Computational algorithms and computer programs for predicting the boundaries of stable, unstable, and limit-cycle behavior for the wheelset and more complex rail-car analytic models, using the describing-function type of analysis, are presented and reviewed.
The Frictional Mechanism on the Surface of Metal Being Plastically Deformed by Drawing
Authors: Kawai N. , Nakamura T. , Iwata M.
Published: November 2010

To examine welding phenomena in deformation process, two-dimensional drawing-type friction tests have been carried out, using mild steel as the work metal. On the holder-surface a boundary lubrication state holds throughout the drawing process, while on the die-surface welding starts at the die exit and increases as the drawing progresses. The latter phenomenon is due to an expansion of the surface area. The frictional shear stress in the boundary lubrication region is proportional to the real contact pressure on both surfaces. The one at the welding region is nearly equal to the yield shear stress of the work metal.
Mechanical Couplings—A General Geometrical Theory, Part 1: Theorems on Algebraic Loci and Couplings
Authors: Fichter E. F. , Hunt K. H.
Published: November 2010

In the broad category of couplings considered the two coupled bodies have either one or two relative degrees of freedom. Points, planes, and lines guided by such couplings trace a variety of spatial loci restricted by the requirement that they must all be algebraic. The order, class, or degree of such loci is related to the tracing element, and is proved to be always exactly identifiable with an invariant property of a particular coupling, here called the “feather” of the coupling. This property is central to two new theorems which unify many hitherto distinct facets of linkages. Some shortcuts are revealed to assist in more detailed study of mechanical movements.
Application of Instantaneous Invariants to the Analysis and Synthesis of Mechanisms
Authors: Roth B. , Yang A. T.
Published: November 2010

The objective of this paper is to make instantaneous invariants a more accessible tool for problem solving in the field of kinematics. We present a systematic procedure to determine the instantaneous invariants of a rigid body under geometric constraint, develop a process by which kinematic properties of rigid body motion can be expressed in terms of instantaneous invariants, and apply instantaneous invariants to solve typical kinematic synthesis problems. Four examples are given in detail for illustrative purposes.
Synthesis of Spring Parameters to Satisfy Specified Energy Levels in Planar Mechanisms
Authors: Matthew G. K. , Tesar D.
Published: November 2010

The potential energy storage capabilities of linear springs are integrated with the nonlinear motion of mechanisms to provide approximation of desired counter-loading functions. The approximating function is required to be identical to the desired function at a number of precision points. The work is directly analogous to the algebraic form of kinematic synthesis, thus enabling an immediate conceptual grasp by those already familiar with kinematics.
The Multiport Lever: A Mechanical Logical Element
Authors: Freudenstein F. , So¨ylemez E.
Published: November 2010

In its basic form the multiport lever consists of a link that can pivot about one of a number of axes or ports, depending upon a force balance. The two-port lever occurs quite frequently in machinery and mechanical devices. As far as we know, however, multiport levers have not been recognized as a basic logical element. Neither do they appear to have been used for more than two ports. In this investigation we define and generalize the concept of a multiport-lever configuration, develop its analytical mechanics (Theorems 1–4) and consider the design of the lever as a switching element. The logical behavior of the multiport lever does not correspond to that of any known switching element, although similarities to threshold gates can be observed.
KINSYN III: A New Human-Engineered System for Interactive Computer-Aided Design of Planar Linkages
Authors: Rubel A. J. , Kaufman R. E.
Published: November 2010

KINSYN III is the latest version of a computer-aided linkage design system with features not previously described. Concentrating on the new features, this paper describes the system and includes case study photographs. The system has capabilities for either synthesizing or constructing pin- or slider-jointed planar linkages of almost any topology and for analysis of this same class of mechanisms. Emphasis is on synthesis techniques and man-computer graphical interaction. Problems in linkage synthesis and design are discussed along with KINSYN III’s interactive approach to their solution.
On the Drawability of Sheet Metal in Noncircular Cups
Authors: Hsu T. C. , Lee S. Y.
Published: November 2010

The drawability of sheet metal, hitherto based on and restricted to the drawing of round cups, as in the Swift test, is generalized to cover noncircular cups. The way to measure the extent of drawing is first generalized from the drawing ratio to the draw-in at the completion of the cup. It is demonstrated that the draw-in at the completion of the cup depends on the choice of the product boundary as well as on the size, the shape, and the orientations of the blank. “Drawability of the material” is, strictly speaking, a meaningless term, although the drawability of different materials can be compared in the same drawing process and that of the same material can be compared in different processes. The concept of drawability in noncircular cups, so defined and analyzed, also serves to indicate the degree of utilization of a material in any particular drawing operation.
On Cage-Plane Motion
Authors: Bottema O. , Veldkamp G. R.
Published: November 2010

In a recent paper F. Freudenstein and E. So¨ylemez investigate the motion of the centers of spheres in rolling contact with two planes having coplanar motions. It appears that the said motion is a rigid one. The authors call it the cage-plane motion. In their analysis of the motion they use the theory of instantaneous invariants to obtain a number of interesting results [1]. In this paper, the cage-plane motion is treated by means of vector methods. It turns out that this is an easy way to obtain most of the results of Freudenstein and So¨ylemez and to extend these results in various respects.
Theory of Linear Continuous Extrusion—Linex
Authors: Black J. T. , Voorhes W. G.
Published: November 2010

LINEX is a friction actuated, continuous extrusion process for metals. It is fundamentally a linear continuous extrusion process using two-sided gripping of feedstock with the opposed sides being lubricated. The feedstock is carried into a unique die configuration called a diefork, where it upsets and develops sufficient pressure for extrusion. Basic design and theory of the process are presented, employing a new concept called modified force diagram to help explain the theory of process.
High-Speed Lateral Stability of a Freight Car Related to Modifications of Conventional Trucks
Authors: Andresen J. A. , Byrne R.
Published: November 2010

High speed lateral stability of freight cars is one facet of a truck performance mode requiring improvement in control. A 70-ton (63.6-mt) freight car truck of conventional three-piece design was analyzed and tested on a dynamic simulator leading to recommendations for truck modifications to improve high speed lateral stability. These modifications and others were later field tested with a 70-ton (63.6-mt) freight car to demonstrate the degree of control derived from single as well as multiple changes to the truck. The results are presented in terms of RMS graphs.
Bunker Design—Part 4: Recommendations
Authors: Everts R. , Van Zanten D. C. , Richards P. C.
Published: November 2010

The results of the preceding experimental investigation have been applied to the design of bunkers. Examples are given which show how the required wall thickness can be determined by horizontal pressures or by the axial stress in the wall, depending on the flow properties.
Nonlinear Vibrations of Orthotropic Plates Carrying Concentrated Mass
Authors: Karmakar B. M.
Published: November 2010

Following Berger’s approximate method for large deflections, nonlinear transverse free vibrations of an orthotropic right isosceles triangular plate, simply supported along its edges and carrying a concentrated mass, have been investigated in this technical brief.
Theoretical and Experimental Study of the Conform Metal Forming Process
Authors: Tirosh J. , Grossman G. , Gordon G.
Published: November 2010

An analytical and experimental investigation of a new continuous extrusion process (the “Conform Process”) is presented. The extruding force in this process is provided by frictional shear generated by a rotating wheel against which the workpiece is pressed. Expressions are derived for predicting the pressing force and driving power required to extrude continuously a workpiece of unlimited length under optimal conditions. The analysis is substantiated by experiments with satisfactory agreement.
Optimal Group Scheduling and Machining-Speed Decision Under Due-Date Constraints
Authors: Ham I. , Hitomi K. , Nakamura N. , Yoshida T.
Published: November 2010

A group scheduling model which is associated with group technology concepts was developed on the multiple production stages. In group scheduling where jobs are classified into several groups, optimal decision is to be made as to sequences of groups and jobs in each group. Both optimal group and optimal job sequences were determined so as to minimize the total flow time with the minimum number of tardy jobs. In addition, optimal speeds minimizing the production cost were determined under the optimal sequences.
Modelling of Elastic-Plastic Bending of Beams Using a Roller Bending Machine
Authors: Hansen N. E. , Jannerup O.
Published: November 2010

A model for bending steelbeams with rectangular crossection on a three-roller bending machine has been set up. The main effort has been paid to the geometry of the process. The basis for the model is an assumed triangular moment distribution between the rollers, and, considering the stress-strain relationship of the actual material (cold-drawn steel), the calculations based on the model lead to a curvature function which differs much from the often assumed function: the circle. The calculated curvature functions have been compared to experimentally obtained functions, and good agreement has been found.
Design of Computer Control for Manufacturing Systems
Authors: Koren Y.
Published: November 2010

An analysis is presented of computerized numerical control (CNC) for manufacturing systems. Two types of CNC systems referred to as Reference-Pulse and Sampled-Data are discussed. In the first system, reference pulses are generated by the computer and supplied to an external digital control loop. With the Sampled-Data technique, the computer serves as a comparator of the control loop and transmits the position error at fixed time intervals. The basis for selection of the particular type of CNC system and the required system parameters are given.
A Reliable Spline Coupling
Authors: Brown H. W.
Published: November 2010

Involute spline couplings are commonly used in aircraft to transmit power to gearboxes, generators, pumps, and other engine driven accessories. Spline driven accessories which are cantilever mounted on an aircraft engine are of special concern to the user as these interface splines characteristically exhibit extremely poor reliability. To compound the problem, replacement of splines is difficult and costly due to their inaccessibility. Whereas the engine driven accessory may demonstrate a mean time between failures (MTBF) of 2000 hr., the spline coupling typically fails within 500 hr. Consequently, the degree of maintenance demanded by spline wear conflicts with the operational requirements of military or commercial aircraft. Failures can also compromise flight safety. This paper reviews recent spline research directed at understanding the characteristics and problems of conventional involute splines. It also discusses the design, development, and application of the circular spline coupling (MS14169) which was developed to solve spline wear problems being experienced in military aircraft.
A Study of Oil/Water Separation in Corrugated Plate Separators
Authors: Jaisinghani R. A. , Sprenger G. S.
Published: November 2010

Simplified trajectory calculations and small scale experiments suggest that the mechanisms of oil separation in corrugated plates are similar to those of other plate separators and that the radius of curvature is not an important design parameter. Bouyancy force and flow fields control oil drop rise, while drop-interface coalescence should be important when plates are completely oil covered. Results suggest that interdrop coalescence, due to the periodically constricted and expanding flow, is not an important mechanism. Large scale (3–6 gpm) tests show that with light influent oil, corrugated plate separators perform better than simpler baffled vessels. With viscous, low interfacial tension oils, a simpler baffled separator performs better than the corrugated stack separator. This is probably due to viscous oil blockage in the plates and formation of a “foamy” oil-water mixture of high specific gravity.
On the Use of Heated Rolls for Hot-Rolling of Metals
Authors: Batra S. K. , Popoff A. A.
Published: November 2010

The use of heated rolls in hot-rolling of metals is explored and its possible advantages are discussed. Simplified heat-transfer analyses are performed and residual thermal stresses are estimated to lend support to the claimed advantages. Using tungsten and beryllium strips, laboratory experiments were performed to check the feasibility of the concept. The observed degree of reduction per pass and the measurement of surface temperature of the strips, at exit, verify the predictions of the analyses quite well. It is anticipated that the analyses developed in the paper can be used in predicting the performance of other metals in hot rolling with heated rolls.
Relationship of Mechanical Characteristics and Microstructural Features to the Time-Dependent Edge-Notch Sensitivity of Inconel 718 Sheet
Authors: Wilson D. J.
Published: November 2010

Time-dependent notch sensitivity of Inconel 718 sheet was observed at 900 deg F to 1200 deg F (482–649 deg C). It occurred when edge-notched specimens were loaded below the yield strength and smooth specimen tests showed that small amounts of creep consumed large rupture life fractions. The severity of the notch sensitivity was reduced by decreasing the temperature of the solution treatments, increasing the time and/or temperature of aging and increasing the test temperature to 1400 deg F (760 deg C). Elimination of time-dependent notch sensitivity correlated with a change in dislocation motion mechanism from shearing to bypassing precipitate particles.
The Indentation and Scratch Hardness of Plastics
Authors: Barlow D. A.
Published: November 2010

Static and sliding indentation tests on vinyl chloride-acetate copolymer and nylon 66 are described, and form part of a study of the deformation and wear of gramophone records. The vinyl was unusual in showing considerable work softening. Static indentation tests covered the whole range from the fully elastic to the fully plastic condition, and behavior was consistent with the Hertz equations, but the accuracy of the Meyer law is doubtful. Sliding indentation tests included measurement of the depth of track under load on flat and curved surfaces, and observations on the onset of instability, and the formation of a chip. These data will be used for the calculation of distortion on record playback due to deformation of the groove wall under load.