bluuebunny/crossref_metadata_2025 huggingface dataset:
Allocation of Tolerances to Minimize Cost of Assembly
Authors: Spotts M. F.
Published: November 2010

When there are variations in the costs of producing the dimensions directly involved in an assembly, the paper shows how to allocate the tolerances to give the assembly of minimum cost.
The Slotted Conical Disk Spring
Authors: Schremmer G.
Published: November 2010

The slotted conical disk spring is a modification of the regular conical disk spring or Belleville spring inasmuch as it has regularly arranged slots extending from the inside diameter. A single disk of the slotted type undergoes a larger deflection at a smaller load than a regular disk spring of comparable dimensions, thereby combining some of the advantages of the disk spring and the cantilever type spring in a single unit. It is used, where stacking is undesirable, a relatively large outside diameter is tolerable, and a regressive load-deflection-diagram is desired, like in clutch applications. The theory presented here allows the design of slotted disk springs without the lengthy trial and error procedure that has been used so far. Experiments show the validity of the new theory.
Springback of Wire Products Considering Natural Strain
Authors: Palazotto A. N. , Seccombe D. A.
Published: November 2010

This paper makes use of the Ramberg-Osgood stress-strain relationship to evaluate the springback angle for wire products. Natural strain is present in the analysis. In order to incorporate the natural strain expression into the equations, a least-squares polynomial approximation is developed primarily to transform the Ramberg-Osgood equation. Results are compared with experimental values for various radii and angle of bends using several copper alloys with different strain hardening characteristics.
Flow Stress of Metals and Its Application in Metal Forming Analyses
Authors: Altan T. , Boulger F. W.
Published: November 2010

Forming load and energy can be determined if the flow stress of the deforming, material is known at the temperature and strain-rate conditions existing during the process. In this study domestic and foreign melalforming articles were reviewed and the available flow stress data have been presented for selected carbon, stainless, and tool steels; aluminum, copper, and titanium alloys; magnesium, uranium, zircaloy, molybdenum, tungsten, tantalum, and niobium. Whenever possible, data are presented by calculating and tabulating coefficients K and n to express strain hardening (flow stress σ¯ = Kε¯n), and C and m to express strain-rate dependency (σ¯=Cε¯˙m). Examples are given to illustrate the use of flow-stress data with simple formulas in predicting pressures in upset forging, closed-die forging, and cold extrusion.
Wear Characteristics of Ceramic Tools
Authors: Ham I. , Narutaki N.
Published: November 2010

Comparative cutting performance tests of two ceramic tools in machining cast iron, AISI-4340, H-11 steel were made, and the wear patterns, wear rates, and tool life data are analyzed to evaluate the performance characteristics of ceramic tools in comparison with that of carbide tools. Also the wear process and mechanism of ceramic tools are investigated by scanning electron microscope techniques and electron microprobe analyses. Some specific causes and mechanism of tool wear are evaluated in relation to the cutting performance data.
On Building Models for the Grinding Process
Authors: Law S. S. , Wu S. M. , Joglekar A. M.
Published: November 2010

A new technique of building models for the grinding process is introduced. The grinding model is postulated in terms of grain distributions on the abrasive wheel and kinematic grinding conditions. Transverse workpiece profiles are conjectured as sample realizations of the stochastic grinding process. The sample spectrum of experimentally ground workpiece profiles is proposed as a means to estimate parameters in the postulated model through a nonlinear regression method. A model for a specified grinding process was developed based upon ten workpieces ground within a preselected practical region. The model is limited to single-pass surface grinding without crossfeed. The model was evaluated in regard to its validity, versatility, and sensitivity.
Dimensional Synthesis of Mechanisms for Function Generation Using Marquardt’s Compromise
Authors: Chen F. Y. , Chan Ven-Lin
Published: November 2010

This paper presents the application of Marquardt’s least squares compromised scheme to the synthesis of mechanisms for generating functions. Examples are given for synthesizing the planar four-bar linkages, five-bar geared linkages as well as a spatial mechanism.
Research Into the Best Strength-Silence-Cost in Designing Gears and Generating Tools
Authors: Ramond P.
Published: November 2010

In the field of designing cylindrical gear teeth for automobile gear boxes, this paper shows the advantages resulting from designing gear teeth and cutting tools simultaneously to obtain the best possible compromise (strength, quietness, and cost). This paper underlines the benefit of integrating the complete dimensional designing of teeth and tools, using computers extensively, in a specialized department having a good knowledge of gears and generating machines and tools.
The Measurement of Actual Strains at Gear Teeth, Influence of Fillet Radius on Stresses and Tooth Strength
Authors: Winter H. , Hirt M.
Published: November 2010

With miniature strain gauges having a 0.6 mm gauge length, the strains were measured that occurred at various places in the fillet of spur gears (modulus: m = 10 mm). With this method, gears were tested of varying fillet radii. From the measured results stress concentration factors could be derived that can be used to calculate the actual stresses from the nominal stresses. The measured stresses were compared with the stresses that had been determined photoelastically and analytically according to the method of the finite elements and the integral equation method. As a consequence, it appears to be possible to apply the general strength laws to the gear tooth strength and to superpose the gear tooth stresses upon other stresses (e.g., stresses caused by shrink fitting of a wheel rim).
Eccentric Gearing
Authors: Mitome Ken-ichi , Ishida Kisuke
Published: November 2010

This paper is concerned with an analysis and a design of eccentric gears. First the analysis makes the motion of the gears clear. As a result, the theoretical maximum eccentricity, the maximum change of the geometric center distance, and the angular velocity ratio are obtained. Next, two methods of designing are described and two pairs of eccentric gears are designed as examples. Finally, an approach for helical eccentric gears is presented.
In-Vacuo Modal Dynamic Response of the Human Skull
Authors: Nickell R. E. , Marcal P. V.
Published: November 2010

A finite element model of a human skull is analyzed in order to determine the lowest natural modes of vibration. A doubly curved, triangular, thin shell element formulation is used, within the framework of a general-purpose program, to investigate the effect of various support systems on the frequencies and modal shapes. The frequencies are found to be in good agreement with the results of other investigators and the modal shapes offer some insight into a modified theory of craniocerebral damage that includes both skull rotation and cavitation as pathogenic mechanisms.
On the Stability of Porous Journal Bearings
Authors: Conry T. F. , Cusano C.
Published: November 2010

This investigation deals with the stability characteristics of lubricated porous journal bearings. Using the short-bearing approximation and a fully cavitated film, the regions of stability are determined by simulation of the nonlinear differential equations of motion. Stability curves are presented for values of the design variable Φ from 0.0001 to 0.02. As Φ increases, the area of the region of stability decreases. For values of Φ greater than 0.001, the value of the dimensionless speed tends to decrease with increasing static eccentricity ratios at the threshold of stability.
Sinusoidal Response of Composite-Material Plates With Material Damping
Authors: Siu C. C. , Bert C. W.
Published: November 2010

A general forced-vibration analysis is presented for laminated anisotropic rectangular plates including material damping. The theory used is the laminated version of the Mindlin plate theory and includes thickness-shear flexibility and rotatory and coupling inertia. Solution is obtained by the Rayleigh-Ritz method, extended to include the energy dissipated and the work done by the excitation. The analysis is applied to prediction of the resonant frequencies and associated nodal patterns and damping ratios of the first five modes for a series of rectangular plates with free edges. The plates considered consist of unidirectional boron-fiber/epoxy composite material with respective fiber orientations of 0, 10, 30, 45, 60, and 90 deg. Using ply stiffness and damping properties obtained from micromechanics analyses and constituent-material experimental properties, the agreement with the corresponding experimental results reported in the literature are excellent.
Transient Response of Rotor-Bearing Systems
Authors: Kirk R. G. , Gunter E. J.
Published: November 2010

The equations of motion necessary to calculate the transient response of a multimass flexible rotor supported by nonlinear, damped bearings are derived from energy principles. Rotor excitation may be the result of imbalance, internal friction, rotor acceleration, nonlinear forces due to any number of bearing or seal stations, and gyroscopic couples developed from skewed disk effects. The method of solution for transient response simulation is discussed in detail and is based on extensive evaluation of numerical methods available for transient analysis. Examples of the application of transient response for the analysis of rotor bearing systems are presented and compared to actual machine performance. Recommendations for the use and extension of the present system simulation model are discussed.
Deflections in Radially Loaded Thin Elastic Rings
Authors: Kurajian G. M. , Na T. Y.
Published: November 2010

Equations are developed for determining radial deflections in thin elastic circular rings which are subjected to any number of radial load sets or repeated distributed radial load functions; where within each set or repeated function, the loads are equal in magnitude, in sense, and in spacing. Reference is made to a previous paper by the authors [1] in which formulations were presented enabling the determination of internal loads in such loaded rings, a necessary prerequisite for deformation analysis. Examples requiring necessary computer solutions are included.
The Reduction of Gas Turbine Idle Emissions by Fuel Zoning for Compressor Bleed
Authors: Clements T. R.
Published: November 2010

Two methods of reducing the idle emissions of gas turbine engines have been investigated. The methods were (1) fuel zoning, whereby a portion of the fuel nozzles were shut down and all of the fuel passed through the remaining nozzles and (2) larger than normal compressor overboard bleed. Both methods operate on the fact that a combustor’s efficiency increases as the fuel/air ratio is increased from idle to full power conditions. Fuel zoning increases the local fuel/air ratio making those portions of the combustor which are operating more efficient. This method has been shown to reduce the idle emission of total hydrocarbon by 5 to 1 in a double annular combustor sized for a large augmented turbofan engine. Operating with a larger than normal compressor overboard bleed allows increasing fuel/air ratio without increasing idle thrust. By using this method in a P&WA™ JT3C-7 engine a reduction of 2 to 1 in the emission of total hydrocarbon was demonstrated.
Concepts of Multiphase Flow Related to the Jenike Design Method
Authors: Emery R. B.
Published: November 2010

Hypotheses are presented here for improving bulk solids flowability. They are directed toward a quantitative design goal for gas-solids flow systems. An effort is made to relate gas control in gas-solids flow systems to the Jenike design method. Cohesion and friction in slumped beds are frequent barriers to flow. Gas or liquid moving through bulk solids interstices can reduce interparticle cohesion. Changes in interstitial fluid pressure can modify friction angles and so change channel flow factors and bulk solid flow functions. Mass flow can be achieved in gas-solids flow systems using comparatively large hopper half apex angles.
Dynamic Vibration Absorbers That Have Increased Effectiveness
Authors: Snowdon J. C.
Published: November 2010

The effectiveness of a three-element dynamic absorber and of dual dynamic absorbers in reducing the transmissibility across a simple spring-mass system at resonance has been investigated and shown to be considerably greater than that of the conventional dynamic absorber. From the complete information provided, much in graphical form, it is possible to design and to estimate the performance of both the three-element and the dual dynamic absorbers for a wide range of absorber masses. Utilizing design parameters that have been determined and specified here for the first time, it is shown 1) that the three-element absorber can be more effective than a conventional absorber of twice its mass, and 2) that by use of dual absorbers, it is possible to obtain a significant trough in transmissibility while avoiding the two resonant peaks of large magnitude that are normally introduced at neighboring frequencies. The three-element absorber requires no increase, and the dual absorbers require only a modest increase in mass beyond that of the conventional dynamic absorber.
Bounding Solutions for Performance of Vibratory Plows
Authors: Scerbo L. J. , Pope D. L.
Published: November 2010

This paper discusses the reduction in the applied drawbar force required to penetrate soil with vibrating plows. Harmonically forced linear and orbital motions of a plow blade are investigated. A rigid blade, vibrating with constant amplitude and a two-parameter soil model is used to represent the system. The assumption that the soil force opposes the instantaneous blade velocity vector is sufficient to describe the soil-blade interaction. Bounding solutions, which relate applied drawbar force to average plowing speed and other system parameters, are obtained as simple equations. These equations put into perspective the relative merits of each of these vibratory motions.
Tool Edge Roundness and Stable Build-Up Formation in Finish Machining
Authors: Abdelmoneim M. Es. , Scrutton R. F.
Published: November 2010

The results of cutting force measurements when machining materials which do not form a sizable unstable built-up-edge are compared with the results of a theoretical analysis. This analysis, based partly on the use of circular cylindrical surfaces of velocity discontinuity around the base of the tool, yields specific energy values which are uniquely determined by the value of the undeformed chip thickness in relation to the tool edge radius.
Rotor Resonant Speed Reduction Caused by Flexibility of Disks
Authors: Dopkin J. A. , Shoup T. E.
Published: November 2010

An analysis is developed to include the effect of disk flexibility and gyroscopic forces on the resonant frequencies of an axisymetric rotating shaft with multiple disks and bearings. The shaft and disks are divided into constant-section segments with lumped masses. A transfer matrix analysis is used to obtain the resonant frequencies and mode shapes for linear, undamped, circular orbit motion. Several diverse rotor and disk configurations are studied with a range of disk stiffnesses at rotating speeds from zero to synchronous whirl speed. It is found that disk flexibility can significantly reduce the rotor resonant speeds, particularly at low speed. Some general conclusions and first-approximation methods are presented.
Expansion Factors for Two Variable Area Flow Meters
Authors: Ruegg F. W.
Published: November 2010

Data acquired in the years 1958 to 1960 at the Naval Ship Engineering Center under sponsorship of the American Society of Mechanical Engineers are used to derive semiempirical equations for the performance of two variable area meters with both liquid and gas flow. As the measurements are put to a useage for which they were not intended, the data treatment is considered illustrative of the application of a flow equation derived by an analysis based upon a force and momentum balance. The hydraulic flow coefficient is expressed in terms of a function of (a) pressure drop divided by float weight and of (b) a dimensionless length ratio β for float position. Density ratio is used to modify the function of β to derive the expansion factor Y for gas flow as suggested by the analysis. Reasonable agreement between measured and derived values of Y is demonstrated, and approximate measures of the velocity profiles in the meter are derived from the correlation equations. One set of air tests at one float position in which the viscous influence number N was changed from 500,000 to 783,000 indicated (within this range) a possible insensitivity of the derived function of β to change of N.
Membrane Processing in the Metal Finishing Industry
Authors: Goldsmith R. L.
Published: November 2010

Two important applications of membrane processing in the metal-finishing field are the use of reverse osmosis for electroplating waste treatment, and ultrafiltration for concentration of oily wastes prior to disposal. Waste waters from electroplating contain contaminants of high toxicity, but also of substantial potential value. Reverse osmosis has been used to close the loop on treatment of individual plating bath rinse waters, returning concentrates to the baths, and reusing purified water for rinsing. A discussion of advantages and limitations is presented for treatment of various plating baths. Reverse osmosis has also been used to concentrate electroplating shop mixed effluents, with up to 95 percent water recovery for reuse. The low-volume concentrate is dried for ultimate solids removal, and waste-water treatment becomes closed loop. Data are presented for this application. Spent oil-containing coolants present the metal-finishing industry with a difficult waste-treatment problem. Conventional disposal of the 1–5 percent emulsions by chemical destruction, incineration or contract hauling is expensive. Ultrafiltration has been employed to concentrate emulsions to over 50 percent oil. These are readily incinerated with no fuel addition required, and work has been done which shows that reuse of the oil either upgraded to a fuel or a lubricant is the best answer for the concentrate. Data are presented for concentration of several wastes.
The Bending Problem of Axially Constrained Beams
Authors: DasGupta S. , Koeneman J. B.
Published: November 2010

The effects of axial constraints on the bending of beams sometimes can be an important factor in the design of apparatus. This nonlinear problem is approached by (a) an exact differential equation method, (b) an approximate deformation pattern method, and (c) a finite element method. Numerical results are presented which show that neglecting the axial force gives deflections which are several times higher than the correct solution. The methods are shown to be in agreement and universal design curves are presented.
Augmented Diffusion in Flowing Blood
Authors: Hyman W. A.
Published: November 2010

An analysis of the simultaneous action of Brownian diffusion and diffusion induced by red blood cell rotation is presented in order to illustrate the form of the combined effect of these two processes. The results indicate a nonlinear combination such that the effective diffusion coefficient is smaller than that obtained by linear addition of the separate processes. The dependence of the effective diffusion coefficient on shear rate is also obtained.
Analytical Prediction of the Heat Transfer From a Blood Vessel Near the Skin Surface Cooled by a Symmetrical Strip
Authors: Chato J. C. , Shitzer A.
Published: November 2010

A steady-state analytical method has been developed to estimate the amount of heat extracted from a blood vessel running close to the skin surface which is cooled in a symmetrical fashion by a cooling strip. The results indicate that the optimum width of a cooling strip is approximately three times the depth to the centerline of the blood vessel. The heat extracted from a blood vessel similar to the carotid artery by such a strip is about 0.9 w/m-deg C, which is too small to affect significantly the temperature of the blood flow through a main blood vessel, such as the carotid artery.
On the Structural Design of Tubular Joints
Authors: Visser W.
Published: November 2010

Stresses in thin-walled tubular joints can be calculated with finite-element computer programs that employ ‘thin-shell’ elements. Such a program, designated SATE, has been developed specifically with the object of determining stress distributions in complex tubular joints as generally encountered in the offshore industry. The program has been applied to several joint geometries and good agreement has been observed between experimental and calculated results. The program thus provides insight into the structural design of tubular joints. Using the SATE program, the influence of changes in design of both unstiffened and stiffened tubular joints on the stress-concentration factor has been studied. In this context, the current API recommendations for simple tubular joint design are discussed. Calculations have demonstrated that in the design of large tubular joints, allowance should be made for membrane action rather than for bending of the chord and brace walls. Such an approach leads to joints of low stress concentration.
The Experimental Measurement of Casing Wear Due to Tripping—Part 2: Wire-Line 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 running wire line. Wear tests were run using full-size samples of casing and wire line. Tests were run 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 major conclusion reached is that the presence of abrasive solids in the mud greatly accelerates wire-line wear.
The RCRRC Five-Link Space Mechanism—Displacement Analysis, Force and Torque Analysis and Its Transmission Criteria
Authors: Lee Ing-Ping Jack , Bagci Cemil
Published: November 2010

Displacement, and force and torque analyses of the RCRRC five-link space mechanism are performed using 3 × 3 screw matrix and dual vectors. Expressions for all the displacements in the mechanism are given. Input-output displacement equation is obtained in both eighth order and 16th order polynomials in half-tangents of the angular displacement. The solution of the 16th order displacement equation shows that the RCRRC mechanism may have 16 geometric inversions for a set of dimensions. The eighth order displacement equation, which conforms with that obtained by the Unified Theory which uses dual spherical trigonometry, is an incomplete relationship and it only gives the displacements of half of the existing geometric inversions. Numerical examples and photographs of the geometric inversions are given. The force and torque analysis of the RCRRC five-link space mechanism is performed by joint force analysis. Dual inertia forces are neglected, and the motion of the mechanism is known. Explicit expressions for the dual force components at the pair locations are given, as well as the matrix solution. Transmissivities of the mechanism are defined. Force and torque analysis of one of the geometric inversions is performed in a numerical example.
Optimum Synthesis of Two-Degree-of-Freedom Planar and Spatial Function Generating Mechanisms Using the Penalty Function Approach
Authors: Alizade R. I. , Mohan Rao A. V. , Sandor G. N.
Published: November 2010

This paper presents the synthesis of two-degree-of-freedom function generating mechanisms as a mathematical programming problem. The optimum set of dimensions of a mechanism are determined using a penalty function approach. Also, a new algorithm is developed for finding the first mechanism satisfying all inequality constraints to serve as an initial approximation. A single objective function as well as the equality and inequality constraints are expressed explicitly from conditions of linkage closure, mobility, and transmissibility. The method is demonstrated through an example for a spatial RSSRP function generating mechanism.
Kinematic Analysis of Spatial Mechanisms Via Successive Screw Displacements
Authors: Kohli Dilip , Soni A. H.
Published: November 2010

A new, unified method is proposed and demonstrated to conduct kinematic analysis of spatial mechanisms involving revolute, cylindrical, prismatic, helical and spherical pairs. The paper derives the equations for the successive screw displacements, and the equations for pair constraints. Using these equations, closed-form relationships for displacement, velocity and acceleration of single or multi-loop spatial mechanisms are obtained by (1) breaking the mechanism at a critical joint (2) unfolding the mechanism along a straight line (3) providing successive screw displacement at each joint and (4) reassembling the mechanism to form a closed loop. The application of this newly developed approach is demonstrated by considering an example of a two-loop spatial mechanism with revolute, cylindrical and spherical pairs.
The Natural Frequencies and Critical Speeds of a Rotating, Flexible Shaft-Disk System
Authors: Chivens D. R. , Nelson H. D.
Published: November 2010

An analytical investigation into the influence of disk flexibility on the transverse bending natural frequencies and critical speeds of a rotating shaft-disk system is presented. The geometric model considered consists of a flexible continuous shaft carrying a flexible continuous circular plate. The partial differential equations governing the system motion and the associated exact solution form are developed. Numerical solutions are presented covering a wide range of non-dimensional parameters and general conclusions are drawn.
Influence of Geometric Imperfections on Vibrational Frequencies of Thin Rings
Authors: Gartner Joseph R. , Bhat Shrikant T.
Published: November 2010

A relatively thin—thickness to radius ratio—circular ring with rectangular cross section has been investigated to numerically evaluate the effect of eccentricity on the in plane bending natural frequencies and mode shapes. The assumed boundary conditions correspond to a ring freely supported in space such that it is free to translate and rotate with rigid body motion. A truncated Fourier series solution is assumed in an energy formulation to obtain numerical approximations of the eigenvalues and the corresponding eigenvectors for different eccentricities. Extensional and inextensional models for both Flu¨gge and Love-Timoshenko ring models were considered with two thickness to radius ratios. Results show different rates of decrease in the magnitudes of the natural frequencies for different mode configurations. Existence of closely spaced frequencies along with modal coupling are noticeable at 50 percent eccentricity.
Compound Mounting Systems That Incorporate Dynamic Vibration Absorbers
Authors: Snowdon J. C.
Published: November 2010

The transmissibility across novel compound or two-stage mounting systems is discussed, and representative calculations of transmissibility are compared for systems with intermediate stages that comprise either (1) a rigid mass plus a dynamic vibration absorber, (2) dual beams loaded symmetrically by equal lumped masses, or (3) dual beams to which multiple dynamic vibration absorbers are attached. In the first case, the undesirable secondary resonance of the compound system can be suppressed effectively by the dynamic vibration absorber, for which appropriate design data are given. In the latter two cases, lumped masses or dynamic vibration absorbers are applied to each intermediate beam of the compound system at the locations of the four upper mounts that support the vibrating item from below. In turn, the beams are supported at each end by single antivibration mounts on a rigid foundation. The “secondary” resonance of the compound system that incorporates the multiple dynamic absorbers can be suppressed heavily by them; and it is shown how the excitation of a high-frequency resonance of the intermediate beams can be avoided, at the same time, by judicious choice of upper mount location. Design data for the multiple absorbers, which have relatively small mass, are tabulated.
Piledriver Noise: Acoustic Radiation From a Cylindrical Pipe Pile Under Periodic Axial Impacts
Authors: Fredberg Jeffrey J. , Manning Jerome E.
Published: November 2010

The acoustic radiation caused by periodic axial impacts on a cylindrical pipe pile of finite length is calculated. The axial velocity at all points on the pile surface is specified in terms of the excitation, the pile properties, and the ground impedance. It is assumed that the reflection of the structural wave at the pile-ground interface is a linear process, and that the radial pile velocity is simply related to the axial velocity through Poisson coupling. The pile motion is then used as a boundary condition for the acoustical space and the total acoustical power radiation and its spectral decomposition are predicted. Possible methods of noise control are discussed.
Spline Wear-Effects of Design and Lubrication
Authors: Ku P. M. , Valtierra M. L.
Published: November 2010

Spline couplings are widely used to transmit power or drive accessories, or to operate components within accessories. Their principal advantages are mechanical simplicity, compactness and light weight, and low cost. Although spline couplings have a reputation of being able to accommodate some angular misalignment, the dangers of tooth fracture, fatigue, and wear that may result should be recognized. Unfortunately, it is exceedingly difficult to achieve perfect alignment in practice; thus, the design process should prudently allow for some minimum misalignment attainable and accept a reasonable penalty. This paper is concerned with the wear of the spline teeth, which is the minimum price that must be paid if misalignment is present. Those design- and lubrication-related parameters that may be employed to minimize tooth wear are discussed.
Experimental Measurement of the Dynamic Force Response of a Squeeze-Film Bearing Damper
Authors: Vance John M. , Kirton Alan J.
Published: November 2010

An experimental study of the hydrodynamic force response of a squeeze-film bearing damper with end seals was carried out. Measurements of the pressure distribution about a journal constrained to move in a circular orbit were made for the journal orbit centered in the annular clearance and offset from the center of the annular clearance. The effects of cyclic flow in a radial inlet were studied for the case of the journal orbit centered in the annular clearance. For the off-center case the pressure distribution around the damper was measured for four different combinations of eccentricity, radial velocity, and angular velocity of the line of centers, chosen in such a way as to allow calculation of the four bearing coefficients defined by Tondl. The experimentally determined pressure distributions were numerically integrated to determine the force components of the squeeze film. The results are compared to the “long bearing” and the “short bearing” solutions of Reynolds’ equation. For the centered case, good agreement was found with the shape of the “long bearing” solution. Higher-than-predicted pressures and forces for light viscosity oil are explained by showing that this case is operating in the Taylor vortex flow regime. Similar calculations indicate that turbine dampers can also operate with vortex or turbulent flow.
Elimination of the Branch Problem in Graphical Burmester Mechanism Synthesis for Four Finitely Separated Positions
Authors: Waldron K. J.
Published: November 2010

A graphical construction is presented which, when used for Burmester mechanism synthesis for four finitely separated positions, enables the designer to avoid solutions which will not pass all design positions without being disconnected. The construction is applied to the circle point curve and locates all regions of that curve which give acceptable solutions. The procedure is simple, requiring only construction of circles and straight lines. It is also compatible with Modler’s technique for ensuring that the linkage passes the design positions in the desired order.
Estimation of Cumulative Fatigue Damage Under Random Loading
Authors: Abu-Akeel A. K.
Published: November 2010

A method is presented that leads to accurate estimation of the cumulative fatigue damage incurred in a randomly loaded structural element when loading is given in the form of spectral density load, or stress, plots. The load plots are here approximated by a series of straight lines and a closed formula is obtained to yield the damage incurred by the load within each straight line segment. The method avoids the errors that result from human misjudgment in the commonly used curve-stepping approach. It is also adaptable for computer applications and can be incorporated in a stress calculation program to save on computation time. In comparison to curve stepping, five straight-line segments may give the same accuracy as a hundred curve steps. This contrast, however, depends on the degree of irregularity of the load curve.
Displacement of a Ring Subject to Uniform Radial Loads
Authors: Naghdi A. K.
Published: November 2010

Thick rings are extensively used in various machine elements and structures. These rings are ordinarily acted upon by irregular loadings on their boundaries. However, there are cases where the rings are subject to uniformly distributed radial loads. Examples are the cases of a ring fitted on a rotationally symmetric wheel by heating or a ring rotating with a constant angular speed, etc. The solution for stresses and displacements in a ring subject to a uniformly distributed radial load is also important for the fact that it serves as the first component in the Fourier series for the solution of the general case of inplane loading of a ring. In this investigation the displacements of rings with various cross sections under the actions of uniform radial loads are obtained. Two different methods of theory of elasticity are employed to find the solutions for rings with solid circular and tapered cross sections. An approximate third solution is also derived for the case of a ring with a symmetrical cross section having no re-entrant corners. Numerical results for the displacements of various rings indicate that the latter solution accurately matches the former elasticity solutions, and the classical solution for rectangular cross-section rings, in a wide range.
Use of Response Surface Methodology to Select a Cutting Tool to Maximize Profit
Authors: Claycombe W. W. , Sullivan W. G.
Published: November 2010

A technique is presented which uses Response Surface Methodology to select a cutting tool in order to maximize profit. Different tools are analyzed to determine what combinations of cutting speed, feed, and depth of cut will give maximum profit for each kind of tool. Only then may different tools be compared. There is a possibility that the tool which is capable of yielding maximum profit may be most economical at operating conditions which are somewhat anomolous. With conventional tests a suboptimal tool may be selected, or the best tool may be used at suboptimal operating conditions. The contribution of this article is the expression of profit as a function of the direct physical decision variables and the subsequent optimization. The use of these techniques with economic decision theory is unique.
Instabilities Arising From the Frictional Interaction of a Pin-Disk System Resulting in Noise Generation
Authors: Earles S. W. E. , Lee C. K.
Published: November 2010

A steel pin, supported on a flexible cantilever, is pressed against a thin steel disk which rotates at a uniform angular speed. The orientation of the pin’s central axis to the plane of the disk, the bending and torsional stiffnesses of the pin support, the stiffness of the disk, and the line of action of the resultant interactive force are all shown to affect the self-induced coupled frequencies and modes generated. The analysis of the experimental arrangement in terms of a three-degree-of-freedom pin subsystem and a single-degree-of-freedom disk element suggests that the system is unstable for certain combinations of the variables. The instabilities are shown to belong to a class of “geometrically induced” or “kinematic constraint” instability. The region of squeal-noise generation within the experimental rig is shown to correspond to the oscillatory unstable region predicted theoretically. The noise generated is similar to disk-brake squeal, and so the work furthers the understanding of this practical problem.
Grinding of Glass: The Mechanics of the Process
Authors: Huerta M. , Malkin S.
Published: November 2010

An investigation of the material removal process in grinding glass and the effects of the grinding process on the surface structure and fracture strength of the finished product is reported in two papers. This first paper is concerned with the mechanics of material removal for grinding a large number of glasses and some glass-ceramics over a wide range of operating conditions with both silicon carbide and diamond grinding wheels. Experimental results indicate that the specific grinding energy generally increases with the softening temperature of the glass, and is an order of magnitude smaller for grinding with diamond wheels than for grinding with silicon carbide wheels. From observations of individual grinding scratches and an analysis of the experimental results, it is concluded that virtually all of the grinding energy is expended by viscous deformation. Material removal occurs by flow into chips with silicon carbide abrasive and by brittle fracture preceded by viscous deformation with diamond abrasive. The specific grinding energy with diamond is much less than with silicon carbide, since a much smaller volume of material undergoes viscous deformation when grinding with diamond.
A Dynamic Simulation of Wave Impact Loads on Offshore Floating Platforms
Authors: Giannotti J. G.
Published: November 2010

Some of the most critical loads to consider in developing design criteria for offshore platforms are those caused by wave hydrodynamic impact. The effect of these loads can be of a local nature in the form of plating damage as a result of impulsive loading, or it can be felt on the overall structure in the form of induced vibration, and increased bending moments and shears. Traditionally, the prediction of these loads has been highly empirical and designers have had to rely heavily on conservative factors of safety in order to account for the lack of confidence in these predictions. The current degree of sophistication of advanced techniques of structural analysis such as the finite element method has not been matched by equally sophisticated loads prediction methods. Consequently, the advantages offered by the computerized structural analysis schemes are considerably reduced due to the unacceptable load inputs. This paper fills part of this void by presenting an analytical model for predicting wave impact loads for the design of offshore platforms. The method is based on the Payne Impact Program which has been used before for predicting impact pressures and loads acting on high speed marine vehicles. The model simulates six-degrees-of-freedom and allows impacts at any wave heading. As inputs it requires geometric information, sea state definition, and a description of the relative motion of platform and wave. It is particularly suited to allow analysis of the results in probabilistic form, so that the severity and frequency of occurrence of impacts can be predicted.
Measurement of Temperature Distribution Within Tool Using Powders of Constant Melting Point
Authors: Kato S. , Yamaguchi K. , Watanabe Y. , Hiraiwa Y.
Published: November 2010

A method was developed to measure tool temperature distribution within the tool by means of fine powders that have a constant melting point. The method involves observation of the boundary line formed by melted and unmelted powder scattered on the tool surface. It is clarified that temperature distribution within the tool is easily and accurately measured in this manner. Temperature distributions were compared with results obtained from analyses based on Loewen and Shaw’s theory, modified on the assumption that heat distribution due to friction along the rake face is not uniform but, rather, like real frictional distribution in cutting, and the fraction of heat flowing into the tool varies along the rake face.
A Survey of Optimization Methods Applied to the Design of Mechanisms
Authors: Root R. R. , Ragsdell K. M.
Published: November 2010

A complete survey of the application of optimization techniques to the design of mechanisms is given. The survey begins with the work of Da Vinci, Newton, and Chebychev and progresses to the most contemporary contributors including Freudenstein, Tomas, Siddall, Fox, Gupta, and Tesar. An effort is made to be complete and to show the complimentary development of the two important fields of optimization and mechanism synthesis.
The Failure-Experience Matrix—A Useful Design Tool
Authors: Collins J. A. , Hagan B. T. , Bratt H. M.
Published: November 2010

A three-dimensional failure-experience cell matrix is proposed for the purpose of organizing and analyzing existing failure experience data. In the proposed matrix the three axes represent failure modes, elemental mechanical functions, and corrective actions. The usefulness of the failure-experience matrix is demonstrated by investigating over 500 individual failed parts from U. S. Army helicopters. It is proposed that data from all industry should be gathered and inserted into a central failure-experience matrix and made accessible to all designers.
The Effect of Receiver Pressure on the Observed Flow Pattern in the Hydrostatic Extrusion of Bimetal Rods
Authors: Story J. M. , Avitzur B. , Hahn W. C.
Published: November 2010

An experimental study was conducted to determine the acceptable combinations of process variables for the production of a niobium-titanium superconducting alloy in a pure aluminum matrix by hydrostatic extrusion. Conditions for sound flow and defective flow are shown on plots of percent reduction in area versus die semicone angle. The superconductor used was a 56 percent Nb-44 percent Ti alloy surrounded by a matrix of 99.995 percent pure aluminum. The study was performed in three phases. Single-core billets were extruded into atmospheric pressure with reduction in area, die semicone angle, and the ratio of the volumes of the two phases being varied. Single-core billets were extruded into receiver pressure with reduction in area and die semicone angle being varied. Billets with three cores were extruded with reduction in area, die semicone angle, friction, and receiver pressure being varied. In all cases there was a light mechanical bond between the two materials produced by interference fitting of the cores into drilled holes. Experimental results showed that increasing the receiver pressure increases the range of acceptable process variables to produce sound flow. Although it was possible to produce sound flow, the results were not always consistent and repeatable. This is largely due to the great difference in strength between the soft aluminum and the hard superconductor and the difficulty in accurately controlling the bond strength. It is expected that the beneficial effect of receiver pressure will be even more pronounced with a tighter control on bonding.
Design Analysis of a Snap-Action Mechanism
Authors: Motherway J. E.
Published: November 2010

A simple analytical approach is used to describe the nonlinear behavior of an initially curved, transversely loaded beam with fixed ends; the end supports are assumed to be rigid (constrained against displacement along the beam axis). It is shown that, for the proper choice of initial shape, the beam duplicates Belleville spring behavior while having the added advantage of no support point friction. The negative rate necessary for snap-action can be readily determined from curves or calculations. Equations are presented in forms which are convenient for use by the designer.
Precision Insertion Control Robot and Its Application
Authors: Takeyasu K. , Goto T. , Inoyama T.
Published: November 2010

A tactile-controlled robot that makes possible precision inserting operations with a clearance of only a few microns is described. The principal part of this robot is the insertion control unit, which integrates positioning ability, sensibility, and flexibility, both mechanically and electronically. The most important feature of this robot is effective utilization of the flexible mechanism. A theoretical study proves the notable advantage of flexibility in precision inserting operations. As an insertion control algorithm suited flexibility, an adaptive search method that uses only one tactile sensor is developed. An experimental evaluation shows that a gentle and dexterous insertion simulating that of an experienced operator is possible using this control method. Computers are not used in operations; only a simple sequence controller is required.
Analysis of Thermal Stresses and Residual Stress Changes in Railroad Wheels Caused by Severe Drag Braking
Authors: Johnson M. R. , Welch R. E. , Yeung K. S.
Published: November 2010

A finite-element computer program, which takes into consideration nonlinear material behavior after the yield point has been exceeded, has been used to analyze the thermal stresses in railroad freight car wheels subjected to severe drag brake heating. The analysis has been used with typical wheel material properties and wheel configurations to determine the thermal stress field and the extent of regions in the wheel where the yield point is exceeded. The resulting changes in the residual stress field after the wheel has cooled to ambient temperature have also been calculated. It is shown that severe drag braking can lead to the development of residual circumferential tensile stresses in the rim and radial compressive stresses in the plate near both the hub and rim fillets.
Stochastic Geometry of Anisotropic Random Surfaces With Application to Coated Abrasives
Authors: Pandit S. M. , Nassirpour F. , Wu S. M.
Published: November 2010

This paper analyses the stochastic geometry of anisotropic random surfaces. Explicit expressions are derived for computing three-dimensional surface spectral moments from two-dimensional profile spectral moments. A new approach for obtaining good estimates of profile spectral moments from digitized measurements is presented. Application to actual data on five profiles of coated abrasive papers illustrates that the procedure is simple, efficient, and statistically optimal and is applicable to any type of homogeneous surface. Some typical characteristics of coated abrasive surface geometry such as the density of summits, the maximum slope, and the principal direction are calculated and their physical interpretations are explained.
Application of a New Penalty Function Method to Design Optimization
Authors: Schuldt S. B. , Gabriele G. A. , Root R. R. , Sandgren E. , Ragsdell K. M.
Published: November 2010

This paper presents Schuldt’s Method of Multipliers for nonlinear programming problems. The basics of this new exterior penalty function method are discussed with emphasis upon the ease of implementation. The merit of the technique for medium to large non-linear programming problems is evaluated, and demonstrated using the Eason and Fenton test problems.