bluuebunny/crossref_metadata_2025 huggingface dataset:
A Possible Mechanism for Causing Eccentricity in Sleeved Backup Rolls on Cold-Rolling Mills
Authors: Patula E. J.
Published: November 2010

A theoretical analysis has shown that axial slipping of the sleeve on the roll arbor rather than plastic deformation of the roll necks may be the cause of backup-roll eccentricity on cold-rolling mills. The force levels required to initiate the slipping motion are less than the levels required to plastically yield the necks. Furthermore, the degree of eccentricity caused by relative motion may be sufficient to produce unacceptable gage variations in the rolled product. Finally, a suitable thermal treatment may be used to relieve the internal frictional stresses generated by the slipping motion.
An Algorithm for Computer Guidance of a Manipulator in Between Obstacles
Authors: Loeff Luis A. , Soni A. H.
Published: November 2010

A mathematical algorithm is proposed that will generate an incremental motion for each position of the manipulator. Repeated use of this algorithm will automatically direct the mechanical arm (manipulator) to a specified destination avoiding collisions with obstacles.
A Load Calibration Technique for Use on Large Industrial Presses and Small Testing Machines
Authors: DePierre V. , Davis S. O. , Gurney F. J.
Published: November 2010

A load calibration technique based on the plastic deformation of a ring specimen is described. The method is applicable to any size press at loads up to full capacity. The method consists of determining the true flow stress of a heat of material by compression of small ring specimens on a calibrated test machine and treating the geometric change of the ring mathematically. Larger rings from the same heat of material are then deformed in large industrial presses or smaller testing machines which are to be calibrated. The geometric changes in the ring specimen and the previously determined flow stress are treated by the same mathematical analysis to determine the deformation pressure and thus the deformation load. A comparison is made of the calibration from the ring cell with other calibrations already determined on a mechanical crank press and a hydraulic extrusion press. The ring cell is shown to yield highly accurate load information.
On the Probabilistic Distributions of Stress and Strength in Design Problems
Authors: Dao-Thien My , Massoud M.
Published: November 2010

This paper presents an approach to obtain the stress and strength density distributions in reliability design problems. The density and cumulative distributions of the stress and strength are obtained in the form of multiple integrals. Linear regression analysis is used to plot estimates of the cumulative distributions on probability paper. The distribution with the minimum error is chosen. A computer program to perform the calculations and to select the appropriate distribution is developed. An example is presented to illustrate the application of the method.
A Technique for Determining Damping Values and Damper Locations in Multi-Degree-of-Freedom Systems
Authors: Kanianthra J. N. , Speckhart F. H.
Published: November 2010

In complicated multi-degree-of-freedom systems, it is often necessary to choose linear damping values and determine their locations that will give a desired performance. The method presented in this paper describes procedures by which the damping values and damper locations for prescribed damping ratios in all principal modes can be found. Two numerical examples are included to illustrate the method.
Wind-Powered Electric Utility Plants
Authors: Jayadev T. S. , Smith R. T.
Published: November 2010

This paper describes the general operating modes of wind-powered electric utility plants under constant-speed or variable speed classifications. It is shown that for a particular set of wind frequency–velocity spectra there are a number of attractive system configurations, so far as total yearly energy production is concerned. Thus, detailed cost effectiveness studies and additional research will be required to develop practical wind electric conversion systems (WECS).
Dynamic Film Pressure Measurements in Journal Bearings for Use in Rotor Balancing
Authors: Christensen E. , Tonnesen J. , Lund J. W.
Published: November 2010

The paper presents the results of an experimental investigation where membrane transducers in the journal bearing wall are used to measure the dynamic oil-film pressures caused by rotor unbalance whirl. The results are applied successfully to balancing the rotor, and the experimental measurements of amplitude and pressure response are found to agree well with theoretical predictions, based on a linear analysis. The measurement accuracy of the pressure transducers compare favorably with the accuracy obtained with shaft displacement probes.
Compressibility Effects in Electrochemical Machining
Authors: Fluerenbrock F. , Zerkle R. D. , Thorpe J. F.
Published: November 2010

Based on bubbly two-phase flow an equation for the speed of sound in the ECM frontal gap is derived, and it is seen that the sonic speed is well within reach of the electrolyte velocities usually encountered in ECM. Thus the Mach number can become equal to one, which represents a choking condition. The practical significance of the choking phenomenon and other compressibility effects are discussed, and experimental data are presented. An explanation for the flow lines or striations frequently observed with radial outflow configurations is also given.
Verification of a One-Dimensional Two-Phase Flow Model of the Frontal Gap in Electrochemical Machining
Authors: Fluerenbrock F. , Zerkle R. D. , Thorpe J. F.
Published: November 2010

A set of six equations, which are based on the ECM model developed by Thorpe and Zerkle, can be solved numerically to yield the one-dimensional distributions of pressure, temperature, gas density, gap thickness, void fraction, and electrolyte velocity in the rectilinear ECM frontal gap under equilibrium conditions. The validity of the model, which also applies to radial flow geometries, is confirmed by comparing experimental pressure and gap profiles with theoretical predictions. It is shown that for a given set of operating parameters there is a minimum supply pressure below which no machining is possible. When machining steel with an aqueous NaCl electrolyte the deposition of a black smut (Fe(OH)2) occurs beyond a certain smut-free entrance length, which was experimentally found to be proportional to the inlet gap thickness.
A Note on Blade Loss Dynamics of Rotor-Bearing Systems
Authors: Kirk R. G. , Hibner D. H.
Published: November 2010

The equations for a single-mass rotor are examined for maximum response following an impact load created by a blade loss. The close examination of the undamped system gives insight and understanding to the dynamic response of the rotor system during an actual blade loss. The time transient response orbits for the single-mass system are presented for operation below, coincident with and above the given natural frequency. The orbits clearly indicate the ratio of maximum response relative to steady-state (i.e., overshoot ratio). The results of the influence of various damping ratios on the transient response peak amplitude are presented in dimensionless form. The blade loss transient response of a three bearing, eighteen-degree-of-freedom rotor system is presented to illustrate the validity of the basic concepts developed in the single-mass rotor analysis.
Acrylic Plastic Spherical Shell Windows Under Point Impact Loading
Authors: Stachiw J. D. , Burnside O. H.
Published: November 2010

Acrylic plastic spherical shell sector windows with 117-deg included angle and outside radius of 24-in. (61 mm), have been impacted at their center, with a 12,500 lb (5662 kg) weight, in a simulated ocean environment. Velocities of impacts ranged from 0.205 to 10.702 ft (0.06 to 3.26 m) per second. It has been found that fracture of windows is initiated by tensile stresses on the concave surface of the window, directly below the point of impact. Compressive stresses, generated by external hydrostatic pressure, decrease the destructive effect of tensile stresses introduced by point impact loading. For 2.25 and 4.0-in. (57 and 101 mm) thick windows the critical impact velocities were found to fall into the 1.5 to 3 ft (0.45 to 0.91 m) per second range, the exact value being a function of window thickness and external hydrostatic pressure. A finite element analysis was found to agree rather well with the experimental. This analysis can be employed to predict, with a reasonable degree of confidence, the critical impact velocities for acrylic plastic spherical windows in the bows of submersibles.
The Effects of Opening Roller Wire Design and Operating Speed on the Properties of Open-End Cotton Yarn
Authors: Vaughn E. A. , Cox T. S.
Published: November 2010

An important parameter to consider when spinning yarns using the open-end system is what combinations of comber roll wire design and speed will yield the most desirable yarns. The major goal of this research was to determine whether any significant trends in yarn properties could be traced to changes in these parameters. A parameter incorporating the different number of teeth per cm, comber roll speeds, and effects of twist on the amount of opening and defined as “beats per fiber” was investigated and found to have no correlation to any tested yarn properties. Other results indicated that yarn properties were more sensitive to changes in comber roll speed than to changes in wire type. The experimental data indicate that a properly selected set of opening parameters can yield yarns with different characteristics of strength, elongation, evenness, and defects. Some evidence supports the theory that increasing comber roll speeds will produce more even yarns.
The Effect of Casing Wear on the Burst Strength of Casing—Part 1: Joint Leakage
Authors: Bradley W. B.
Published: November 2010

A theoretical analysis has been performed to determine the effects of wear on the burst strength of casing. Burst failure occurs either by a leakage at the casing joint or by rupturing of the casing wall. Joint leakage and the effect of casing wear on joint leakage are discussed in this paper. Rupturing of the casing wall is treated in a companion paper [1]. The results of the analysis presented in this paper show that, for practical purposes, joint leakage under internal pressure is unaffected by casing wear.
Suppression of Rotor-Bearing System Vibrations Through Flexible Bearing Support Damping
Authors: Tessarzik J. M. , Chiang T. , Badgley R. H.
Published: November 2010

A bearing damper, operating on the support flexure of a pivoted pad in a tilting-pad type gas-lubricated journal bearing, has been designed, built, and tested under externally applied random vibrations. A 36,000 rpm, 10 Kwe turbogenerator had previously been subjected to external random vibrations, and vibration response data had been recorded and analyzed for amplitude distribution and frequency content at a number of locations in the machine. Based upon data from that evaluation, a piston-type damper was designed and developed for each of the two flexibly-supported journal bearing pads (one in each of the two three-pad bearings). A modified turbogenerator, with dampers installed, has been retested under random vibration conditions. Root-mean-square vibration amplitudes were determined from the test data, and displacement power spectral density analyses have been performed. Results of these data reduction efforts have been compared with vibration tolerance limits and previously reported response characteristics of the unmodified machine. Results of the tests indicate significant reductions in vibration levels in the bearing gas-lubricant films, particularly in the rigidly mounted pads. The utility of the gas-lubricated damper for limiting rotor-bearing system vibrations in high-speed turbomachinery has thus been demonstrated.
Physical Interpretations of the Instabilities Encountered in the Deflection Equations of the Unconstrained Pipeline
Authors: Daley G. C.
Published: November 2010

For a pipeline modeled as having constant rigidity, horizontal tension, and submerged weight per unit length, there is a maximum value that the maximum sag-bend moment attains as the distance from the pin-supported end of the pipe to the sea floor increases. This paper presents the results of a parametric study analyzing a pipeline displaced from the sea floor to some pipeline construction configuration. The pipeline is modeled as a continuous beam having constant submerged weight per unit length and a constant horizontal tension or force with one end supported vertically by the sea floor. The governing differential equations are solved in terms of dimensionless combinations of the three characteristic variables—the submerged weight per unit length, the flexural rigidity, and the constant horizontal tension. This allows any possible pipeline configuration meeting stated constraints to be analyzed. The analysis performed specifies the maximum sag-bend moment. This maximum sag-bend moment is changed by varying the sea floor vertical force until a further change in sea floor reaction does not give a pipeline configuration. This maximum attainable maximum sag-bend moment is then computed and graphed as a function of the three characteristic pipeline values, the horizontal tension, the flexural rigidity, and the submerged weight per unit length.
On Reciprocating Toroidal Seals
Authors: Fazekas G. A.
Published: November 2010

A review of the inverse solution of elastohydrodynamic problems has shown certain conditions on the pressure function and the possible singularity of the film shape. Such a singularity can be avoided by certain boundary conditions. When applied to a □ ring, the solutions obtained agree reasonably with some test data and show how to reduce leakage.
An Experimental Investigation of Stick-Slip in Hydrostatic Extrusion Using Wax to Simulate Metals
Authors: Egerton D. , Rice W. B.
Published: November 2010

This paper describes an experimental investigation undertaken to check the explanation advanced by Rice and Iyengar for the violent pressure fluctuations which they observed during hydrostatic extrusion of wax. The results support the explanation advanced by Rice and Iyengar, confirming their suspicion that extrusion actually stops during the period of violent pressure fluctuations and reinforcing their contention that for short periods of time during each pressure pulse the velocity necessary for initiation of fluid film lubrication is exceeded, causing fluid in the form of a film to be transported into the die during those periods.
Transient Torsional Vibration of Steam Turbine and Generator Shafts due to High Speed Reclosing of Electric Power Lines
Authors: Hizume A.
Published: November 2010

Transient torsional vibration induced on modern large turbine and generator shafts by high-speed reclosing is investigated qualitatively and quantitatively, assuming linearity and no damping as the first approximation. The effect of repeated impositions is analyzed both for sinusoidal torque fluctuation and for stepwise torque fluctuation. It is shown that the danger of high-speed reclosing is attributable to repetitive imposition (as many as four times); furthermore, the severity of transient vibration is decisively influenced by the timing of repeated impositions. The effect of three-phase high-speed reclosing on a typical 600MW machine is calculated both by computer and by modal analysis. The large response predicted, which is far beyond the elastic limit, is possible to be induced under actually feasible timing. Absolutely safe three-phase high-speed reclosing could not be achieved by strengthening the shaft because the strengthened shaft becomes sensitive to sinusoidal torque fluctuation.
Tubesheet Design in U-Tube Exchangers Including the Effect of Tube Rotational Restraint
Authors: Soler A. I.
Published: November 2010

A clamped, circular plate under uniform pressure simulating a U-tube heat exchanger tubesheet is studied to ascertain the effect of tube rotational restraint on the tubesheet design. This effect is not normally considered in tubesheet design; however, it is shown here that for low-pressure units, the inclusion of tube rotational stiffness can lead to a measurable strengthening effect.
Methods for Improving the Knuckle Boom Capacity in Truck-Mounted Cranes
Authors: Sridhar B. N.
Published: November 2010

Presented herein are two different concepts for improving the knuckle boom capacity of truck-mounted cranes. The first concept deals with an improved Planar four-bar linkage using the two-position synthesis, as well as with recommendations for optimizing the linkage. The linkage design employing the two-position synthesis was built as hardware with fairly close agreement between calculated and test data. The second concept is concerned with a constant moment-arm mechanism using a rack and pinion arrangement.
Hunting Stability of Rail Vehicles with Torsionally Flexible Wheelsets
Authors: Doyle G. R. , Prause R. H.
Published: November 2010

The effects of torsionally flexible wheelsets on the hunting stability of rail vehicles have been investigated by solving the eigenproblem. The primary model is that of a single truck with two torsionally flexible wheelsets. Results for a complete car model consisting of the car body, two trucks and four torsionally flexible wheelsets are also presented for comparison. This study shows that the hunting critical speed of rail vehicles is reduced significantly by the use of torsionally flexible wheelsets.
Experimental Investigation of the Characteristics of Dynamic Cutting Process
Authors: Nigm M. M. , Sadek M. M.
Published: November 2010

The dynamic response of the shear plane and the variations of the dynamic cutting coefficients are experimentally investigated at various values of feed, cutting speed, rake angle, clearance angle, frequency, and amplitude of chip thickness modulation. Wave generating and wave removing cutting tests, in which high-speed photography is used to investigate the geometry of chip formation, are carried out. The theoretical model of dynamic cutting developed in [1] is assessed with reference to these experimental results. A comparison between this model and previous models in relation to the experimental results is also presented.
Spherical Sector Windows With Restrained Edge for Undersea Applications
Authors: Stachiw J. D.
Published: November 2010

A new concept for the mounting of spherical sector windows has been experimentally evaluated under short-term, long-term, and cyclic pressure loadings. The new mounting concept requires that the spherical sector windows be provided with square edges instead of conical edges. The horizontal bearing surface of the square edge carries the axial and the vertical bearing surface the radial thrust of the spherical sector window. Experimental evaluation of the new mounting concept has shown that the spherical windows with square edges are subjected to larger flexure moments than similar windows with conical edges. However, the short-term critical pressures of spherical sector windows with square edges and included angle 75 deg < α < 180 deg were found to be only 10 percent less than those of similar windows with conical edges. For spherical sectors with α < 75 deg the square edge mounting provides significantly higher short-term implosion pressures than conical edge mountings. Based on the short-term critical pressures, strains, stresses, and cyclic fatigue data generated by this study, the spherical shell sector windows with square edge mounting are considered acceptable for service in manned submersibles, habitats, or diving bells.
A Dependable Method for Solving Matrix Loop Equations for the General Three-Dimensional Mechanism
Authors: Hall A. S. , Root R. R. , Sandgren E.
Published: November 2010

A new method of generating solutions for the matrix method of linkage analysis is considered. Optimization techniques are used to close the matrix loop equations iteratively until they are sufficiently close to closure to allow a solution by Newton’s method. The method is especially applicable for generating the initial closed position of a general three-dimensional mechanism. This technique is demonstrated on several three-dimensional mechanism examples.
Free Convection at Supercritical Pressures in Cryo-Fluid Helium-I
Authors: Caspi S. , Lee J. Y. , Frederking T. H. K.
Published: November 2010

In the course of He II-He I phase transition studies, one phase of the investigations has been concerned with free convection in He I with the aim of simulating the heat transfer in rotating superconducting windings. A geometry similar to C-frame loops has been used in studies of free convection between the λ-curve and the transposed critical curve at pressures between 0.3 and 1.5 MPa. Related model calculations have been carried out for cellular convection. A comparison of the data obtained shows reasonable agreement with the model results.
The Preparation of Calcium Superoxide at Subambient Temperatures and Pressures
Authors: Ballou E. V. , Wood P. C. , Spitze L. A. , Wydeven T. , Stein R.
Published: November 2010

We have previously reported on the preparation of calcium superoxide, Ca(O2)2, from calcium peroxide diperoxyhydrate, CaO2·2H2O2. In that work, the preparation of a product of higher purity than that reported elsewhere was ascribed to the carefully controlled reaction conditions. The effect of temperatures between 25° and 60°C (298–333 K), reaction time, and reactant packing were studied. In further experiments reported here, disproportionations at lower temperatures and a range of reaction chamber pressures were studied. Disproportionations at 0°C (273 K) and surface spreadings of 312 to 36 cm2/g resulted in 59–61 percent purity Ca(O2)2, showing that higher surface loadings could be used in the reaction dish at subambient temperature than at ambient temperature. This is a significant feature for prospective scale up of the mass prepared in a single experiment. Reactions were studied at chamber pressures between 6 μm and 300 mm Hg (0.8 Pa–40 kPa) at 30°C (303 K). The optimum pressure for product purity was 90 μm Hg (12 Pa), possibly because the reactant overheated at lower pressures. Product purity at higher pressures improved when molecular sieve desiccant was mixed with the reactant.
Graphical Output–Oriented Computer Model of a Railroad Freight Car With Conventional Trucks
Authors: Luttrell N. W.
Published: November 2010

The paper describes a 13-degree-of-freedom, frequency domain, computer model of a railroad freight car riding on conventional North American three-piece trucks. These 13 degrees of freedom incorporate roll, pitch, bounce, bending, and twisting of the body, as well as lateral, swivel, and parallelogramming of each truck. This idealized freight car is driven at 200 discrete frequencies from 0.1 to 20.0 cycles per second. The driving functions are derived from the Fourier components of track geometry measurements taken from actual test tracks. Although the model is linear, coulomb damping is approximated by equivalent viscous coefficients at each frequency. Printed output is provided; however, the basic product of the program is a series of two-color graphs produced on a mechanical plotter. These include a Nyquist diagram, giving indications of the freight car’s lateral stability on tangent track, and PSD plots illustrating the frequency breakdown of the various vehicle responses. Comparisons are made between the computed PSD plots and actual test data for specific conditions.
Effect of Track Geometry and Rail Vehicle Suspension on Passenger Comfort in Curves and Transitions
Authors: Doyle G. R. , Thomet M. A.
Published: November 2010

Passenger comfort is an important constraint on high-speed operation in curves and transitions. The effect of track geometry and vehicle suspension characteristics on passenger comfort were investigated with a six-degree-of-freedom, time domain simulation of the car body dynamics. The rail vehicle was simulated at constant speed on transitions and curves to generate acceleration profiles at a passenger’s seat location. The main conclusion of this study is that modern rolling stock can negotiate curves at a higher unbalanced superelevation than is recommended in the current AREA formula without exceeding passenger comfort standards. Also, the minimum spiral lengths as determined by the AREA formula are adequate for passenger cars with stiff roll characteristics, such as the Metroliner vehicles.
An Orthomorphic Rheological Model of the Grinding of Wood
Authors: Dornfeld D. A. , DeVries W. R. , Wu S. M.
Published: November 2010

Grinding wood to produce a pulp for papermaking is termed mechanical pulping. To better understand and control this grinding process, a rheological model is postulated that accounts for the elastic and viscous properties of the wood in two orthogonal directions. From the model it is shown that these properties impart a phase lag between the normal and tangential grinding forces, and experimental measurements collected under five grinding conditions agree with the model prediction. Based on measured pulp properties, the grinding condition with the minimum phase lag yielded the best quality pulp, suggesting that the calculated phase lag could be used as a quality control tool to eliminate conventional pulp testing during production or as a feedback signal to control grinder operation in the mechanical pulping process.
Machining Economics and Tool Life Variation—Part 1: Basic Considerations and their Practical Implications
Authors: Levi R. , Rossetto S.
Published: November 2010

The joint distributions of economic parameters corresponding to “optimum” conditions (minimum cost, and maximum production rate), as affected by a single tool wear mechanism, are analyzed and the information process is examined using a Bayesian approach. Results obtained for an example show that even scanty experimental evidence may be profitably exploited. However, the size of confidence regions for parameters is quite large unless a very large amount of information is available.
Machining Economics and Tool Life Variation—Part 2: Application to Models for Machining Processes
Authors: Rossetto S. , Levi R.
Published: November 2010

A simple machining operation is modeled according to some management choices by stochastic simulation, taking into account two main tool failure mechanisms. Under the assumption that premature tool failures account for either work interruption or production of defective pieces, the effects of tool change schedule, production block size and sudden failure on production rate and cost are assessed. Some minimum regions are found for expected values of dependent variables, which have no counterpart for upper bound values.
An Experimental Strategy for Designing Tool Life Experiments
Authors: Zdeblick W. J. , DeVor R. E.
Published: November 2010

An investigation of the tool life experimental environment and its effect on designing tool life tests is presented. The D-optimal design criterion is introduced as a tool life experimental strategy particularly suited to the tool life experimental situation typified by (1) the use of nonlinear tool life model forms, (2) constrained operability regions which are irregularly shaped, and (3) the inhomogeneous nature of tool life variation. Linear and nonlinear tool life models are examined with the D-optimal design criterion. Comparisons with the 3-level factorial design and the Central Composite Design are presented. A significant reduction in the required number of tool life tests is obtained when D-optimal designs are employed. In particular, improvement in the predictive capabilities of the model is obtained along the constaint boundaries where the economic optimal operating condition will most likely be located.
Multi-Tool Machining Analysis—Part 2: Economic Evaluation in View of Tool Life Scatter
Authors: Ravignani G. L. , Zompi A. , Levi R.
Published: November 2010

A method developed for the attainment of economic objectives in single-tool machining operations is extended to multi-tool machining. The stochastic nature of tool life is taken into account, as well as the uncertainty of available information, by introducing confidence level for tool life among the parameters considered. Time and cost penalties due to sudden tool failure are also taken into account. An example pertaining to a simple machining operation shows that under the conditions selected the minimum cost region falls well over the ninety per cent mark of confidence level for tool life.
Some Experiments on Dynamic and Quasi-Static Forging of Aluminum at Elevated Temperatures
Authors: Samanta S. K.
Published: November 2010

The paper describes the results of hot and warm forging tests on aluminum specimens, using a modified Hopkinson pressure-bar in which impact velocities up to 100 m/s could be obtained. The maximum energy available was 30000 Nm, but for the work described here 24000 Nm was used at an impact velocity of 90 m/s. A short description of the apparatus is given. A typical punch load/displacement curve is presented. A comparison is made with forging at very low speed, and the effect of impact velocity on die filling, forging load, microstructure and hardness of the forged components is assessed. Two components of different geometries were forged. Contrary to original expectations, all trials in the high-velocity forging of one component were unsuccessful.
Effects of Thermal Loading on Foil and Sheet Composites With Constituents of Differing Thermal Expansivities
Authors: Hoffman C. A.
Published: November 2010

A study was made to estimate the magnitudes of elastic stresses and elastic-plastic stresses and strains in sheet or foil laminar composites. Using a model tungsten/80Ni + 20Cr laminar composite and assuming cooling or heating through a temperature range of 80–2000 deg F (26.5–1093.5 deg C), calculated elastic stresses exceeded published or estimated strengths of the constituents. Elastic-plastic stress-strain solutions resulted in lower estimated stress levels but with the concomitant occurrence of sufficiently large strain ranges to suggest possible thermal fatigue problems. Limited experimental studies using tungsten/80Ni + 20Cr foil and sheet laminar composites, slowly cycled between 80 and 2000 deg F (26.5–1093.5 deg C) or rapidly cycled between 80 and 1600 deg F (26.5–871 deg C) produced varying degrees of observable structural damage in from 1 to 11 cycles depending upon temperature transition rate and laminae thickness; these particular results might not occur with other combinations of materials.
Prediction of Inelastic High Temperature Materials Behavior by Strain-Rate Approach
Authors: Berkovits A.
Published: November 2010

An experimental study of the influence of strain rate on the inelastic properties of well-aged Udimet 700 at 925 C shows a unique relationship between strain rate, strain and stress for this material. This relationship, which is presented graphically as strain rate as a function of strain, is used to compute material flow behavior under loading histories including stress-strain, creep, stress relaxation, and creep under varying stress. Results obtained compare well with predicted behavior.
Influence of the Application of Quick Thermal Welding Cycles in the Toughness of Carbon Steels Susceptible to Aging
Authors: Prata S.
Published: November 2010

A number of cases of brittle fracture in welded structures can be explained by an accelerated aging resulting from the use of welding thermal cycles on strain-hardened steels. This paper presents new experimental results of an investigation of this phenomenon as well as a rationale for it. Results on rimmed steels indicate that there is a critical temperature, below the A1 transformation point, which results in the maximum loss of notch toughness. The magnitude of the embrittlement suggests that the standard test recommended for strain aging susceptibility of these steels should be modified to provide better measure of the effect. Some further practical recommendations are made about these steels.
Representation of the High-Temperature Tensile Behavior of Reannealed Type 304 Stainless Steel by the Voce Equation
Authors: Swindeman R. W.
Published: November 2010

Tensile tests were performed on a reference heat of type 304 stainless steel (heat 9T2796) in the laboratory reannealed condition. Testing temperatures ranged from 25 to 760 deg C (77 to 1400 deg F) and strain rates were varied from 1.5 × 10−6 to 8.3 × 10−2/s. Several models were developed to represent the tensile curves, and each model was restricted to a specific range of applicability. For the inelastic strains below 0.001 a Ludwik-type formulation was developed; it was independent of strain rate but applicable for temperatures up to 760 deg C. For the strain range 0.001 to 0.05 a second Ludwik-type formulation was developed with minimal strain rate dependence, and the model was restricted to temperatures not exceeding 593 deg C (1100 deg F). For inelastic strains above 0.001 an alternative model was based on the Voce equation. The Voce model was applicable for all temperatures and strain rates and for strains to the uniform strain at the ultimate strength. The ability of the Voce model to represent tensile behavior at strain rates well below those that are practical in the laboratory experimentation was checked by comparing predicted ultimate tensile strength data against creep strength data for minimum creep rates corresponding to the tensile strain rates. The agreement was good. The ability of the Voce model to predict uniform strain behavior was also examined. In the creep range the Voce model overestimated uniform strains for temperatures below 649 deg C (1200 deg F) and underestimated them for temperatures above 649 deg C (1200 deg F).
The Effect of Varying Degrees of Cold Work on the Stress-Rupture Properties of Type 304 Stainless Steel
Authors: Gold M. , Leyda W. E. , Zeisloft R. H.
Published: November 2010

Cold work enhances the room temperature tensile properties of austenitic stainless steels. There are few data on the effect of varying degrees of cold work on elevated temperature properties. Such information is needed to set design limits on the use of cold-work enhanced properties in the creep range. ASTM A-193 B8 bars were given three levels of cold work. Tensile properties, creep-rupture properties, and the resulting microstructures were determined and compared with those of annealed bar. There is a temperature limit, dependent on the degree of cold work, beyond which the enhancement of creep-rupture properties is not observed.
Interpretation of Irradiation Effects on the Fracture Toughness of a Pressure Vessel Steel in Terms of Crack Tip Stress Analysis
Authors: Parks D. M.
Published: November 2010

The model of Ritchie, Knott, and Rice [10], relating the critical tensile stress for initiation of unstable cleavage fracture of mild steel to the cryogenic temperature-dependence of plane strain fracture toughness (KIc), is applied to a pressure vessel steel, ASTM A533B. It is shown that the fracture criterion of achieving the critical tensile stress over a characteristic microstructural distance is essentially unaffected by neutron irradiation. Thus, it appears that the effects of irradiation on the temperature-dependence of KIc in the cleavage range can be quantitatively assessed solely in terms of the effects on the yield and flow properties of the material.
Tensile Properties of Thermally Exposed Type 304 Stainless Steel
Authors: Steichen J. M.
Published: November 2010

The influence of thermal exposure at 800, 1000, and 1200°F (427, 538 and 649°C) on the tensile properties of type 304 stainless steel has been experimentally determined. Specimens were exposed in static sodium for durations of 1000, 3500 and 10,000 hr. Tests were performed at room temperature and the respective exposure temperatures at nominal strain rates from 3 × 10−5 to 10 s−1. Exposure at temperatures to 1000°F (538°C) did not greatly alter the elevated temperature strength, ductility, or strain rate sensitivity of the subject material. At 1200°F (649°C) strength properties were unchanged by exposure at this temperature while ductility was increased at the lowest strain rate and slightly reduced at the higher rates. The room temperature strength was unchanged and ductility slightly reduced after exposure for 10,000 hr at each temperature.
Creep and Rupture Behavior of Weld-Deposited Type 16-8-2 Stainless Steel at 593°C
Authors: Ward A. L. , Blackburn L. D.
Published: November 2010

The creep and rupture behavior of weld-deposited Type 16-8-2 stainless steel at 593°C was investigated over the time range from 3.6 × 104 s to 2.5 × 107 s. Equations relating stress (σ) to the time to rupture (tr), the time to the onset of tertiary creep (tt), and the time to produce a given creep strain (tεc) were obtained: lntr=81.3456−12.176lnσlntt=80.0786−12.176lnσlntεc=Aεc−13.0lnσAεc=87.3633+1.32066lnεc+0.446428[lnεc]2+1.08131[lnεc]3+6.96513×10−3[lnεc]4 The experimental results indicate that the control of welding parameters (e.g. current, voltage, and travel speed) within reasonable ranges can yield weld deposits with consistent time-dependent properties. Limited data suggest that high temperature (1065°C) post-weld annealing significantly alters only the flow curve for plastic deformation, while long-term thermal exposure at an intermediate temperature (565°C) produces only minor changes in either the plastic deformation or creep behavior of the weld materials.
Residual Strains Around Coldworked Fastener Holes
Authors: Sharpe W. N.
Published: November 2010

A hole which is plastically expanded and then allowed to contract is referred to as coldworked. The residual strains around holes which were coldworked by an industrial process were measured in this work and compared with theoretical analyses. Agreement between theory and experiment is not very good.
The Viscoplastic Bending of Copper-Nickel and Steel Tubing
Authors: Frick T. M. , Neubert V. H.
Published: November 2010

Experimental data for dynamically loaded viscoplastic beams with a tubular cross section where elastic strains are a significant part of the total strain are obtained for two materials, 1020 steel and 70/30 copper-nickel alloy. Maximum strain rates are 0.78 and 1.89 s−1, respectively. This work defines a successful experimental approach for obtaining dynamic data and provides results which can be used in defining failure for optimal design. A moment-curvature constitutive relation, including rate effects, is fitted to the data.
Sulfur-Dioxide Removal From a Pilot Moving Grate Furnace Stack Gas
Authors: Whitten C. M. , Hagstrom R. G.
Published: November 2010

Peabody Coal Company, under contract to the National Center for Air Pollution Control, has investigated sulfur-dioxide removal from a pilot moving grate furnace stack gas by the addition of calcium bearing dry additives to the flue gas and to coal before burning. Effects of additive feed rate, residence time, temperature, and particle size on sulfur-dioxide removal were studied, and calcination, calcium-oxide utilization, and additive efficiency were determined.
The Large Diesel Engine: Its Role in Automated Pipelines
Authors: Brady William C. , Erickson Bruce G. , Kelgard Erik
Published: November 2010

The special requirements involved in the application of large diesel engines to automated pipeline service are covered in this paper. Further, these requirements are presented from three important points of view, those of the pipeline designer-constructor, the prime mover manufacturer, and the pipeline operator. The needs of these spheres of influence are combined in an integrated system. Though relating specifically to pipeline service, many principles and concepts apply to all automated engine systems.
Some Experimental Results of Two Concepts Designed to Increase Turbine Blade Loading
Authors: Lueders H. G. , Roelke R. J.
Published: November 2010

A number of advanced blade concepts to efficiently increase turbine blade loading are being experimentally investigated. Tests made with a single-stage turbine rig have shown two of the advanced blade designs (i.e., the tandem blade and jet-flap blade) to be potentially promising. The design of these two blades and a base plain blade, together with a comparison of the test results, are presented. All three blades were designed to the same velocity diagrams. The design diagrams are based on free-vortex flow and have a significant amount of flow deceleration across the rotor hub. Test results of the three rotor configurations, obtained with the same stator assembly, are presented. The results include turbine airflow, efficiency, and reaction characteristics along with rotor exit surveys.
Some Experimental Results of Two-Dimensional Compressor Cascades at Supersonic Inlet Velocities
Authors: Starken H. , Lichtfuss H. J.
Published: November 2010

The paper presents two-dimensional cascade results which have been obtained in transonic and supersonic cascade windtunnels. The upstream Mach number range is 1,0 ≤ M1 ≤ 1,4. Tests have been carried out with three different blade shapes; these are double-circular-arc and wedge profiles. The influence of solidity on the performance of these cascades has been investigated. A detailed analysis and calculation of the shock losses shows the great influence of profile shape on the total pressure loss coefficient. The profile losses are roughly constant in the investigated Mach number range. In addition, some measurements for different back pressures are presented. These results are analyzed with the aid of a simple calculation, which shows that the axial velocity-density ratio has to be considered as an important parameter in supersonic cascade measurements.
Contributions to the Measurement and Calculation of Stresses in Plane Rotating Disks Without Rotational Symmetry
Authors: Gallus H. E.
Published: November 2010

The paper gives details of the experimental and theoretical work of the author on the above-mentioned subject. The first part of the paper deals with the experimental investigations of plane rotating disks whose rotational symmetry is disturbed by notches of any shape such as U-type notches, splining, keyways, and eccentric holes. The method of the stroboscopic photoelastic procedure will be described in detail, as well as the various results shown in numerous diagrams and photographs taken of the test arrangements and fringe patterns of the models. The offered material will give detailed information on the improvements of the stroboscopic photoelastic method made by the author. The second part of the paper is concerned with the application of integral equations to the stress calculation in plane rotating disks without rotational symmetry. Based on the source-like representation of the plane state of stress by Weinel, the stress problem of rotating disks without rotational symmetry is solved. The solution of the integral equations of Fredholm’s type on digital computers is carried out according to a well-known method of Oellers. The results obtained for some examples, such as the determination of the tangential stresses in the rim of plane rotating disks with variously curved boundary, are shown in diagrams.
An Investigation of Annulus Wall Boundary Layers in Axial Flow Turbomachines
Authors: Gregory-Smith D. G.
Published: November 2010

In the calculation of the flow in a turbomachine, empirical correction factors have previously been used to allow for the effect of the annulus wall boundary layers. A calculation method has been produced which includes the estimation of the growth of the boundary layers and the associated secondary flows. The results from an experimental investigation of the flows past a row of inlet guide vanes and an isolated rotor row are compared with the theoretical predictions. The agreement is good except for the growth of the boundary layer where the swirl is high.
Electrofluid Dynamic Energy Conversion Present Status and Research Areas
Authors: Lawson Maurice , Von Ohain Hans
Published: November 2010

This paper presents in depth the major basic performance characteristics of electrofluid dynamic (EFD) energy conversion processes, which are shown to be complementary to magnetofluid dynamic processes. With a view toward making possible effective thermal-electric energy conversion without moving parts, the potential compatibility of incorporating low pressure ratio EFD processes into high pressure ratio thermodynamic cycles is shown. Investigations of scaling, similarity, performance characteristics, and the effects of physical properties of working media containing electric charges of one polarity are used as a basis to determine the major problems and corresponding research areas in EFD energy conversion. In general these are: Generation of Charged Colloids; Electrode and Conversion Duct Geometry; and Fluid Dynamic Energy Transfer Phenomena in Multicomponent, Multiphase Flows. Also given are typical configurations of EFD energy converters, and a look at potential applications, especially those associated with encapsulated, long-duration power supply for operations in space, under the ocean, or at remote unattended sites.
An Analysis of Flow Through a Mixed Flow Impeller
Authors: Senoo Yasutoshi , Nakase Yoshiyuki
Published: November 2010

In this report, a method of analyzing steady, three-dimensional, subsonic, nonviscous flow through a turbomachine with arbitrary hub and shroud shapes and with a finite number of blades is presented. In order to make the analysis manageable, the stream surfaces are assumed to be axisymmetric. Position and shape of these surfaces, which depend upon the work of blades, are obtained by a meridional plane solution using a quasi-orthogonal coordinate system. The flow condition on these surfaces of revolution and the work of blades are obtained by a new blade-to-blade solution and the results are used to improve the meridional plane solution. This procedure is repeated until solution converges. Some numerical examples are given.
Powering of Natural Gas Pipelines
Authors: Robinson S. T.
Published: November 2010

An expression is developed for natural gas pipeline flow in terms of station power rather than the usual differences in the squares of the pressures, thus making it possible to directly evaluate the relative worth of power addition to existing lines or evaluate pipe versus power for new lines. Specific power requirements in terms of power per unit flow are combined with engine fuel requirements, making it possible to express station fuel consumed as a percentage of gas pumped, thus providing a figure of merit for various power plant-compressor systems. It is pointed out that with increasing gas costs and higher flow systems, the use of an axial flow gas line compressor should be examined because of the promise of higher efficiency obtainable with such a machine.
Impingement Cooling Performance in Gas Turbine Airfoils Including Effects of Leading Edge Sharpness
Authors: Metzger D. E. , Baltzer R. T. , Jenkins C. W.
Published: November 2010

An experimental study of the heat transfer characteristics of impingement into cavities which model the cooled leading edges of gas turbine engine airfoils is presented. The study includes both two-dimensional slot jets and single lines of evenly-spaced circular jets. For broad cylindrical cavities correlations are given for the maximum heat transfer rates attainable with optimum positioning of the jet nozzle with respect to the cooled surface. For elongated narrow cavities heat transfer rates relative to these maximum values are presented for a variety of cavity shapes.