bluuebunny/crossref_metadata_2025 huggingface dataset:
An Investigation in the Field of Elastohydrodynamics
Authors: Kodnir D. S. , Zhilnikov E. P.
Published: November 2010

The paper contains our new solutions of steady-state elastohydrodynamic problems, such as: 1) an isothermal one, in which the influence of roughness has been considered; 2) an isothermal one for a Newtonian fluid having viscosity dependence on pressure different from Barus’ law; 3) an approximate nonisothermal one for a Newtonian fluid considering the friction forces arising as a result of both rolling and sliding; 4) an isothermal one for a Maxwell fluid with large and small Weissenberg numbers; 5) a nonisothermal one for a Maxwell fluid with large Weissenberg numbers.
Workpiece Surface Roughening in a Hydrodynamically Lubricated Metal Forming Process
Authors: Wilson W. R. D.
Published: November 2010

A mathematical model for the roughening of the workpiece in a hydrodynamically lubricated metal forming process is developed. Roughening is assumed to result from local variations in the workpiece flow strength. The results of the analysis are compared with previous experimental measurements.
Correlation of Spectrographic Oil Analysis Data With SEM and X-Ray Data by Direct Examination of Particles in Hydraulic Oils
Authors: Johari O. , Corvin I. , Samudra A. V. , Staschke J.
Published: November 2010

The Spectrographic Oil Analysis Program (SOAP) is a standardized procedure for spectrochemically determining the average analysis of all particles present in a sample of oil from hydraulic or lubricated systems. In the present program scanning electron microscopy (SEM) and X-ray analysis were employed to study the morphology and chemistry of individual particles collected from oil samples. Also, a large collection of particles could be studied for obtaining an average analysis of all the particles in the analyzed area. Comparisons of SEM/X-ray data with SOAP data, and their correlation with conditions of parts showed good correlation for the aluminum-containing particles in the aircraft hydraulic system. Though not detected by SOAP, SEM/X-ray analysis showed several particles containing silicon (identified mostly as silica with X-ray diffraction), most of which were typically larger than 5 microns.
Analysis of the Stiffness and Damping Characteristics of an Externally Pressurized Porous Gas Journal Bearing
Authors: Rao N. S.
Published: November 2010

The dynamic behavior of an externally pressurized porous gas journal bearing is analyzed by assuming one dimensional flow through porous wall. A periodic (displacement) disturbance is imposed on the bearing, and the dynamic pressure distribution is determined by small perturbations of the Reynolds equation. Stiffness and damping for various design conditions are calculated numerically using a digital computer and presented in the form of design charts and tables.
The Frictional Dynamics of Lubricated Elastomers in Contact With Regularly Spaced Sliders
Authors: Gujrati B. D.
Published: November 2010

The study on friction of distributed rigid sliders on lubricated rubber flats, reported here, shows that the overall friction coefficient increases with larger inter-slider spacings but never exceeds that of a single slider. Also, the tractionability of sliders arranged in a linear array becomes greater when the array is oriented away from the traveling direction. These effects are governed by the interaction of the indentation strain fields and of the dynamic (or creep) deformation/recovery processes imposed on the rubber by individual sliders. The frictional performance of bilinear array of sliders is also discussed.
A Study of the Stability of an Externally-Pressurized Gas-Lubricated Thrust Bearing With a Flexible Damped Support
Authors: Boffey D. A.
Published: November 2010

Externally-pressurized gas bearings are prone to a dynamic instability known as pneumatic hammer. This paper examines the possibility of using a flexible damped bearing support to suppress the instability. A circular thrust bearing having a central feed hole and pocket is employed in the feasibility study. The linearized gas film dynamic coefficients are derived using an adaptation of an existing solution to Reynolds equation for a long rectangular bearing. Only stability of the equilibrium position is considered. Results obtained for a support having a stiffness comparable to the stiffness of the gas film show that damping in the support can substantially improve stability.
On a Diffusion Wear Model for High Speed Steel Tools
Authors: Venkatesh V. C.
Published: November 2010

The observation of a white diffusion layer at the HSS tool-BUE (mild steel) interface and in the crater, its composition and its identity are discussed here. Diffusion wear by itself is not a dominant mode of wear but depletion of elements from the tool surface makes it more prone to wear by plastic deformation to a larger extent and by abrasion to a lesser extent. Plastic deformation in coated carbide tools and Loladze’s diffusion wear model for carbide tools are used to project a diffusion wear model for HSS tools at low to medium and at high speeds.
An Approximate Equation for Predicting the Isothermal and Nonisothermal Starved Rolling Traction in an E.H.L. Line Contact
Authors: Goksem P. G. , Hargreaves R. A.
Published: November 2010

In this paper a new inlet distance variable for the starved rolling traction is introduced. By applying a statistical linear regression analysis to the starved E.H.L. question, this new inlet distance parameter enables a seminumerical formula for the prediction of the starved isothermal and nonisothermal rolling traction to be derived. The formula applies for a starved E.H.L. line contact and covers a wide range of the nondimensional materials, thermal loading, speed, load and inlet distance variables. A numerical example using several of the equations developed in this paper has been included in Appendix 1. For the isothermal case, the general formula developed shows good agreement with the two specific semianalytical results reported by Archard and Baglin [11], 1975.
Numerical Solution of the Planar Hydrostatic Foil Bearing
Authors: Eshel A.
Published: November 2010

The steady state problem of the planar hydrostatic foil bearing is analyzed and solved numerically. Two techniques of solution are used. One method is simulation in time with asymptotic approach to steady state. This is achieved by a preprocessor which automatically sets up the numerical computer program. The second method is an iterative shooting technique. The results agree well with one another. Curves of pressure and typical film thickness versus flow are presented.
Measurement of Separator Contact Forces in Ball Bearings Using a Derotation Prism
Authors: Nypan L. J.
Published: November 2010

A derotation prism was used to produce a stationary image of balls deflecting a portion of the separator. Ball to cage contact forces in a 110 mm bearing at speeds to 12,000 rpm were found to be 25 N (five lb) maximum. Inner race land contact force was found to vary up to 20 N (four lb).
Straight-Air Disk Brake Systems for Heavy Vehicles
Authors: Yamamoto M. A.
Published: November 2010

Disk brake usage has increased significantly on various applications that presently are hydraulically operated. Air-over hydraulic systems will be replaced by advanced applications of straight-air brakes by eliminating the complexity of such systems. The air-over hydraulic and electric-over hydraulics inherent problems have been solved. Mechanisms for heavy duty are discussed while considering its linearity, durabilty and dependability. The continuous duty capability of the straight-air disk brakes would phase out the retarders. The air disk brake has versatility and can be used to modify the spring set brake in heavy industry.
The Efficiency of Gears in Consideration of Gear Size and Skewness of Gear Axes
Authors: Fujii Y. , Shimachi S.
Published: November 2010

From the investigation about the dimensions of skew-axes gears now in common use, the ratio of the pitch radius of pinion to that of gear is found to depend almost only upon the gear ratio. On the other hand, the offset of the gear axes is desired to be as large as possible in usual cases of gear transmission mechanisms. Under these situations, the position of the mean contact point where a pair of gear teeth is expected to transmit power in high efficiency is investigated. The results are as follows: 1) The mean contact point which corresponds to high efficiency is in the neighborhood of the ruled surface swept by the instantaneous axis as the gear ratio continuously varies. 2) The majority of the mean contact points of gears now in use nearly coincide with the point mentioned in 1.
Model Verification of Mixed Dynamic Systems
Authors: Chrostowski J. D. , Evensen D. A. , Hasselman T. K.
Published: November 2010

A general method is presented for using experimental data to verify math models of “mixed” dynamic systems. The term “mixed” is used to suggest applicability to combined systems which may include interactive mechanical, hydraulic, electrical, and conceivably other types of components. Automatic matrix generating procedures are employed to facilitate the modeling of passive networks (e.g., hydraulic, electrical). These procedures are augmented by direct matrix input which can be used to complement the network model. The problem of model verification is treated in two parts; verification of the basic configuration of the model and determination of the parameter values associated with that configuration are addressed sequentially. Statistical parameter estimation is employed to identify selected parameter values, recognizing varying degrees of uncertainty with regard to both experimental data and analytical results. An example problem, involving a coupled hydraulic-mechanical system, is included to demonstrate application of the method.
Bending of Stub Cantilever Plate and Some Applications to Strength of Gear Teeth
Authors: Tobe T. , Kato M. , Inoue K.
Published: November 2010

Finite element analysis of stub cantilever plate with varying thickness considering transverse shear deformation and elastic deformation of built-in edge is presented and applied to strength of spur gear teeth. Bending moment at built-in edge and deflection of both uniform plates and gear teeth are calculated and illustrated. The results show close agreement with experimental ones. It is examined that well-known Wellauer’s moment image method gives good approximation of moment at the root except in case of corner point loading. Further application of the analysis is developed to longitudinal load distribution on the contact line on spur gear teeth caused by misalignment error showing good agreement with experimental results by Niemann and Reister. The present method can be applied to strength of helical gear teeth.
Bending Stress in Gear Teeth Having Circular Arc Profiles—Part 1: Analysis
Authors: Errichello R.
Published: November 2010

The bending stress in the root fillets of gear teeth having convex, circular-arc profiles has been calculated using a new analytic model. The gear tooth is modeled as a wedge with the load applied at the apex. Graphs of the nondimensional bending stress variation along the tooth length are presented for 14.5 deg, 30 deg, and 47.5 deg normal pressure angle, and 5 to 45 deg helix angles. It is shown that gears with larger helix angles have higher bending stresses for the same value of allowable surface stress.
Frequencies and Loss Factors of Multicored Sandwich Beams
Authors: Rao D. K.
Published: November 2010

The sandwich beam analyzed in the present paper consists of layers of elastic and viscoelastic material of arbitrary thickness and material. No restrictive assumptions are made on the bending and shear rigidities of the cores. Higher-order effects like rotatory inertia, bending, and extension of the core, which were ignored in previous theories, are included in the equations of motion presented herein. Exact equations for finding resonant frequencies and loss factors are given for simply-supported beams, while for other boundary conditions, these quantities are computed by variational method. Analysis of numerical results indicates that unsymmetricizing the face layers is superior to unsymmetricizing the core layers. It also showed that uniformly high damping over a wide frequency range can be obtained only by the use of stiff cores, but this is followed by a reduction in the maximum loss factor.
Dynamic Stability of Elastic Mechanisms
Authors: Badlani M. , Kleinhenz W.
Published: November 2010

A study of the dynamic stability of a slider-crank mechanism with an undamped elastic connecting rod is presented using the Euler-Bernoulli and Timoshenko beam theories. It is shown that new regions of instability exist when rotary inertia and shear deformation effects are included in the analysis.
Symmetrical Algebraic Motions in the Plane
Authors: De Sa S. , Roth B.
Published: November 2010

Planar symmetrical motions are those planar motions for which, in every position, the fixed and moving centrodes are symmetrical with respect to the pole-tangent. When the centrodes are algebraic curves the motion is called an algebraic symmetrical motion. The concept of kinematic mappings is used to establish the properties of such motions and also to obtain the equations of the paths generated by the points of the moving plane. Finally it is shown how this concept may be used to classify motion.
Performance Criteria for High-Speed Crank-and-Rocker Linkages—Part I: Plane Crank-and-Rocker Linkages
Authors: Funabashi H. , Freudenstein F.
Published: November 2010

Criteria are given for evaluating the performance and determining the dimensions of plane crank-and-rocker mechanisms suitable for operation at high speeds. In contrast to the classical procedure of simulating the acceleration pattern of the slider-crank mechanism by means of centric crank-and-rocker linkages, a family of crank-and-rocker linkages has been found, with a more nearly sinusoidal acceleration pattern, i.e., one which tends more nearly to simulate the acceleration variation of a scotch yoke. At the same time the transmission-angle variation and the ratio of minimum to maximum link lengths is controlled. A pocket-calculator procedure is described and illustrated by means of a numerical example.
Optimal Programming of Working Cycles for Industrial Robots
Authors: Bedini R. , Lisini G. G. , Sterpos P.
Published: November 2010

The problem of optimizing the working cycle of an industrial robot equipped with two independent arms is stated and put in mathematical form. The exact solution of this problem seems to be very difficult; the paper proposes approximate solutions for some typical manufacturing processes, carried out by implementing on a minicomputer standard algorithms of Operations Research and heuristic procedures. Examples of the use of the developed software are reported.
Transmission Errors and Noise of Spur Gears Having Uneven Tooth Profile Errors
Authors: Yuruzume I. , Mizutani H. , Tsubuku T.
Published: November 2010

The problems of involute spur gear noise and transmission errors are studied by meshing m3, 40z spur gears. Five kinds of tooth profile errors, such as convex, concave and wave-like, were formed on the test gear teeth by grinding. The value of each tooth profile error is divided into 3 grades, according to the Gear standards of JIS. Transmission errors of 15 test gears and a master gear were measured by a single flank gear rolling tester with a planetary gear system. Gear noise and strains near tooth fillets were measured by running these test gears on a gear noise testing machine with a power absorbing system, in an anechoic room. This paper presents experimental results and studies of the influence of tooth profile error forms on single flank rolling errors, situation of tooth contacts and gear noise while running.
Optimal Design of Multi-Edge Cutting Tools for BTA Deep-Hole Machining
Authors: Latinovic V. , Blakely R. , Osman M. O. M.
Published: November 2010

The design procedure of optimal multi-edge BTA deep-hole machining tools with unsymmetrically located cutters and preliminary test evidence are presented. Based on a mathematical model of cutting forces in terms of fundamental cutting parameters of the tool, a multivariable, nonlinear objective function was derived and modified to an unconstrained type with bounded decision variables. A numerical, direct search method, accelerated in distance, was selected to minimize the objective function. This procedure insures, on one hand, a predetermined cutting force resultant necessary for tool guidance; on the other hand, it minimizes the variation of cutting edge pressure. A relatively fast computer routine was adapted to provide the optimal tool parameters, which then were used to design cutting head prototypes. Two trepanning heads of three and two cutters were manufactured and tested at production facilities. The test results showed that the cutting force resultant was well predicted in both heads and that they were well guided. Much higher feed rates were possible compared to those achieved with single-edge tools without any loss of hole accuracy straightness or surface finish.
The Lanchester Damper—A Design Procedure for Optimizing the Damping Ratio for a Cylindrical Slug Damper Fitted to a Machine Element
Authors: Au Y. H. J. , Ng K. W. , New R. W.
Published: November 2010

The present work shows how the equations of motion for a Lanchester damper can be modified to include the effects of a damper slug rolling inside a cavity within the parent body, and of the kinetic energy of the damping fluid. The effect of the slug rolling is to reduce the performance of the damper below that predicted by the standard theory and to require a different value for damping at the optimum condition. These effects are significant when the build-up of self-excited type of vibrations are to be prevented, and when small forced vibrations are to be controlled. Fluid kinetic energy effects can be neglected when the damping fluid is gaseous, but not necessarily so when it is a liquid.
Vibration of Beams Carrying Discrete Dampers and Masses
Authors: Satter M. A.
Published: November 2010

Vibration of beams carrying discrete dampers and masses has been studied using standard Fourier transform method. It has been shown that the discrete damping coefficients can be expressed as a function of a uniformly distributed damping coefficient and this leads to a considerable simplification of the mathematics involved. A simply supported and a clamped beam have been considered, but emphasis for numerical calculations has been given on the simply supported beam. The calculations have been verified experimentally.
Technology Transfer in the Design of Adjustable Linkages
Authors: Tao D. C. , Yan H. S.
Published: November 2010

When the input crank is in line with the fixed link, the circling-point curve degenerates into a circle and straight line. This characteristic applied to a four-bar linkage with symmetrical coupler curves can be utilized to design linkage mechanisms adjustable for variable circular arcs. The design technique is simple and should stimulate the designer’s interest.
Displacement Analysis of Spatial 7R Mechanisms Suitable for Constant-Velocity Transmission Between Parallel Shafts
Authors: Gilmartin M. J. , Duffy J.
Published: November 2010

Three types of spatial 7R mechanisms are identified as being suitable for transmitting motion with a constant velocity ratio between two parallel shafts. A displacement analysis of each type is made using a vector loop method in conjunction with the Unified Theory method. Numerical results are presented for an example of each type. It is also shown how the double Hooke joint coupling for parallel shafts is a special case of one of these three types.
Fabrication of Pressure Vessels
Authors: Ando Yoshio
Published: November 2010

Heavy section steel pressure vessels for light water reactor and aluminum tank for liquefied natural gas carrier are chosen to review the fabrication of pressure vessels. With regard to RPV, materials, effects of fabrication thermal history, fabrication procedure and advanced welding technique are dealt with. For the fabrication of aluminum cryogenic tanks for LNG carrier, a special factory equipped with plasma arc cutting, various automatic gas metal arc welding machines and so on, is advisable.
A Self-Organizing Mesh Generation Program
Authors: Jones R. E.
Published: November 2010

A two-dimensional mesh generation program producing quadrilateral elements is presented. It uses a modular, flexible input scheme, and incorporates some existing techniques of initial mesh generation. Some new, more powerful mesh smoothing techniques are developed, and automatic mesh restructuring techniques are coupled with smoothing techniques to produce improved meshes without user interaction.
Response of Spherical Shells of Composite Materials to Localized Loads
Authors: Kliger H. S. , Vinson J. R.
Published: November 2010

In order to better understand the response of spherical portions of composite material pressure vessels, the stresses and deformations in a thin, specially polar orthotropic shallow spherical shell subjected to a localized loading at the apex are analyzed. Although the shell studied is geometrically thin, transverse shear deformation is included because the ratio of in-plane modulus of elasticity to transverse shear modulus is between 20 and 50 for many composite materials of interest. Methods of analysis are presently available for analyzing the effects of localized loads on thin isotropic spherical and cylindrical shells, and isotropic, shallow spherical, sandwich shells. The methods presented herein provide the ability to treat the use of composite materials. The analytic solutions are obtained in terms of modified Bessel functions of noninteger order and complex argument. In digital computation these functions are transformed into a set of nondimensionalized, rapidly convergent infinite series. Over 500 computer runs have been made and reported on herein to provide a better understanding of the effects of parameters such as ratio of circumferential to meridional modulus of elasticity, ratio of circumferential modulus of elasticity to transverse shear modulus, various boundary conditions, degree of shell shallowness, and loaded area.
An Approximate Model for an Elastic-Plastic Pipe Element Under Combined Loading
Authors: Larson L. D. , Stokey W. F. , Franzen W. E.
Published: November 2010

An approximate model for the elastic-plastic analysis of a pipe element under combined loading is developed. The model is obtained by generalizing a limit load solution for combined pressure, bending, torsion and axial load to include strain hardening. For various combinations of loading of tubes, curvatures and twist angles are predicted and compared with experimental results and those predicted by a more rigorous analytical approach. The comparison shows that good results are obtained from the approximate model.
Transient Creep Analysis With Finite Deformations
Authors: Kulkarni A. K. , Ellyin F. , Neale K. W.
Published: November 2010

A method for obtaining stresses and displacements under conditions of transient creep is illustrated, with finite deformations taken into account. A mixed variational for mutation due to Sanders, et al. [1] is used and numerical results are given for the finite-displacement analysis of a thin tube under internal pressure and a laterally-loaded circular plate. These results are compared with existing experimental and theoretical results, and the agreement is found to be very satisfactory.
Inelastic Analysis of a Straight Tube Under Combined Bending, Pressure and Thermal Loads
Authors: Chern J. M. , Pai D. H.
Published: November 2010

This paper describes the formulation of and solution to the problem of elastic-plastic-creep analysis of a thin circular cylinder subjected to combined bending, pressure and thermal loads. These loads may vary with time in any arbitrary manner. Solution procedures based on direct integration and successive approximation are described, and numerical examples are presented to illustrate the interaction of load parameters. The application of the present model to design problems is also given and compared with a finite element solution.
On Shallow Shells of Transversely Isotropic Materials
Authors: Raju P. P.
Published: November 2010

This paper presents an improved shell theory for the analysis of shallow shells of composite materials such as pyrolytic graphite, that exhibit certain unusual and complex thermal properties. In the formulation of this theory, the effects of transverse isotropy, transverse shear deformation and thermal expansion through the thickness are taken into account. In the specific case of shallow spherical shell, the governing equations are reduced to two coupled second order ordinary differential equations. The Meissner constant is defined to include a term representative of transverse shear deformation. These two equations are then fused into a single second-order complex differential equation. By means of Langer’s method of asymptotic integration a solution of the homogeneous differential equation is obtained. Edge load solutions are developed for two edge loads (bending moment and shear resultant). Particular solutions are also obtained for various mechanical and thermal loads. Several numerical examples are presented to prove the validity of the assumptions in the present theory and the accuracy and the adequacy of this theory in the prediction of the behavior of shallow shells of composite materials.
Fracture of Defects Approaching a Free Surface
Authors: Gibbons W. G. , Andrews W. R. , Clarke G. A.
Published: November 2010

A testing program has been run using off-centered-cracked (OCC) plate specimens to demonstrate the fracture characteristics of tunnel defects in specimens with various ligament lengths between the near surface crack tip and a free surface. Measured strain values and the fracture results compared favorably with theory up to the limits of the analyses. An empirical equation which calculates the near surface stress intensity provides extended calculational capabilities. In addition, fatigue crack growth and fracture velocities plus fracture toughness were measured for a Cr-Mo-V steel.
Plane Strain Crack Arrest Characterization of Steels
Authors: Crosley P. B. , Ripling E. J.
Published: November 2010

The data presently available on the plane strain crack arrest toughness (KIa) of steels are reviewed, using as a definition of KIa the stress intensity factor, K, a short time after a run-arrest segment of rapid crack extension. The data indicate that KIa, defined in this way, is a material property, i.e., it is independent of the manner in which it is measured. Calculations, available in the literature, on the dependence of dynamic K on a crack velocity are used to justify this invariance. It is also shown that KIa may be the minimum value of toughness, at a given temperrature, as a function of loading rate.
Displacements and Stresses in Precision Welded Bellows
Authors: Dressler R. F. , Kountouras N. V.
Published: November 2010

A mathematical method is derived which permits calculation, based upon linear shell theory, of all stresses and displacements in a precision welded bellows having any number of layers, when displaced due to internal fluid pressure. If the meridional shape contains large curvatures or sharp corners the shell theory is replaced by the theory of solid elastic tori, which is used also for including the effects of the welds. As computation errors would eventually invalidate solutions for bellows with too many layers, a boundary layer technique is devised to overcome this difficulty. The method may therefore be applied to a bellows with any large number of layers without increase in the overall percentage error in displacement. An exact error check is possible in the solution for the transverse shear, indicating with our present step-intervals and medium size computer, errors of less than one percent.
Analysis of Defects in Welds
Authors: Bartholome G. , Vasoukis G.
Published: November 2010

The judgment of welds with defects in reactor components is done by nondestructive as well as destructive material testing, stress analysis, and fracture mechanics. The following investigations are required: The kind, position, and size of defects in welds (stress relief cracks, hot tearing) is determined through nondestructive and destructive material testing. Strength, toughness, and subcritical crack-growth data are measured for weld-material, heat-affected zone and base material. The determination of strength, toughness, and subcritical crack growth of the heat-affected zone is very difficult, because the heat-affected zone is small and irregulary distributed. Therefore the heat-affected zone is simulated through suitable heat treatment. From this it is possible to estimate the behavior of original welds. Through the defect, material, and stress data the safety of welds with defects is proved. Additionally the margin of this safety is determined. The experimental verification of the calculations is done through a pulsating test of model under original loading conditions, including all specified loads.
Steady-State Crack Propagation in Pressurized Pipelines Without Backfill
Authors: Kanninen M. F. , Sampath S. G. , Popelar C.
Published: November 2010

In a previous paper, a simplified dynamic-shell theory representation was formulated for steady-state motion in a pipeline without backfill. The present work extends this model by (1) incorporating a gas dynamics treatment to determine the axial variation in the pressure exerted by the gas on the pipe walls, and (2) incorporating a plastic yield hinge behind the crack tip. Solutions to the governing dynamic equations are obtained for these conditions and used to calculate the steady-state dynamic energy release rate as a function of crack speed. In the single full-scale experiment in which an independent estimate of the dynamic fracture energy is available for a pipe without backfill, the model predicts a steady-state speed of 780 fps. This can be compared with measured speeds which ranged from 725 to 830 fps in the test. Because the calculated steady-state dynamic energy release rate exhibits a maximum, it is suggested that this approach may offer a basis for crack arrest design of pipelines.
The ANSI B31 Code for Pressure Piping—Its Past, Present, and Future
Authors: Pandorf E. C.
Published: November 2010

This Code Committee has been in existence since 1925, and has supplied written codes since 1935. The objectives of the code are identified in this paper, and the personnel, organization, liaison activities, and code sections are described. Two examples are included to demonstrate how B31 can go about broadening its scope of coverage of piping systems. Finally, the main challenges of the future are identified and the course of action is delineated.
Spectral Analysis of Complex Systems Supported at Several Elevations
Authors: Thailer H. J.
Published: November 2010

This paper presents the theoretical justification for a method for computing realistic system response from seismic spectral analyses. The method is applicable to complex discrete mass systems which are supported at several locations within a structure and at which different floor response spectra are defined.
Low-Alloy High-Strength Steel for Boiler Tubes (LowC-9Cr-2Mo)
Authors: Yukitoshi T. , Nishida K. , Oda T. , Daikoku T.
Published: November 2010

High-strength steel tube HCM9M (LowC-9Cr-2Mo) steel, which shows the intermediate high-temperature strength between austenitic stainless steels and commercial low-alloy steels, has been developed. It has superior weldability, workability and oxidation resistivity. At present HCM9M tubes have been in-service test as reheater and superheater tubing at the 165,000 kW boiler in Japan without trouble. This report deals with the practical properties of HCM9M steel, service test experience and high temperature strengthening mechanism of the steel from morphological viewpoint of carbide.
Thermal Shock Testing of Fillet-Type Tube-to-Tubesheet Welds
Authors: Apblett W. R. , Montrone E. D. , Wolowodiuk W.
Published: November 2010

To prove the inherent integrity of the fillet-type tube-to-tubesheet welds proposed in the initial design of the Intermediate Heat Exchanger for the Liquid Metal Fast Breeder Program Fast Flux Test Facility, a seven-tube model was built with prototypical tubes and welds. The welds were subjected to thermal shocks well in excess, both in severity and numbers, of those that the plant units may be expected to experience. Post-test examinations of the welds confirmed that no failures had occurred during the test. However, minor cracks were observed in the weld root area upon microscopic examination of the weld cross sections. This paper describes the test model and the results obtained from it.
Stratapax Drill Bit for Gulf Coast Drilling
Authors: Radtke R. P. , Bridwell H. C. , Handsel R. A.
Published: November 2010

A drill bit employing GE Stratapax drill blanks has been developed for Gulf Coast drilling. Single point cutting tests demonstrated superior impact qualities of Stratapax when compared to natural diamonds. A new “pocket” brazing technique was developed to achieve a suitable attachment to a hard matrix bit body. Laboratory drilling tests suggest that high rates of penetration can be anticipated in future field tests.
Structural Design for a 10-GWh SMES Vacuum Vessel
Authors: Bennett J. G. , Anderson C. A.
Published: November 2010

An approximate solution to the problem of the nonlinear elastic deformation of a periodically point-supported cylindrical shell is obtained. This solution is used to investigate the structural design of the vacuum vesssel for the large underground SMES concept. Vacuum vessel designs are evaluated by varying such parameters as shell thickness, support, spacing, material properties and physical configuration to keep the amount of material used and construction cost to a minimum.
An Assessment of Overburden Stability in the In-Situ Gasification of Texas Lignite
Authors: Thompson T. W. , Edgar T. F. , Gray K. E.
Published: November 2010

In-situ gasification can be competitive with shaft mining for the exploitation of coal at depths too deep for surface mining. The lignite deposits in Texas may be well suited to this process because of their high reactivity, comparatively high field permeabilities and closeness to industrial demand centers. Controlled operation of a gasification facility demands a knowledge of the likely behavior of the overburden and other surrounding rocks. Fracture or collapse of the roof rock can lead to excessive gas loss, water influx and subsidence effects. The overburden in much of Texas is weak and poorly compacted. Early roof collapse seems inevitable, and substantial upward caving may occur. Subsidence could be significant if high extraction ratios are used.
Three-Dimensional Analysis of an Elastic Plate-Cylinder Intersection by the Boundary-Point-Least-Squares Technique
Authors: Redekop D.
Published: November 2010

The boundary-point-least-squares technique is applied to the axisymmetric three-dimensional elasticity problem of a hollow circular cylinder normally intersecting with a perforated flat plate. The geometry of the intersection is partitioned into three parts. Boundary conditions on the middle part and continuity conditions between adjacent parts are satisfied using the numerical boundary-point-least-squares technique while the governing elasticity equations and all other boundary conditions are satisfied exactly. Sample theoretical results are presented for the case of axisymmetric radial tension loading on the plate. The results compare favorably with previously published experimental data and provide supplementary data to theoretical results obtained using existing shell theory solutions.
Some Field Permeation Properties of Fractured Permian and Triassic Sandstones in Northwest England
Authors: Crook J. M. , Howell F. T.
Published: November 2010

The 1000 m thick series of Permian and Triassic sandstones in Northwest England exhibit both intergranular and fissure flow. However, estimates of their relative importance can be distorted by the statistical manipulation of test data. Additional parameters which are believed to independently identify the mechanism of flow are examined. These include variation of field permeability in 171 boreholes with respect to depth and radius of the pumped bore, distance from tectonic zones and consideration of the regional distribution of fluid bodies. Interpretation suggests that intergranular flow is dominant despite the fractured nature of the rock mass.
Contributions of the ORNL Piping Program to Nuclear Piping Design Codes and Standards
Authors: Moore S. E.
Published: November 2010

Since 1967, ORNL Piping Program has been engaged in providing information for the development of stress indices to be used in the analysis of piping components for nuclear power plants. This effort has surveyed the piping manufacturing industry and analyzed that industry’s products; has combed the technical literature for pertinent engineering data; has performed theoretical and experimental analysis of nuclear piping components; and has defined, tested, and improved indices for the stress-index method of analysis for piping components. This paper briefly reviews the history of piping-analysis standards; outlines the philosophy of the stress-index method of analysis; and explains some of the specific contributions made by the ORNL program to the Codes and Standards. Current and future work is also noted.
On Through Cracks at Interference Fit Fasteners
Authors: Shah R. C.
Published: November 2010

Approximate stress intensity factors (SIF’s) are derived for through-the-thickness cracks originating at an interference fit fastener- (IFF-) filled hole in a uniaxially loaded plate. SIF’s are determined using a previously formulated procedure of deriving approximate SIF’s from the normal stress distribution at the location of the crack in an uncracked plate. An approximate elastic-plastic solution for the normal stress distribution is derived for a uniaxially loaded plate containing an IFF-filled hole. Stress distributions obtained from the approximate solution compare well with those obtained from elastic-plastic finite element analyses for various loading conditions, interference levels and fastener plate material combinations. SIF’s for through cracks at IFF’s are presented graphically for various ratios of crack length to hole radius and diametral interference to hole diameter, applied uniaxial stresses and the plate-fastener material combinations. Finally, these SIF’s are used to predict residual cyclic lives of test specimens containing through cracks at IFF’s. Agreement between the calculated and actual lives is very good.
Assessment of Tensile and Creep Data for Types 304 and 316 Stainless Steel
Authors: Sikka V. K. , Booker M. K.
Published: November 2010

An evaluation is presented for variations in tensile and creep properties of types 304 and 316 stainless steels. United States data and data from two foreign countries, Japan (NRIM data) and Britain (BSCC data), were evaluated for different products separately and for the combined data on all products. United States data were shown to contain the largest variations in both tensile and creep properties, with Japanese data the least. For a given country no distinction could be made in variations in tensile properties of types 304 and 316 stainless steels but variations in standard error of estimate (SEE) for all creep properties analyzed were significantly lower for type 316 stainless steel than corresponding variations in creep properties of type 304 stainless steel. The data from each of these countries showed the same creep rupture strength (at 104 hr) for type 316 stainless steel; this was not true for type 304 stainless steel. Results of the analysis performed in this paper showed that the U. S. and foreign data on types 304 and 316 stainless steels could possibly be combined for the determination of design stress intensity limits.
Plastic Strain Concentrations in Ligaments
Authors: Porowski J. S. , O’Donnell W. J.
Published: November 2010

The sheet perforated with a uniform array of circular holes arranged in a square pattern is investigated. The plastic strains are derived for progressive in-plane loading which eventually results in gross yielding. The finite element method is used to obtain numerical solutions. Plane stress conditions and elastic perfectly plastic solid material properties are assumed. Thus the results provide conservative values of plastic strain concentrations for a considerable range of perforated materials. The plastic strain multipliers for equibiaxial and pure shear loading are given for three ligament efficiencies of the penetration pattern. The tendency of forming highly localized plastic strains with progressive yielding is observed, and the implications of the results in plastic design are discussed.
A Methodology for Evaluating the Variability in Fracture Properties of Ferritic Nuclear Pressure Vessel Steels
Authors: Stahlkopf K. E. , Smith R. E. , Server W. L. , Wullaert R. A.
Published: November 2010

A methodology is presented upon which an effective material property design curve can be based. The methodology is a statistically developed procedure which allows appropriate confidence limits to be established. The application of this methodology is a goal of a recently completed fracture toughness program of the Electric Power Research Institute (EPRI), and the results of this program are presented in this paper. The methodology is designed to allow the formulation of a statistically based KIR (reference toughness) curve as contrasted with the present approach which is found in Appendix G, Section III, of the ASME Boiler and Pressure Vessel Code.
An Analysis of a Wire-Wrapped Mechanical Crack Arrester for Pressurized Pipelines
Authors: Freund L. B. , Li V. C. F. , Parks D. M.
Published: November 2010

Because of the difficulties which have been encountered in efforts to establish fracture toughness standards for arrest of running shear fractures in pressurized pipelines, the possibility of introducing mechanical crack arresters on such pipelines is currently being explored. The purpose here is to discuss the mechanics of the crack arrest process for a mechanical arrester which is fabricated by loosely thread wrapping ductile steel wire rod around a segment of the pipe. The net effect of the wire rod arrester as the crack approaches is to substantially increase the axial in-plane strain in the pipe wall adjacent to the fracture path from the value it would have in the absence of the arrester. The result is that, in the presence of the arrester, the growth of a circumferential tensile fracture can become more favorable than continued growth of the axial tensile fracture, and a criterion for arrest of the axial fracture based on this result is proposed. Through an analysis of rapid crack propagation in a pressurized pipeline, the arrest criterion leads to an expression for the minimum ductility of the wire rod necessary for crack arrest. The required minimum ductility for the wire rod is estimated for system parameters corresponding to available full-scale test data, and the results compare favorably with the independently measured actual ductility of the arrester material.
Accurate Numerical Solutions for Elastic-Plastic Models
Authors: Schreyer H. L. , Kulak R. F. , Kramer J. M.
Published: November 2010

The accuracy of two integration algorithms is studied for the common engineering condition of a von Mises, isotropic hardening model under plane stress. Errors in stress predictions for given total strain increments are expressed with contour plots of two parameters; an angle in the pi-plane and the difference between the exact and computed yield surface radii. The two methods are the tangent predictor-radial return approach and the elastic predictor-radial corrector algorithm originally developed by Mendelson. The accuracy of a combined tangent predictor-radial corrector algorithm is also investigated. For single-step constant-strain-rate increments the elastic predictor-radial corrector method is generally the most accurate, although errors in angle can be significant. The use of a simple subincrementation formula with any one of the three approaches yields results that would be acceptable for most engineering problems.
Elevational gradients of bryophyte diversity, life forms, and community assemblage in the southern Appalachian Mountains
Authors: Stehn Sarah E. , Webster Christopher R. , Glime Janice M. , Jenkins Michael A.
Published: November 2010

We investigated the influence of fine-scale elevational gradients and overstory disturbance on bryophyte distribution, diversity, and community composition. Bryophyte species cover and richness were sampled across 60 randomly selected plots within high-elevation spruce–fir ( Picea – Abies ) forests of Great Smoky Mountains National Park. Ordination and regression analyses revealed a fine-scale elevation gradient (700 m) in bryophyte community composition. Observed changes in bryophyte diversity and community composition were also associated with variation in deciduous basal area and thus litter composition, the prevalence of herbaceous plants, and the degree of canopy openness resulting from balsam woolly adelgid ( Adelges piceae Ratz.) infestation. Although overstory disturbances, such as those caused by the adelgid, create suitable substrate for bryophyte colonization, the corresponding increase in light availability and deciduous basal area may alter bryophyte diversity and community assemblages.
Trends in growing space efficiency of four boreal forest species based on yield table data
Authors: Smith Victor G.
Published: November 2010

Yield tables are used to identify trends in growing space efficiency (GSE) and to relate GSE to self-tolerance and intraspecific competition. The method is useful when data specifically collected for this purpose are not available. Plonski’s normal yield tables for jack pine (Pinus banksiana Lamb.), paper birch (Betula papyrifera Marshall), trembling aspen (Populus tremuloides Michx.), and black spruce (Picea mariana (Mill.) B.S.P.) are used. An exponential volume–age function was partitioned into volume–area and area–age functions. The exponents of these two components form the B/D ratio, which is used to determine the mode of the stand at a given time, e.g., if B/D is <3/2, then the stand is in area occupation mode, and if B/D is >3/2, then the stand is in area exploitation mode. The dominant mode is the one most responsive to availability of growth resources, showing greater acceleration when resources are plentiful and more rapid deceleration when resources are scarce. Jack pine and paper birch are identified as area occupiers, whereas trembling aspen and black spruce are area exploiters and are therfore self-tolerant. Asymmetric competition was deemed to be present for paper birch throughout the life of the stand on site class I and for trembling aspen on all sites prior to senescence.
HEAVY ION CONSTRAINTS IN THE PARAMETRIC COUPLING MODEL
Authors: MARRANGHELLO GUILHERME F. , VASCONCELLOS CESAR A. Z.
Published: November 2010

The relativistic parametric coupling model is used here to describe global static properties of nuclear matter and neutron stars. Using recent observational data related to neutron star properties and experimental results of heavy-ion collisions, we review some properties of the effective model and we impose this way new constraints on its coupling constants. Then we analyze the consequences on already known parameters of nuclear matter, i.e., the compression modulus, the effective nucleon mass, and the maximum neutron star mass predicted by integrating the Tolman–Oppenheimer–Volkoff equations. To achieve this goal, we have explored the parametric coupling model in a wide range of parameters. We made use of recent data on flow analysis to constraint this parameter. Our results indicate values for the compression modulus of nuclear matter and for the maximum mass of neutron stars which are in good agreement with the observational data.