bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Studies on Thermoelastic Effects in Hydrodynamically Lubricated Face Seals
Authors: Banerjee B. N. , Burton R. A.
Published: November 2010

Experiments are reported where face-seat specimens were operated hydrodynamically at conditions close to thermal equilibrium. Changes in surface waviness and mean film thickness were monitored, and compared with theoretical predictions of thermal growth of waviness. Discrepancies were attributed to imperfect response of the gimbals to axial run-out. This run-out was increased by thermal effects at high sliding speeds and led to interactions which influenced the growth of two-lobed waves on the contact face. Operation proved stable, as predicted, under the carefully controlled operating conditions of fixed axial load and self aligning contact.
Hydrodynamic Effects in a Misaligned Radial Face Seal
Authors: Etsion I.
Published: November 2010

Hydrodynamic effects in a flat seal having an angular misalignment are analyzed, taking into account the radial variation in seal clearance. An analytical solution for axial force, restoring moment, and transverse moment is presented that covers the whole range from zero to full angular misalignment. Both low pressure seals with cavitating flow and high pressure seals with full fluid film are considered. Strong coupling is demonstrated between angular misalignment and transverse moment which leads the misalignment vector by 90 degrees. This transverse moment, which is entirely due to hydrodynamic effects, may be a significant factor in seal operating mechanism.
Dynamics of Rolling-Element Bearings—Part I: Cylindrical Roller Bearing Analysis
Authors: Gupta P. K.
Published: November 2010

An analytical formulation for the roller motion in a cylindrical roller bearing is presented in terms of the classical differential equations of motion. Roller-race interaction is analyzed in detail and the resulting normal force and moment vectors are determined. Elastohydrodynamic traction models are considered in determining the roller-race tractive forces and moments. Formulation for the roller end and race flange interaction during skewing of the roller is also considered. Roller-cage interactions are assumed to be either hydrodynamic or fully metallic. Simple relationships are used to determine the churning and drag losses.
Gas-Lubricated Porous Bearings of Finite Length—Self-Acting Journal Bearings
Authors: Wu Erh-Rong
Published: November 2010

The effects of porosity on the performance of gas bearings are investigated. A thin-wall approximation is developed to simplify the coupling between the Reynolds equation in the fluid film and the three dimensional Laplace equation in the porous matrix. The Newton-Raphson method is used to linearize the modified Reynolds equation and the column method is employed to solve the system of linear equations in matrix forms. The solution of a solid-wall bearing is included as a special case. Bearing characteristics are presented in tables and charts for varied permeabilities, slip coefficients, porous layer thicknesses, eccentricity ratios, length-to-diameter ratios, and for a wide range of compressibility number.
Amplitude Effects on the Dynamic Performance of Hydrostatic Gas Thrust Bearings
Authors: Stiffler A. Kent , Tapia R. R.
Published: November 2010

A strip gas film bearing with inherently compensated inlets is analyzed to determine the effect of disturbance amplitude on its dynamic performance. The governing Reynolds’ equation is solved using finite-difference techniques. The time dependent load capacity is represented by a Fourier series up to and including the third harmonics. For the range of amplitudes investigated the linear stiffness was independent of the amplitude, and the linear damping was inversely proportional to (1 − ε2)1.5 where ε is the amplitude relative to the film thickness.
Adiabatic Solutions for Finite Journal Bearings
Authors: Pinkus Oscar , Bupara Sargit S.
Published: November 2010

The paper offers a method of including variable viscosity in bearing analysis by the use of a simple energy equation uncoupled from the Reynolds equation. The relevant adiabatic solutions are made independent of the specifics of the kind of lubricant used and of its initial conditions. Performance results such as load, friction, maximum temperature, flow, etc. are given for the two axial-groove journal bearing covering three L/D ratios, three values of the adiabatic parameter E, and the full range of eccentricities. The effect of variable viscosity on the performance of misaligned bearings is also examined.
Dynamic Tooth Loads and Stressing for High Contact Ratio Spur Gears
Authors: Cornell R. W. , Westervelt W. W.
Published: November 2010

A time history, closed form solution is presented for a dynamic model of spur gear systems for all practical contact ratios. The analysis determines the dynamic response of the gear system and the associated tooth loads and stressing. The dynamic model is based on work done by Richardson and Howland [2, 3], and assumes the two gears act as a rigid inertia and the teeth act as a variable spring of a dynamic system excited by the meshing action of the teeth. Included in the analysis are the effects of the non-linearity of the tooth pair stiffness during mesh, the tooth errors, and the tooth profile modifications. Besides reviewing the features, solution, and program of this analysis, preliminary results from applying the analysis are presented, which show that tooth profile modification, system inertia and damping, and system critical speeds can affect the dynamic gear tooth loads and stressing significantly.
Dynamics of a High-Speed Sliding Power Collector in Consideration of Sliding Friction
Authors: Yoshida K. , Shimogo T.
Published: November 2010

Considering the sliding friction force produced between a contactor and a rigid collecting rail with a randomly wavy surface, the paper deals with the dynamics of a sliding power collector for a very-high-speed railway. An analytical model is formulated, which has two contact points and takes into account the pitching of a contactor, the stiffness of the sliding direction in a contactor support system, and the nonlinearity of the contact stiffness between a contactor and a rail. Mainly, the influences of the sliding friction and the contact stiffness on the dynamic characteristics, i.e., the contact force variation, the probability of contact break, etc., are investigated. The equivalent linearization technique is applied in the analysis. To verify the analytical results, digital simulations are carried out by preparing the artificial collecting rail wave.
Theoretical and Experimental Investigation of a New Plane Toothed Wheel and Its Enveloping Hourglass Worm
Authors: Ishida K. , Ueda H. , Ohashi S. , Fukui Y.
Published: November 2010

This paper relates to the properties of the surface of contact or the line of contact on a new plane toothed wheel which is inclined properly to the axis of the wheel and on its enveloping hourglass worm by using the theory of envelope, numerical computations, manufacturing process of this hourglass worm gears, and their experimental results. From this investigation, it can be ascertained that the surface of contact is nearly tangential to the circumference of the worm surface. The line of contact is almost upright to the direction of sliding surface. When the inclination angle of the plane tooth of the wheel axis is 22 deg, the tooth bearing on a wheel tooth is in its center portion, and good condition. We carried out various tests with a speed-reducing gear solely manufactured by several trials, using such materials as ABB2 (special aluminum bronze) for a worm and S45C (high-frequency-quenched) for a wheel. Results were obtained from the tests. They are as follows: because of no wearing in a wheel, little irregularity is caused on a worm tooth form; wearing in a worm is very little because the interlocking is made with the entire surface; power consumption may be reduced by more than 10 percent as compared with a conventional unit. Furthermore, we are confident that a power transmission capacity may be more than doubled also by this new product.
Critical Speeds, Stability and Response of a Geared Train of Rotors
Authors: Lund J. W.
Published: November 2010

A method is described for calculating the coupled torsional-lateral vibrations in a geared system of rotors. It considers both forced vibrations, caused by mesh errors or by mass unbalance, and free, damped vibrations whose complex eigen frequencies define the damped critical speeds and the stability of the rotor system. The rotors, supported in fluid-film bearings, are calculated independently, using the Holzer method for torsional vibrations and the Myklestad-Prohl method for lateral vibrations, after which they are coupled through impedance matching at the gear meshes. The resulting equations are solved for the unknown mesh contact forces, and the roots of the coefficient matrix determinant give the eigenvalues of the system. The method is efficient and readily programmed.
Mechanical Reliability Confidence Limits
Authors: Kececioglu D. , Lamarre G.
Published: November 2010

Charts are presented relating the lower one-sided confidence limit on the reliability, RL1, to the effective sample size, ne, calculated from the sample sizes used to estimate the failure governing stress and strength distributions, or f(s) and f(S) respectively, and a factor K which is a function of the estimated means and standard deviations of f(s) and f(S). These graphs cover an ne range of 5 to 1000, confidence levels of 0.80, 0.90, 0.95, and 0.99, and lower one-sided limits on the reliability of 0.85 to 0.9145. The equations used to develop these charts are derived and two examples of their applications are given.
On the Nonlinear Response of a Relief Valve
Authors: Dokainish M. A. , Elmadany M. M.
Published: November 2010

The free and forced response of a relief valve system has been analyzed. The valve system consists of a valve having a mass, resting on a seat having nonlinear spring characteristics, and retained by a helical spring which is considered to be a distributed parameter element. The response curves of the first and third harmonic and one-third subharmonic, the amplitudes of which vary with the frequency of the external force, are investigated and presented graphically. It is found that harmonic, higher-harmonic, and subharmonic response of the system may become unstable within certain frequency ranges. Jump and hysteresis phenomena analogous to that of nonlinear single-degree-of-freedom systems are observed. It is also observed that subharmonic vibration may exist in a number of specified frequency ranges.
Gear Mesh Excitation Spectra for Arbitrary Tooth Spacing Errors, Load and Design Contact Ratio
Authors: Remmers E. P.
Published: November 2010

The tendency for gear pairs to exhibit vibration, noise and dynamic tooth loads is influenced by tooth spacing errors, load, design contact ratio and profile modifications. This paper describes an analytical method for assessing the influence of these factors on the excitation force at the gear mesh for gears with a form of profile modification which gives zero excitation at design load in the absence of spacing errors. Amplitude modulation characteristics of the excitation spectrum are of interest since this effect often results from gear manufacturing processes. Tooth spacing errors tend to spread the gear mesh excitation energy over a band. Excitation orders inherent in the gear pair without spacing errors are reduced in amplitude, and the excitation energy shows up in closely adjacent side bands if the errors are a low order nature. Random type spacing errors tend to spread the excitation energy over a broad band while reducing the inherent components except near design load. This would tend to attenuate gear noise and dynamic tooth loads associated with resonant conditions of a gear system.
Model Formulation of Complex Mechanisms With Multiple Inputs: Part I—Geometry
Authors: Benedict C. E. , Tesar D.
Published: November 2010

As the first of two companion papers for the analysis of multi-degree of freedom mechanisms, this as Part 1 treats the geometry in terms of the subunit Assur groups. Explicit matrix formulations are given to establish the intermediate and total influence coefficients of the system geometry. A detailed presentation is given for the two-degree of freedom five-bar linkage to illustrate the application of the general formulation.
Multiport Models for the Kinematic and Dynamic Analysis of Gear Power Transmissions
Authors: Allen R. R.
Published: November 2010

The kinematics of a gear power transmission may be characterized by a power-conserving kinematic transformation between independent and dependent angular velocities. The conjugate of this transform provides a relation between input and output torques. A bond graph multiport representing these kinematic relations provides a power-conserving core to which dissipative, inertial, and compliance effects may be added. This dynamic model of a power transmission may be connected with other machine elements (such as other kinematic mechanisms, motors, driveshafts, and loads) to form large-scale, computable dynamic models. Bond graph techniques are shown to facilitate the process of developing and assembling computable dynamic models for the study of gear trains as elements of machine systems. A numerical example is presented.
A State Space Method for Optimal Design of Vibration Isolators
Authors: Hsiao M. H. , Haug E. J. , Arora J. S.
Published: November 2010

A state space method of optimal design of dynamic systems subjected to transient loads is developed and applied. In contrast to the conventional nonlinear programming approach of discretizing the time interval and constructing a high dimension nonlinear programming problem, a state space approach is employed which develops the sensitivity analysis and optimization algorithm in continuous state space, resorting to discretization only for efficient numerical integration of differential equations. A numerical comparison of the state space and conventional nonlinear programming methods is carried out for two test problems, in which the state space method requires only one-tenth the computing time reported for the nonlinear programming approach.
A Manual Approach to One-Dimensional Minimization
Authors: Afimiwala K. A. , Mayne R. W.
Published: November 2010

An interactive method for manually performing one-dimensional searches is presented. The user computes the function at selected points and the results at each iteration are graphically displayed. As the shape of the function becomes apparent the minimum is readily identified. An experiment was designed to compare the performance of the manual scheme with that of an automated one-dimensional minimization method. Statistical analysis showed that at low accuracies the subjects performed as well as the automated procedure and that there was no significant difference among them. However, at higher accuracies the user’s performance seemed to depend on his natural ability and his effective use of the options for magnifying the display.
Multiparametric Optimization of Four-Bar Linkages
Authors: Spitznagel K. L. , Tesar D.
Published: November 2010

An approach for selecting optimal four-bar linkages satisfying four coplanar multiply separated positions is presented. The mechanisms are synthesized by use of Burmester theory, and evaluation is made on the basis of 1) ‘necessary’ conditions, and 2) assigned weighting factors and regions as applied to various design criteria. Sequential expansions and evaluations in terms of compact collections of best linkages are used to approach optimum solution. An interactive computer program which handles all optimization calculations and related input is presented and discussed. The program is structured to allow the user a maximum of control over all stages of the optimization process. An example dealing with a realistically specified knee joint orthosis is included.
Elimination of Branch, Grashof, and Order Defects in Path-Angle Generation and Function Generation Synthesis
Authors: Waldron K. J. , Stevensen E. N.
Published: November 2010

Path-Angle Generation and Function Generation synthesis problems are restated as Plane-Position (or Motion Generation) problems, enabling the use of the classical Burmester technique and recent extensions that permit the avoidance of Branch, Grashof, and Order defects. An example of the solution of a Path-Angle Generation problem is given.
General Forms of Index Ratios and Generation of Variable Index Ratios by Series-Connected Geneva Mechanisms with Single or Multiple Driving Pins
Authors: Bagci C.
Published: November 2010

General forms of the index ratios in series-connected Geneva mechanisms having single and multiple driving cranks, including the cases of alternately driven slots and internal Geneva mechanisms, are given. Cases eliminating the jerk and acceleration at the beginning and end of the motion period are defined. Possible slot-number and pin-number combinations are investigated. Index ratios are defined in terms of a “parameter of variance.” By redefining the parameter of variance in a series-connected Geneva mechanism drive the new position of the crank driving the output Geneva wheel is redefined to generate a new value of the index ratio. Geneva mechanisms can be designed to generate index ratios that can be varied up to 346.9578. Along with the design equations, complete design tables are given for the selection of Geneva mechanism drives to generate constant or adjustable index ratios within desired range, thus broadening the design opportunities with Geneva mechanisms. Design examples are included.
Application of Optimization Techniques to the Production of Plastic Pellets
Authors: Johnson G. E. , Townsend M. A.
Published: November 2010

In this paper the manufacture of pellets from extruded plastic strands is treated as a constrained nonlinear programming problem. Complete model development is given. The advantages and disadvantages of various optimization strategies and algorithms are discussed; a solution is also obtained by Johnson’s Method of Optimum Design (MOD). Substantial increases in production rates are indicated with attendant favorable changes in the energy consumed in the production of a unit mass of product.
A Method of Optimum Design
Authors: Johnson R. C.
Published: November 2010

Paper describes a method of optimum design (MOD) having many practical applications, particularly in mechanical engineering design. Topics covered for this MOD include its evolution, the basic procedural steps, classes of problems, some general strategy for execution, unique features, and limitations. Finally, several examples are presented which illustrate specifically some of the characteristics and features of this MOD.
A Parametric Study of Elastic-Plastic-Creep Buckling of a Thin Cylindrical Shell
Authors: Berman I. , Chern J. M. , Gupta G. D.
Published: November 2010

The elastic-plastic-creep buckling of a long thin cylindrical shell with initial out-of-roundness subjected to uniform external pressure is herein studied. The work is carried out by means of an economical computer program which consistently accounts for the effects of load changes and plastic strains and which has a calculation procedure based on direct integration. The ratio of the sustained load to the initial buckling load is discovered to be a parameter which relates the sustained load to the buckling time without explicit reference to the geometric parameters for the conditions considered. Other results are uncovered concerning the effect of: the shape of the imperfection, the temperature variations and the choice of creep relations on initial buckling load and buckling time. Alternatives to the expensive and time consuming calculations to meet the requirements of the time factor of safety on Code Case 1331 of the ASME Boiler and Pressure Vessel Code for Class 1 nuclear components are explored. Recommendations are made.
Low Cycle Fatigue of Nuclear Pipe Components
Authors: Heald J. D. , Kiss E.
Published: November 2010

This paper presents the results of low-cycle fatigue testing and analysis of 26 piping components and butt-welded sections. The test specimens were fabricated from Type-304 stainless steel and carbon steel, materials which are typically used in the primary piping of light water nuclear reactors. Components included 6-in. elbows, tees, and girth butt-welded straight sections. Fatigue testing consisted of subjecting the specimens to deflection-controlled cyclic bending with the objective of simulating system thermal expansion type loading. Tests were conducted at room temperature and 550 deg F, with specimens at room temperature subjected to 1050 psi constant internal hydraulic pressure in addition to cyclic bending. In two tests at room temperature, however, stainless steel elbows were subjected to combined simultaneous cyclic internal pressure and cyclic bending. Predictions of the fatigue life of each of the specimens tested have been made according to the procedures specified in NB-3650 of Section III[1] in order to assess the code design margin. For the purpose of the assessment, predicted fatigue life is compared to actual fatigue life which is defined as the number of fatigue cycles producing complete through-wall crack growth (leakage). Results of this assessment show that the present code fatigue rules are adequately conservative.
Simplified Second Stage Creep/Relaxation Analysis of Moderately Complex Spatially Three-Dimensional Piping Systems
Authors: Workman G. H. , Rodabaugh E. C.
Published: November 2010

An analysis technique for predicting the second stage creep/relaxation response of moderately complex spatially three-dimensional piping systems is presented herein. The theoretical development of this technique is based on two major assumptions. The first assumption is that at any time the behavior of the piping system can be associated with two components. One is an elastic component which is recoverable, and the other is a creep/relaxation component, which is not recoverable. The second major assumption, the simplifying assumption, is that the creep/relaxation strains due to axial, bending, and torsional loading can be decoupled and strains due to internal pressure can be neglected. Utilizing small displacement linear strain assumptions, the elastic stress-strain and creep/relaxation stress-strain rate laws can be integrated over the pipe’s cross section to yield generalized force-deformation relationships. The method of initial strains associated with the matrix displacement method of structural analysis is now applied to generate the solution of the creep/relaxation problem. This formulation utilizes two distinct types of piping elements. The first is a straight uniform pipe element and the second is a circularly curved pipe element, which incorporates both elastic and creep/relaxation flexibility factors. The end result of this formulation is a digital computer program capable of analyzing spatially three-dimensional piping systems under creep/relaxation conditions that can be represented by a series of straight or circularly curved pipe elements subjected to applied forces, displacements, and/or thermal change. An example analysis is included.
A J Integral Analysis for the Compact Specimen, Considering Axial Force as Well as Bending Effects
Authors: Merkle J. G. , Corten H. T.
Published: November 2010

An important fracture mechanics problem is the determination of fracture toughness values with small specimens that fail after yielding. The J integral has an explicit meaning in terms of notch tip conditions in the plastic range and can be calculated from a single specimen test data. In this paper, an improved J integral analysis is developed for the compact specimen by considering the combined loading that exists on the net section. The analysis agrees with linear elastic fracture mechanics in the elastic range and gives a result close to that given by the equivalent energy method in the plastic range.
Elastic-Plastic Analysis of Blunt Notched CT Specimens and Applications
Authors: Wilson W. K.
Published: November 2010

An elastic-plastic plane strain analysis of blunt notched compact tension specimens used in fatigue crack initiation tests is presented. Using this analysis it is shown that under conditions of constrained plastic flow in the notch region, the functional relationship between total notch strain and an elastically calculated notch stress is nearly the same for different notch sharpnesses. This material dependent functional relation is shown to hold for some other geometric stress concentrations as well. Under conditions where this relationship is the same it should be possible to correlate fatigue crack initiation data by means of the elastically calculated notch stress.
Energy Approach for Creep-Fatigue Interactions in Metals at High Temperatures
Authors: Fong Jeffrey T.
Published: November 2010

An analysis of the so-called creep-fatigue interactions in a reannealed AISI type 304 stainless steel with and without holdtime at 593 deg C (1100 deg F) is presented with a numerical example. The analysis is based on a series of papers on the thermodynamics of materials exhibiting both time-dependent and permanent-set behavior under mechanical and/or thermal loadings [15–18]. Assuming isothermal loadings, the analysis consists of an “operational” decomposition of the total mechanical work into a stored part (long-term elasticity), and two dissipated parts, namely, an instantaneous component and a delayed component due to viscoelasticity. Each of the two dissipated components is again subdivided, operationally, into an “intrinsic” part (atomic diffusion and motion of dislocations), and a “structural” part (lattice strains and propagation of microcracks). The significance of the energy approach in unifying microscopic and macroscopic testing data and in formulating multi-axial design criteria for high-temperature components such as pressure vessels, turbine rotors, steam piping, etc., is discussed.
Propagation and Opening of a Through Crack in a Pipe Subject to Combined Cyclic Thermomechanical Loading
Authors: Hsu T. R. , Bertels A. W. M.
Published: November 2010

The present investigation deals with the propagation and opening of a single crack in a thin wall pipe subject to cyclic pressure and thermal loading. A thermoelastic-plastic analysis based on the finite element variational technique is used to calculate the stress and displacement fields in the vicinity of the growing crack. A special type of element known as a “breakable element” is developed to model the gradual propagation of the crack. Kinematic work hardening is included to account for the Bauschinger effect of the pipe material when subjected to cyclic plastic deformation.
Mechanical Properties of Roll Extruded Nuclear Reactor Piping
Authors: Steichen J. M. , Knecht R. L.
Published: November 2010

The elevated temperature mechanical properties of large diameter (28 in.) seamless pipe produced by roll extrusion for use as primary piping for sodium coolant in the Fast Flux Test Facility (FFTF) have been characterized. The three heats of type 316H stainless steel piping material used in this study exhibited very consistent mechanical properties and chemical compositions. Tensile and creep-rupture properties exceed values on which the allowable stresses for ASME Code Case 1592 on Nuclear Components in Elevated Temperature Service were based. Tensile strength and ductility were essentially unchanged by aging in static sodium at 1050°F (566°C) for times to 10,000 hr. High strain rate tensile tests showed that tensile properties were insensitive to strain rate at temperatures to 900°F (482°C) and that for temperatures of 1050°F (566°C) and above both strength and ductility significantly increased with increasing strain rate. Fatigue-crack propagation properties were comparable to results obtained on plate material and no differences in crack propagation were found between axial and circumferential orientations.
Analysis of Fatigue-Crack Growth in a High-Strength Steel—Part II: Variable Amplitude Block Loading Effects
Authors: Sullivan A. M. , Crooker T. W.
Published: November 2010

To investigate load sequencing effects in fatigue-crack growth, surface flaw or part-through crack (PTC) specimens of a high-strength pressure vessel steel were subjected to variable-amplitude cyclic loading. Blocks of different load sequences and stress-ratio (R) patterns and cyclic lengths were employed. Crack-growth rate (da/dN) data were analyzed within the framework of linear elastic fracture mechanics using the stress-intensity range parameter, ΔK. The da/dN data were found to correlate well with a seauence-independent formulation of ΔK derived using nominal mean stress, σm, for the loading blocks studied. However, it proved necessary to utilize the normalizing relationship discussed in “Analysis of Fatigue-Crack Growth in a High-Strength Steel—Part I: Stress Level and Stress Ratio Effects at Constant Amplitude”, to account for stress-ratio effects observed under the variable-amplitude block loading. Only the sequential block pattern of high-low-intermediate produced a significant crackgrowth retardation. Predictions made using the sequence-independent normalizing procedure compare favorably with those using the Willenborg model. It is concluded that useful predictions for structural life under variable-amplitude cyclic loading sequences can be made for a wide variety of high-strength pressure vessel applications using sequence-independent analysis procedures.
Shear Fracture Propagation by DCB Testing
Authors: Koshiga F. , Kurita Y. , Akiyama T. , Kawahara M.
Published: November 2010

A shear fracture propagation in steel was investigated with the aid of spring-loaded DCB testing, that was developed as a laboratory simulation test of shear fracture propagation in pressurized gas pipelines. The dynamic aspects of fracture propagation were studied experimentally, mainly to obtain an average strain rate as well as strain distribution ahead of propagating shear crack with high velocity. Taking into account the influence of strain rate, experimental results were analyzed with a simple Dugdale model on steels of different toughness or of different ductility. Thus, an associated critical strain turned out to be a material resistance against shear fracture propagation, which is insensitive to propagation velocity. This material resistance was well correlated to uniform elongation in static tensile test. The correlation between material resistance and Charpy shelf energy is also discussed.
Increasing the Fracture Resistance of Cemented Carbides During the Drilling of Iron Ores
Authors: Peck J.
Published: November 2010

Investigation shows that there is a preferred cobalt content for a given hardness of a cemented carbide insert when used in a bit which is drilling iron ore. Two parameters determine the hardness of a cemented carbide: cobalt percent and tungsten carbide grain size. By manipulating these two parameters, a number of cemented carbide materials can be made which have the same hardness. Three iron-ore drilling tests have been conducted where test bits contained materials having essentially the same hardness, but where the materials were varied through a range of cobalt content and tungsten carbide grain size. Graphs are presented which depict the effect on fracture resistance of varying the cobalt content-tungsten carbide grain size. In each test, one material showed superior fracture resistance. The test bits drilled iron ores such as hematite or taconite.
Pressurized Cylindrical Shell With a Rigid Circular Inclusion
Authors: Bonde D. H. , Rao K. P.
Published: November 2010

The effect of a rigid circular inclusion on stresses in a cylindrical shell subjected to internal pressure has been studied. The two linear shallow shell equations governing the behavior of a cylindrical shell are converted into a single differential equation involving a curvature parameter and a potential function in nondimensionalized form. The solution in terms of Hankel functions is used to find membrane and bending stressses. Boundary conditions at the inclusion shell junction are expressed in a simple form involving the in-plane strains and change of curvature. Good agreement has been obtained for the limiting case of a flat plate. The shell results are plotted in nondimensional form for ready use.
Propagating Buckle Arrestors for Offshore Pipelines
Authors: Johns T. G. , Mesloh R. E. , Sorenson J. E.
Published: November 2010

When an underwater pipeline is buckled in the presence of sufficient external pressure, a propagating buckle is initiated, and the buckle front will propagate along the pipeline until a region of much less external pressure is reached. This paper describes the results of experimental research on methods of arresting the advancement of a propagating buckle along the pipeline. The arresting capacities of three types of buckle arrestors conceived during this program, free-ring, welded-ring, and heavy-walled section arrestors, are described in detail. Results of propagating pressure experiments are also presented.
The Background of ASME Code Case 1828: A Simplified Method of Analyzing Part B Flanges
Authors: Schneider R. W. , Waters E. O.
Published: November 2010

The 1974 Edition of ASME Boiler and Pressure Vessel Code Section VIII, Division 1, provides rules for the analysis and design of identical pairs of Part B flanges (flat face flanges in metal-to-metal contact). The theory has been extended on a consistent basis to cover the analysis of a pair of nonidentical Part B flanges but since the resulting procedure is laborious, action to include the rules has been delayed pending further consideration by the cognizant ASME Code Committees. In the interim a simplified method suitable for analyzing both identical and nonidentical pairs of Part B flanges has been developed and is available as ASME Code Case 1828: “A SIMPLIFIED METHOD FOR ANALYZING PART B FLAT FACE FLANGES WITH METAL-TO-METAL CONTACT OUTSIDE THE BOLT CIRCLE.” The purpose of this paper is to describe the simplified method and to derive some of the more important equations which are contained in the Code Case.
The Forces on a Cylinder Oscillating Sinusoidally in Water: Further Experiments
Authors: Dalton C. , Hunt J. P. , Hussain A. K. M. F.
Published: November 2010

This paper deals with wave forces on a single cylinder. The wave forces are simulated in a laboratory by oscillating a cylinder sinusoidally in water otherwise at rest. This effort is a parametric study relating a force coefficient to such variables as instantaneous Reynolds number, period parameter, and d/νT. The force is not decomposed into drag and inertia components, but is represented as a continuous function of the previously mentioned parameters. The idea is to determine how the acceleration affects the force. Considerable deviation from a Reynolds-number only dependence is noted for low Reynolds numbers. The steady-flow drag coefficient value is asymptotically obtained for large Reynolds numbers.
Elastic and Elastic-Plastic Buckling of Internally Pressurized 2:1 Ellipsoidal Shells
Authors: Galletly G. D.
Published: November 2010

Elastic and elastic-plastic buckling pressures for internally-pressurized 2:1 ellipsoidal shells with diameter-thickness ratios in the range 750 < D/t < 1500 are given in the paper. The effects of σyp, E and linear strain hardening on the buckling pressures were investigated and both flow and deformation theories utilized. Some experimental/theoretical correlations are also given. The elastic pcr’s differ from some which have been published recently and the elastic-plastic pcr’s are believed to be new. For steel shells, flow and deformation theories sometimes gave contradictory buckling predictions but this was not the case with the aluminum shells which were investigated.
Analysis of Elastic-Plastic Plates and Shells Under Cyclic Loading
Authors: Neale K. W. , Nazli Z.
Published: November 2010

The behavior of elastic-plastic plate and shell structures under repeated loading is considered. The typical problem is formulated in incremental or “rate” form, and a variational method is applied to furnish an approximate solution in a stepwise fashion. In the analysis, Ziegler’s model of kinematic hardening is adopted together with a generalization of Masing’s rule for multi-axial stress states in order to describe material response under cyclic loading. Examples of application of the analysis include cylindrical shells and circular plates subjected to cyclically varying loads. The accuracy of the approximate solution in each case is assessed through a comparison of numerical results with published experimental data for monotonic loading conditions.
Bursting Pressure as the Basis for Cylinder Design
Authors: Manning W. R. D.
Published: November 2010

This paper gives a brief account of the developments carried out in the Northwich, England, laboratories of Imperial Chemical Industries Limited (ICI) which led to this method of design being used in the first commercial high-pressure polyethylene plant, which went on stream in 1939 at a working pressure of 150 MPa (approximately 22,000 psi). The essential requirement was to determine the lowest value of the bursting pressure, but the difficulty in this is that experimenters tend to get erroneously high values because they raise the pressure too fast. An analytical approach, based on stress/strain relations derived from torsion tests, was therefore developed for comparison. The problems of increasing scale were then resolved by building and operating progressively larger laboratory vessels, leading to those of 10-liter capacity which were used for the polyethylene pilot plant in 1937, operating at pressures up to 200 MPa (approximately 29,000 psi).
Fracture in Straight Pipes Under Large Deflection Conditions—Part II: Pipe Pressures
Authors: Love W. J. , Emery A. F. , Kobayashi A. S.
Published: November 2010

A finite difference hydrodynamic code was developed to determine the pressures in a dumbbell pipe configuration when a through crack in the pipe wall was permitted to run along the length. Computations were made for hot water pressurized pipes for two different situations: the crack tips were cusp shaped, restricted in maximum opening, and moved at prescribed subsonic or supersonic speeds; the crack configurations were computed by iterating with the structural code (Part I). The pressurized water computations were made with special equations of state for the two-phase flow in the channel and in the crack exit plane. Significant differences in pressure profiles were obtained for the supersonic and subsonic crack speeds. The air calculations were implemented by use of the perfect gas equations of state to evaluate the differencing system, its stability and the effects of the cross-sectional area change and sonic choking. The air computations followed the exponential pattern suggested by Kanninen’s simplified model when no channel choking downstream of the crack tip occurs.
Review of Lower-Bound Limit Analysis for Pressure Vessel Intersections
Authors: Biron A.
Published: November 2010

On the basis of a study of several recent papers concerned with the lower-bound computation of the collapse load of pressure vessel intersections, a review is made of the satisfaction, or nonsatisfaction, of the requirements of the lower-bound theorem of limit analysis. It is shown that, whereas for rotationally symmetric structures true lower bounds have been obtained, for a nonsymmetric case such as a right cylinder-cylinder intersection it is difficult to avoid so me approximations. If attempts are to be made to develop general purpose limit analysis programs, the consequences of approximations of the type used so far must be evaluated with care if significant results are to be obtained.
Fatigue Crack Propagation in A533B Steels
Authors: Wilson A. D.
Published: November 2010

The influence of steelmaking practice on the fatigue crack propagation behavior of A533B low alloy plate steels is examined. Conventional practice, calcium-treated and electroslag-remelted steels were investigated in 6 specimen orientations. A significant improvement in the isotropy of fatigue crack growth rates and a consistent overall improvement in fatigue crack growth rate were found in going from the conventional practice, to the calcium-treated, to the electroslag-remelted materials. The fatigue crack growth rate differences within a material and between materials were attributed to material differences in nonmetallic inclusion quantities and morphologies.
Determination of Stress Intensity Factors for Gradient Stress Fields
Authors: Bloom J. M. , Van Der Sluys W. A.
Published: November 2010

This paper evaluates eight different analytical procedures used in determining elastic stress intensity factors for gradient or nonlinear stress fields. From a fracture viewpoint, the main interest in this problem comes from the nuclear industry where the safety of the nuclear system is of concern. A fracture mechanics analysis is then required to demonstrate the vessel integrity under these postulated accident conditions. The geometry chosen for his study is that of a 10-in. thick flawed plate with nonuniform stress distribution through the thickness. Two loading conditions are evaluated, both nonlinear and both defined by polynomials. The assumed cracks are infinitely long surface defects. Eight methods are used to find the stress intensity factor: 1–maximum stress, 2–linear envelope, 3–linearization over the crack length from ASME Code, Section XI, 4–equivalent linear moment from ASME Code, Section III, Appendix G for thermal loadings, 5–integration method from WRC 175, Appendix 4 for thermal loadings, 6–8-node singularity (quarter-point) isoparametric element in conjunction with the displacement method, 7–polynomial method, and 8–semi-infinite edge crack linear distribution over crack. Comparisons are made between all eight procedures with the finding that the methods can be ranked in order of decreasing conservatism and ease of application as follows: 1–maximum stress, 2–linear envelope, 3–linearization over the crack length, 4–polynomial method, and 5–singularity element method. Good agreement is found between the last three of these methods. The remaining three methods produce nonconservative results.
The Compression of Thick-Walled Tubes by External Pressure
Authors: Llorens R. E.
Published: November 2010

In a previous work the author enunciated a procedure for the analysis of tension specimen subjected to high pressure. Utilizing these results to define the work-hardening function the present paper attempts to ascertain the external pressure to which a thick-walled tube must be subjected to develop a given deflection at the internal surface of the member. It is found that the predictions of both the distortion energy and maximum shear theories are approximately one standard deviation higher than the experimental results of Bridgman. Thus, both sets of computations lie within the limits of experimental scatter with the calculations of the maximum shear theory representing a slight improvement over those of the distortion energy theory.
Experimental Stress Analysis for Four 24-in. ANSI Standard B16.9 Tees
Authors: Hayes J. K. , Moore S. E.
Published: November 2010

This paper describes the experimental stress analysis of low cycle fatigue tests of four tees tested by Combustion Engineering, Inc. (C-E) under subcontract to Union Carbide Nuclear Division. These tests are part of the ORNL Design Criteria for Piping and Nozzles Program which is being conducted for the development of design criteria for nuclear power plant service piping components. The test assemblies were fabricated at C-E from commercially obtained ANSI B16.9 tees and matching diameter steel pipes welded to the tees, with suitable end closures and fixtures for applying the loads. The tees tested and discussed in this report are described in the following: Tee Number/Material/Nominal Size: T–11/carbon steel/24″×24″×24″ sch 160; T–12/carbon steel/24″×24″×10″ sch 40; T–13/carbon steel/24″×24″×10″ sch 160; T–16/stainless steel/24″×24″×24″ sch 10. Each tee test assembly was instrumented with approximately 240 rectangular strain gage rosettes for determining elastic stress distributions, and six linear variable displacement transducers for determining flexibility factors. Elastic-response tests were conducted for 12 loading conditions consisting of internal pressure, pure bending and torsional moments and direct force loads applied individually to the branch pipe extension and to one end of the run pipe. The other run pipe extension was fixed rigidly to the loading frame. Automatic data handling equipment and data reduction techniques were used to process the strain gage readings. For each loading condition, stress distributions were determined and the locations and magnitudes of the maximum stresses were identified. Test results are presented and compared with appropriate design formulas of the ASME Boiler and Pressure Vessel Code, Section III. After the elastic-response tests were completed, three of the tees were low-cycle fatigue tested by pressure cycling using transformer oil. The T-11 and T-13 tees were pressure cycled for 100 psig (790 kPa) to 7000 psig (48 360 kPa); whereas, the T-12 tee was pressure cycled from 0 psig (100 kPa) to 1800 psig (12 510 kPa). A low-cycle fatigue test was performed on the T-16 tee assembly by applying a bending moment to the branch pipe in the plane of the tee with the tee pressurized to a constant internal pressure of 300 psig (2170 kPa). All low-cycle fatigue tests were performed until a through-the-wall fatigue crack occurred as evidenced by a leak. Subparagraph NB-3653.6 of ASME Code, Section III, Division I, Nuclear Power Plant Components was used to calculate the fatigue design life and comparisons were made with the experimentally determined fatigue life.
Seismic Design Study on Cantilever Cylindrical Shells
Authors: Wu J. N. C. , Cory J. F.
Published: November 2010

The best way to design a nuclear steam generating system to withstand seismic stresses is to establish a mathematical model, to which seismic loading can be applied, to determine the dynamic responses of the system. A practical approach for establishing such a model is to idealize the components in terms of beam elements which form the essential building blocks of the analytical model. The major shell structures of reactor vessels and steam generators are usually supported at a single elevation in the system, and are often simulated by cantilever beam elements. The use of a beam element to represent shell structure must be justified. This paper presents the results of a parametric study of thin-walled cylindrical shells which are clamped at one end while the other end is free. By using 3-D plate/shell finite element analysis, the region of application, where the beam element can reasonably simulate to shell structure, has been defiined as the combination of its geometrical parameters, e.g., the thickness/radius and length/radius. As an illustrative example, the 3-D finite element method has been used to investigate the seismic analysis of a cantilever cylindrical shell similar to the Clinch River LMFBR reactor vessel. The numerical values are compared with those produced by a beam element model. The results and conclusions obtained by this investigation can be applied to improve dynamic modeling techniques in general.
Downhole Measurements of Thermal Conductivity in Geothermal Reservoirs
Authors: Murphy H. D. , Lawton R. G.
Published: November 2010

The line source method of determining thermal conductivity is extended to include the transient effect associated with the fluid in flowing geothermal wells. The general equations describing transient heat flow are utilized. Approximate solutions are derived and compared to the exact solution of the general equations. The proposed method is operationally simple since the heater, and the associated problems of obtaining adequate thermal contact between the heater and the sides of the borehole are eliminated. Using this method downhole measurements were obtained and favorably compared with laboratory measurements on characterized core specimens taken from wells in a hot dry rock geothermal reservoir.