bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Tests of the Scaling Laws for Air Clearing in Water-Type Pressure Suppression Systems
Authors: Anderson W. G. , Huber P. W. , Sonin A. A.
Published: November 2010

Experiments were conducted to test the validity of the scaling laws which have been put forward for the small-scale modeling of the air clearing phase of flow into the condensation pool of a pressure suppression system. Three geometrically similar wetwells (differing in linear dimension by a factor of 4) were used, along with two liquids (differing in density by a factor of 3) and three gases (differing in enthalpy by a factor of 10). When using different pressures, liquids, and gases, the dimensionless pressures were in excellent agreement as long as the four scaling parameters were held constant. The enthalpy flux must be scaled by the use of an orifice to ensure that the pressures will scale. Our tests uncovered two areas where the scaling laws will not hold if the proper precautions are not taken. First, the vapor pressure of the pool liquid must be sufficiently low. Secondly, peak downloads will scale only if the containment walls are rigid and precautions are taken to eliminate small air bubbles in the liquid.
An Experimental Study of Natural Convection Heat Transfer in Concentric and Eccentric Horizontal Cylindrical Annuli
Authors: Kuehn T. H. , Goldstein R. J.
Published: November 2010

An experimental study has been conducted to determine the influence of eccentricity and Rayleigh number on natural convection heat transfer through a fluid bounded by two horizontal isothermal cylinders. Eccentricity of the inner cylinder substantially alters the local heat transfer on both cylinders, but the overall heat transfer coefficients change by less than 10 percent over the range of eccentricities investigated. Heat transfer results using the concentric geometry are given for Rayleigh numbers from 2.2 × 102 to 7.7 × 107 which includes regions of conduction, laminar convection, and partially turbulent convection.
Two-Phase Flow on the Shell-Side of a Segmentally Baffled Shell-and-Tube Heat Exchanger
Authors: Grant I. D. R. , Chisholm D.
Published: November 2010

This paper reviews work carried out at the National Engineering Laboratory, UK., related to pressure drop flow patterns and phase distribution on the shell-side of segmentally baffled shell-and-tube heat exchangers. The experimental work reported was carried out using air/water mixtures in model exchangers of rectangular cross section with tube nests containing approximately 40 tubes. Data were obtained on crossflow pressure drop and on the pressure drop attributable to the windows. In certain configurations the void fraction and flow pattern maps were obtained. The geometric conditions examined related to configurations appropriate to operation as condensers and boilers. Correlations for pressure drop and void fraction were developed and flow pattern maps obtained.
Band Radiation within Diffuse-Walled Enclosures—Part I: Exact Solutions for Simple Enclosures
Authors: Nelson D. A.
Published: November 2010

Exact radiative transfer solutions for an isothermal medium confined within an isothermal enclosure are given for the planar, cylindrical and spherical configurations. The emphasis is upon band radiation and diffuse reflections. Specular reflections are also considered because solutions are easily obtained and are of interest for comparative purposes as well as intrinsic value.
A Numerical Study of Three-Dimensional Roll Cells within Rigid Boundaries
Authors: Chan A. M. C. , Banerjee S.
Published: November 2010

Three-dimensional natural convection, roll cells within rigid enclosures have been studied with a previously developed numerical technique based on the marker and cell method. Given identical initial conditions, the velocity and temperatures fields are found to be sensitive to the thermal boundary conditions on the side walls and the aspect ratio of the enclosure. Two-dimensional results are also obtained and compared with the corresponding three-dimensional results. The two-dimensional calculations do not agree well with the three dimensional ones, especially for enclosures having aspect ratios less than unity. This indicates that care must be taken in analyzing natural convection problems of this type with two-dimensional methods.
Three-Dimensional, Steady-State Heat Conduction in Cylinders of General Anisotropic-Media
Authors: Chang Y. P. , Poon K. C.
Published: November 2010

This paper provides the analytical solution of three-dimensional steady-state heat conduction in solid and hollow cylinders of general anisotropic-media. By the use of Fourier transforms and a change of variables the partial differential equation is reduced to Kummer’s equation. Some calculated results for a solid cylinder are shown and discussed. A parameter γ is found to represent the coupling effect of three-dimensional anisotropy. For small values of γ, an approximate solution is recommended. The inequality σ > 0 which was found in an earlier paper is further discussed.
Further Contributions to the Study of the Leidenfrost Phenomenon
Authors: Betta V. , Mazzei P. , Naso V. , Vanoli R.
Published: November 2010

Experimental values of both the minimum wall temperatures for spheroidal state and the total vaporization times of water, n-octane and carbon tetrachloride drops are presented. A novel apparatus was used and tests were run in a wall temperature range scarcely investigated by other authors. Vaporization times are compared with correlations accounting for the diffusive evaporation and these are suggested to be applied in ranges different from those recommended by the authors.
A Study of Lubricated Direct-Extrusion Process of High-Strength and
High-Melting-Point Materials, With Isothermal Surface of Die and
Container
Authors: Hsu Y. C.
Published: November 2010

Numerical solutions for an isothermal case are presented for the direct extrusion process of a cylindrical body with viscous plastohydrodynamic lubrication at high operating temperature and pressure. The extrusion pressure at die predicted by the present theory, and measured correspondingly by experiment are seen to agree well. As such, this agreement supports the validity of the assumptions in the present theory. For this typical experimental case, the additional data, which are not measured by experiment, are calculated by the present theory. Furthermore, a more fundamental understanding is provided for design data with regard to the interaction of the physical parameters such as extrusion ram speed, percent reduction in area, half of the included die angle, preheat billet temperature, exit pressure of lubricant film, lubricant properties, and extruded materials. These design data are offered in a form whereby they may be applied broadly to a variety of practical direct extrusion processes.
Helical-Grooved Journal Bearing Operated in Turbulent
Regime
Authors: Chow C. Y. , Vohr J. H.
Published: November 2010

An analysis for helical bearings operated in turbulent regime, with negligible inertia in an incompressible fluid film, was performed [10, 11]. The analysis is based on the linearised lubrication theory developed by Ng and Pan [4]. The outlines for this analysis and, in particular, the bearing performance data for various helical groovings are given in this paper. The data presented include the bearing performance at the steady state, the stiffness and damping coefficients, and the critical mass of journal in both laminar and turbulent regimes. To facilitate designs, these data are computed for optimal geometries of helical grooved bearings to provide maximum radial stiffness at various Reynolds numbers. In addition, the effect of external pressurized supply of lubricant are shown in the performance curves.
Squeeze Film Bearing for the Elimination of Oil Whip
Authors: Sweet Joel , Genin Joseph
Published: November 2010

In this paper we demonstrate that with sufficient external damping the bearing instability known as oil whip, commonly observed in rotating systems, can be eliminated. However, the amount of external damping required to alter the undamped case is prohibitive. This leads to the development and analysis of a mathematical model for a squeeze film bearing. We show that it can supply the necessary external dissipative force required to eliminate the oil whip phenomenon.
The Dynamic Characteristics of a Turborotor Simulator Supported on Gas-Lubricated Foil Bearings—Part 3: Rotation in Foil Bearings of Reduced Length, With Starting and Stopping Unaided by External Pressurization
Authors: Licht L.
Published: November 2010

Experiments and analysis, reported in detail in references [1] through [5], demonstrated that high-speed rotors, supported by foil bearings, were free from whirl-instability and sensitivity to excitation at frequency equal one half the speed of rotation. It was shown also that the foil bearing could accommodate thermal and geometrical distortions, combining this attribute with excellent wipe-wear characteristics and tolerance of particles. The present investigation was directed toward the solution of two important problems: (a) the reduction of foil bearing length without detriment to rotor performance, and (b) the elimination of the foil-lift system and attainment of multiple start-stops without the aid of external pressurization. A description of experimental methods, which lead to the realization of the foregoing objectives, is given.
Stability Considerations for a Gas-Lubricated Tilting Pad Bearing—Part 2: Analytical Refinements and Stability Data
Authors: McCabe J. T. , Chu T. Y. , Elrod H. G.
Published: November 2010

A method for generating the film response of a single gas-lubricated tilting pad journal bearing is derived and it is shown how the results can be used to provide both steady-state and stability data for a three pad bearing. The nature of tilting pad bearing stability is discussed with the aid of frequency response plots, mode shape computations and two illustrative limiting cases. In the first, the bearing pivots are locked and the shaft is free to translate; in the second, the rotor is restrained from translating but the pads are free to pitch. Finally, a design example is given and a comparison is made between a three shoe bearing with design data based on the step-jump method and a four shoe bearing with design data based on the frequency response method.
Oil Flow Through Journal Bearing
Authors: Kulkarni G. R.
Published: November 2010

Oil feed rate is an important parameter governing the operating characteristics of a journal bearing. In the present paper investigation is carried out to explore the effect of oil groove location and supply pressure on the oil feed rate to the bearing. These results are further used to get variation in Sommerfeld number and attitude angle for different oil groove locations and supply pressures. The results indicate that oil groove location has a great influence on oil feed rate to the bearing. It is also observed that oil supply arrangement does not have a significant influence on Sommerfeld number and attitude angle.
Nonlaminar Behavior in Bearings: A Critical Review of the Literature
Authors: Saibel E. A. , Macken N. A.
Published: November 2010

The state-of-the-art of nonlaminar behavior in bearings is presented. Analytical and experimental studies are discussed. It is pointed out that the basic flow field is still not clearly understood, and that there is much more information needed before design data can be accurately predicted.
The Excitability of Flexible Rotors in Short Sleeve Bearings
Authors: Hahn E. J.
Published: November 2010

Assuming the short bearing approximation and constant lubricant properties, the root loci of the pertinent characteristic function were obtained for the linearized model of a simple symmetric flexible rotor bearing system. Using these loci, design maps consisting of lines of constant damping and vibration frequency pertaining to the dominant roots are presented as a function of the equilibrium eccentricity ratio and a frequency parameter for relevant degrees of flexibility. These maps display undesirable operating regions where external disturbances such as shock or unbalance loading are likely to excite undesirable vibrations, as well as regions of instability. The maps may conveniently be used to determine the effect of changing journal speed, lubricant viscosity and/or bearing clearance. Increased flexibility is seen to reduce the stability threshold in a predictable manner and to reduce damping at the pin-pin critical speed. The approach is applicable to more complex rotor bearing systems. It is felt that the use of such maps will enhance the understanding of rotor bearing system behavior, particularly at operating regions close to the stability threshold.
Correlation of Magnetic Perturbation Inspection Data With Rolling-Element Bearing Fatigue Results
Authors: Parker R. J.
Published: November 2010

A magnetic perturbation technique was used to nondestructively detect subsurface non-metallic inclusions in the inner races of 207-size, deep groove ball bearings. The bearings were fatigue tested at 2750 rpm under a radial load of 5860 newtons (1320 lb). The inner races were subsequently sectioned at fatigue spall locations and at magnetic perturbation signal locations. Analyses of the data indicated good correlation between magnetic perturbation signals and inclusion size and location. Exclusion of those bearings that had significant magnetic perturbation signals did not alter the statistical life of the bearings.
Rheology of Lubricants in Real Bearing Contacts
Authors: Kannel J. W. , Bupara S. S.
Published: November 2010

Experimental traction-slip and lubricant film-thickness data have been determined for selected lubricants to provide information for use in conjunction with the design of lubricated machine elements. The traction-slip experiments were performed using a rolling-disk rheometer which closely simulates those conditions existent in real lubricated contacts; the film-thickness data were obtained using an X-ray technique. The range of experimental conditions included two rolling speeds (5000 and 10,000 rpm), several contact pressures [(690 – 2400 MN/m2) (100 to 350 ksi)], and three temperatures [(338, 366 and 423 K) (150, 200, and 300 F)]. The slip conditions imposed on the lubricants ranged as high as 6 m/s (1200 fpm) which is equivalent to a shear rate of approximately 0.5 × 108 sec−1. Interpretative analyses have been developed to infer basic lubricant properties from the experimental data. These analyses include time delay parameters and “dynamic” pressure-viscosity parameters. The analytical treatment of the data provides: (1) a generalization of the experimental data to apply over a wider range of conditions than those actually covered, and (2) a basis for comparing lubricants and obtaining a more fundamental understanding of lubricant behavior.
Analysis of an All-Metallic Resilient Pad Gas-Lubricated Thrust Bearing
Authors: Anderson W. J.
Published: November 2010

A new type of resilient pad gas thrust bearing that does not contain any elastomers in the bearing assembly is described and analyzed. The bearing consists of sector-shaped pads mounted asymmetrically on resilient foil beams. The effects of bearing design parameters on performance are shown. Performance of a resilient pad bearing is compared with that of a pivoted pad bearing.
Dissipative Heating Effects and End Corrections for Viscous Newtonian Flow in High Shear Capillary Tube Viscometry
Authors: Jakobson J. , Winer W. O.
Published: November 2010

The effect of dissipation heating on the apparent viscosity measured in capillary tube viscometry is described in this paper. Conditions of low Reynolds number and high shear are assumed. End corrections to the tube flow, found to be 3π/16 times the diameter of the tube, are incorporated. The flow curves show decreasing apparent viscosity when the shear stress increases. The configuration of the flow curves plotted in logarithmic presentation are found to be identical for fluids with Newtonian behavior. Convection is the predominant mechanism in removal of the heat in short capillary tube. The estimated upper bound for the shear stress obtainable in short length capillary tubes appears to be of the order of magnitude of 10 MPa limited primarily by the pressure drop associated with the constant end correction from the flat ended inlet and exit of the tube.
A Simplified Model for the Elastohydrodynamic Traction Between Rollers
Authors: Allen Charles W.
Published: November 2010

The elastohydrodynamic lubrication of two rollers in combined rolling and sliding is considered. A simple rheological model to predict the traction is presented. The model is based upon an exponential pressure dependent viscosity at low pressures and a linear shear stress/pressure relationship at high pressures. The slope of the latter is assumed to be a function of the rolling and sliding velocities. The model is used to analyze the traction data of two recently published experimental investigations of other authors and good agreement is achieved in most cases. The model should be of considerable use to designers in the preliminary analysis of rolling contact systems in combined rolling and sliding.
A Cantilever Mounted Resilient Pad Gas Thrust Bearing
Authors: Etsion I.
Published: November 2010

A gas thrust bearing consisting of flat sector shaped pads mounted on resilient metallic cantilever beams is described and analyzed. Compliance and stiffness of the bearing assembly are discussed and the effects of bearing design parameters on performance are shown. A design example is presented and a special case where zero axial movement of the runner can be obtained is pointed out.
Systems of Finite Elements for Finite Bearings
Authors: Allaire P. E. , Nicholas J. C. , Gunter E. J.
Published: November 2010

Systems of finite elements are organized using matrix notation for finite length bearings. Most fluid film bearings have surface areas which can be divided into a grid of elements whose nodes are labeled in matrix form. The resulting equations for nodal pressures are block tridiagonal and the solution is easily obtained with direct methods. Analysis of both general slider and journal bearings is included. The choice of how the film is divided into elements can significantly affect the error involved in the numerical solution and some criteria are developed for optimizing the division scheme. In the analysis of a square squeeze pad of uniform thickness, choosing the diagonal sides of elements nearly perpendicular to the pressure gradient direction gives an error in the calculated load carrying capacity of over two times that obtained by aligning element diagonal sides approximately with the pressure gradient direction. For rotating bearings, varying the grid spacing in the circumferential direction directly as the film thickness and properly choosing diagonal alignment can significantly reduce computer time.
Wear of Titanium and Titanium Alloys Under Conditions of Rolling Stress
Authors: Krause H. , Scholten J.
Published: November 2010

One of the most important conditions necessary for high-speed railway traffic is a clear reduction of the unsprung masses. The fact that even with light-weight wheelsets, the steel tires still constitute over 50 percent of the total weight, shows that it is here, by utilizing the lightweight materials, that the most promising possibility of weight reduction lies. For this reason, the frictional and wear behaviour of various titanium alloys was investigated and compared with that of normal steels. From the positive results, it would appear worthwhile carrying out further investigations under practical conditions as an adequate assessment cannot be obtained on the basis of the laboratory tests alone.
On the Transmissibility of Short Porous Journal Bearings
Authors: Cusano C. , Conry T. F.
Published: November 2010

The transmissibility characteristics of oil-lubricated porous journal bearings are analytically determined for a rigid rotor mounted in both the horizontal and the vertical positions. The bearing model used in this investigation is the short-bearing approximation with isothermal conditions and a 180-degree cavitated film. All data presented are for a range of unbalances that may commonly be encountered in practice. These data show that operating conditions exist for which porous journal bearings exhibit transmissibility characteristics that are superior to those of corresponding solid journal bearings. All data presented for porous bearings were obtained by using a bearing with a wall thickness-to-length ratio of 0.2.
Mechanism of Lubrication by Surrounding Gas Molecules in Adhesive Wear
Authors: Soda Norimune , Sasada Tadashi
Published: November 2010

To explain quantitatively the lubricating effect of gas molecules on adhesive wear, the authors have introduced a new concept of mean free time of a small contact point. When a bridge formed between two contact points is sheared off and a small clean surface is exposed to surrounding gases, it must have a free time t until it forms the next bridge when sliding. During this time t, the gas molecules attack the clean spot and can easily form a chemisorbed monolayer when the contact pressure p is low or when the sliding speed v is low. The authors have verified the fundamental relation between the mean free time t and the value pv, and have found that the critical transition point from the mild to severe wear corresponds to the condition where the mean free time of a sheared junction is just enough to be covered by the chemisorbed monolayer of surrounding gas molecules.
Radial Forces in a Misaligned Radial Face Seal
Authors: Etsion I.
Published: November 2010

Radial forces on the primary seal ring of a flat misaligned seal are analyzed, taking into account the radial variation in seal clearance. An analytical solution for both hydrostatic and hydrodynamic effects is presented that covers the whole range from zero to full angular misalignment. The net radial force on the primary seal ring is always directed so as to produce a radial eccentricity which generates inward pumping. Although the radial force is usually very small, in some cases it may be one of the reasons for excessive leakage through both the primary and secondary seals of a radial face seal.
Isothermal Hydrodynamic Lubrication in Hydrostatic Extrusion of a Work-Hardening Material
Authors: Thiruvarudchelvan S.
Published: November 2010

Using a numerical method the film thickness and the pressure distribution in hydrostatic extrusion of a work-hardening material under hydrodynamic conditions are determined. A minimum or critical speed for full fluid lubrication to develop is predicted. The effect of the length of die-land on the critical speed, and the effect of speeds above the critical speed on the extrusion pressure are also presented.
Squeeze Film Damping of Non-Newtonian Fluids
Authors: Shah J. , Hunt J. B.
Published: November 2010

In order to determine the overall dynamic response of a machine to a forcing function the damping effect of the bearings in the machine must be known. The damping effect of oil lubricated bearings has been widely published, but the squeeze film damping effect of grease lubricated bearings has hitherto been unestablished. It has been assumed in the past that the grease can be treated as a Newtonian fluid with a viscosity equal to that of the base oil. This assumption is shown to produce damping coefficients which overestimate the actual damping coefficient by up to a factor of 7.
Reflections on Some Aspects of Lubrication of Concentrated Line Contacts
Authors: Markho P. H. , Clegg D. B.
Published: November 2010

New formulas are presented for two important lubrication parameters of a flooded, concentrated line contact, namely the tangential pressure force component under elasto-hydrodynamic (EHD) conditions and the film thickness in the “intermediate” region defined by Dowson and Whitaker [1]. The latter region, which separates the rigid-isoviscous region from the elastic-piezoviscous (or EHD) region, has not, so far, been represented by an equation. The first formula was obtained simply by curve-fitting, using the method of least squares, from data largely available in the published literature; while the second is basically a third degree Hermite osculating polynomial with four end conditions.
Extremes of Morison-Type Wave Loading on a Single Pile
Authors: Moe G. , Crandall S. H.
Published: November 2010

A statistical estimate of the extreme wave force per unit length acting on a section of a fixed cylindrical pile in a random sea-state is derived. The random motion of the sea is described by a spectrum of wave heights in conjunction with linear wave theory. The wave force is assumed to depend linearly on the water particle acceleration and non-linearly on the water velocity according to the Morison formula. The interaction of the velocity and acceleration contributions and the contribution of a small steady current are accounted for by an asymptotic approximation valid for large forces. The expected rate of occurrences of extremes based on a simple peak definition agrees satisfactorily with a more elaborate result based on a true maximum definition. The formulas derived here provide a basis for a design-force procedure which could provide an improvement over the design-wave procedure commonly used for the analysis of offshore structures.
A Simple Stability Analysis for Flexible Rotors in Tilting Pad Bearings
Authors: Bulanowski E. A.
Published: November 2010

A simplified stability analysis for flexible rotors in tilting pad bearings is developed which provides a convenient and practical approach for the consideration of nonsynchronous vibrations during the design phase of rotor bearing systems. It is known that the synchronous unbalance response of a single mass Jeffcott rotor in linear isotropic bearings is identical in form to the response of a simple spring-mass-damper system excited by a rotating unbalance. This paper demonstrates that the free vibrations, and hence the system damping factor, of a distributed mass flexible rotor in tilting pad bearings may be analyzed using a single mass, two tier spring-damper model. The relationship between the system damping factor and rotor stability is discussed. Non-synchronous tilting pad bearing characteristics are incorporated into the expression for the damping factor, and nondimensional curves are presented which establish values of the damping factor as a function of operating speed, critical speed, bearing clearance and Sommerfeld number. The subject curves provide a quick method for establishing stability guidelines during rotor design and for comparing existing rotor bearing systems.
The Riccati Transfer Matrix Method
Authors: Horner G. C. , Pilkey W. D.
Published: November 2010

The Riccati transfer matrix method is a new technique for analyzing structural members. This new technique makes use of an existing large catalog of transfer matrices for various structural members such as rotating shafts. The numerical instability encountered when calculating high resonant frequencies, static response of a flexible member on a stiff foundation, or the response of a long member by the transfer matrix method is eliminated by the Riccati transfer matrix method. The computational time and storage requirements of the Riccati transfer matrix method are about half the values for the transfer matrix method. A rotating shaft analysis demonstrates the numerical accuracy of the method.
Bending Stress in Gear Teeth Having Circular Arc Profiles—Part 2: Experimental Investigation
Authors: Errichello R.
Published: November 2010

The results of a two-dimensional photoelastic investigation of the bending stress in the root fillets of gear teeth having convex, circular-arc profiles are presented. It is shown that the wedge theory predicts the compression stresses more closely than the Lewis equation. On the tension side of the tooth the Lewis parabolic model predicts the stresses more closely than the wedge model for low-pressure angles, but for pressure angles greater than 30 deg, the Lewis equation is inappropriate and the wedge theory predicts the tensile stress reasonably well.
Reliability of Machinery Using Fatigue Damage Accumulation Due to Random Vibrations
Authors: Xistris G. D. , Sankar T. S. , Ostiguy G. L.
Published: November 2010

A new approach to machinery maintenance using fatigue damage accumulation theory is presented. The vibration generated by industrial equipment is related to the stress history experienced by the internal machine elements at the corresponding measurement points assuming a linear elastic and isotropic behavior. The resultant stress history is modeled as a piecewise stationary, Gaussian wide band process. Employing Miner’s linear damage hypothesis in conjunction with available constant amplitude fatigue data, expressions for the expected accumulated fatigue damage and its variance are developed. A machinery maintenance program based on the accumulated damage parameters calculated directly from the properties of the exhibited vibration history is proposed. The main advantage of this method is that it provides equipment reliability in terms of known and measurable system properties.
On Certain Least-Squares Synthesis Methods Misconceptions
Authors: Sutherland G. H.
Published: November 2010

This paper shows a fundamental flaw in previously published linear superposition least-squares synthesis techniques. These techniques have the desirable noniteration characteristic. However, this paper shows, by a reformulation of the method, that they are based on a false premise. Numerical results bear this out. A Lagrange-multiplier technique is suggested as a superior alternative.
Design of an Extreme Crash Resistant Transport Package
Authors: Andersen J. A. , Duffey T. A.
Published: November 2010

A crashworthy package was developed for the air transport of plutonium. The package utilizes redwood, with embedded metal shells, for shock mitigation and fire retardation. The innermost structural element is a pressure vessel, with high sealing integrity under hydrostatic, crush, thermal, ballistic, and corrosive attack. The design was optimized for crash resistance, consonant with practical air transport requirements.
Design of Pressure Vessels for Elevated Temperature Service
Authors: Berman I.
Published: November 2010

Design of high reliability nulcear components for use at elevated temperatures is considered. The design is related to the design of structures at lower temperatures and structures with lesser reliability requirements. The application of Design by Analysis is considered in some detail. It is concluded that procedures in addition to Design by Analysis are required for reliable results at elevated temperatures. Some approaches are suggested.
Influence of Head Thickness on Yield Pressure for Cylindrical Pressure Vessels
Authors: Biron Andre´ , Veillon Jean
Published: November 2010

Results are presented for the limit analysis of pressure vessel heads of torispherical and ellipsoidal shapes in order to evaluate the influence of different head thicknesses for a given cylinder thickness. Comparison is made with presently used configurations as recommended by the ASME Code. It is found in particular that increasing the knuckle thickness of a torispherical head would provide a significant increase in yield pressure without excessive additional material.
Stationary Creep Stresses for Elliptical Cross-Sectional Pipe Bends Subject to In-Plane Bending
Authors: Spence J.
Published: November 2010

A theoretical analysis is presented which allows the determination of the stationary creep stresses acting in a smooth curved pipe of initially elliptical cross section when subject to in-plane bending. The bend is assumed to be of constant thickness and “thin” compared with its cross-sectional axes. The analysis is based on an energy approach and uses a simple power-type creep constitutive law. Results are presented in nondimensional fashion in terms of the maximum linear elastic beam bending stress in a straight tube. A large range of possible geometries is covered.
Vibration of a Fluid Conveying Pipe Carrying a Discrete Mass
Authors: Wu T. T. , Raju P. P.
Published: November 2010

This paper presents a method to predict the dynamic response of a fluid conveying pipe carrying a discrete mass when the flow velocity is less than its critical value. A general expression for the normal modes of a vibrating pipe with various boundary conditions is newly derived herein. Also presented for a particular case are the numerical results of eigenfunctions and eigenvalues which can be used to calculate the dynamic response of a simply-supported pipe with an attached discrete mass at its mid-span.
Dynamic Response of Laminated Composite Shells Under Radial or Hydrostatic Pressures
Authors: Wilcox M. W. , Abhat O. B.
Published: November 2010

The increased usage of laminated, composite materials in structural applications has resulted in the necessity of analytical investigations of these structures with respect to their static and dynamic response. An important vibration problem of thin cylindrical shells is the prediction of vibratory response of such shells subjected to membrane stresses. These stresses may be due to pressures, axial compressions, torques, temperatures, etc. This paper is aimed at the development of an analytical method to treat the free vibrations of laminated-composite, circular, cylindrical shells subjected to initial stresses.
Improved Construction of Multilayer Vessels to Apply the ASME Code Section VIII, Division 2
Authors: Yamauchi T.
Published: November 2010

It has been made possible to design the multilayered vessel by employing stress analysis according to ASME Section VIII, Division 2, using the construction method of reinforcing the flexual rigidity at the discontinuous part, and assuring the shell thermal conductivity to some fraction of the solid wall shell. Nondestructive inspection for the welding part has been tested to improve the construction method by the test piece.
Elastoplastic Analysis of Space Framework: Initial Force Schemes
Authors: Lee K. N.
Published: November 2010

Based upon the Morris and Fenves yield criterion for space frameworks, two initial force schemes are presented to analyze the elastoplastic behavior of space frameworks. One is the initial force iterative scheme, which follows the initial stress scheme proposed by Zienkiewicz, et al. The other is a self-equilibrating force scheme, which predicts the next yielding sections and determines the corresponding load increments, deflection and internal forces of the system by solving a set of quadratic equations. Several sample problems are presented. The results show that the load deflection curves obtained by using either scheme are identical. Note that for plane frameworks, element forces and load parameters corresponding to the subsequent yielding sections are identical to those obtained by using the classical limit analysis.
Wave Propagation in Fluid-Conveying Piping Constructed of Composite Material
Authors: Bert C. W. , Chen T. L. C.
Published: November 2010

An analysis is presented for the propagation of free harmonic waves in fluid-conveying, thin-walled, circular cylindrical shells of orthotropic material. The shell motion is modeled by using the dynamic orthotropic version of Love’s first-approximation linear shell theory and the fluid forces are described by applying linear potential flow theory. Frequency spectra are presented for both axisymmetric and unsymmetric types of modes, using an exact solution. Also, simplified approximate expressions are presented for some cases of practical importance. Emphasis is placed upon the difference between the behavior of pipe constructed of fiberglass-epoxy composite material and that of steel pipe.
Inelastic Response of Nuclear Piping Subjected to Rupture Forces
Authors: Anderson J. C. , Singh A. K.
Published: November 2010

A numerical procedure which can be used to evaluate the inelastic dynamic response of piping systems subjected to blow-down forces is described. The following finite elements are used to represent the piping system: (1) bilinear beam element, (2) bilinear curved beam element, and (3) bilinear support element with an initial gap. The method is then used to evaluate the dynamic response of two typical segments of a main steamline.
On the Interpretation of the Acoustic Emission Signals
Authors: Lucia A. C. , Redondi G.
Published: November 2010

The A.E. signals are of nonstationary random type, the nonstationarity being connected with the evolution of the source, whose characterization is here pursued by the development of methodologies of statistical analysis of non stationary signals. The A.E. signal is hypothesized to be constituted by a combination of a stationary random component and a deterministic one, whose behavior represents the evolution of the source. The determination of this latter component is carried out for signals from tensile tests on C.T. specimens. A second approach to the signal interpretation problem is also presented. It is based on the representation of the A.E. signal as random pulses of varying duration and amplitude.
The New Edition of ANSI B31.3—Some Significant Changes
Authors: Moody D. W.
Published: November 2010

The new edition of ANSI B31.3 retains established code rules for most petroleum refinery piping with little change. However, significant additions have been made to cover 1) safe handling of unusually hazardous fluids, 2) provisions for safeguarding certain piping systems, and 3) nonmetallic piping. These additions resulted primarily, but not entirely, from expansion of the scope of ANSI B31.3 to cover chemical plants as well as petroleum refineries. Other additions have been made to cover handling of low-hazard fluids and severe cyclic conditions. Metric equivalents have been added for design formulas.
Evaluation of Steel Plate Quality by Through Thickness Testing
Authors: Lentz J. S.
Published: November 2010

The mechanical properties and degrees of isotropy of SA-516 grade 70 plate steels produced by conventional, ladle flux-treated, calcium-treated, and electroslag remelting procedures were characterized by tension and impact testing in three orientations. The primary variables influencing these factors included the sulfur content and degree of sulfide shape control. For the practices examined, tensile elongation and reduction of area, and Charpy impact strength improved with decreasing sulfur content, leading to the conclusion that the volume fraction of sulfide inclusions determines the levels of ductility. The isotropy of the ESR, CaT, and LFT plates, highest in the order ESR CaT>LFT demonstrated that at equivalent sulfur levels, the type, size and distribution of inclusions also exhibited a strong influence. Based on through-thickness ductility, the susceptibility of A516-70 plate steels to lamellar tearing was highest in the order CON>LFT>CaT>ESR. Conventionally melted plate steels are not suitable for applications where lamellar tearing might occur.
An Improved Basis for Formulating Acceptance Criteria for Structural Welds
Authors: Ellingwood B. R.
Published: November 2010

Improvements in current weld acceptance criteria can be achieved if the standards are derived from structural reliability and integrity considerations. These criteria require an assessment of the effect on expected service performance of defects remaining in the weld. The inherent randomness in many of the parameters affecting weld reliability requires that the acceptance criteria have a probabilistic basis. Performance criteria can then be formulated which are consistent with levels of uncertainty and desired reliability.
Pressure Tubes: The Pressure Vessels in the CANDU Nuclear Power Reactor
Authors: Ross-Ross P. A.
Published: November 2010

One of the main engineering characteristics of the CANDU nuclear power reactor is the use of pressure tubes rather than one large pressure vessel to contain the fuel and coolant. The power reactor basically consists of a calandria, which is a vessel containing the low pressure heavy water moderator, end shields, and an array of identical pressure tube assemblies which project through the end shields and calandria. This paper briefly describes the CANDU reactor, some of the design and development done in support of the pressure tube concept, and the Canadian experience with pressure tubes.
Fracture in Straight Pipes Under Large Deflection Conditions—Part I: Structural Deformations
Authors: Emery A. F. , Love W. J. , Kobayashi A. S.
Published: November 2010

The dynamic motion of an axially oriented through crack in a pressurized cylinder was studied numerically. Both small and large deflection theories were used, with the results suggesting that large deflections may be important for elastic, but not for plastic stress fields. Computations were also made with pressures predicted by consideration of fluid outflow through the crack and indicate that the crack shape near the tip is independent of the pressure profile.
Nonsymmetric Buckling of Internally Pressurized Ellipsoidal and Torispherical Elastic-Plastic Pressure Vessel Heads
Authors: Bushnell D.
Published: November 2010

Bifurcation buckling pressures of ellipsoidal and torispherical heads joined to a cylinder are calculated with use of the BOSOR5 computer program. Predicted behavior is found to be sensitive to prebuckling geometric nonlinearity as well as material non-linearity, the former effect increasing the critical pressure and the latter decreasing it. In one case use of flow theory leads to a prediction that no buckling will occur whereas use of deformation theory leads to the opposite conclusion. A change in the slope of the post-yield hardening rate of the material dramatically affects the prebuckling behavior.
Application of Strainrange Partitioning to the Prediction of Creep-Fatigue Lives of AISI Types 304 and 316 Stainless Steel
Authors: Saltsman J. F. , Halford G. R.
Published: November 2010

As a demonstration of the predictive capabilities of the method of Strainrange Partitioning, published high-temperature, low cycle, creep-fatigue test results on AISI Types 304 and 316 stainless steel were analyzed and calculated cyclic lives compared with observed lives. Predicted lives agreed with observed lives within factors of two for 76 percent, factors of three for 93 percent, and factors of four for 98 percent of the laboratory tests analyzed. Agreement between observed and predicted lives is judged satisfactory considering that the data are associated with a number of variables (two alloys, several heats and heat treatments, a range of temperatures, different testing techniques, etc.) that are not directly accounted for in the calculations.
Elevated Temperature Elastic-Plastic-Creep Test of an Elbow Subjected to In-Plane Moment Loading
Authors: Imazu A. , Miura R. , Nakumura K. , Nagata T. , Okabayashi K.
Published: November 2010

This paper describes the results of test on elastic-plastic-creep behavior of a 12-in. Sch. 20 type 304 stainless steel elbow-pipe assembly subjected to in-plane moment loading at 600°C (1112°F). During the test, loads at seven different levels were applied to the specimen. In each stage of the test, the load, deflection, strains at specific locations, and ovalization of the cross section were measured. The results were compared with Spence’s theoretical predictions on the stationary creep behavior of smooth curved pipes and the inelastic solutions obtained by the MARC finite element analysis program.
Dynamic Plastic Response of an Immersed Pipe
Authors: Srinivasan M. G. , Krajcinovic D. , Valentin R. A.
Published: November 2010

The dynamic plastic deformation of a rigid-ideally plastic pipe subjected to an internal pressure is reduced when the pipe is surrounded by a fluid. A method to determine the added (virtual) mass which reflects the resistance of the fluid being displaced by the deforming pipe is described herein. The expression for the added mass is derived in form of an integral which in turn is solved by means of numerical techniques recognizing the asymptotic behavior of the argument. A single parameter family of curves is given for the added mass. An approximation in the form of a polynomial is also computed for the added mass in order to simplify the subsequent determination of the plastic deformation of the pipe.
Residual Ductility and Residual Stresses in Formed Heads
Authors: Gerdeen J. C.
Published: November 2010

The residual ductility and the residual stresses in formed heads, hemispherical and torispherical, are calculated using computer techniques: a program for plastic loading and a separate program for unloading. Thickness variations are accounted for in forming. Forming in both uniform and nonuniform spinning and stamping operations are considered. Strain hardening is included.
Seals for Geothermal Roller Drill Bits
Authors: Hendrickson R. R. , Carwile C. , Matson L. , Winzenried R. W.
Published: November 2010

A significant factor contributing to short bit life and attendant high costs for geothermal drilling is the lack of seals for elevated temperatures. To assist development of a high-temperature seal, a test facility was constructed to simulate the seal environment in a roller bit during geothermal drilling. Although none of the tested elastomers appear suitable for compression seals above 200°C, extensive testing was performed to determine their exact limits. Several new heterogeneous seal designs were found usable to higher temperatures.
Implosion Analysis of Concrete Cylindrical Vessels
Authors: Suzuki H. , Chen W. F. , Chang T. Y.
Published: November 2010

Concrete constitutive relations which can simulate the overall material behavior up to and including its ultimate state under general triaxial loading conditions have been developed. The proposed constitutive relations include: 1) plastic deformation considering the effect of hydrostatic pressure, 2) a dual criterion predicting the fracture of concrete in terms of either stresses or strains, and 3) post-fracture behavior of concrete. Corresponding to the constitutive model, a finite element analysis procedure has also been utilized. Based on the proposed model, implosion pressures and load-deformation responses of several concrete vessels were obtained. The numerical results correlate quite well with the experimental data when the dual criterion was used.
A Uniaxial Damage Accumulation Law for Time-Varying Loading Including Creep-Fatigue Interaction
Authors: Ostergren W. J. , Krempl E.
Published: November 2010

A differential form for damage accumulation is proposed wherein the rate of damage accumulation is equal to a product of two functions. The first depends only on the present damage and the second has the present value of the controlled quantity (stress or strain) and its time rate as its argument. Such an equation leads to the usual linear damage accumulation law and is incapable of modelling sequence effects. A power function form is proposed and integrated for a trapezoidal waveform with unequal tension and compression holdtimes. Using total strains only this equation can model the separate influences of frequency, holdtime, unequal effects of tension and compression holdtime, as well as mean stress (strain) effects. It includes Coffin’s frequency approach as a special case. The equation is shown to correlate low-cycle fatigue data with holdtime of type 304 stainless steel at 1200°F (649°C) and of cast IN 738 at 1600°F (871°C). It is then used to predict the lifetime for other tests for which no experiments have yet been reported.