bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stress Intensity Factors for Internally Pressurized Thick-Wall Cylinders
Authors: Underwood JH 
Published: March 2009

Selected stress intensity factor solutions from the literature are related to the problem of internally pressurized thick-wall cylinders with straight-front and curved-front cracks. The recent K solutions of Bowie and Freese and Rice and Levy are combined in an estimate of the K solution for a pressurized cylinder with a semielliptical crack originating along the inner wall. The estimate of K is compared with the available experimental and analytical K data for shallow cracks.
The estimated K solution is modified to account for various complex loadings in pressurized cylinders. Included are modifications to describe (1) lack of pressure on the crack surfaces in pressurized cylinders, (2) residual stress in the wall of pressurized cylinders, and (3) a combination of an unpressurized crack and residual stress in the wall. The effect of cyclic pressure loading on K is also discussed in relation to Throop's work on fatigue of pressurized cylinders.
Delay Effects in Fatigue Crack Propagation
Authors: von Euw EFJ , Hertzberg RW , Roberts R 
Published: March 2009

The fatigue crack propagation behavior resulting from variations in load is examined for 2024-T3 aluminum alloy, from both a macroscopic and a fractographic point of view. A peak load is found to cause retardation of the crack growth rate, which becomes more pronounced as the percentage overload or baseline stress intensity level or both is increased. The delaying effect of the overload is observed to exist for a calculated crack length increment equivalent to the plastic zone size formed during the peak load. Multiple overloads and high-low block loading sequences are found to result in additional retardation. For a given ΔK and percentage overload it is noted that the greatest retardation occurs when λ equals 1 (λ = Kmax/ΔK).
It is observed that the macroscopic fracture surface appearance (that is, transition to plane stress) is a function of the crack growth rate. From fractographic examination it is found that the initiation of microvoid coalescence during fatigue occurs when plane stress conditions are achieved; this limits the extent of the stretch zone associated with an overload cycle. As a result, the stretch zone is found to be followed by striations in plane strain and by dimples under plane stress conditions. The size of the stretch band is observed to depend on the stress intensity level during the overload cycle.
The usefulness of closure concepts in aiding the understanding of fatigue crack propagation under uniform and nonuniform loading conditions is considered. Evidence is given to demonstrate the general applicability of closure concepts for analysis of macroscopic and fractographic fatigue crack propagation results.
Fatigue Crack Growth Analysis of Pressurized Water Reactor Vessels
Authors: Riccardella PC , Mager TR 
Published: March 2009

The concepts of linear elastic fracture mechanics are applied to perform a fatigue evaluation of a pressurized water reactor vessel. The results of this work indicate that, for the types of flaws which could exist in a reactor vessel, fatigue crack growth due to normal operating conditions during the design life of the vessel is negligible. We have previously presented a simplified technique to approximate the potential for fatigue crack growth in the beltline region of a typical pressurized water reactor vessel during the forty-year design life of the vessel. The beltline region is the most critical from the standpoint of irradiation embrittlement of the material, and thus was the first to be considered. However, there are several areas in a reactor vessel which are more critically stressed during operation than the beltline region, and the crack growth in these regions must be considered before any general conclusions are drawn concerning the vessel.
In this paper, the following four regions of the reactor vessel are considered separately: (1) the closure head, (2) the nozzle shell course, (3) the beltline region, and (4) the lower head. A fatigue crack growth analysis is performed on the most critically stressed location in each region. Initial flaw sizes are assumed which are conservative upper bounds of the types of flaws which could exist in the hardware. Crack tip stress intensity factors are estimated using continuous surface flaw expressions, after linearizing the thermal and pressure stress distributions through the thickness of the vessel. An estimate of the degree of conservatism introduced by these two major approximations is included. Fatigue crack growth data from various sources were used. The sensitivity of the data to such variables as temperature, irradiation, and biaxiality is discussed.
Rayleigh Waves for Continuous Monitoring of a Propagating Crack Front
Authors: Buck O , Ho CL , Marcus HL , Thompson RB 
Published: March 2009

A simple ultrasonic system which uses Rayleigh (surface) waves is briefly described. Applied to a part-through crack (PTC) specimen the wave is attenuated according to the crack depth. Functional relations of the crack depth and hence the stress intensity factor versus the number of load cycles N or the crack growth rate da/dN versus the cyclic stress intensity range ΔK are therfore easily obtained by continuously monitoring such a surface wave.
The system is sufficiently sensitive to actually show an “apparent” crack depth change during a single load cycle: at a low load level, the crack depth seems to be smaller than at high load level. This indicates that at low load levels internal compressive stresses at the crack tip resist crack opening. At high load levels, however, these internal stresses are overcome and the crack opens up to its actual size. This observation should be useful for interpretations of crack closure behaviors, crack retardation effects during spike loading, and other plasticity effects in the vicinity of the crack tip.
Fracture Mechanics Consideration of Hydrogen Sulfide Cracking in High Strength Steels
Authors: Bucci RJ , Paris PC , Loushin LL , Johnson HH 
Published: March 2009

Hydrogen sulfide (H2S) stress corrosion cracking studies were conducted within the framework of fracture mechanics for several high strength steels (AISI 4340, 4140, HY-80, and HY-130). For all the steels and strength levels investigated (σys = 80 to 150 ksi), H2S stress corrosion cracking was found to exist. For each of the alloys investigated, a valid plane strain KIscc (which indicates the demarcation between detectable rates of crack extension, Δa/Δt ⩾ 10-5 in./min and those below these rates) was measured and found to depend significantly on yield stress with decreasing KIscc values reported for increasing yield stress.
A limited investigation of crack growth kinetics found crack growth rates to accelerate most rapidly from presharpened fatigue cracks when loaded to K levels just beyond the KIscc threshold. In several instances, especially with the highest strength alloys, stress corrosion crack velocities attained peak values before being “damped” to some steady state velocity at increased K levels. The crack velocity damping might in part be attributed to crack division or plasticity effects associated with increasing plastic zone size to thickness ratio at higher K levels.
The Evaluation of Creep Damage in a Cr-Mo-V Steel
Authors: Goldhoff RM , Woodford DA 
Published: March 2009

An attempt has been made to determine and quantify the accumulation of creep damage in Cr-Mo-V steel. Damage is defined in terms of post exposure rupture data and hardness measurements which are shown to be interrelated. Correlation between the post exposure rupture life and the initial exposure parameters are achieved by simple parametric techniques which then form the basis for graphical representation of damage accumulation as a function of exposure time, stress, and temperature.
The way in which these curves may be used to predict failure under nonsteady conditions of stress and temperature is described. In general the linear life fraction cumulative damage rule is unrealistic for this material, although under certain restricted conditions it may give a reasonable prediction of life. Apart from the measured nonlinearity with time of damage accumulation, the present results confirm that the common assumption of a unique failure criterion independent of the test conditions cannot be justified.
Predictive Testing of Aircraft Structures
Authors: Rosenfeld MS 
Published: March 2009

The historic development of airframe structural testing is reviewed and the role played by structural testing in the development of reliable airframe structures is discussed. The threefold safety-factor, safe-life, and fail-safe design approach provides reliable airframe structures when complemented by an effective laboratory test program that includes static, dynamic, and fatigue tests.
Using an iterative analytical and test approach, the operational strength limits of an airframe can be predicted fairly accurately from the static test results. However, predictions of the safe service life from fatigue test data alone leaves much to be desired because of the large variations in service usage. Nevertheless, the alarming cost of modifying aircraft in service has forced an almost complete acceptance of laboratory structural fatigue testing as an economical way of doing business.
The ability to predict the lives (actually the lives remaining) of individual aircraft depends upon the development of an instrument that would measure the fatigue damage actually incurred. Until that time, frequent and rigidly controlled periodic inspections must be performed on all aircraft, and an elaborate scheme of progressive preventive maintenance is mandatory.
Stress Corrosion Crack Protection from Coatings on High Strength H-11 Steel Aerospace Bolts
Authors: Taylor E 
Published: March 2009

Stress corrosion cracking of high strength aerospace bolts is mostly limited to alloy steels, whose susceptibility to pitting corrosion is generally a secondary requirement compared to the outstanding tensile and fatigue properties needed. In order to provide environmental resistance for the bolt, a coating or plating is usually applied, which protects the underlying metal. In many cases, the coating chosen has proven to be inadequate. Therefore, a program was initiated to perfect a test method and gather reliable results from which predictable performance data could be obtained.
Many coatings were ultimately evaluated by a simple laboratory test method in which the coated bolt was statically stressed and exposed to a corrosive medium until failure occurred. The test is capable of evaluating a wide variety of coatings in periods from a few hundred to several thousand hours.
Detecting Acoustic Emission in Large Liquid Metal Cooled Fast Breeder Reactors
Authors: Anderson TT , Gavin AP , Karvinen JR , Price CC , Reimann KJ 
Published: March 2009

Research at Argonne National Laboratory on acoustic emission and closely related areas is oriented to goals of the liquid metal cooled fast breeder reactor (LMFBR) program. These goals include acoustic monitoring of reactor core and power plant components, acoustic detection of boiling in liquid sodium, and acoustic emission testing of materials at elevated temperatures. For monitoring of sodium-filled components, several types of acoustic emission sensors are being developed for operation in sodium at temperatures to 650 C. These sensors contain the high temperature, radiation resistant, piezoelectric material, lithium niobate which is clamped or bonded to the sensor housing.
Reactor components have been monitored acoustically with both high temperature (620 C rating) accelerometers and with standard accelerometers. The acoustic surveillance tests have shown: (1) flowrate-dependent noise in a sodium-cooled nuclear reactor (EBR-II) and in a sodium component test facility (CCTL); (2) sodium-oxide binding within an EBR-II primary pump; and (3) a loose drain tube in the EBR-II primary sodium to secondary sodium intermediate heat exchanger.
New Method for the Statistical Evaluation of Constant Stress Amplitude Fatigue-Test Results
Authors: Bastenaire FA 
Published: March 2009

Using the experimental and theoretical results of previous research work, the author presents a probabilistic description of constant stress amplitude fatigue-test results. This description includes the S-N curves (or equiprobability of fracture curves), P-S curves (or stress-response curves), P-N curves (cumulative distribution functions of fatigue endurances), and accounts for the occurrence of runouts.
A method of estimation of the model coefficients which uses the information provided by all the specimens tested (broken or unbroken) is also presented. The application of this method is demonstrated through five examples for each of which several hundred test results are available.
A Study of Thermal Ratchetting Using Closed-Loop, Servo-Controlled Test Machines
Authors: Stentz RH 
Published: March 2009

A new testing technique has been devised for studying thermal ratchetting behavior. It employs low-cycle fatigue-type specimens (hourglass shape) in conjunction with two closed-loop, servo-controlled testing machines operating in unison to provide an exact simulation of the familiar three-bar assembly.
Diametral extensometers are employed in conjunction with an analog strain computer to provide instantaneous values for the total axial strain and to isolate the mechanical and thermal strain components. Stress-strain measurements are recorded continuously throughout each cycle to provide an extensive evaluation of the response to initial load level, maximum and minimum cycle temperatures, hold-time effects, different specimen diameters, and rate of temperature cycling. Demonstration tests are described which employ 304 and 316 stainless steel specimens subjected to an initial stress level of 10 000 psi and a temperature cycle from 1100 to 800 F.
Cyclic Inelastic Deformation and the Fatigue Notch Factor
Authors: Leis BN , Gowda CVB , Topper TH 
Published: March 2009

Cyclic inelastic deformation response and the fatigue notch factor are presented and discussed for two metals of contrasting stress-strain behavior (2024-T351 aluminum alloy and SAE 1015 mild steel). Thin circular or elliptical notch plates fabricated from these metals were subjected to cyclic straining in a servo-controlled testing machine.
Experimental results obtained from the deformation studies indicate that for small scale confined plasticity, the transient notch response had little effect on nominal deformation resistance. However, as the size of the zone increased or the degree of confinement decreased, transient notch response was reflected in the overall deformation response. These results are discussed in terms of cyclic stress and strain concentration factors and related to notch plate deformation through Neuber's rule. In the low endurance region, the results indicate that the deformation analysis employed, rather than a material “size effect,” is responsible for values of Kf less than Kt.
On The Physical Justification of the Term “State of Fatigue of Materials Under Cyclic Loading”
Authors: Burbach J 
Published: March 2009

In the quest for a physical justification of the term “state of fatigue of materials subjected to cyclic loading,” the present paper first investigates the question what conclusions must be drawn, if states of fatigue (Ω) exist that can be characterized by a single number (0 ≤Ω ≤ 1). It was found that, if such states of fatigue do in fact exist, they can be determined experimentally, and the mathematical relationships of cumulative damage with regard to irregular loading are then fixed and can be stated: no additional model assumption, for example, the arbitrary assumption of an analytical function for Ω, will then be necessary and would be wrong.
If it is not possible for states of fatigue to be characterized by a single number, not even for a limited selection of types of loading, then it is likewise impossible to give any simple or closely accurate mathematical relationship for the actual cumulative damage. Nevertheless, it is possible in such cases to make safe life estimates, but it is only by experiment that the degree of certainty of such estimates can be determined in any particular case.
Fracture Toughness Testing and its Applications
Authors: ASTM Committee E-24  
Published: March 2009

Description
The development of various new high-strength alloys and the broadening range of their applications, particularly in aerospace and in cryogenics, has brought about increased emphasis on the study of fracture characteristics. As a result, the technology of testing for fracture toughness and crack propagation has grown rapidly in recent years. So, too, has understanding of how to apply this testing technology to design problems such as selection of materials, heat treatment, welding procedures, structural shape and size, and effects of environment.
Composition and Rheology of Roofing Asphalt
Authors: Brown AB , Sparks JW 
Published: March 2009

A survey of twenty two roofing-grade asphalts of wide commercial distribution in the United States and Canada and derived from a number of different domestic and foreign crude oils shows that they differ widely in sulfur content, less widely in oxygen content, but are quite similar in type composition, in susceptibilities, and in softening point, penetration, and ductility.
One of these asphalts, considered as representative, was studied with respect to its deformation response in time to low and unidirectionally applied stresses, similar to those encountered in service under forces of gravity and of thermal expansion and contraction. This asphalt behaved as a linear viscoelastic material. Its response pattern could be analyzed in terms of pure Hookean elasticity and pure Newtonian viscosity with interactions in the form of Kelvin and Maxwell compound elements. It was characterized by a high degree of damped or Kelvin elasticity, operative over a wide range of retardation or relaxation times, and a minimum of instantaneous (Hookean) elasticity and of nonrecoverable viscous (Newtonian) flow. Such rheological measures are the basic units of mechanical behavior. It is hoped that eventually they may provide solutions, in fundamental engineering terms, to problems of strength and failure in asphaltic structures.
Some Qualitative Effects of Composition and Processing on Weatherability of Coating-Grade Asphalts
Authors: Mertens EW , Greenfeld SH 
Published: March 2009

The weathering characteristics of coating-grade asphalts cannot be associated with the crude-oil source of the asphalt alone because fluxing stocks, catalysts, fillers, and added materials can affect the weatherability markedly. The results are not general, however, but vary with different asphalts.
A fluxing oil added to the base residuum doubled the weatherability of one asphalt but reduced the life of another asphalt to less than half of the unfluxed asphalt. Similarly, a catalyst doubled the durability of one asphalt system but reduced that of another by one third.
Asphalts responded differently to the addition of polymers. Of the three asphalts tested, the weatherability of one was unaffected, another was improved, and the third was made poorer. The response to the addition of limestone dust stabilizer varied among the several asphalts. The improvement in weatherability ranged from only 20 per cent to as high as 140 per cent. The weatherability of products produced from crude oils obtained from different areas of the same field can also vary. Such differences were observed for asphalts derived from different areas in three different fields. The difference was as large as 100 per cent in one field.
Industrial Pitches
Authors: Pittman CU , Donegan JW 
Published: March 2009

Industrial pitches comprise those coal-tar pitches that are used in the manufacture of other products, principally as saturants, plasticizers, or binders. They are produced by distillation from high-temperature coke-oven tars selected and blended to give the properties required in the finished product. To insure uniform performance under any of the widely diversified conditions of use, industrial pitches are rigidly specified and controlled.
The manufacture of the principal products in which industrial pitches are used are briefly described. In addition, the requirements for the pitches used in these products are given. Empirical tests that can vary in their procedure and thus produce variable results are now used to determine the commonly specified properties. A uniform code of nomenclature and evaluation procedures is needed to permit industry-wide standardization in specification writing.
X-Ray Energy Spectrometry in the 0.1 to 10 Å Range
Authors: Fitzgerald R , Gantzel P 
Published: March 2009

Energy spectrometry utilizing a solid-state detector (silicon) for X-ray elemental analysis is described, and compared with wavelength spectrometry.
Parameters which influence the spectrometers energy resolution, energy detection range, and countrate capabilities are reviewed. Measured performance of a spectrometer (200 eV FWHM resolution for 6.404 keV radiation) is demonstrated for both X-ray and electron specimen excitation.
Energy Dispersion X-ray Analysis with the Transmission Electron Microscope
Authors: Bender SL , Duff RH 
Published: March 2009

The addition of X-ray emission analysis capabilities to a conventional transmission electron microscope offers a new analytical dimension to the microscopist.
The availability of Si(Li) solid-state X-ray detectors with energy resolutions superior to any previous type of X-ray detector provides the microscopist with an efficient system for elemental analysis that does not interfere with normal microscope operation.
A commercially available Si(Li) detector has been installed on a transmission electron microscope capable of forming a 1.6-µm-diameter spot at the specimen plane with the following characteristics of operation (a) X-radiation from the specimen, the specimen holder, the mounting grid, and the objective aperture (if in place) are the only signals detected; (b) no degradation of detector resolution by the magnetic fields of the microscope lenses or the proximity of the incident electron beam to the detector (a few millimeters) is observed; and (c) X-ray signals from particles 1000 Å in diameter are detectable with peak-to-background ratios of about two.
Design and Application of X-ray Emission Analyzers Using Radioisotope X-ray or Gamma Ray Sources
Authors: Rhodes JR 
Published: March 2009

This paper reviews the present state of development and application of X-ray emission spectrometry using radioisotope X-ray and gamma ray sources for excitation, and energy discrimination and dispersion techniques for spectrum analysis.
The design and use of instrumentation is characterized by the choice of one of the two main methods of energy selection now employed. The balanced filter method is simple but restricted to sequential determinations of single elements and so finds its main use in small, hand-portable, battery-operated analyzers for field, laboratory, or industrial use. Energy dispersion with high resolution silicon or germanium detectors permits simultaneous collection of the whole excited spectrum and so promises rapid multielement analysis. Available equipment is more suited to laboratory conditions.
Relevant components of radioisotope X-ray spectrometers are described. Emphasis is placed on source-specimen-detector configurations, sources, source-target assemblies, absorption edge filters, and relevant properties of detectors. Equations for estimating the feasibility of a given analysis are derived, and interferences due to absorption, enhancement, and heterogeneity effects are discussed.
A major portion of the paper is devoted to a review of published applications and covers elemental analysis from aluminum to uranium, and measurement of coating thickness. References are made where appropriate to available portable, industrial, and laboratory instruments.