bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical Modeling of Ductile Tearing Effects on Cleavage Fracture Toughness
Authors: Dodds RH , Tang M , Anderson TL 
Published: March 2009

Experimental studies demonstrate a significant effect of specimen size, a/W ratio and prior ductile tearing on cleavage fracture toughness values (Jc) measured in the ductile-to-brittle transition region of ferritic materials. In the lower-transition region, cleavage fracture often occurs under conditions of large-scale yielding but without prior ductile crack extension. The increased toughness develops when plastic zones formed at the crack tip interact with nearby specimen surfaces which relaxes crack-tip constraint (stress triaxiality). In the mid-to-upper transition region, small amounts of ductile crack extension (often &lt; 1–2 mm) routinely precede termination of the J-Δa curve by brittle fracture. Large-scale yielding, coupled with small amounts of ductile tearing, magnifies the impact of small variations in microscale material properties on the macroscopic fracture toughness which contributes to the large amount scatter observed in measured Jc-values.
Previous work by the authors described a micromechanics fracture model to correct measured Jc-values for the mechanistic effects of large-scale yielding. This new work extends the model to also include the influence of ductile crack extension prior to cleavage. Ductile crack extensions of 10–15 · the crack-tip opening displacement at initiation are considered in plane-strain, finite element computations. The finite element results demonstrate a significant elevation in crack-tip constraint due to macroscopic “sharpening” of the extending tip relative to the blunt tip at initiation of growth. However, this effect is offset partially by the additional plastic deformation associated with the increased applied J required to grow the crack. The initial a/W ratio, tearing modulus, strain hardening exponent and specimen size interact in a complex manner to define the evolving near-tip conditions for cleavage fracture. The paper explores development of the new model, provides necessary graphs and procedures for its application and demonstrates the effects of the model on fracture data sets for two pressure vessel steels (A533B and A515).
Fracture Toughness Measurements Using Small Cracked Round Bars
Authors: Giovanola JH , Homma H , Lichtenberger M , Crocker JE , Klopp RW 
Published: March 2009

This study investigated using small precracked round bars (CRBs) for measuring fracture toughness values representative of material fracture resistance in large, thick components (so-called plane strain fracture toughness). The three alloys tested with CRBs (titanium-10V-2Fe-3Al, HY-130 steel, and A508 class 2A steel) cover a broad range of fracture behaviors. K or J values at crack initiation were calculated using the experimental load and displacement records. The fracture tests were complemented with scanning electron microscope observations and finite element analyses of round bars with different ratios of crack depth to bar diameter.
The CRB data were compared with independently measured toughness data obtained with larger bend specimens. In two cases, toughness values measured with precracked round rs for a given material and mode of fracture were in good agreement with those measured with larger standard fracture mechanics specimens; the exception was A508 steel at 204°C, and the lower values in this case may have occurred because the microstructural features influencing fracture were large in relation to the uncracked ligament size of the CRB. Finite element simulations of the CRB indicate that in the fully plastic regime the constraint factor Q is low (-0.75 to -0.85) for shallow crack specimens but increases with deformation (from -0.6 to -0.1) for deeply cracked bars. Experimentally, this difference in onstraint was evidenced by a transition from ductile to cleavage fracture mode in (embrittled) HY-130 steel specimens with shallow and deep cracks, respectively.
This limited feasibility study showed the potential of small CRB specimens for measuring representative plane strain fracture toughness. More work is needed to optimize specimen size and precracking methods and to improve and validate test evaluation methods.
Constraint Effects in Testing Different Curved Geometries of Zr-2.5Nb Pressure Tube Material
Authors: Davies PH , Shewfelt RSW , Järvine AK 
Published: March 2009

Constraint effects in testing different curved geometries of Zr-2.5Nb pressure tube material have been studied with the aim of understanding discrepancies between toughness (critical crack length) values obtained from small specimens and burst tests. Crack growth resistance or deformation J-R curves were obtained on unirradiated pressure tube material at room temperature using small 17 and 34 mm wide curved compact specimens, 60 mm wide curved centre cracked specimens and burst test specimens.
The J-R curves from the burst tests were in excellent agreement with those from the curved compact specimens at short crack extensions (up to 2 mm per crack tip). However, at larger crack extensions the burst test J-R curves deviated from the small specimen results, being higher than those from the 17 mm specimen but only slightly lower (about 10%) than those from the 34 mm specimen up to 6 mm crack growth; i.e. the onset of instability at maximum pressure. In comparison, the J-R curves from the centre cracked specimens were well above those of the curved compact and burst test specimens at all crack extensions. The results suggest that the crack tip constraint of the burst test is most similar to that of a compact specimen, the centre cracked specimen having a much lower crack tip constraint. Fractographic studies confirmed the experimental results.
Size and Deformation Limits to Maintain Constraint in KIc and Jc Testing of Bend Specimens
Authors: Koppenhoefer KC , Kirk MT , Dodds RH 
Published: March 2009

The ASTM Standard Test Method for Plane-Strain Fracture Toughness of Metallic Materials (E399-90) restricts test specimen dimensions to insure the measurement of highly constrained fracture toughness values (KIc). These requirements insure small-scale yielding (SSY) conditions at fracture, and thereby the validity of linear elastic fracture mechanics.
Recently, Dodds and Anderson have proposed a less restrictive size requirement for cleavage fracture toughness measured in terms of the J-integral (Jc), as given by a,b,B ≥ 200 Jc/σ0. The size requirement proposed by Dodds and Anderson increases the applicability of fracture toughness experiments by expanding the range of conditions over which fracture toughness data meeting SSY conditions can be reliably measured. This investigation compares the proposed size requirement with that of ASTM Standard Test Method E399 and, by comparison with published experimental data for various alloys, provides validation of the new requirements.
Miniaturized Notch Test Specimen and Test Machine Design
Authors: Manahan MP , Stonesifer RB , Soong Y , Burger JM 
Published: March 2009

Charpy V-notch specimens are widely used within the nuclear industry to monitor the effects of neutron damage to the reactor pressure vessel (RPV) beltline region. There is an ever-increasing need to obtain more notched bar impact data as plants age. Many plants will require more specimens for surveillance during the license renewal period. Other plants have experienced more embrittlement than originally anticipated, and it will be necessary to develop plant-specific Charpy shift trend curve models to ensure continued safe operation. Since physically based trend curves have not yet been validated, the use of plant-specific data will save the utilities operations costs since overly (arbitrarily) conservative models are no longer needed. Miniature specimens have also been used to characterize the material condition after vessel annealing. The use of miniaturized specimens which can be fabricated from previously tested full sized specimens offers one solution to this need for more fracture data.
Experiments performed using side-grooved miniaturized notch test (MNT) specimens have demonstrated that 1/16 scale miniature specimens can be designed to yield transitional fracture behavior and that the fracture appearance and energy-temperature curves can be quantitatively related to the conventional ASTM E23 specimen data. This paper presents the results of a study focused on designing an optimized MNT specimen and test machine. A combination of literature review, metallurgical analysis, and finite element analysis was used to consider such design parameters as minimum specimen cross-section, specimen length, notch acuity, the use of side grooves, side groove geometry, support span, and striker geometry. Two dimensional and three dimensional, elastic-plastic, large deformation, finite element analyses were used to compare stress/strain fields for standard and miniaturized specimens. Specimen and test machine geometries have been developed to ensure continuum requirements are met, the MNT specimen stress fields simulate those of the conventional specimen, and scatter for the miniature data is minimized.
Measurement of Multiple-Site Cracking in Simulated Aircraft Panels Using AC Potential Drop
Authors: Jablonski DA 
Published: March 2009

The characterization of multiple-site damage by use of laboratory test specimens is an important precursor to the understanding of multiple-site damage in aging aircraft. As the number of damage sites in the laboratory specimen increases, it becomes more time-consuming to measure crack initiation and growth from the various sites. Typically the crack initiation and crack growth would be measured either visually or with a low-power microscope. This technique is accurate, but it is labor-intensive. To decrease the time necessary to obtain multiple-site crack growth rate data, an automated crack length measuring technique, AC potential drop, was investigated.
This AC potential drop technique was applied to aluminum test specimens under fatigue cycling conditions as well as monotonic R-curve testing. Aluminum ALCLAD 2024 test specimens of three different specimen geometries were examined. Specimens with a single-hole were used to examine the effects of lead placement on the sensitivity of AC potential drop. Three-hole specimens were used to simulate multiple-site cracking from several holes. Riveted specimens containing one row of three rivets were used to examine multiple-site cracking from fasteners. Optimum current and potential lead geometries were determined for each specimen geometry. Relationships between the AC potential and crack length were determined for AC current frequencies of 3, 10, and 30 kHz. The sensitivity of AC potential drop in measuring crack initiation was investigated. The sensitivity was found to increase substantially with increasing AC current frequency.
Whole House Fenestration Energy Consumption as a Function of Variable Window Air Leakage Rates
Authors: Kehrli D 
Published: March 2009

Residential building energy consumption is dependent on many variables. The heat loss or gain attributable to fenestration products can be a significant portion of the whole building load. The fenestration industry is currently developing and implementing new test methods and rating procedures to more accurately account for fenestration energy transfer. One of the tools being developed by the National Fenestration Rating Council (NFRC) is a PC-based program called Residential Fenestration (RESFEN) heating and cooling load use and costs.
This paper will provide a review of the energy and cost impacts that variable air leakage rates of several types of window products can have on overall window energy usage as modeled in four typical building designs located in the United States. The analysis was performed with the RESFEN software as part of an NFRC sensitivity study on this issue.
Acid Deposition Effects on Materials: Evaluation of Electric Contact Materials after 4 Years of Exposure
Authors: Tidblad J , Leygraf C , Kucera V 
Published: March 2009

In 1987 a co-operative field exposure program within the UN Economic Commission for Europe was initiated. The aim of the program is to evaluate the effect of sulfur pollutants in combination with NOx and other pollutants on the atmospheric corrosion of important materials. This work presents results from the evaluation of the electric contact materials nickel, copper, silver and tin after 4 years of exposure.
Dry deposition of SO2 dominates the corrosion of nickel, which forms amorphous and crystalline basic nickel sulfate, whereas both O3 and NO2 accelerate the dry deposition of SO2 on copper. Silver forms Ag2S as the dominating corrosion product. Since H2S is not measured within the program it has not been possible to estimate its contribution. The formation of oxides with different stoichiometries dominates the corrosion of tin and no equation has been found that relates the weight increase of tin to environmental data. Particulate ammonium sulfate contributes to the weight increase of all metals.
Corrosion Study of Carbon Steel and Zinc-Comparison Between Field Exposure and Accelerated Tests
Authors: Johansson E , Gullman J 
Published: March 2009

The results from accelerated atmospheric corrosion test methods do not generally correspond very well to corrosion behaviour under practical conditions. The aim of the present investigation is to increase the understanding of the influence of temperature, wetness and sulfur dioxide concentration in the air. Special attention is given to the extent to which results from accelerated tests differ from the results of outdoor exposures.
Carbon steel and zinc have been exposed outdoors at four different test sites and to climate chamber test procedures. The study includes corrosion attack measured as mass loss of test plates and corrosion product characterization by x-ray diffraction.
The investigation shows that studying corrosion with regard to both mass loss and corrosion products formed during climate chamber exposures and field exposures, valuable knowledge is obtained about improvements of accelerated test methods.
Laboratory Testing of Dispersants under Arctic Conditions
Authors: Brandvik PJ , Knudsen OØ , Moldestad MØ , Daling PS 
Published: March 2009

The effectiveness of relevant dispersants for use under “Arctic conditions” has been tested with the IFP dilution test. “Arctic conditions” in this context are defined as low temperature (0°C) and water salinities varying between 0.5% and 3.5%. The study was performed in three steps with a screening activity first, where 14 dispersants were tested on water-in-oil (w/o) emulsions from two weathered oil types. In the next step five dispersants were tested on both weathered water free oils and w/o emulsions from four different oil types. As a third step, dispersant effectiveness as a function of salinity (0.5 to 3.5%) was tested with the most effective dispersants at high and low salinity.
The results from this study shows that many of the most used dispersants which previously have shown an excellent effectiveness at high sea water salinity (3.5%) may give a very low effectiveness at low salinity (0.5%). Recently developed products especially designed for low salinity use (e.g. Inipol IPF) are very effective at low salinities, but suffer from a rather poor effectiveness at higher salinities. This is of significant operational importance in Arctic oil spill combat operations since the salinity of the surface water may vary due to ice melting.
This study of dispersants' effectiveness under Arctic conditions shows the need for development of dispersants with high effectiveness both at low temperature (0°C) and over a wide range of salinities (3.5% to 0.5%). Dispersant development has been an limited but important activity at IKU for the last five years and one of the objectives for an ongoing Arctic program at IKU is to develop such new dispersants for use under Arctic conditions.
Dispersant Application by Fire Monitor
Authors: Major RA , Chen ACT 
Published: March 2009

Several years ago, Exxon Company, International, found itself with a need for a rugged system for open ocean use in applying dispersant which could be quickly installed on supply boats and would use readily available parts at remote offshore drilling sites. Fire monitors appeared promising, since they had been used effectively to disperse some minor spills in the past, and visually they appeared to produce a relatively-uniform spray pattern. Calculations also showed that fire monitors could potentially cover three to four times the area covered by a conventional boom because of a wider swath and the potential for greater boat speed due to a lesser effect of pitching and rolling on monitors that on booms. There were questions, however, about the uniformity of the dosage, the difference in the droplet size produced, and their effect on dispersant performance.
Exxon conducted several test programs to more thoroughly evaluate fire monitors for dispersant application, and these programs are the subject of this paper. The first test program involved the testing of numerous nozzles with modifications and monitor elevation angles to determine what combination would give the most uniform dosage in the likely offshore wind conditions. Once a nozzle was selected, the droplet pattern from the monitor nozzle and from a conventional dilute spray boom were analyzed using high speed video. These tests were followed by application tests of COREXIT 9527 by fire monitor, dilute boom, and neat boom to spilled oil at the Imperial Oil Limited Wave Basin in Calgary. The major content of this paper deals with the results of those tests. Finally, at-sea tests were successfully conducted in the North Sea.
The Impact of Oil Dispersant Solvent on Performance
Authors: Fiocco RJ , Lessard RR , Canevari GP , Becker KW , Daling PS 
Published: March 2009

Modern oil spill dispersant formulations are concentrated blends of surface active agents (surfactants) in a solvent carrier system. The surfactants are effective for lowering the interfacial tension of the oil slick and promoting and stabilizing oil-in-water dispersions. The solvent system has 2 key functions: 1) reduce viscosity of the surfactant blend to allow efficient dispersant application, and 2) promote mixing and diffusion of the surfactant blend into the oil film. A more detailed description than previously given in the literature is proposed to explain the mechanism of chemical dispersion and illustrate how the surfactant is delivered by the solvent to the oil-water interface.
Laboratory data are presented which demonstrate the variability in dispersing effectiveness due to different solvent composition, particularly for viscous and emulsified test oils with viscosities up to 20,500 mPa∙s. Other advantages of improved solvent components can include reduced evaporative losses during spraying, lower marine toxicity and reduced protective equipment requirements. Through this improved understanding of the role of the solvent, dispersants which are more effective over a wider range of oil types are being developed.
Common Data Processing Needs for Materials Databases
Authors: Nishijima S 
Published: March 2009

An international collaborative work known as VAMAS shows that the same set of factual materials data could result in totally different property values when the analysis model and computational method are different. The work is followed by a collection of models and methods for a wide range of materials properties, with the intention to provide a better awareness to the database builders and users.
Establishment of commonly accepted methods for handling fatigue and creep properties data is under way at the Iron and Steel Institute in Japan. This includes consensus formation among concerned experts for the development of common data processing software to be used in their database systems. Other examples show that the use of these common systems will enhance the further development and use of computerized materials property data.
Heavy Metal Concentration in Bay Sediments of Japan
Authors: Fukue M , Koto Y , Nakamura T , Yamasaki S 
Published: March 2009

Because industry discharge wastes into the sea, marine sediments can be contaminated with various kinds of hazardous and toxic substances. This study discusses how the “degree of pollution” of heavy metals affects the marine sediments from Osaka Bay and Tokyo Bay.
In this study, the concentrations of various metals, such as manganese, iron, aluminum, titanium, vanadium, copper, phosphorus, etc., were measured from sediment samples obtained from different sites in the bays. However, the results had to be corrected because background concentrations for each metal differ with site location and grain size characteristics. The large difference between background and individual concentrations at various soil depths indicates that the surface layers of the seabed are significantly polluted with some species of heavy metal and other elements.
Soil-Bentonite Design Mix for Slurry Cutoff Walls Used as Containment Barriers
Authors: Rad NS , Bachus RC , Jacobson BD 
Published: March 2009

Soil-bentonite slurry cutoff walls (SBSCWs) have been used for decades by geotechnical engineers in conjunction with soil excavation to control ground water movement. In recent years, soil-bentonite slurry cutoff walls have been increasingly used as containment barriers around contaminated soils to impede or, in some cases, nearly eliminate the off-site migration of contaminated ground water or other potentially hazardous liquids. Because of this recent application, the conventional design methodologies for the soil-bentonite slurry cutoff walls, specifically the requirements for the soil-bentonite slurry mix acceptance, have been adjusted. Low hydraulic conductivity, workability, and physical stability commonly used as the main acceptance criteria for conventional soil-bentonite slurry mixes are no longer the only governing parameters. Compatibility of the soil-bentonite slurry mix with the ground water/liquid is as important and should be considered a major factor in the soil-bentonite slurry mix design.
The paper presents the procedures used and the results obtained during an extensive laboratory testing program performed to select varying soil-bentonite slurry mix components for a soil-bentonite slurry cutoff wall constructed around an old landfill at a former oil refinery. The landfill is underlain to varying depths by a coarse granular soil that has been exposed to oil-products. Compatibility of three commercially available bentonite products with the free oil products and the oil-contaminated ground water found at some locations in the landfill was initially investigated. Based on the test results, one of the bentonite products was selected for use in the soil-bentonite slurry testing program. A clayey soil from a borrow source, potable water from the site, and subsurface soils from the proposed soil-bentonite slurry wall alignment were used to form different soil-bentonite slurry mixes. Slump tests were performed to evaluate the workability of the mixes. Based on the test results, a single mix was selected for further study, including permeability/compatibility testing. The results of the compatibility testing program are presented and discussed in the paper. A specific design mix methodology for evaluating the chemical compatibility of soil-bentonite slurry mixes with permeants is proposed.