bluuebunny/crossref_metadata_2025 huggingface dataset:
A Study of Rust Morphology, Contamination and Porosity by Backscattered Electron Imaging
Authors: Simancas J , Scrivener KL , Morcillo M
Published: March 2009

Atmospheric corrosion is a complex process involving many variables including metal, atmospheric environment, and exposure conditions. Once the corrosion process has been initiated and a continuous film of corrosion products covering the whole surface of steel has been established, the kinetics of the corrosion process will be controlled by (a) the thickness of corrosion product layer, (b) their morphology (degree of compactness, crack network, etc.), and (c) the nature and distribution of the different phases. This work explores the potential of backscattered electron (BSE) imaging as a tool for the study of atmospheric corrosion. The sensitivity of the backscattered signal to small differences in average atomic number and variations in microporosity, allows study of the discontinuous nature of the atmospheric corrosion process and the distribution of contaminants in the corrosion product layers. Quantitative image analysis of BSE images has also been used to characterize the compactness of rust layers.
Galvanic Protection of Steel by Zinc under Thin Layer Electrolytes
Authors: Zhang XG , Valeriote EM
Published: March 2009

The galvanic protection distance and protection area of steel by zinc under thin layer electrolytes were determined based on measurements of the potential and galvanic current distributions of a zinc/steel couple. The protection distance was found to increase with increasing conductivity and thickness of the electrolyte and with decreasing surface area of the steel. The galvanic protection area was found to proportionally increase with increasing area of the steel to a certain value, then decrease with further increase in steel area. The galvanic corrosion rate of zinc increased with the steel area up to acertain size, then decreased slightly with a larger area. It decreased sharply as the distance between zinc and steel increased.
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.
Evaluation of Cyclic Fatigue as a Means of Assessing the Performance of Construction Joint Sealants: Silicone Sealants
Authors: Lacasse MA , Bryce JE , Margeson JC
Published: March 2009

Five types of silicone based high performance construction sealant were subjected to cyclical movements using manually adjusted vices until rupture of the specimens occurred. Failure of these sealant specimens during cyclic fatigue testing allowed comparison with previously obtained results for silicone sealants. Sealant fatigue behavior was compared with the fatigue behavior of elastomers and rubbers in order to gain a more quantitative understanding of sealants subjected to fatigue testing. These results were used to give an assessment of sealant performance in relation to their dynamic fatigue life based upon sealant resistance to cyclic deformation.
Performance of Band-Aid Sealant Joints
Authors: Myers JC
Published: March 2009

This paper examines the performance of band-aid sealant joints through tensile and cyclic laboratory tests and finite element analysis. The testing includes joints with different bond breakers and band-aid shapes. The paper compares the results of this research with that of previous studies on performance of butt and fillet sealant joints. The results of this study provide a rational basis for designing and constructing band-aid sealant joints. The paper recommends design guidelines for these joints.
Statistical Evaluations of Results of Testing Methods to Evaluate Performance of Chemical Dispersants for Oil Spills
Authors: Renard EP , Clayton JR , Inlow M , Hom W , Lee SE
Published: March 2009

Crude and/or refined oil products accidentally released into coastal or oceanic waters will result in the formation of surface slicks that create hazards to sea life. Such releases can be mitigated by the use of chemical dispersants under appropriate conditions. However, the potential performance of these agents for dispersing oil in marine situations must be known prior to their use at spill sites. Therefore, reliable methods for evaluating and quantifying performance measurements for dispersants are necessary so that dispersant performance can be better estimated. An important component in any testing method for candidate dispersants (as well as other spill treating chemicals) is the precision associated with repeated measurements made with the method. This paper presents a statistical evaluation of results from tests that were conducted to evaluate the performance of different dispersants with a number of laboratory test methods. The overall test design for the study included three test methods, two to five test oils (depending on the method evaluated), three commercially available dispersants, and analytical measurements at three spectrophotometric wavelengths. The evaluation was conducted in support of the research program of EPA's Releases Control Branch, Risk Reduction Engineering Laboratory to support the EPA work group concerned with Subpart J (Dispersant Effectiveness and Toxicity) of the National Contingency Plan (NCP). A major goal of the parent study on which this work is based has been to estimate the variability or precision for repeated measurements with test methods and provide the best estimate of this precision for the proposed revision of Subpart J of the NCP for dispersant performance testing.
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.
Data Management Demands of Complex Materials Models
Authors: King TM , Over HH , Webster GA
Published: March 2009

A well-established materials property database did not provide adequate support for complex materials modeling. By recognizing the fundamental nature of experimental procedures, the current paper proposes a recursive hierarchical structure to provide a more flexible and uniform data model. By no longer concentrating on the differences between tests, the new data model allows the retrieval of the diverse, numerous, and complex experimental data that are necessary for complex materials modeling. The retrieval of any specific materials property occurs according to a query pattern that does not change dependent on the test type. Thus, analysis routines should be able to access directly the materials property database with a consistent method, enhancing the transparency of this aspect of the software.
Pavement Materials Property Databases for Pavement Management Applications
Authors: Uddin W
Published: March 2009

Pavement layer structure and layer material property data play a key role in the development of pavement performance models, pavement design and analysis procedures, diagnostic evaluation of premature pavement deterioration, and selection of cost-effective maintenance/rehabilitation alternatives. This paper describes system design considerations for the end user interface and analysis requirements related to pavement material property database management. Case studies of material database development and implementation include the long-term pavement performance (LTPP) studies of the Strategic Highway Research Program, network-level pavement management applications on the state level, and a recent United Nations highway maintenance management project. Reference is made to the steps taken to ensure quality assurance, database integrity, and database security. Relational data-base tools provide an excellent facility for system development that should consider a number of key identifiers. The most important property data are the historical material data of all layers at the time of construction. For pavement management applications, the scope and data categories are limited and dictated by the end users and economic considerations.
Delivering Materials Engineering Information Using Hypermedia Systems
Authors: Arents HC , Thuy VT , Vancoille MJS , Bogaerts WFL
Published: March 2009

The availability of reliable and detailed information on the properties, behavior, and characteristics of materials is of crucial importance to engineers during materials engineering processes, that is, designing, manufacturing, installing, and maintaining industrial components and installations. The challenges facing computerized information tools that must provide effective support for these materials engineering processes are threefold: to develop materials information systems for use by engineers that allows structured, standardized access to diverse, highly interconnected information on materials. In this paper, we discuss how the use of hypermedia tools and techniques allows us to address these three challenges. We contend that the rich diversity and interconnectedness of materials information can only be adequately captured using the hypermedia data model. We also discuss how, using the interface functionals of a hypermedia tool, we can tailor the interface of a materials information system to the task-related needs of the corrosion engineer. We illustrate this by examining two hypermedia materials information systems that have been developed in cooperation with our research group: the Active Library® on Corrosion (ALC) and CONNAISSANCE™. The ALC is a CD-ROM based hypermedia system with a large but fixed collection of corrosion engineering information that can be consulted on the engineer's personal computer. CONNAISSANCE™ is a unique hypertext system with continuously updated materials engineering information that can be accessed and consulted on-line.
An Intelligent Object-Oriented Database System for Materials Information
Authors: Smith FJ , Krishnamurthy MV , Tripathy SR , Sage P
Published: March 2009

Materials information systems are used normally to provide data that is input to a separate design or test system that then computes the characteristics of some item or entity being designed or examined. This paper concerns the study of an integrated system that includes both the data and design systems together; therefore, it includes not only data on the property of materials but also knowledge on the geometry of the item being designed. In addition, it includes formulas representing the laws of physical science used to carry out the calculation needed to compute the necessary characteristics of the item. This kind of system can determine the optimum materials for the design of an item, rather than simply retrieve material properties. It may replace the simple search and retrieve systems available today, and it is argued that the complexity of such a system could only be achieved using an object-oriented methodology.
Database and Knowledge Acquisition for Ceramics Design
Authors: Xia Z , Lai S , Hu Z , Lu Y
Published: March 2009

To aid in the development of advanced ceramics, a materials design system was constructed. The system can be used to improve properties of ceramics by changing the composition and processing parameters. The system includes the following modules: the advanced ceramics database, the evaluation and optimization modules, the knowledge base, and the artificial neural network. Starting with the desired properties, a ceramics database will be sought. If suitable materials can be found, an evaluation module can be used to select the best one. If a suitable material is not found, the optimization module can be used to select a material with the desired property values as a reference material for materials design. The materials design system needs a large knowledge base. This knowledge base includes many relationships between composition, processing parameters, and properties. The traditional expert system or artificial neural network can be employed to acquire the knowledge base. Compared to traditional methods, the neural network is a more efficient tool for multidimensional, complex, and quantitative problems, especially problems with unknown rules. A combination of these two methods works best. Using the knowledge base obtained, users can predict the experimental results.
A Comparison of Three Smoke Test Methods
Authors: Fritz TW , Hunsberger PL
Published: March 2009

Techniques for the measurement of smoke are of significant international interest. Smoke test methods exist in Australia, Europe, Japan, North America, United Kingdom and the Nordic countries. In this study the more recent of these tests, the ISO single chamber test (ISO 5659) and the cone calorimeter (ASTM E 1354) are compared against an established test, the NBS smoke chamber (ASTM E 662). Six products, representing a wide range of anticipated responses, are examined to characterize the equipment and to compare the results of each test method. It is demonstrated that good repeatability can be achieved with these methods. Distinct results and differences in rank-ordering of products can be expected, because of the differences between the methods. Discussion and observations on the operation and calibration of the equipment are included. In the ISO test, repositioning the pilot flame and inclusion of the pilot flame with the 50 kW/m2 flux exposure improved the ignition repeatability for the range of products we tested.
Presentation of Parts of Eurocodes on Structural Fire Design
Authors: Kruppa J
Published: March 2009

A set of structural Eurocodes dealing with the basic materials used in construction (concrete, steel, wood, masonry) has been accepted in Europe as a pre-standard. A part of each covers Structural Fire Design. In Eurocode 1, thermal and mechanical actions are given. In Eurocodes 2 to 6, calculation methods for assessing fire resistance of structures can refer either to tabulated data or to simple calculation methods or advanced methods. When fire protection material is needed to increase the fire resistance, necessary data are obtained from fire test results.
Current Controversies in Fire Resistance Testing
Authors: Beitel JJ
Published: March 2009

Currently, several issues are causing controversy in the review of ASTM fire resistance standards. The predominant issues are the time/ temperature curve, the use of positive pressure, and the use of the hose stream test. These issues are discussed, and an historical background is provided. Recommendations for their resolution are provided. The resolution of these issues will assist in the harmonization of test standards with other standards organizations.
Development of the SHRP Superpave Mixture Specification Test Method to Control Thermal Cracking Performance of Pavements
Authors: Roque R , Hiltunen DH , Buttlar WG , Farwana T
Published: March 2009

The indirect tensile creep and failure test at low temperatures (ITLT) was selected by SHRP to control thermal cracking performance within the SUPERPAVE mixture design and analysis system. Fundamental viscoelastic properties and fracture parameters obtained from the test are used in the SUPERPAVE thermal cracking model to predict thermal cracking performance (cracking as a function of time) of asphalt pavements of variable thicknesses in different temperature regimes. This approach gives pavement and mixture designers the capability of determining not only that one mixture is better than another, but also quantifies how much better one mixture is than another in terms of its cracking performance. The background and principles used to identify this test method are presented in this paper along with the results of analytical and laboratory work conducted to identify specific test procedures. Comparisons between cracking predicted using ITLT test results and observed cracking in over 35 test sections in the United States and Canada have indicated that this test is suitable for control of thermal cracking of asphalt mixtures.
Behavior Analysis of Asphalt Mixtures Using Triaxial Test-Determined Properties
Authors: Fwa TF , Low BH , Tan SA
Published: March 2009

The mix design procedure for asphalt mixtures by the Mrshall method does not furnish material property parameters that can be used analytically for structural thickness design and performance analysis of pavements. This research illustrates that this missing link can be bridged by the use of laboratory triaxial test-determined properties to characterize asphalt mixtures. By means of finite element analysis using triaxial test-determined properties as input, it is illustrated that the stress-strain behavior of asphalt specimens up to failure can be simulated for the following three loading conditions: triaxial test, Marshall test, and indirect tension test. Laboratory tests involving four different asphalt mixtures are performed to provide the verification 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.
Data Requirements for Advancing Techniques to Predict Dredge-Induced Sediment and Contaminant Releases—A Review
Authors: Averett DE
Published: March 2009

In many areas of the world, contaminated sediments are being considered a major factor in the redistribution of toxic chemicals in the environment. While removal of contaminated sediments from the aquatic environment is often the preferred alternative for reducing the potential impacts of contaminated sediment, regulatory agencies and the public often express concern about contaminant releases during dredging operations. The U.S. Army Corps of Engineers continues to develop techniques for making a priori estimates of the sediment resuspension rates and contaminant releases during hydraulic and mechanical dredging activities. However, appropriate field data to verify and refine these techniques for a wide range of conditions are currently limited. Data needs include physical and operational characteristics of the dredge, waterway characteristics, sediment characteristics, sediment contaminant data, and water quality data collected during the dredging activity. This paper discusses key parameters required to improve the current predictive techniques and outlines the type of monitoring program needed to improve the comparability of the techniques to measured releases. The recommended monitoring program is derived from experiences with previous monitoring efforts. Planners of future dredging demonstrations are encouraged to collect similar data in order to advance the state of the art for predicting sediment and contaminant releases associated with dredging.
Field Demonstrations of Sediment Treatment Technologies by the USEPA's Assessment and Remediation of Contaminated Sediments (ARCS) Program
Authors: Garbaciak S , Miller JA
Published: March 2009

The Great Lakes National Program Office (GLNPO) of the U.S. Environmental Protection Agency (USEPA) has established the Assessment and Remediation of Contaminated Sediments (ARCS) Program in response to the Water Quality Act of 1987. The ARCS Program was charged with assessing and demonstrating remedial options for contaminated sediment problems in the Great Lakes. A set of technologies was identified, through a literature survey, for laboratory and field testing with sediment samples collected from five Great Lakes Areas of concern. Laboratory tests were conducted using nine processes, and pilot-scale (field-based) demonstrations of bioremediation, sediment washing, solvent extraction, and low-temperature thermal desorption were conducted at five sites. Analyses were performed on feed materials and all process residues showing polychlorinated biphenyl (PCB), polynuclear aromatic hydrocarbon (PAH), and heavy metals removal efficiencies ranging from > 6% to 99%. This paper presents the results of the five pilot-scale demonstrations conducted by the ARCS Program.
Modeling Air Emissions from Contaminated Sediment Dredged Materials
Authors: Valsaraj KT , Thibodeaux LJ , Reible DD
Published: March 2009

Volatilization rates for hydrophobic organic compounds from a confined disposal facility (CDF) containing contaminated dredged material are presently unknown. The primary purpose of this study is to indicate the availability of theoretical models for the evaluation of volatile emissions from a CDF. Four emission locales are identified and modeled: the sediment relocation (dredging) locale, the exposed sediment locale, the ponded sediment locale, and the vegetation-covered sediment locale. Rate expressions are derived to estimate the volatile organic chemical (VOC) emission from each locale. Emission rates (in mass of total VOCs per unit time) are primarily dependent on the chemical concentration at the source, the surface area of the source, and the degree to which the dredged material is in direct contact with air. The relative magnitude of these three parameters provides a basis upon which a tentative ranking of emission rates from the different locales can be given. Exposed sediment results in the greatest estimated emissions of volatiles followed by water with high levels of suspended sediments, such as might occur during dredging or during placement in a CDF. Expected to be lower in volatile emissions are dredged materials covered by a quiescent water column or vegetation.
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.
Design and Performance Verification of a Soil-Bentonite Slurry Wall for the Hydraulic Isolation of Contaminated Sites
Authors: Hollenweger R , Martinenghi L
Published: March 2009

The polluted ground of contaminated sites is often encapsulated by diaphragm walls, with concrete or concrete-stabilized earth being common construction materials in Europe. At the Institute of Geotechnical Engineering at the Swiss Federal Institute of Technology Zurich, new material mixtures that contain a high percentage of clay minerals have been developed over the past few years. Two experimental diaphragm walls, one in Switzerland andone in Germany, were constructed using such materials. A diaphragm wall 55 m deep using this mixture is currently being placed to encapsulate a contaminated landfill site in Germany. In this paper, an evaluation of the new mixture and results from both the experimental and full-scale walls, as well as complementary laboratory investigations, are presented and examined.
Critical Analysis of Sediment Quality Criteria and Hazard/Risk Assessment Tools
Authors: Galvez-Cloutier R , Yong RN , Chan J , Bahout E
Published: March 2009

The Canadian Federal Environmental Assessment Review Office is funding the Geotechnical Research Centre to facilitate their participation in the analysis of the Environmental Impact Statement during the public hearings of the Lachine Canal decontamination project. A summary and critical analysis of recent research and practical experience in the interpretation and application of sediment quality criteria and hazard/risk assessment tools was prepared for use in a comparative examination for the Lachine project.

This present survey shows that various approaches can be taken when establishing both sediment quality and remediation criteria, in light of an increasing preference for flexible guidelines that can be adjusted according to specific site conditions and that will marry more than one approach.

Depending on the complexity of the decontamination scenario, there exist different levels of application in the analysis of the hazard and risk. Simple and complex models are available, but their actual application in ongoing sediment decontamination projects is minimal due to lack of understanding of the basics of contaminant exposure assessment and exposure routes.
Two-Parameter (J-Q) Fracture Characterization of Ductile Tearing
Authors: Wu S-X , Mai Y-W
Published: March 2009

CTOD tests have been carried out for compact tension speci mens with a/W=0.6, double-edge notched tension specimens with a/W=0.9 and 0.5, single-edge notched tension specimens with a/W=0.5, three-point bend specimens with a/W=0.5 and 0.1 and center-cracked tension specimens with a/W=0.5. The results of the CTOD tests show that the crack initiation toughness of the material increases as the in-plane plastic constraint of the specimens decreases. The recently proposed two-parameter (J-Q) fracture characterisation technique has shown that the near-tip fields under very general conditions of loading in finite bodies can be described by two parameters, J and Q. A theoretical model of void nucleation and growth in the J-Q fields ahead of the crack tip is given in this paper. This model predicts the relationship between the crack initiation toughness (Ji or δi) and the constraint parameter Q. Comparison of experimental results of CTOD tests gives good agreement with theory.
Tests and Analyses for Fully Plastic Fracture Mechanics of Plane Strain Mode I Crack Growth
Authors: McClintock FA , Kim Y-J , Parks DM
Published: March 2009

Under monotonic loading, structures should ideally be ductile enough to provide continued resistance during crack growth. Such fully plastic behavior is of interest in design against collisions, tank car accidents, earthquakes, and ship groundings. For fully plastic crack growth in low strength alloys, existing asymptotic solutions for elastic-plastic growing cracks are not applicable because they reach the fracture strain only in regions small compared to the inhomogeneities of the actual fracture process.

For the limiting case of non-hardening fully-plastic plane strain crack growth, in a number of geometries and loadings the near-tip fields are characterized in terms of three parameters: an effective angle 2θs between a pair of slip planes, and the normal stress σs and the increment of displacement δus across the planes. This three-parameter characterization is in contrast to the one- or two-parameter (K or J and T or Q) characterization in linear or non-linear elastic fracture mechanics. These θs, σs, and δus parameters are found from the far-field geometries and loadings through slip line fields or least upper bound analyses based on circular arcs. The resulting crack growth, in terms of the crack tip opening angle (CTOA), is a function of θs, σs and the material. The geometry of the crack growing between two moving slip planes emanating from its tip reduces this function to the critical fracture shear strain left behind the slip planes, γf, as a function of σs, γf(σs) is found theoretically from a hole initiation and growth model. It is also found from preliminary fully plastic crack growth experiments on unequally grooved specimens with fixed-grip extension or 4-point bending of a 1018 CF steel. At high triaxialities and also after strain aging, cleavage intervened abruptly, even during stable, slow deformation.
Three-Dimensional Crack Growth Assessment By Microtopographic Examination
Authors: Lloyd WR , Piascik RS
Published: March 2009

The initial stage of the stable tearing process in two 2.3 mm sheet 2024-T3 aluminum alloy M(T) specimens are analyzed using fracture surface microtopography reconstruction techniques. The local crack tip opening angles (CTOA) in the interior of the specimens are determined relative to both crack extension and through-thickness position. The microtopographic analysis of cracks grown in the L-T and T-L orientations reveal that interior CTOA is comparable to those measured on the surface using standard optical analysis methods. Similar to surface CTOA results, interior (mid-thickness) CTOA exhibit a transient behavior; CTOA transitions from high angles, at near crack initiation, to a lower steady-state value of 5 deg. and 4.2 deg. for L-T and T-L, respectively, at crack lengths greater than 1.5 mm Fracture surface topographic projection maps are used to study the evolution of crack front tunneling during the initial stage of the fracture process. Stable tearing initiates at mid-thickness followed by a crack front tunneling process to a depth of approximately 2 mm. A brief discussion of the basis of the fracture process reconstruction method is provided and comments on the general utility of microtopographic fracture surface examination for general assessment of elastic-plastic and fully-plastic fracture processes are made.
CTOD (δ5) Estimate of Mis-Matched Joints Using the ETM-MM Procedure
Authors: Hornet P , Koçak M , Hao S , Cornec A , Schwalbe K-H
Published: March 2009

Defect assessment analyses of engineering structures require information on the elastic-plastic crack driving force. The Engineering Treatment Model (ETM) has been developed at the GKSS Research Center to estimate the crack tip opening displacement CTOD (δ5) and the J-integral for homogeneous specimens. When the plasticity properties of base and weld metals are different, which is referred to as weld strength mis-match, the defect assessment procedures need to be modified accordingly. Therefore, the ETM has recently been extended (ETM-MM) to predict the CTOD for tension loaded wide plates with transverse strength mis-matched welds containing through thickness cracks parallel to the weld / base metal interface, in the middle of the weld by finite element calculations and analytical considerations.

This paper presents the comparison between the estimates of the ETM-MM procedure and the experimental results of as-welded (AW) and stress relieved (SR) highly overmatched weld CCT specimens. The ETM-MM predictions have been obtained using the yield stress (σ0) and strain hardening exponent (n) data approximated from the true ((σ0t, nt) and the engineering (σ0e, ne) stress-strain curves of the base and eight overmatched weld metals. The ETM-MM procedure generally provides very good estimates; however, it always yields conservative estimates of the CTOD (δ5) for all eight CCT panels with the use σ0e and ne data. On the other hand, the use of σ0t and nt values provides a better agreement with the experimental results for a large range of CTOD (δ5) cases.
Experiments and Analyses on Undermatched Interleaf Specimens in Bending
Authors: Parks DM , Ganti S , McClintock FA , Epstein JS , Lloyd LR , Reuter WG
Published: March 2009

Model weldment fracture specimens have been fabricated, tested, and analyzed using finite elements. The specimens consist of an interleaf of commercially pure titanium diffusion-bonded to a harder alloy titanium. A deep edge crack is introduced symmetrically into the interleaf, and the specimens are loaded in pure bending. Variation of the thickness (2h) of the soft interleaf layer provides insight into effects of weld geometry in strongly undermatched weldments tested in plane strain bending. Ductile crack growth (beyond blunting) initiated at loads giving J ≿ 95 kJ/m2 in all specimens. In the thickest interleaf geometries, stable tearing was obtained, but in the thinnest interleaf (2h ≿ 3 mm), crack initiation resulted in a massive pop-in of 5.4 mm across an initial ligament of 12 mm. Finite element studies show that the thinnest interleaf geometry had slightly higher peak stress triaxiality at the beginning of cracking, and that the highest triaxiality extended over a larger region than in the thicker interleaf specimens loaded to the same initiation J-values. More importantly, the blockage of plastic straining above and below the crack tip in the 3 mm interleaf specimen forced higher values of plastic strain to spread forward into the ±45‡ sector of highest stress triaxiality directly ahead of the crack tip. The higher strains, in conjunction with the slightly higher stress triaxiality, led to the unstable pop-in initiation.
Analysis of Damage and Failure in Metal Matrix Composites
Authors: Brust FW , Majumdar BS , Newaz GM
Published: March 2009

This paper presents the results of the analysis of the constitutive response of a model Metal Matrix Composite (MMC) system. The model is described first, followed by some direct comparison of predicted response to corresponding experimental data. An important result discussed here is that when model verification is made, it is important to compare load direction response to the experimental data, but also, comparisons to the out of load direction response must be made, or the model may not be performing as desired. Some discussion of failure predictions using simple models is also made here.
Cyclic Fatigue Mechanisms in Partially Stabilised Zirconia
Authors: Hoffman MJ , Wakayama S , Mai Y-W , Kishi T , Kawahara M
Published: March 2009

Cyclic fatigue crack growth rate and crack resistance curve testing were undertaken on 6 different grades of Mg-PSZ. The width of the transformation zone at the flanks of the cracks was determined using Raman spectroscopy and, combined with R-curve toughening values, used to ascertain the level of crack-tip shielding during cyclic fatigue crack growth and hence the crack-tip stress intensity factor amplitude. By normalising the crack-tip stress intensity factor amplitude with the intrinsic toughness of the material, it was found that the cyclic fatigue threshold stress intensity factor was independent of the extent of crack-tip shielding and a function of the stress intensity factor at the crack tip. In situ SEM observations of cyclic fatigue revealed crack bridging by uncracked ligaments and the precipitate phase. Under cyclic loading the precipitate bridges were postulated to undergo frictional degradation at the precipitate/matrix interface with the degree of degradation determined by the cyclic amplitude. Acoustic emission testing revealed acoustic emissions at three distinct levels during the loading cycle: firstly, near the maximum applied stress intensity factor caused by crack propagation; secondly, at the mid-range of the applied stress intensity factor attributed to crack closure near the crack tip, presumably as a result of transformation induced dilation; and thirdly, intermittently near the base of the loading cycle as a result of fracture surface contact due to surface roughness at a significant distance behind the crack tip. Crack closure near the crack tip due to dilation is proposed to significantly reduce the crack tip stress intensity factor amplitude and hence the degree of cyclic fatigue.
Fatigue Crack Growth Behavior of Al-Li Alloy 1441
Authors: Prakash RV , Parida BK
Published: March 2009

Fatigue crack growth behavior of Al-Li alloy 1441 having a marginally lower lithium content, compared to 80xx and 20xx series Al-Li alloys is presented in this paper. This investigation was conducted on single edge tension -SE(T)\3 — specimens, under constant amplitude as well as under MiniLCA flight spectrum loading with the specific objective of determining the effects of stress ratio, orientation, thickness and cladding. Three thicknesses were considered: 1.2 mm(clad and unclad), 2.0 mm(clad and unclad) and 8.0 mm unclad. Constant amplitude fatigue tests were conducted at stress ratios of -0.3, 0.1 and 0.7. Testing was performed under ambient conditions and along three orientations, namely L-T, T-L and L+45 degrees. Crack growth characteristics of this alloy are compared with that of BS:L73 (2014-T4 equivalent) for assessing the possibility of replacing BS:L73.

Significant effect of stress ratio on crack growth rate was observed in all thicknesses. However, in case of 1.2 and 2.0 mm thick sheets, the effect was minimal at intermediate-crack growth regime. The orientation of the specimen does not adversely affect the fatigue crack growth behavior of 8.0 mm and 2.0 mm thick specimens. However, for 1.2 mm unclad sheet crack growth resistance in L-T direction was found to be superior to that along T-L direction. In majority of test cases considered, no significant effect was observed on crack growth rate due to thickness or cladding. Crack growth characteristics of Al-Li alloy 1441 and Al-Cu alloy BS:L73 under constant amplitude as well as MiniLCA spectrum loading are similar in the low and intermediate-crack growth rate regime. Based on these observations, it is felt that this Al-Li alloy has the potential for future aerospace applications.
The Application of a Logic Framework for Fatigue Crack Growth Analyses to Microstructural Effects
Authors: Xu JG , Liu HW
Published: March 2009

△K has been widely used to correlate da/dN data. The relation between da/dN and △K is usually found empirically. However, fatigue crack growth relations can also be derived theoretically. Three fatigue crack growth theories are derived for the state of small scale yielding and plane strain. These three theories constitute a logic framework useful for fatigue crack growth analyses. The application of the logic framework to the analyses of microstructural effects on fatigue crack growth is illustrated.

The fatigue crack growth curve of 7075-T651 aluminum alloy has five distinct regions. A fatigue crack grows by crack-tip shear decohesion forming striations and by brittle fractures of particles followed by localized shear decohesion at these microcracks forming dimples. The logic framework helps to relate the fatigue crack growth behaviors in these five regions to the fractures of inclusions and to the resistance of grain boundaries and dispersoids to shear decohesion.
Fracture Mechanics Life Prediction Computer Code Verification and Validation
Authors: Wilson CD
Published: March 2009

The verification and validation (V&V) of a fracture mechanics life prediction computer code is an essential task. The confidence level of results is directly related to the effort invested in the V&V process. The V&V process of life prediction software is broken two major parts: computer code assessment and fracture mechanics assessment. The fracture mechanics assessment is divided into three V&V tasks: fracture mechanics parameters, baseline predictions, and advanced predictions. The details of validating the stress intensity factor solution for a surface crack in a finite plate is discussed. Example V&V results are reported for NASCRAC Version 2.0 and NASA/FLAGRO Version 1.3. NASCRAC has significant errors in implementing a fatigue crack growth algorithm. In addition, the surface crack stress intensity factor solution in NASCRAC does not agree well with established analytical and experimental benchmark results. NASA/FLAGRO has computer coding problems which affect its portability.