bluuebunny/crossref_metadata_2025 huggingface dataset:
Byproduct Gypsum
Authors: Pressler JW
Published: December 2008

The United States was the world's leading consumer of crude gypsum in 1982, with a demand of 16 million metric tons in the manufacturing of gypsum wallboard as a set retarder in cement, and some demand for its uses in agriculture. Only about 4% of this was byproduct gypsum sold for agricultural land plaster. Byproduct gypsum is the chemical end product of industrial processing plants, consisting primarily of calcium sulfate dihydrate, CaSO4·2H2O. The oldest byproduct-gypsum-producing industry is that of the phosphate rock chemical processing in Florida. Large sludge ponds and retaining stockpiles are accumulating, and total tonnage may approach 1 billion metric tons by year 2000. The United States has no firm plans for recycling and utilization of this and other forms of byproduct gypsum. Environmental pressures because of solid pollution and the increasing cost of land may influence the United States to develop better utilization within the next ten years. Projected production of byproduct gypsum from coal burning power plant fluegas desulfurization systems may be equal to the production tonnage of 30 million metric tons per year of phosphogypsum by 1990, thus adding more social and economic pressures for utilization.

Japan phased out natural gypsum production in 1976, and now is recycling 6 million metric tons per year of byproduct gypsum for wallboard, cement, and plaster. She is now leading the world in the technology of utilization of byproduct gypsum, with a balance established between supply and demand. European countries have active research and development projects but are still dumping many million tons per year into the sea.

It is suggested that the United States use more of the increasing tonnages of byproduct gypsum for its traditional uses of wallboard, plaster, and as a set retarder in cement. Other high-tonnage uses are offered, such as cellular foamed gypsum for insulation, road construction, gateway supports in coal mines, and its potential as the largest sulfur resource in the world.
Statistical Aspects of Designs for Studying Sources of Contamination
Authors: Liggett WS
Published: December 2008

A design for studying sources of environmental contamination must start with a basis for distinguishing the contamination of interest from the background. As part of this basis, the design should provide a method for assessing the sampling and measurement error. Because of problems with reports of none detected, the design should also include a plan for analyzing intermediate laboratory results in addition to the reported values. This paper discusses these aspects of design in the context of monitoring the groundwater around a waste management facility. A design appropriate for spatially and temporally varying backgrounds is proposed and illustrated with monitoring results from Alabama and Florida. To assess the sampling error, the proposed design specifies resampling each well after a period of a few days. Experiments to check this procedure are suggested. The proposed design incorporates and supplements the Environmental Protection Agency laboratory method for total organic halide. In addition, this paper illustrates some difficult design problems that involve nonnormality and nonlinear measurement methods.
Determination of Measurement Data Quality and Establishment of Achievable Goals for Environmental Measurements
Authors: Mitchell WJ , Rhodes RC , McElroy FF
Published: December 2008

In recognizing the need for measuring and documenting the quality of environmental measurements obtained in its monitoring projects and for setting achievable data quality goals for such projects, the Environmental Protection Agency, issues a number of guidance and informational documents addressed to those needs. This paper reviews one of those documents, a comprehensive compilation of the quality of measurements actually obtained with various environmental measurement methods in all environmental media. Included are a brief discussion of the rationale and purpose of the document, limited reviews of the four designated measures of data quality (precision, accuracy, completeness, and method detection limit), and explanations of the format used to list the data quality information. Examples of actual data listings from the document are also included.
Quality Assurance Project Plans—A Key to Effective Cooperative Monitoring Programs
Authors: Brossman MW , Hoogheem TJ , Splinter RC
Published: December 2008

The use of cooperative monitoring programs, involving the co-mingling of data of the regulated community and the “regulators,” can lead to effective utilization of resources and contribute to cooperative solutions to our pollution control programs. Such benefits can only be realized, however, under controls which ensure the comparability and validity of data obtained through well-defined roles and work plans. A key to this control is the Work/Quality Assurance (QA) Project Plan developed cooperatively by the type of team reflected in the authorship of this paper, namely by federal, industry, and state/municipal representatives.

A comprehensive Work/Quality Assurance Project/Work Plan Guidance document has been developed in the Office of Water, U.S. Environmental Protection Agency (EPA), which should effectively meet QA requirements for a wide range of users and types of water-monitoring tasks. This guidance document is designed to cover all aspects of water environmental measurement from field sampling through laboratory analysis and data reduction and, where applicable, computer input.

The document integrates a work plan with a QA plan eliminating the dual effort of overlapping plan developments and assuring practical incorporation of quality assurance/quality control. In addition, the combination of the work plan and QA plan provides a comprehensive basis to establish sound coordination and agreement for cooperative monitoring tasks. This guidance document is currently in pilot implementation throughout the United States.
Quality Assurance of U.S. Geological Survey Water-Quality Field Measurements
Authors: Erdmann DE , Thomas JD
Published: December 2008

Each year many thousands of water-quality measurements are made in the field by personnel of the U.S. Geological Survey's Water Resources Division. To insure the accuracy of these measurements, an external quality assurance program was officially established in March 1979. The initial phase of this program was concerned with specific conductance and pH measurements. Reference samples are submitted semiannually to field analysts for measurement of these parameters with the same techniques and instruments used in the field. Both the personnel and the instruments involved in making the determinations are recorded. When the data are complete, a report defining the quality of the analytical results is prepared and circulated to appropriate District, Regional, and National offices. Field data, in addition to their immediate use, are normally placed in a national data base and are available to all hydrologists. As a result, the quality of field measurements can have a profound effect on their investigations. The quality assurance program described is designed to insure that the field data of the Water Resources Division are highly accurate.
An Analytical Method and Quality Control Program for Studies of Currently Used Pesticides in Surface Waters
Authors: Kramer JW , Baker DB
Published: December 2008

Studies of the transport and loading of currently used pesticides in rivers draining large agricultural river basins pose numerous problems for the analytical laboratory. Most of the annual export occurs during the first two runoff events following the period of major pesticide application. Rapidly changing pesticide concentrations during these events require the use of automatic samplers for collections over the hydrograph. Each sample must be scanned for a wide variety of pesticides and samples frequently contain high concentrations of suspended sediments.

We have developed an analytical procedure which focuses on those pesticides which can be directly extracted in methylene chloride and analyzed by capillary gas chromatography. The procedure includes: extraction with methylene chloride; sonication to break up sediment-extractant-water emulsions; drying over sodium sulfate (Na2SO4); concentration with Kuderna-Danish apparatus; transfer to isooctane; and splitless injection into two capillary columns equipped with nitrogen-phosphorus thermionic detectors. The procedure provides quantification of the following pesticides: linuron, EPTC, butylate, ethoprop, trifluralin, phorate, simazine, atrazine, terbufos, fonofos, diazinon, cyanazine, metribuzin, alachlor, metolachlor, chlorpyrifos, penoxalin, and two atrazine metabolites. The dual column injection allows simultaneous confirmation of 14 of the compounds listed above.

The quality control (QC) program relies heavily on automated features of the analytical system. An autosampler allows analyses of a large number of QC samples including recalibration standards, blanks, replicates, spikes, and linearity checks. A data acquisition system provides chromatograms and detailed data reports for both capillary columns. Automatic transfer of the data reports to a computer system facilitates data quality review and data correction. The analytical procedure and associated quality control program provide an effective method for analyzing the large number of samples required in pesticide loading studies during runoff events in large rivers.
Establishing Destruction Efficiency for Hazardous Waste Incinerators
Authors: Colby BN , Picker JE
Published: December 2008

The expansion of technology has brought a critical need to dispose hazardous wastes safely and permanently. The historic approaches to disposal, such as land filling, discharge into waterways, and deep well injection have begun to exhibit severe environmental and human health safety problems. These in turn have resulted in legislation such as the Clean Water Act, the Toxic Substances Control Act, and the Resources Conservation and Recovery Act, all of which regulate and establish responsibility for hazardous materials. One universally desirable feature in hazardous waste disposal is once-and-for-all destruction of the waste. Incineration (i.e., thermal oxidation) is considered by many to offer this feature. There is, however, a need to demonstrate destruction efficiency in order to satisfy environmental regulations and to aid in public acceptance of the process.

Establishing incineration destruction efficiency for regulatory compliance is a challenging technical problem owing to the variety of sampling and analysis techniques which may be involved. It is also a challenging documentation problem owing to the potential for “concerned citizen” initiated litigation. Both of these problems require application of sound quality assurance (QA) protocols in order to generate destruction eficiency data of known and documented quality. It is these QA protocols which are the subject of this presentation. Issues addressed include the representativeness of samples and sample collection, the precision and accuracy of analytical methods and destruction efficiency calculations, and the documentation associated with establishing data quality. Emphasis is placed on those QA approaches that can be applied to data sets of limited size normally associated with incineration destruction efficiency evaluations.
Quality Assurance in Acid Precipitation Measurements
Authors: Campbell S , Scott H
Published: December 2008

The growing interest in acid deposition has led to a proliferation of laboratories engaged in such studies. High-level quality assurance (QA) procedures are required for each program to standardize the diverse measurement methods in use and to determine the validity of differences in measurements widely separated in space and time. Both inlaboratory (quality control) and external (quality assurance) procedures are required. A complete QA program for acid precipitation measurements must address program objectives; site selection and operation; operator selection and training; sample collection, handling, and analyses; and data checking, storage, retrieval, and transmission. Objective criteria must be developed for detecting adulterated samples and invalid data. Appropriate laboratory and field blanks must be collected and analyzed. Standard techniques (sample spiking, replicate analysis of standards and samples) should ensure the reliability of analytical results. Relevant quality assurance data, including analytical detection limits, blank values, and the variability of replicate determinations, must be supplied with each data transmittal. Experimental information should be available upon request. The measurement of the pH of dilute solutions such as rain is particularly difficult; differences as large as 0.3 pH unit may be observed in replicate analyses of the same sample using different electrode types. Laboratory results are presented demonstrating typical variability to be expected in the collection, storage, and analysis of rainwater for major ions, including hydrogen ion.
The Role of NBS Standard Reference Materials in Quality Assurance of Environmental Measurements
Authors: Alvarez R
Published: December 2008

Analyses of environmental samples of known homogeneity by different laboratories often disagree seriously. Discrepant data may result from poor methodology, improper instrument calibration, faulty experimental techniques, or from a combination of these factors. One approach towards obtaining accurate data is through the use of Standard Reference Materials (SRMs) issued by the National Bureau of Standards under federal statutes. SRMs are homogeneous, stable materials with certified chemical or physical properties, and are used in calibrating instruments, validating laboratory data, developing methods of known accuracy, and referring data from different laboratories to a common base. Of the approximately 900 SRMs listed in the current SRM catalog, over 90 have been developed for use in improving the accuracy of environmental analyses. Environmental matrix SRMs certified for priority pollutants include gases, atmospheric dust, water, sediments, biological materials, and fuels. In addition, calibrator solutions of organic priority pollutants, such as halocarbons, and polycyclic aromatic hydrocarbons, are available for determining instrumental response factors, and adding accurate amounts of these compounds to samples.
Establishing an Environmental Quality Assurance Program
Authors: Eggenberger LM
Published: December 2008

Specific steps leading to the establishment of an Environmental Quality Assurance Program in an analytical laboratory are enumerated and discussed. Aspects of a model Quality Assurance Program that applies fundamental principles and methods to selected laboratory instrumentation and analytical protocols for the attainment of accurate, reliable results are reviewed. Discussion includes specific factors such as method validation, certification, sample handling, security, documentation, and continuing data assessment.

Objectives and problem areas characteristic of newly implemented programs, such as building a data base, interim control limits, reference standards, and categorizing and prioritizing prospective control areas, are included in the discussion.
Interlaboratory Quality Assurance Aspects of the International Joint Commission's Great Lakes Monitoring Programs
Authors: Aspila KI , White RE , Clark JL
Published: December 2008

Quality assurance activities that identify comparability of environmental data produced by over 50 laboratories that support the Canada-United States Great Lakes International Surveillance Program are described. The activities include the development and use of stable natural reference standards for waters, sediments, and fish in an interlaboratory comparison studies program. The interlaboratory studies are designed to include 10 to 15 stable natural samples that for most studies are analyzed for 10 to 15 constituents by 25 to 35 laboratories. A typical simple study on total phosphorus in water is described. Interlaboratory results for each sample are ranked and then laboratory measurement bias identified by the method of Youden. Results deviating significantly from the interlaboratory median values are flagged by the method of Clark. A laboratory specific report is then prepared and provided to each participating laboratory and is made available to report writers who must typically work with results from different laboratories. These quality assurance activities are constructive and effective. Remedial measures are taken to improve the laboratory measurement process.
Effects of Compaction Temperature and Effort on the Engineering Properties of Asphalt Concrete Mixtures
Authors: Kennedy TW , Roberts FL , McGennis RB
Published: December 2008

In recent years there has been a trend toward operating asphalt plants at lower mixing temperatures. These lower temperatures result primarily from a desire to conserve the energy required to produce the mixtures. The most direct result of lower mixing temperatures is lower temperatures during compaction. The effect of these lower compaction temperatures on performance has not been established, but laboratory studies have led to some questions that need to be addressed. The purpose of this paper is to summarize the results of a field and laboratory study performed at The University of Texas at Austin, Center for Transportation Research, to analyze the effect of lower compaction temperatures on the engineering properties of asphalt concrete mixtures.

Both the field and laboratory studies were conducted as part of an investigation of premature distress of a recycled asphalt concrete overlay. It is significant to note that field observations, as well as laboratory results obtained during construction, indicated that the specified laboratory densities were attained. Even though other factors contributed to the distress, data developed as a part of this study showed that the low compaction temperatures during construction had an adverse effect on the engineering properties of the asphalt concrete and thus contributed significantly to the development of the premature distress.

The field study included examining the construction records to evaluate factors, such as mixing and compaction temperatures, as well as density and Hveem stability of job control laboratory specimens. In addition, a condition survey was performed to determine the nature and extent of the observed distress.

The laboratory study involved preparation of specimens under different combinations of compaction temperature and density observed in the field with subsequent testing to determine Hveem stability, and dry and wet static tensile strengths. The results presented in the paper include a discussion of the interaction between compaction control parameters and the occurrence of distress. Results from these studies indicate that lower mixing and compaction temperatures produce adverse effects on the engineering properties of hot mixed asphalt concrete.
Experiences of Corps of Engineers in Compaction of Hot Asphalt Mixtures
Authors: Brown ER
Published: December 2008

This paper discusses the historical development and present procedures used by the Corps of Engineers for specifying, obtaining, and evaluating density of hot mix asphalt concrete. To obtain satisfactory density requires that proper equipment and experienced personnel be used for construction of the asphalt concrete. Experiences with various rollers and rolling techniques that have proven satisfactory are discussed. The lack of density obtained in longitudinal joints has always been a problem in airfield construction, and on most airfield pavements initial damage begins in these longitudinal joints. Statistical quality control procedures are used to insure that unbiased evaluation of in-place density is obtained. Control charts are used to record density results and to identify trends in density that may indicate potential problems before they become significant.
Pennsylvania's Experience in the Compaction of Asphalt Pavements
Authors: Kandhal PS , Koehler WC
Published: December 2008

During 1974 through 1977, premature pavement distress in the form of loss of fines (matrix) and ravelling (loss of aggregate particle larger than 6.35 mm [¼ in.]) was observed on several asphaltic concrete overlay projects in Pennsylvania. Statistically designed detailed investigations were conducted to determine the cause of this premature distress. Cores 152 mm (6 in.) in diameter were obtained at random and tested for density, air void content, mix composition, and rheological properties of the recovered asphalt. Lack of adequate compaction (high air void content) was determined to be the primary cause of distress. Nuclear control-strip techniques were used on these projects for compaction.

The following data obtained from these investigations are included in the paper: (1) correlation of air void content with the extent of loss of fines and ravelling (rated as none, slight, moderate, and severe from field observations) and (2) correlation between the percent compaction data obtained by two methods (core density and nuclear gage density) at the same locations on the distressed pavements.

Statistical analysis of the data from these projects indicated that (1) the percent compaction just after construction should be at least 92% of the maximum specific gravity of the mix to prevent the premature distress in the pavement and (2) the nuclear gage cannot be relied on completely by the user agency for acceptance purposes; it is most suited for compaction quality control by the contractor during construction.

A statistical (end result) specification for compaction was developed and implemented by the Pennsylvania Department of Transportation in 1978. Density cores are obtained and tested at the central laboratory. The adoption of this compaction specification has resulted in a very significant improvement statewide in the initial compaction levels of asphalt pavements. The paper gives the outlines of this compaction specification, test procedures, and implications. The data on actual compaction levels (based on approximately 6000 core tests) achieved statewide in 1981 have been analyzed statistically for both binder and wearing courses.
Effect of Percent Compaction on Asphalt Mixture Life
Authors: Bell CA , Hicks RG , Wilson JE
Published: December 2008

One of the major difficulties in asphalt concrete pavement construction is the control of materials and the subsequent level of payment to contractors for materials not conforming to specifications. The effect of this noncompliance on pavement serviceability is not fully established; however, it frequently results in reduced payments to contractors, which, in turn, causes much controversy between the two parties. Specific mixture properties outside specification tolerance, which are accepted by most agencies through reduced payment include percent compaction, asphalt content, and mix gradation. The reduced payment used normally relies heavily on the experience and judgment of the agencies; therefore, there is often wide disparity in the pay adjustment factors used.

The paper summarizes currently available techniques for estimating the modulus and fatigue life of asphalt mixtures and shows how these, together with existing failure criteria for fatigue and permanent deformation may be used to estimate the effects of changes in compaction on pavement life. Secondly, the results of extensive laboratory tests on asphalt mixtures from three projects in Oregon are reported. Tests were performed to evaluate the effect of mix variations (including density) on mix properties (modulus, fatigue life, and resistance to permanent deformation). Tests were run using both as-compacted and conditioned (vacuum saturated followed by freezing then heat soaking) specimens. The test used throughout was the ASTM Repeated Load Diametral Test (D 4123-82) modified slightly such that fatigue life could be evaluated.

The results of the test program indicated that percent compaction (or void content) was the most significant factor affecting mix performance. An increase in void content is associated with a decrease in modulus, fatigue life, and resistance to permanent deformation.

The result of the study findings was the development of new asphalt concrete compaction specifications for the state of Oregon. Not only does the Oregon Department of Transportation (DOT) now require a higher standard of compaction (91% of American Association of State Highway and Transportation Officials [AASHTO] T209 maximum specific gravity), but they have also spelled out clearly the penalties for not achieving density.
Standardization of Sampling and Analysis Methods for High-Purity Copper Cathodes: A British View
Authors: Butler DH
Published: December 2008

Draft for Development 78 (DD78), “Higher Purity Copper Cathode”, published by the British Standards Institution requires the support of agreed methods of sampling and analysis capable of showing whether the impurities specified are below the limits set. This paper summarizes the state of development of methods for sampling and analysis of high-purity copper cathode arrived at in the U.K. with international support. The aims of work in progress are discussed.
Sampling and Analysis of Copper Cathodes: A User's Viewpoint
Authors: Roesch CJ
Published: December 2008

A review is given of the methods and procedures used to sample and obtain chemical analysis for copper cathode at the Hawthorne Works of Western Electric in Chicago, Illinois. The discussion includes a description of the tests used to evaluate the quality of copper rod.
An Analysis of Variance of Impurity Distributions in Electrolytically Refined Copper Cathodes
Authors: Cardinal AL , Montes G , Farraro JT
Published: December 2008

Analysis of variance was conducted on impurity distributions in cathodes selected from Phelps Dodge (El Paso Refinery) and two others known to operate highly efficient tank houses. The within-cathode variation confirmed previous findings. The variation between cathodes for most elements detected, however, was significantly lower than anticipated. This could be attributed to recent advances in tank house technology.
Copper Cathode Sampling in Scandinavia
Authors: Ludvigsson BM
Published: December 2008

A Scandinavian working group with members from Boliden Metall, Elektrokoppar, Gränges Metallverken, Outokumpu, and Jernkontoret has been working on problems related to copper cathode quality. One of the main initial problems was finding an accurate sampling method for cathodes. In order to investigate the distribution of impurities in a copper cathode, one representative cathode was cut into 100 pieces. Each piece was given a position number and melted to give an analyzable homogeneous sample. The results indicated that the most reasonable sample would be a vertical, 50 to 100 mm wide, strip from the center of the cathode. The method used to obtain the sample was named the Vertical Strip Method (VSM). This sampling method has been used several times when processing cathode lots to rod. Statistical calculations have shown good and significant correlation between the mean values for most of the elements. The number of cathodes taken for sampling can be as few as 4 to 6.
Prediction of Wire Rod Quality from Cathode Analyses: Input/Output Sampling of a Shaft Furnace Operation
Authors: Tuddenham WM , Brenza JJ
Published: December 2008

Rod produced from copper melted in a shaft furnace provides an excellent means of monitoring cathode quality if the feed is segregated according to source and correlated with output. While this approach is feasible in some fully integrated operations, specific cathode sampling procedures must be used in the case of direct cathode sale. By careful sampling and analysis of input to and output from a rod casting operation a more quantitative understanding of the requirements and limitations for sampling cathode lots was developed. The cathodes were sampled by drilling, by saw-cutting, and by cutting cathode strips. Statistical analysis of the data demonstrated the superiority of saw-cut samples over drill samples for predicting impurity concentrations in cathode lots.
Precision of Electrorefined Copper Assaying
Authors: Parr JC , Braithwaite JW
Published: December 2008

A principal measure of the quality of electrorefined copper cathodes is impurity content. As such, good analytical precision is needed to identify subtle improvements in quality and to ensure that industry specifications are being satisfied. The object of this study was to determine and document the current state of refined copper analytical precision. Three levels of precision were evaluated. The highest level was determined from the sequential analyses of over 100 wire rod samples. The implications of this precision on both impurity specifications and actual content in cathodes are discussed. The study of the day-to-day precision and long-term precision among several laboratories was determined from analyses made on standard samples. A statistical comparison of the long-term and sequential data is given.

Based on the data presented in this paper, two areas of refined copper assaying which require improvement are evident: (1) precision of long-term interlaboratory analyses of many elements and (2) detection limits for others. If appropriate analytical accuracies and precisions are to be achieved, substantial progress in analytical methodology will be required.
Mode I Stress Intensity Factors for Point-Loaded Cylindrical Test Specimens with One or Two Radial Cracks
Authors: Parker AP , Andrasic CP
Published: December 2008

Weight (or Green's) functions are obtained, using an accurate modified mapping collocation numerical technique, for cylindrical specimens with either one or two internal or external radial cracks. Radii ratios (the ratio of external/internal radius) of 1.25, 1.5, 1.75, 2.0, 2.5, and 3.0 are considered. The weight functions are used to obtain stress intensity (K) factors for radial loading by point forces symmetrically located about the crack line and about an axis at right angles to the crack line, through the center of the specimen. The maximum errors associated with the solutions are estimated at 1%.

Notable features of the results obtained include a significant range of crack lengths with near-constant K-values, and configurations in which K changes sign as the crack length is increased. The point force configurations are suited to serve as cylindrical test specimens, either for fracture toughness or fatigue crack growth testing.
An Elastic-Plastic Finite Element Analysis of Crack Initiation, Stable Crack Growth, and Instability
Authors: Newman JC
Published: December 2008

An elastic-plastic (incremental and small strain) finite element analysis was used with a crack growth criterion to study crack initiation, stable crack growth, and instability under monotonic loading to failure of metallic materials. The crack growth criterion was a critical crack-tip-opening displacement (CTOD) at a specified distance from the crack tip, or equivalently, a critical crack-tip-opening angle (CTOA). Whenever the CTOD (or CTOA) equaled or exceeded a critical value, the crack was assumed to grow. Single values of critical CTOD were found in the analysis to model crack initiation, stable crack growth, and instability for 7075-T651 and 2024-T351 aluminum alloy compact specimens. Calculated and experimentally measured (from the literature) CTOD values at initiation agreed well for both aluminum alloys. These critical CTOD values from compact specimens were also used to predict failure loads on center-crack tension specimens and a specially designed three-hole-crack tension specimen made of the two aluminum alloys and of 304 stainless steel. All specimens were 12.7 mm thick. Predicted failure loads for 7075-T651 aluminum alloy and 304 stainless steel specimens were generally within ±15% of experimental failure loads, while the predicted failure loads for 2024-T351 aluminum alloy specimens were generally within ±6% of the experimental loads. The technique presented here can be used as an engineering tool to predict crack initiation, stable crack growth, and instability for cracked structural components from laboratory specimens such as compact specimens.
Stress Intensity Distributions and Width Correction Factors for Natural Cracks Approaching “Benchmark” Crack Depths
Authors: Smith CW , Kirby GC
Published: December 2008

A series of frozen stress photoelastic experiments were conducted on natural surface flaws in both wide and finite width flat plates under uniform uniaxial tension. The flaws grown under monotonic load were semielliptic and retained that shape (but with varying aspect ratio) up to 75% of the plate depth. The stress intensity distributions compared favorably with the predictions of the Newman-Raju analysis, but were slightly higher at the points of maximum flaw penetration for the deeper flaws. The crack growth path of the photoelastic models differed from that resulting from fatigue tests on aluminum up to a/T ≈ 0.3. The difference is conjectured to be caused by crack closure in the fatigue tests.
Recent Advances in Crack-Arrest Technology
Authors: Rosenfield AR , Mincer PN , Marschall CW , Markworth AJ
Published: December 2008

Statistical analysis of the variability of crack-arrest toughness (Ka) is reviewed. The standard deviation of Ka is 12 MPa · m1/2 for an individual heat of low-alloy steel and 15 MPa · m1/2 when data for all heats are referred to the Charpy 41-J (30 ft-lb) temperature. These results aid in the definition of acceptable size limitations for crack-arrest test specimens. Miniature specimens (50 by 50 by 12.7 mm) are shown to give acceptably conservative results when tested in the vicinity of the reference transition temperature.
Application of High-Temperature Fracture Mechanics to the Prediction of Creep Crack Growth for a γ-γ′ Nickel-Base Superalloy
Authors: Huang JS , Pelloux RM
Published: December 2008

Creep crack growth rates were measured in a γ-γ′ low-carbon Astroloy at 650 to 760°C. A theoretical model based upon the mechanism of cavity nucleation, growth, and coalescence on the grain boundaries near a crack tip was used to predict the creep crack growth rates in Astroloy. The model assumed that creep crack growth was an intermittent cracking process as observed in the experiments. A crack tip stress field of the HRR type in a creeping medium, derived previously by Riedel and Rice, was used for the analysis. The model gave a good prediction of the dependence of the crack growth rates on test temperature and stress intensity factor. The model does not take into account the crack tip stress triaxiality. However, by assuming that the crack tip stress triaxiality was intermediate between the plane strain and the plane stress, a good correlation was obtained between theory and experimental data.
Load History Effects on the Fracture Toughness of a Modified 4340 Steel
Authors: Landes JD , Leax TR
Published: December 2008

The effect of load history on fracture toughness was examined for a modified 4340 steel where toughness was evaluated in the elastic-plastic regime by the JR-curve test method. Four types of load histories were applied: (1) cyclic loading during R-curve development; (2) fatigue precracking at high load levels; (3) bulk prestraining, both monotonic and cyclic; and (4) slow loading during the R-curve test. These load histories were applied in four separate sets of tests. The resulting JR-curves were compared with R-curves generated for specimens tested in a normal monotonic toughness test. Raising the R-curve was judged as an increase in toughness and lowering it as a decrease. The results showed that (1) the R-curve developed during a cyclic load history has both a monotonic component and a cyclic component, (2) fatigue precracking at high load levels does not affect the R-curve, (3) monotonic bulk prestraining lowers the R-curve whereas cyclic bulk prestraining raises it, and (4) the R-curve may be lowered by decreasing the monotonic loading rate.
Geometry and Size Effects on J-R and δ-R Curves under Plane Stress Conditions
Authors: Hellmann D , Schwalbe K-H
Published: December 2008

J-R curves and δ-R curves were measured on 5-mm-thick compact, three-point bend, and center cracked tension specimens with different widths and different precrack lengths. The crack tip opening displacement (δ) was measured at the fatigue crack tip. The materials tested were an age-hardened aluminum alloy; the same alloy in a furnace cooled, very soft condition; and an alloy steel. It was found that the J-integral correlates three to five times as much crack growth in the tension specimens as in the compact and bend specimens, or, in other words, a valid R-curve detemined on a center cracked tension specimen covers at least three times more crack growth than a valid R-curve determined on a compact or bend specimen of the same width and crack length. Furthermore, δ correlates even more crack growth: a valid δ-R curve determined on a compact or bend specimen covers about five times more crack growth than a valid J-R curve. For center cracked tension specimens the amount of crack growth measured was not sufficient to establish limits for a valid δ-R curve; however, at least 60% of the original ligament width can be expended by crack growth for a valid δ-R curve.

It is worth noting that no geometry effect on the J-R curve and δ-R curve was found as long as the R-curve data could be considered “valid.”
Influence of Loading Rate on the Fracture Toughness of Some Structural Steels in the Transition Regime
Authors: Marandet B , Phelippeau G , Sanz G
Published: December 2008

The fracture toughness of five structural steels was determined as a function of temperature in static and dynamic conditions (˙K ≈ 2 × 104 MPa √m/s). The most significant effect of increasing the strain rate was to shift the KIc-temperature curve towards higher temperatures. The amplitude of the temperature shift between the transition temperatures obtained in static (TKIc) and dynamic (TKId) conditions were compared with the predictions given by different models. It appeared that the variations of yield strength cannot always account for the change of fracture toughness with temperature and strain rate.

A correlation between Charpy V-notch (CVN) transition temperature (TK 28) and dynamic toughness transition temperature (TKId) was established. This correlation is an extension of the one proposed previously between TK 28 and TKIc. Assuming that fracture toughness transition is a thermally activated process, it was possible to calculate theoretically the slopes of the correlations; these were found to be in good agreement with the experimental results.
A Tearing Instability Analysis for Strain-Hardening Materials
Authors: Popelar CH , Pan J , Kanninen MF
Published: December 2008

The usefulness of the tearing instability analysis procedure depends upon the availability of J and dJ/da estimates for load/structure conditions of practical interest. Most of the J-estimation solutions obtained so far have assumed that a limit load condition exists. To broaden the applicability of these approaches, the role of material hardening in stable crack growth and fracture instability is addressed in this paper. The approach employs Turner's η-factor which links J to the strain energy and the remaining ligament in a cracked component. The resulting analysis is quite general and includes all the presently known J-estimation analyses as special cases.
Some Remarks on the History and Development of the ASTM Committee E-37 Purity Method
Authors: Guttman CM
Published: December 2008

The history and development of the ASTM Committee E-37 Purity Method is discussed. The early protocols and resulting round robin data are considered. The importance of the development of suitable sample materials to be used by the task group members in parallel with the methods development is also discussed.
Purity Determination by Simultaneous Differential Scanning Calorimetry-Thermomicroscopy
Authors: Wiedemann HG , Riesen R , Bayer G
Published: December 2008

The application of differential scanning calorimetry (DSC) and of simultaneous DSC thermomicroscopy for purity determination is described. After deriving the mathematical background for the evaluation of the DSC curves, the results of purity determinations are shown for the following substances: cis- and trans-azobenzene, n-tetratriacontane.
Determination of Impurities in Minerals by Means of Standardized Differential Thermal Analysis
Authors: Smykatz-Kloss W
Published: December 2008

Impurities in minerals may be caused (a) by simple admixtures or (b) by crystal chemical substitutions. For the present study standardized differential thermal analyses were performed to investigate the interrelation between thermal effects and chemical composition, for example, to determine the influence of impurities on thermal effects. In the case of thermal decomposition reactions, which are controlled by the partial pressure of a gaseous reaction product (for example, carbon dioxide (CO2) in carbonates), type (a) impurities may be determined by applying special PA-curves (that show the dependence of decomposition temperatures on partial pressure). Small amounts of admixtures of organic matter or sulfides in clays can be detected by intensive oxidation effects. The transition behavior of thenardites (Na2SO4) is influenced by the presence of small amounts of hydrated sodium sulfate. Chemical substitution in copper sulfides may be found by measuring their transition temperatures. In the case of carbonate minerals small amounts of substitutions can be determined by their influence on shape and temperatures of the decomposition effects. The substitution of iron by aluminum in goethites lowers the dehydroxylation temperature and can be determined from a special calibration curve. Substitutions in magnetites lower the Curie temperatures of these ferromagnetic minerals. Because of restricting the investigations on the range of “impurities” in minerals solid solution phenomena are only treated briefly, for example, using the influence of solid solution on the dehydroxylation/decomposition temperatures of the phyllosilicates of the smectite and chlorite series.
Application of Fracture Mechanics on the Space Shuttle
Authors: Forman RG , Hu T
Published: December 2008

During the design stages of the shuttle orbiter, fracture-mechanics concepts were applied extensively to the highly stressed areas of the structure. This was the first space program to require a comprehensive fracture mechanics approach to prevent structural failures from crack or crack-like defects. As anticipated, some difficult problems were encountered. This paper briefly describes some of them together with the procedure used for fracture control on the orbiter. It is believed that the principles and methods as presented herein can serve as an example of fracture control for aerospace and other industries.
Air Force Damage Tolerance Design Philosophy
Authors: Rudd JL
Published: December 2008

This paper summarizes the U.S. Air Force damage tolerance design requirements for metallic airframes. The requirements are a function of the design concept and degree of inspectability of the airframe. Both analytical and experimental requirements are presented. The requirements include the initial damage size, shape, and location, which must be assumed in design. Also presented are the subsequent crack growth and residual strength requirements, which must be satisfied because of the presence of this initial damage.
Droplet Analysis Techniques: Their Selection and Applications
Authors: Bachalo WD
Published: December 2008

Drop size measurement instrumentation is being developed to provide a reliable and accurate means for obtaining drop size data with a minimum expenditure of time. The physical principles involved in the measurement concepts are relatively complicated. Thus, the instrument selection process becomes difficult without at least a general knowledge of the selection criteria, available concepts, and their inevitable limitations. At the same time, there are a broad range of applications with specific measurement goals to be met. The measurement requirements include drop size range, spatial and temporal resolution, and the determination of mass flux. Drop shape can be also an important factor when measuring large droplets that may distort under the prevailing aerodynamic forces. Measurements are further complicated by the need to obtain the results in difficult environments.

In this paper, a general review of drop size measurement applications is given with discussions of the associated conditions affecting the measurements. The descriptions of the measurement conditions and requirements are then related to the corresponding instrument capabilities. An overview of the measurement concepts most commonly used is given and the respective capabilities discussed. Techniques based upon both optical and material probe concepts are considered. The information outlined is intended to provide a guide to the evaluation and inquiries that should be made during the selection of a drop size measurement instrument.
Particle Sizing by Optical, Nonimaging Techniques
Authors: Hirleman ED
Published: December 2008

Optical, nonimaging techniques for sizing liquid particles of diameters greater than 1 μm are reviewed. Nonimaging optical diagnostics separate into two classes, ensemble or multi-particle analyzers and single particle counters (SPC). A discussion and analysis of the theoretical basis, performance characteristics, and calibration considerations for the various methods in each class is presented. Laser diffraction ensemble techniques, crossed-beam dual-scatter interferometric SPC, and finally single beam SPC based on the measurement of partial light-scattering cross sections of the particles are considered in detail.
Sizing Study of Drops Produced by High Diesel Fuel Injection Pressure Sprays
Authors: Popa DM , Varde KS
Published: December 2008

Experiments were conducted to measure droplet sizes and their distribution in high-pressure diesel fuel sprays. Fuel droplets were collected on glass plates which were treated with surface modifier. The droplets were photographed and subsequently analyzed on an image analyzer. The resultant information is used to calculate average diameter, Sauter mean diameter, etc. The degree of automation in the analysis process allows accurate measurement of a large number of photographed drops. It is estimated that the method used here allowed good measurements of small droplets on the order of 0.5 µm. Typical output of the analysis together with the validity of the technique is presented in the paper.