bluuebunny/crossref_metadata_2025 huggingface dataset:
Experiences in Identification and Treatment of Dispersive Clays in Mississippi Dams
Authors: Forsythe P
Published: March 2009

Twenty floodwater retarding dams in Mississippi have been treated to protect them from failure due to tunnel erosion. All of these sites developed severe tunneling characteristics of dispersed soils because of extreme rains in 1973, causing rapid acceleration of the probably latent soil condition.

The Soil Conservation Service in Mississippi initiated a detailed sampling and testing program for every site, not only to design treatment, but also to provide a basis for followup evaluation of performance. All three laboratory tests—dispersion, pinhole, and chemical—correlated well. Field identificaton tests did not correlate as well to actual site conditions or laboratory tests. Field tests were crumb, ultraviolet light, and turbidity.

The primary treatment used was hydrated lime applied in a 15-in. blanket following reworking of the fill to eliminate tunnels. Lime applications varied from 0.5 to 3 percent. Two structures were treated with sand-gravel blanket.

The pH values for lime-treated soils stayed high following application, restricting root penetration and vegetative growth.

Laboratory data coupled with field testing and performance observations provide engineers with a unique opportunity for studies that will evaluate and improve identification and treatment of dispersive clays. Some comparisons are already available and are presented in this paper.
Protecting a Dispersive Soil Storage by Water Treatment
Authors: Grant K , Ingles OG , Lawrence IA , Sommerville PJ
Published: March 2009

Construction of reservoirs and dams in areas with dispersive soil poses several major problems: safety of the retaining walls, safety of the containing slopes, erosion resistance on exposed surfaces, and quality of the storage water. Important aspects of some of these problems are discussed with particular reference to a major new city reservoir constructed recently by the Melbourne and Metropolitan Board of Works on Cardinia Creek, Victoria, Australia. This offstream reservoir stores high-quality, low-turbidity water brought by conduit from other major catchments.

Because there was a potential turbidity problem due to the dispersive nature of the reservoir soils, it was recommended that the ionic concentration of the water be increased by adding specific amounts of salts of calcium or a mixture of salts of calcium and sodium in specified proportions.

Raw gypsum (calcium sulphate dihydrate) was added to the water at the reservoir inlet. The result has been that the clay suspended in the water at the commencement of first filling flocculated and settled, as expected, so that the water is now clear and the whole storage appears to be performing satisfactorily in all respects.

A method for comparing the economic merit of soil versus water treatment is described.
Factors Influencing Dispersive Clays and Methods of Identification
Authors: Heinzen RT , Arulanandan K
Published: March 2009

Recent laboratory studies of the erosive behavior of consolidated soils using the rotating cylinder apparatus showed that the stress required to initiate erosion is affected significantly by the amount and type of clay, pH, organic matter, temperature, water content, thixotropy, pore, and eroding fluid composition.

Using the concept of critical shear stress as measured using the rotating cylinder and the flume, a quantitative criteria for a dispersive clay system is defined as one with a critical shear stress, τc equals zero. Using this criterion, qualitative methods of predicting dispersive clays are examined. It is concluded that most of the qualitative tests used for the identification of dispersive clays suffer from the serious drawback of subjective identification criteria. Proper correlation of the results obtained from the qualitative tests for the condition of τc = 0 will provide a better basis for dispersive clay identification.

The potential use of “free swell test” as a predictive criterion is indicated.
Factors Affecting Spontaneous Dispersion of soil Materials as Evidenced by the Crumb Test
Authors: Holmgren GGS , Flanagan CP
Published: March 2009

Sixty-three soils were examined for spontaneous dispersion by various modifications of the crumb test. This test is considered indicative of dispersive conditions if a colloidal cloud develops when a small soil specimen is immersed in a large volume of water. Soil specimens were examined by this test in the dry state and in a remolded, saturated condition (slightly above the liquid limit). These pieces were immersed in distilled water and in 1 milliequivalent/litre (0.001 N) sodium hydroxide. The results of these tests were compared with the pinhole test as a reference measure of dispersion.

The use of saturated, remolded soil specimens resulted in a more conservative test for dispersion. More dispersive soils were identified properly, but more nondispersive soils were classified incorrectly as dispersive.

The 63 soils were separated further into four classes, depending on the agreement or disagreement of the saturated crumb test with the pinhole test. Chemical, mineralogical, and engineering data were assembled to assist in the search for explanatory variables affecting the discrepancies.

A second series of minicrumb tests was conducted using small remolded aggregates at various moisture contents and immersing them in an array of solutions of various pH and salinity. These arrays were photographed after 2 h to illustrate the effect of these variables on spontaneous dispersion.

The data developed from these several studies were used to illustrate the effects of sodium, salinity, pH, mineralogy, and initial moisture content upon the spontaneous dispersion of soil materials.
Erosion of Unsaturated Clay in a Pinhole Test
Authors: Lewis DA , Schmidt NO
Published: March 2009

An investigation was conducted to determine the influence of dry density and initial water content on the erosion of a compacted dispersive clay. The pinhole test developed by James Sherard and associates was used to model the erosion conditions which occur in earth dams. When the soil specimens, compacted to densities representative of standard and modified Proctor effort were eroded under a roughly constant erosional shear stress, it was found that a minimum amount of erosion occurred at a water content about 2 to 3 percent wet of optimum water content. It was also found that, at the same water content, the amount of erosion tended to decrease with an increase in the dry density. However, neither water content nor density strongly controlled the dispersiveness of the soil. A mechanism of erosion was suggested to account for the observed reactions.

Also, it was found that the turbidity of the eroding water can be correlated with the concentration of suspended soil.
The Role of Dispersion in the Slaking of Intact Clay
Authors: Moriwaki Y , Mitchell JK
Published: March 2009

A series of slaking tests was conducted to identify those conditions under which dispersion is the dominant mechanism of clay slaking. Variables investigated were clay mineralogy, adsorbed cation ratios (sodium/calcium), consolidation fluid electrolyte concentration, water content, and slaking fluid electrolyte concentration.

All clays with sodium ions occupying more than 10 percent of the exchange complex exhibited a dispersion slaking regardless of other conditions, provided the electrolyte concentration of the slaking fluid was lower than 10−3 N.

Observed slaking behavior can be classified into four modes: (a) swelling slaking, (b) dispersion slaking, (c) surface slaking, and (d) body slaking.
Case Histories of Repairs and Designs for Dams Built with Dispersive Clay
Authors: Phillips JT
Published: March 2009

A sample survey of small earth dams in southern Australia showed that approximately 10 percent fail by a physical breach, usually associated with dispersive clays. Where information is available, it has been found that other factors combine to induce the failure. Typical failures are described.

Failures of engineer-designed and supervised dams are rare, but two such failures are described. The analysis of the failures, the repairs to the erosion tunnels, and other treatment to prevent further damage are presented. When first refilled, one dam again failed by an erosion tunnel adjacent to the repair section. Further studies led to this dam being completely demolished and rebuilt, using newly developed details for the reconstruction. These details were developed further for a similar new dam, and other details were used for the raising of another small dam.

The experience gained in the earlier cases led to the development of design details and construction techniques for the dispersive clay core of a 48-m-high earth-rockfill dam, and these are described.
Relevance of Atterberg Limits in Evaluating Piping and Breaching Potential
Authors: Reséndiz D
Published: March 2009

In the last ten years, several researchers have contended that methods in use in soil mechanics do not permit identification of so-called dispersive clays, which are highly susceptible to piping and breaching. They also claim that current design criteria are unreliable for preventing piping and breaching in dam embankments and foundations.

On the basis of available information, the paper reanalyzes whether or not Atterberg limits as used in soil mechanics provide a means to predict piping and breaching potential. To that end, a critical review is made of relevant theoretical knowledge and empirical information regarding the effects of soil properties, compaction, and environment conditions on soil susceptibility to dispersion and erosion.

It is concluded that Skempton's activity, an index derived directly from Atterberg limits, is an excellent indicator of the piping and breaching potential of soils, though compaction water content and salinity of the percolating water should be accounted for as well. The implications of this conclusion on design criteria for water-retaining structures is also discussed.
Identification of Susceptible Soils and Control of Tunnelling Failure in Small Earth Dams
Authors: Rosewell CJ
Published: March 2009

A method for identifying soils susceptible to tunnelling failure in embankments is described. Present design and construction recommendations are given based on laboratory investigations and experience with many small dams.
Concept of Critical Shear Stress in Relation to Characterization of Dispersive Clays
Authors: Sargunan A
Published: March 2009

A laboratory study has been made on the dispersive behavior of selected clay systems when subjected to the disruptive action of flowing water. The studies were made in a rotating cylinder apparatus and thus were mainly confined to dispersion phenomena on the clay boundary. It was observed that surface erosion was initiated with the removal of individual particles or clusters, due to the relative instability of a particle or domain compared with the remainder of the surface. The chemical system was defined in terms of the cation ratio, and the equilibrium solution concentration, and initiation of motion was fixed by measurement of the critical shear stress. An experimental relationship between the critical shear stress, cation ratio, and total salt concentration was shown for the soils studied and explained in terms of the flocculation-deflocculation characteristics. Taking the criterion of instability as that corresponding to zero critical shear stress proved to be advantageous in this study and helped in a satisfactory demarcation of stable and unstable states.
Turbidity and Zeta Potential Measurements of Clay Dispersibility
Authors: Yong RN , Sethi AJ
Published: March 2009

The basic mechanisms identified with dispersive clays have been associated with swelling or repulsive forces. To evaluate clay dispersibility from the particle interaction point of view, suspensions of the soil material can be used where resultant turbidity of the suspension is assessed. In this study, the light transmittance technique for measurement of turbidity is used whereby appropriate calculation techniques can be applied to the measurements to obtain equilibrium clay concentration remaining in suspension in the supernatant.

The adsorption/desorption measurements of the suspensions at various low salt concentrations indicate that desorption of the adsorbed ions from the clay surfaces contributes to clay dispersibility through increases in the double-layer thickness. The presence of amorphous silica and sesquioxides, as might be obtained from selective dissolution in the leaching process, reduces clay dispersibility, as indicated by increased zeta potential and refiltration rates.
Dispersive Soils at Sugarloaf Dam Site, Near Melbourne, Australia
Authors: Stapledon DH , Casinader RJ
Published: March 2009

Site investigations for the Sugarloaf Dam near Melbourne, Australia, revealed the presence of dispersive soils in the residual soils, slope wash, and weathered siltstone at the site. The presence of these soils necessitated careful selection and zoning of dam construction materials and special measures in the design of the dam's cutoff. Possible turbidity problems in the stored water may require treatment of the reservoir bed before impounding as well as of the incoming water.
ASTM Nondestructive Testing Standards Program
Authors: McClung RW
Published: March 2009

The American Society for Testing and Materials' (ASTM) program for developing nondestructive testing (NDT) standards resides primarily in Committee E-7 on Nondestructive Testing. To meet this responsibility, Committee E-7 is subdivided functionally into subcommittees representing most of the major methods of NDT. The many activities necessary to the development of standard documentation that are conducted include industry surveys to determine interest, needs, and practices, performance of experimental studies through extensive cooperative studies in both government and private organizations, document preparation, and interlaboratory testing. Committee E-7 is responsive to requests from other ASTM committees as well as other standard organizations (for example, American Society of Mechanical Engineers). Although benefits to industry have accrued in the consensus standards, significant improvements are needed to provide more relevant, quantitative, reproducible results.
International Nondestructive Testing Standards
Authors: Resnick I
Published: March 2009

The International Organization for Standardization (ISO) and its objectives are described. ISO Technical Committee (TC) 135 on Nondestructive Testing is the committee responsible for developing nondestructive testing (NDT) standards. The American National Standards Institute (ANSI) is the United States member body of ISO. Its activities and organization are explained. The scope and structure of ISO/TC 135 is reviewed, as well as its liaison with a number of other TCs and international organizations having an interest in NDT standards. The United States participates in ISO/TC 135 through the activities of its Technical Advisory Group (TAG) for ISO/TC 135 which also is ASTM Subcommittee E07.91, USA Committee for ISO TC/135, of ASTM Committee E-7 on Nondestructive Testing. Its representation, organization, operating procedures, and activities are reviewed. The steps for developing an ISO standard from the draft document in the working group through its approval by ISO Council is covered. The present status of ISO international standards, draft ISO standards, and draft proposals in the NDT area are provided. The importance of international standards and their effect on trade and related activities is covered briefly.
Nondestructive Testing Standards in the ASME Boiler and Pressure Vessel Code
Authors: Zillmann RW
Published: March 2009

Nondestructive testing (NDT) constitutes an important part of the ASME Boiler and Pressure Vessel Code. Section V deals exclusively with nondestructive examination (NDE). This paper is a general description of all NDE methods referenced in the ASME Boiler and Pressure Vessel Code, the origin of specific standards documented in other societies, adaptation, and modification of these standards to meet ASME Boiler and Pressure Vessel Code requirements, and selection of acceptance criteria by other sections of this Code. The mechanism for implementing revisions in order to keep abreast of technological advances is described briefly and assessed.
Military Standards for Nondestructive Tests
Authors: Hastings CH
Published: March 2009

The growth of nondestructive testing (NDT) technology, its control documentation, application philosophy, and management of its specifications tree are traced from 1920 to the present. The status of military documents on NDT relative to the technology is discussed, inadequacies are defined, and problems resulting from the gap are listed. Although the technology has grown far beyond the scope of coverage in military specifications and standards, this situation can be remedied by the several approaches which are suggested. Three recommendations are made as a suggested optimum, implementable, solution.
Overview—Radiographic Nondestructive Testing Standards
Authors: Aman JK
Published: March 2009

This paper is an overview of the standards in the field of nondestructive testing (NDT) radiography. The objective is to lay the overall framework and direction for more detailed coverage to follow. First, the NDT radiographic system variables are discussed in an effort to point out the need for increased standards activity. This activity should produce better precision in radiographic testing.

A framework of achieving the requisite precision at minimum cost is presented. This framework interrelates radiographic personnel, procedure, equipment and supplies, producing repeatable radiographs. The framework calls for controlling the system, which requires image quality indicators (IQIs) and adequate assurance as to requisite permanence of the radiograph.

The present status and future needs in standardization in each of the areas mentioned is covered. This includes a table of the standards and present activity on each of them.

NDT radiography is a flexible tool. The paper concludes with the challenge of building a more precise radiographic structure.
Classification of Industrial X-Ray Film
Authors: Polansky D
Published: March 2009

A review of the efforts of a task group of American Society for Testing and Materials (ASTM) Committee E-7 on Nondestructive Testing to classify industrial X-ray film will be presented. The introduction of new film and especially automatic X-ray film processors with their relatively high temperature chemistry have changed considerably the sensitometric curves of film relative to that produced at normal temperature with hand processing. The objective of the task group is to classify film in order to indicate potential film performance and differentiate between the films.

The several methods of classification based on speed, speed and gradient, and mass of silver on a film will be discussed. The difficulties of specifying a system that may be too narrow or too broad will be discussed. The equating of film characteristics to the subjectively determined evaluation of radiographic film quality has not been accomplished satisfactorily. Systematic exposures of a standardized test plate have been made at several facilities and will be interpreted by several observers. The analysis of these data may help in equating film characteristics to radiographic film quality and, therefore, be the basis for a film classification system.
Application of Magnetic Particle and Liquid Penetrant Methodology in Petroleum Refineries and Petrochemical Plants
Authors: Detlor LT
Published: March 2009

The magnetic particle and liquid penetrant methods are used routinely in the hydrocarbon processing industries to find surface flaws that usually are not evident visually. Some flaws originate in the material and during fabrication of equipment. Others originate due to service conditions and are often the product of interaction between mechanically induced stresses and corrosion. The competence of those using the methods is a capability factor. Both methods have pluses and minuses in their capability. Finally there probably are things that can be done to improve the effectiveness of the system used.
Standardization of an Automatic Inspection System
Authors: Farrace FT
Published: March 2009

Laser surface inspection of continuous web materials is capable of more objective results than most human inspectors. This fact complicates the standardization and calibration of the laser system. Calibration methods are discussed, including the human operator himself, resolution grids, and other transfer standards.
An Exclosure Method for Quantifying Vertebrate Pesticide Residues from Rangeland Vegetation
Authors: Tietjen HP
Published: March 2009

Tests to quantify the amount of zinc phosphide (Zn3P2) residues deposited on range vegetation were run in conjunction with field efficacy trials of this rodenticide against black-tailed prairie dogs (Cynomys ludovicianus). The tests were designed to evaluate the experimental design and, if the technique proved feasible, to determine residue levels at normal and exaggerated rates of application. Four exclosures were used, each treated with a specific multiple of the bait application rate used in the efficacy trials (X0, X1, X3, and X10). Random vegetation samples were clipped in each exclosure on Days 1, 15, 30, and 60 posttreatment. The on-site exclosure method yielded an accurate estimate of treatment-related residue values and should prove useful for other rodenticidal agents.
A Method for Assessing Deposits of Aerially Applied Aqueous Pest Control Agents
Authors: Cunningham DJ , Schafer EW , Starr RI
Published: March 2009

In field evaluations of a promising bird repellent (mesurol) on target crops, we needed a method to measure the chemical deposits resulting from aerial spray applications. Oil-sensitive “spray” cards were unsuitable because water, not oil, was the carrier.

For spray cards, we used thin-layer chromatographic plates and determined particle size and density of the spray droplets and the resulting deposits of the chemical.
Rat and Mouse Acute Liquid Bait Test Method
Authors: Palmateer SD
Published: March 2009

A method to assess the efficacy of an acute water bait is discussed in considerable detail. The test allows rats and mice a free choice between an acute toxicant-treated water bait and tap water. It is a three-day test. The test solution is considered effective if there is a 90 percent mortality in the rodents tested.
Equipment and Methods Available for Measuring the Behavioral Response of Rodents to Odors
Authors: Salmon TP , Marsh RE
Published: March 2009

Odor attractants or repellents for modifying the behavior of rodent species have received considerable evaluation, but no single apparatus or method has evolved as the most effective. Some of the most useful types of equipment and procedures for olfactory-behavioral studies are described or discussed. Emphasis is placed on the equipment and methods most likely to prove effective and practical for evaluating odor attractants with a potential for use with traps or rodent baits.

Examples of devices used to monitor and record responses to introduced odors include electric eye, body capacitor, sensing grids, and mechanical treadles connected to counters and event recorders. Time-lapse photography and closed-circuit television monitors have their place, as does direct observation, but the labor involved makes them relatively expensive means of collecting data. A simple maze may be the most useful of all the apparatuses reviewed.
Chemosterilant Evaluation in Coyotes: Parameters for Animal Selection and Laboratory Methodology
Authors: Gates NL
Published: March 2009

Investigations were conducted to establish criteria for selecting animals used in coyote chemosterilant research. Conclusions based on results from this study indicate that pen-raised pregnant female coyotes are preferable to wild coyotes for evaluating chemicals for abortifacient properties. Dogs were more practical than coyotes for preliminary out-of-season testing of antispermatogenic agents. Wild or pen-raised coyotes were suitable for use when necrotizing agents were used.

Selected standard hematologic and blood chemistry determination techniques were applicable for the purpose of monitoring systemic side effects of chemosterilant compounds.

Efficacy determination methodology was reviewed for practicality and accuracy. Unilateral testicular ablation was more suitable than biopsy techniques for collection of testicular tissue for histological examination.
Proposed Efficacy Test for Aerosol Dog Repellents that Are Designed to Reduce Damage to Garbage Bags
Authors: Snider CC , McCann JA
Published: March 2009

This efficacy test was designed to provide data to support the registration (by the U.S. Environmental Protection Agency) of dog repellents that claim to reduce damage to garbage bags. A minimum of eight dogs are tested individually within rectangular arenas for 1 h on each of four days. Three garbage bags are placed at each end of each arena. The bags at one end of the arenas are treated with the repellent, and those at the other end are not treated. The treated bags are sprayed and stored for the maximum length of time (prior to testing) for which efficacy is claimed. The amount of ration placed in each bag is calculated to give the dog one third of an “adequate” amount of nutrients. Consequently, the dog receives a free choice between treated and untreated bags and is not forced by hunger to open any of the treated bags. The damage to a bag is recorded as “opened” or “unopened.” Dogs are divided into groups of four, and a 4 by 4 Graeco-Latin square containing days, arenas, dogs, and point of introduction into the arena is constructed for each group. Percent repellency is calculated for each day, each dog, and the total test. Reference tests using six untreated bags are employed as checks on the activity of the dogs in repellent tests.
Considerations in the Application of Aversive Conditioning
Authors: Dorrance MJ , Gilbert BK
Published: March 2009

Recently several researchers have tested aversive conditioning as a method of reducing damage and discouraging approach by carnivores. This paper discusses some general biological considerations in the application of aversive conditioning. Its effectiveness as a control technique will depend, in part, on the characteristics of the wildlife species involved (for example, social organization, individual and species behavior, feeding strategy, annual mortality, and movement); characteristics of the resource being protected (for example, whether it constitutes prey, carrion, space, etc. to the predator, and its desirability and necessity to the predator); and the selection of appropriate aversive stimuli and substrates. Appropriate tests of aversive conditioning are discussed. Specific situations are detailed where aversive conditioning might be most valuable in the control of problem wildlife.
Standard Guideline for the Use and Development of Sodium Monofluoroacetate (Compound 1080) as a Predacide (ASTM Designation E 590-76)
Authors: Wade DA
Published: March 2009

This is a “state of the art” document prepared by the Predator Task Group, American Society for Testing and Materials' (ASTM) Subcommittee E35.17, as a concensus guideline for the use of Compound 1080 in wild canid control. Toxicology, storage and handling, bait formulations, and preparation of baits are discussed. Bait placement, exposure period, disposal, human safety factors, and environmental impact are also treated. Toxicity data and a reference list also are included.
A Cage Test for the Evaluation of House Finch Repellents for Grapes
Authors: Crase FT , DeHaven RW
Published: March 2009

A cage test is described for determining the median effective treatment level (ED50) of a house finch (Carpodacus mexicanus) repellent for grapes. The basic design can be adapted for use with other small birds and clustered fruits. Five problems encountered during the study are discussed. They are aviary mortality of house finches, having to induce the finches to eat grapes by withholding other food, damage caused by finches “testing” treated grapes, probable nonidentical responses of all finches in one cage, and treatment or handling problems with grapes used for residue analysis.
Efficacy Experiments Involving Avian Pest Control Materials: Design Considerations Imposed by the Scientific Method
Authors: Ingram CR
Published: March 2009

Managers and researchers alike often incorrectly discuss efficacy of an avian pest control material. However, a material cannot be universally efficacious. Instead, efficacy can be established only for particular treatment forms of the control material where the treatment form is completely and uniquely specified by the product that is used to carry the material to the pest and the method of delivery of this product. The scientific method requires that experiments be conducted to evaluate the efficacy of treatment forms. This paper emphasizes that design is the appropriate vehicle through which a researcher attempts to ensure that an experiment will yield data pertinent to the hypothesis under investigation. The design process is discussed as it applies to field evaluation of avian pest control materials. Evaluation of efficacy of a treatment form of an avian pest control material and field measurements for efficacy are considered.
Use of Male Coturnix Quail in the Laboratory Development of Avian Chemosterilants
Authors: Schafer EW , Guarino JL , Brunton RB
Published: March 2009

Egg fertility of coturnix quail (Coturnix coturnix) was measured for 35 to 45 days following single oral doses of six candidate chemosterilants to adult breeding males, adult males whose testes has been regressed by photoperiod manipulation, twelve-day-old male chicks, and six-week-old males with undeveloped testes. Azacosterol, 3-chloro-1,2-propanediol, and mestranol were essentially inactive at 100 or 316 mg/kg in all treatment groups. Breeding adults were sterile for 10 to 25 days after doses of 31.6 mg/kg busulfan, 31.6 mg/kg triethylenemelamine, or 316 mg/kg isopropyl methane sulfonate—all alkylating agents. Adults with regressed testes showed reduced fertility or sterility after treatment with busulfan and triethylenemelamine. These tests indicate that the evaluation of male chemosterilants intended for use on wild avian populations during the period of testicular regression should consist of initial tests on breeding adult quail, followed by tests on adult quail with regressed testes if sterility is noted.
Variables Affecting Reproducibility of the Instrumented Impact Test
Authors: Lum PT , Curll CH
Published: March 2009

Instrumented impact test systems have been designed for determination of dynamic fracture toughness properties and utilized for the study of impact properties of materials in many laboratories. Since equipment varies from laboratory to laboratory, variations due to the equipment or instrumentation or both should be examined. This investigation studies variations in dynamic fracture toughness due to the test machine or calibration methods or both. The parameters chosen for the study are the peak load and the fracture energy. Two materials, AISI-4340 steel alloy and 6061-T6 aluminum alloy, were selected to evaluate the variation of these parameters.
Variations in Tensile Behavior of a High-Strength Titanium Alloy Fabricated and Heat Treated in a Heavy Section
Authors: Pasternak RE , Chait R
Published: March 2009

Some titanium alloys have the advantage of possessing the capability of hardening to high strength levels through the thickness of heavy sections. Such an alloy is the metastable beta titanium alloy Ti-8Mo-8V-2Fe-3Al (Ti-8823). This study is concerned with the tensile property variation exhibited by Ti-8823 after its fabrication and heat treatment in heavy section. Information on the tensile behavior was obtained from tension specimens taken from three through-the-thickness locations; outside diameter, midwall, and inside diameter. Values for the following parameters were obtained at each location: yield strength (0.1 and 0.2 percent offset), tensile strength, reduction in area, elongation, and modulus of elasticity. From these data, the variation (standard deviation) for each parameter was determined. Variations in tensile properties as well as hardness measurements of Ti-8823 were compared to those experienced with heavy-section steel gun tube forgings and another titanium alloy in heavy section, namely the alpha/beta Ti-6Al-6V-2Sn alloy.
Statistical Aspects of Mechanical Property Assurance
Authors: Goepfert WP
Published: March 2009

This paper discusses the nature of the variability of the tensile properties of aluminum alloys, the part this variability plays in establishing guaranteed properties, and the problem of establishing sampling plans in specifications that would provide in themselves a high degree of assurance that all the material accepted under such plans meets the established guaranteed properties.
Some Low-Temperature Aging and Durability Aspects of Sulfur/Asphalt Concretes
Authors: Shrive NG , Ward MA
Published: March 2009

Some low-temperature durability tests on two asphaltic concretes and similar concretes with sulfur-modified asphalt as the binder are described. The results of the tests indicate that sulfur-modified asphaltic concretes may be more durable and are potentially more economic than their unmodified asphalt counterparts.
The Effect of Mechanical Properties Upon the Performance of Railroad Rails
Authors: Stone DH , Steele RK
Published: March 2009

The behavior of rails in service is reviewed on the basis of past rail steel research. The formation of rail defects and rail wear are discussed. The mechanical properties of rail steels and their dependence on chemical composition and microstructure are presented.
A Metallurgical Examination of Control-Cooled, Carbon-Steel Rails with Service-Developed Defects
Authors: Sonon DE , Pellegrino JV , Wandrisco JM
Published: March 2009

A metallurgical analysis was made of 33 carbon-steel rail samples selected from service, 31 of which had service-developed defects. The program was formulated to attempt to establish the metallurgical characteristics that promoted the defects and to establish possible interrelationships among these characteristics, the in-location service stresses, and the defects. This paper describes the results of chemical analyses, hardness and tension tests, and the results of wear, deformation, metallographic, and fractographic analyses. A companion paper in this symposium describes the results of Charpy V-notch impact toughness tests, fracture toughness tests, and fatigue tests.

The results of this investigation showed that (a) all the service-developed defects in the rail samples examined were fatigue cracks, (b) all these fatigue cracks initiated at sharp internal notches such as inclusions, and (c) a correlation between the metallurgical properties of the rail samples and defect formation could not be made.

Overall, it is reasonable to conclude that the service lives of the rails investigated would have been longer if the inclusions responsible for crack initiation had not been present. However, it should be noted that most of these rails had service lives lasting 16 years—454 million metric tons (MMT) (500 million gross tons (MGT)) with one sample lasting 22 years—685 MMT (755 MGT). Furthermore, the service stresses, although unknown, were apparently severe as evidenced in the deformation of the rail-heads.

It appears that of greater importance and interest with respect to the effect of steel quality and properties on defect formation in rails would be a study of defects that form early in the rail life. It is recommended that such studies be conducted.
Alloy Steels for High-Strength, As-Rolled Rails
Authors: Smith YE , Fletcher FB
Published: March 2009

A laboratory study was conducted on a broad range of compositional variations of chromium-molybdenum steels for application as high-strength, as-rolled rails. A series of experimental heats was prepared and processed to simulate commercial production of as-rolled 65-kg/m (132-lb/yd) rail, with regard to cooling rate and transformation characteristics. Test specimens were evaluated in terms of hardness, tensile properties, and microstructure. The mechanical properties are related to the observed microstructures. Increasing the molybdenum content of the steel is highly effective in increasing yield strength by refining the pearlite; the appearance of coarse bainite reduces the yield strength. Vanadium contributes additional strengthening, but only under certain conditions where the pearlite is refined. Lowering carbon and adding columbium produces microstructural changes that are not beneficial to the mechanical properties. These results make possible some tentative conclusions regarding the optimization of composition for the commercial production of as-rolled rails in the 760 to 1170 N/mm2 (110 to 170 ksi) yield strength range.
Some Features and Metallurgical Considerations of Surface Defects In Rail Due to Contact Fatigue
Authors: Masumoto H , Sugino K , Nisida S , Kurihara R , Matsuyama S
Published: March 2009

Two unique types of surface defects resulting from contact fatigue have been observed in rail used in high-speed lines in Japan (speed greater than 150 km/h). One of these results from the dark spots which randomly appear on the running surface and develop into transverse defects, and the other is the head check which arises at the gage corner.

An experimental simulation of these defects was attempted through rolling contact fatigue tests. The resulting defects were similar to those found on the running surface. For their initiation, a slip component of load was necessary, in addition to the normal load. Examinations of these defects indicated that they initiated on the contact surface, as did those found in rail, and not at the subsurface where the shear stresses are maximum due to Hertzian contact.

To investigate the effects of microstructure on the initiation and propagation behavior of these defects, coarse pearlitic, fine pearlitic, and tempered martensitic structures were examined. The fatigue limit of each structure showed a good correlation with its tensile strength. In the rolling contact fatigue tests, the fine pearlitic structure exhibited the longest lifetime. However, the tempered martensite had the lowest crack growth rate. Therefore, it is concluded that, to optimize the durability of rail steels, the effect of microstructure should be considered in addition to the tensile properties.
Mechanism of Cleavage Fracture In Fully Pearlitic 1080 Rail Steel
Authors: Park Y-J , Bernstein IM
Published: March 2009

Under service conditions, final failure of rails is usually caused by impact. To elucidate the phenomenon, the mechanism of impact-initiated cleavage fracture has been studied in fully pearlitic rail steel. The study has demonstrated that the early stages of cracking probably occur by strain localization in the ferritic lamellae. By direct correlation studies of fracture surface and microstructure, it has been further shown that a crack usually does not change direction at pearlite colony boundaries. Rather, the prior austenite grain size is the controlling agent for the more effective obstacle to crack propagation, namely, the cleavage facet size. The data show that the facet size is dependent on the prior austenite grain size, although it is always somewhat less, particularly for the larger grain size materials. The reasons why it is an effective parameter to represent the toughness of eutectoid steels are discussed.
Stresses Around Transverse Fissure Flaws in Rails Due to Service Loads
Authors: Sampath SG , Johns TG , McGuire PM , Davies KB
Published: March 2009

The paper describes analysis related to cracks in rails using the finite element method. Attention has been focused on transverse fissure type of defects in railheads, although the approach is more generally applicable. Elastic stress intensity factors are calculated using the crack closure method and compared against values computed directly from node “opening” displacement. Analyses using idealized polynomial type of stress distributions for embedded cracks are viewed in the light of finite element results. A discussion of stresses that can occur in railheads with flaws for some load situations is included.
Fatigue Crack Propagation in Rail Steels
Authors: Feddersen CE , Broek D
Published: March 2009

Baseline fatigue crack growth data at R = 0 and mechanical property data have been generated on 66 different rail materials which are in service on U.S. railroads. These data are evaluated, along with metallurgical variables such as chemical composition and microstructure, in an attempt to develop a correlation of mechanical and metallurgical factors affecting crack behavior in rail steels. The ultimate objective of this effort is the development of a rail failure model to enable the determination of safe inspection intervals, through prediction of fatigue crack growth in rail under service loading.
Comments on Dynamic Fracturing
Authors: Irwin GR
Published: March 2009

A brief review is given of basic definitions and concepts applicable to linear elastic analysis of dynamic fracturing. It is noted that determinations of the crack-extension force, ς, based upon conservation of energy may require adjustment for energy losses elsewhere than at the crack tip. From direct observation of running crack stress fields, crack speed increases rapidly with K toward a limiting speed which is maintained until K becomes large enough to cause crack division. The minimum K value of this relationship is termed KIm. Estimates of KIm by use of the test methods termed KId (dynamic initiation) and KIa (crack arrest) are of practical interest. The uncertainties associated with such estimates as well as testing difficulties are restricted mainly to the region above nil-ductility transition temperature where toughness increases rapidly with test temperature. Use of deep face grooves to overcome testing problems in the high toughness range introduces serious questions as to applicability of test results to natural cracks in heavy section structures.
Analysis of a Rapidly Propagating Crack Using Finite Elements
Authors: Yagawa G , Sakai Y , Ando Y
Published: March 2009

An application of the finite element method to the rapidly propagating crack problem in two-dimensional domain is presented on the basis of the energy balance concept and the consistent mass formulation. The creation of the new crack surface is simulated by splitting the nodal points along the crack line successively. By introducing the Lagrange multiplier approach into the conventional finite element method of crack propagation analysis, the inconsistency in the method is avoided in that the crack grows by one element length at a time. Several numerical examples are given for rectangular plates made of polymethylmethacrylate (PMMA) with and without initial crack to show the applicability of the proposed method.
Effect of Poisson's Ratio on Crack Propagation and Arrest in the Double-Cantilever-Beam Specimen
Authors: Shmuely M
Published: March 2009

A recently proposed finite difference scheme for treating fast propagation and arrest in the double-cantilever-beam (DCB) specimen, which has so far yielded satisfactory results when compared with experimental measurements related to steel and epoxy resin, is here applied to a variety of materials, distinguished in the analysis by their Poisson's ratio only. It is shown that higher Poisson's ratios imply higher ratios between the initiating stress intensity factor and the dynamic material toughness when the same amount of crack growth is considered. The relation between the crack length at arrest and the crack speed, with the latter given with respect to the shear wave velocity, was found to be essentially independent of changes in the material when geometrically similar DCB configurations are considered.
On Effects of Plastic Flow at Fast Crack Growth
Authors: Broberg KB
Published: March 2009

The mechanism of energy dissipation near a fast running crack tip is studied. The presence of low-sound velocities in the plastic region should imply increased resistance to the energy flow from the elastic strain field at increasing crack-tip velocity. Numerical calculations indicate, however, that this is a rather weak effect in cases of small-scale yielding. On the other hand, increased resistance to ordinary plastic flow at increasing crack-tip velocity is found to be a strong effect. Increased resistance to plastic flow implies a smaller plastic region and thereby a smaller energy dissipation in this region. In the region where material separations are initiated, very different stress fields prevail at fast and slowly growing cracks. The implication on the morphology of material separation suggests that the associated energy dissipation should be much higher for very fast growing cracks than for slowly moving ones.
Measurement of Fast Crack Growth in Metals and Nonmetals
Authors: Congleton J , Denton BK
Published: March 2009

The use of a surface deposited resistance grid technique for crack velocity measurements and the extension of its general applicability to brittle solids by the incorporation of a circular time base for single shot, open shutter oscilloscope recording is described. For metal specimens a more direct crack velocity measurement procedure was used, and it was found that the dynamic potential drop across the faces of the propagating crack obeyed an equation of the form Vdynamic = A·v·c, where v is the crack velocity, c the crack length, and A an empirical constant. Crack velocity profiles for three-point-bend tests on polymethylethacrylate and a variously tempered tool steel are presented.
A High-Speed Digital Technique for Precision Measurement of Crack Velocities
Authors: Weimer RJ , Rogers HC
Published: March 2009

The control of propagating cracks in structures first requires an understanding of the interrelationships of microstructure, fractographic features, dynamic stress intensity factor, and crack velocity in materials. Conventional techniques for measuring crack velocity suffer in varying degrees from imprecision, excessively stringent synchronization requirements or poor resolution due to data compression on a single oscilloscope sweep. A new instrumentation concept has evolved from consideration of the advantages and limitations of earlier techniques. High-speed digital data processing techniques are used to measure time of sequential events 300 ns apart to an accuracy of ±50 ns. Temporary storage, high-speed sampling, and a 3:1 multiplexing scheme have been combined with a random access memory structure to enable recording times of as many as three simultaneous events per microsecond. Special templates have been designed to vapor deposit on sample metallic propagation grid configurations that take full advantage of the electronic capabilities of the system. These have 250-μm slits precisely spaced 5 deg apart in radial arrays and 1 mm apart in parallel arrays. Applications to fast fracture, crack branching, fatigue cracking, and stress-corrosion cracking are discussed.