bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of Crack Growth Gages for Service Life Tracking
Authors: Saff CR , Holloway DR
Published: March 2009

An analysis and test program was performed to evaluate the ability of a crack growth gage to monitor crack growth damage in fatigue-critical areas of F-4C/D aircraft structure. Crack growth gages were designed and manufactured for use on the F-4 lower wing skin. The crack growth behavior of the gage and relationship of gage crack growth to potential crack growth in the wing skin were determined through analysis and test. Eight gages were bonded on the Air Force F-4C/D full-scale fatigue test article at Wright-Patterson Air Force Base. Assessments were made of (1) the capability to predict crack growth behavior of the gages mounted on the fatigue test article, (2) the ability of crack growth gage to monitor potential crack growth damage at specified control points, and (3) the impact of manufacturing, installation, and data collection procedures on the utility of the gage as a damage monitoring device. Sheet thickness was found to have a profound effect on crack growth retardation under spectrum loading in 7075-T6 aluminum.
Comparison of Three Acid Extraction-Leaching Test Protocols
Authors: Welsh SK , Gagnon JE , Elnabarawy MT
Published: March 2009

Regulations under the Resource Conservation and Recovery Act of 1976 (RCRA) include the option of evaluating solid wastes for toxicity by extracting the waste with an acid solution and analyzing the extract for certain toxic metals and pesticides. In this study the three acid extraction procedures compared were the Minnesota Pollution Control Agency (MPCA) “Land Disposal Leach Test,” the proposed American Society for Testing and Materials (ASTM) “Leaching of Waste Materials,” and the “Extraction Procedure” described in 40 CFR 250.13(d)(2) of the U.S. Environmental Protection Agency's (EPA) proposed regulations implementing Section 3001 of RCRA. Variables of interest in the three procedures included pH, liquid-to-solid ratio, particle size, duration of extraction, and mixing (shaking) method. Generally, greater amounts of metals were extracted (leached) at the lower pH levels regardless of the test procedure used. EPA and MPCA criteria were used to classify the wastes as hazardous or nonhazardous.
Development of a Method for Determining the Leachability of Organic Compounds from Solid Wastes
Authors: Warner JS , Hidy BJ , Jungclaus GA , McKown MM , Miller MP , Riggin RM
Published: March 2009

This study was undertaken to develop a method for assessing the potential mobility (leachability) of purgeable and semivolatile organic priority pollutants from solid waste materials. The objective was to develop a method that would (1) model the leachability that might occur in a municipal landfill environment, (2) be relatively simple and easily implemented by production-type laboratories at a relatively low cost, and (3) give reproducible results.

The solid wastes studied included aqueous sludges, organic chemical wastes, and inorganic solids. The leaching media studied included distilled water, acetate and citrate buffers, reducing agents, and surfactants. A tumbling device designed by the National Bureau of Standards was used to achieve reproducible mixing of the specimen and the leaching medium with a minimum of particle-size reduction. The device tumbles the mixture of the specimen and leaching medium end over end in a closed container, and is applicable to nearly all solid waste materials.

Previous studies reported in the literature on solid waste leaching tests have generally emphasized the leachability of toxic metals. In order to permit a comparison of our results with previously reported results, the leachates generated were analyzed for metals as well as for organic compounds. Metals were determined by inductively coupled argon plasma spectroscopy (ICAP) and by flame atomic absorption spectroscopy (AAS). Purgeable organics were determined by gas chromatography-mass spectrometry (GC-MS) using Environmental Protection Agency (EPA) Method 624. Phenols, pesticides, and neutral organics were determined by GC-MS using EPA Method 625 with minor modifications. Studies on the precision of the leachability, metal analyses, and GC-MS analyses were performed as an important part of the overall analytical program.

The solid waste leaching procedure developed was shown to be reproducible, easy to use, and suitable for many types of wastes and analytes. Distilled water was found to be as effective as other media studied for leaching organic compounds. Citrate buffer was often much more aggressive than acetate buffer for leaching metals. The aggressiveness of citrate buffer was highly metal and specimen dependent. The degree to which the procedure reproduces the leaching of components in a codisposal environment, which would depend upon the leaching medium used and site-specific conditions, is unknown at this time.
Hot Isostatic Pressed Powder Metal Titanium Implant Devices
Authors: Chandhok VK , Rizzo FJ
Published: March 2009

In recent years, Crucible Compaction Metals Operation has performed a considerable amount of work in developing a ceramic mold process for the production of near-net shape hardware from powder metal with consolidation by hot isostatic pressing (HIP). A detailed description of the process is given herein. Examples of the many configurations made to date are presented along with the comparison of mechanical property data obtained on as-HIPed parts versus conventionally produced material.

Based on the information generated, the ceramic mold process appears to be a viable alternative process for producing titanium implant devices.
Implantable Titanium Feedthrough Reliability
Authors: Dixon DE
Published: March 2009

Implantable titanium feedthrough reliability is characterized by hermetic integrity, optimum mechanical design, and critical process requirements.

Hermetic integrity of a titanium electrical feedthrough depends on the coefficients of linear thermal expansion (CLTE) of the titanium, the sealing material, and the center conductor metal and on the degree of bonding obtained at seal-to-metal interfaces. Microscopic examination of the bond interface between titanium and the sealing material indicated fusion of the titanium oxide with the polycrystalline ceramic. Dilatometer measurements of titanium, a polycrystalline ceramic, and pure platinum (center conductor metal) showed similar CLTE for titanium and platinum, whereas the polycrystalline ceramic CLTE was less, thus ensuring some degree of compression in the sealing mechanism.

Optimum mechanical design was determined by thermal stress methods, which stressed designs through increasing thermal shocks until loss of hermeticity occurred in 50 percent or more of the specimen population. Two designs, one with mechanical reinforcement and the other without, were subjected to thermal shock ranges as severe as 755 K (900°F) to 78 K (−320°F). The plotted data indicated the design with mechanical reinforcement sustained higher levels of thermal shock without loss of hermeticity.

In vitro experiments on titanium feedthroughs with various surface configurations were conducted at low applied voltages (constant and pulse). The data indicated minimal electrochemical degradation at surfaces with maximum electrical leakage paths obtained by addition of ceramic standoff. Electrochemical degradation was measured in terms of insulation resistance between the titanium housing and the platinum pin and correlated to the accelerated battery depletion of a cardiac pulse generator. The battery life was observed to decrease rapidly as the electrical resistance across the titanium feedthrough decreased from 100 000 Ω.

Certain levels of temperature were shown to affect the grain size of titanium. Titanium (Grade 4) feedthrough housings were exposed to different temperature levels for the same 1-h duration. Scanning electron microscopy (SEM) photomicrographs verified by ASTM grain size determinations indicated substantial grain growth above the 1255 K (1800°F) temperature level. Conservative sealing conditions were recommended at less than the titanium beta transus temperature, 1158 K (1625°F), and less than 1-h exposure.
Comparison of Loading Behavior of Femoral Stems of Ti-6Al-4V and Cobalt-Chromium Alloys: A Three-Dimensional Finite Element Analysis
Authors: Tarr RR , Clarke IC , Gruen TA , Sarmiento A
Published: March 2009

Large stiff, small moderately stiff, and small flexible femoral total hip components cemented in the proximal femur have been investigated using a three-dimensional finite element model and validated using experimental strain gage techniques. A physiological load of three times body weight (2000 N), 18 deg from vertical was utilized to compute stresses in the bone, cement, and metal construct.

For a well-fixed total hip replacement, the results show stem stresses to be between 5 and 20 percent of the reported fatigue limits for the metals analyzed. Cement stresses in the proximal-lateral region were negligible for all stems tested. In looking at the failure stress for cement, the proximal-medial cement stresses were seen to be only 4 to 6 percent of the reported compression failure criteria and the distal stresses only 5 to 10 percent of tensile failure criteria.

The proximal-medial bone stress was 30 percent of normal for a titanium alloy small stem, 21 percent of normal for a moderately stiff small stem, and only 6 percent of normal for a large stiff stem. Distal bone stress on the medial cortex was 39 percent higher for the stiff stem than for the flexible stem and 20 percent higher laterally.

In viewing these results in light of the stem design or femoral component failure criteria, the cement does not appear to be the weak link for the well-fixed total hip replacement, regardless of the stem design. If failure initiation does not begin within the cement in a well-fixed hip, physiological changes in the bone may be responsible for loosening at the cement-bone interface, and the cement may then be prejudiced. Some advantages of load transfer to bone are gained with the use of flexible stems, but the significance of these changes can only be confirmed or disputed with detailed clinical and radiographic follow-up.
Influence of Heat Treatment on the Fatigue Lives of Ti-6Al-4V and Ti-4.5Al-5Mo-1.5Cr
Authors: Imam MA , Fraker AC , Harris JS , Gilmore CM
Published: March 2009

This paper reports on the effects of heat treating on phase composition and fatigue behavior of the Ti-6Al-4V and the Ti-4.5Al-5Mo-1.5Cr alloys. Corrosion-fatigue experiments show that the Ti-6Al-4V alloy has the longest fatigue life when heat treated at 900°C and quenched. The Ti-4.5Al-5Mo-1.5Cr alloy has an increased fatigue life under higher strain when heat treated at higher temperatures in the α-β region. Comparison of the fatigue lives of the Ti-6Al-4V and Ti-4.5Al-5Mo-1.5Cr alloys in the mill-annealed condition shows that Ti-4.5Al-5Mo-1.5Cr has improved fatigue behavior in the high-cycle region, but Ti-6Al-4V is superior in the low-cycle region.
Wear of Ti-6A1-4V Implant Alloy and Ultrahigh Molecular Weight Polyethylene Combinations
Authors: Clarke IC , McKellop HA , McGuire P , Okuda R , Sarmiento A
Published: March 2009

In view of published comments that the wear resistance of Ti-6Al-4V alloy bearing against ultrahigh molecular weight polyethylene (UHMWPE) was not adequate for total joint replacements, the literature was reviewed and compared with ongoing hip simulator studies. Two types of laboratory tests were contrasted: those run under “clean” conditions and those run with intentional contamination by acrylic cement particles. Wear-screening devices as well as hip simulators were involved in both types of studies, and both produced a dichotomy of viewpoints on the suitability of the Ti-6Al-4V/UHMWPE combination. However, the two most recent studies with hip simulators indicated that the Ti-6Al-4V-UHMWPE combination performed acceptably well. The published data from a major series of Ti-6Al-4V hip replacements have established excellent clinical and radiographic results. In seven surgical revisitations, the Ti-6Al-4V/UHMWPE combinations showed no sign of adverse wear phenomena. Thus, the clinical observations are supportive of the results of the two most recent hip simulator studies. It may well be that the laboratory models produced a variety of severe test conditions that compromised the performance of the Ti-6Al-4V and resulted in contradictory data. The hip simulator studies are being continued to establish the limits of the laboratory models and their validity with respect to the clinical situation.
Surface Preparation and Corrosion Behavior of Titanium Alloys for Surgical Implants
Authors: Fraker AC , Ruff AW , Sung P , Van Orden AC , Speck KM
Published: March 2009

Surface preparation and corrosion behavior of titanium alloys were studied; both topics deal with the formation of surface oxide films. When metals are prepared for surgical implant use, an effort is made to produce an optimum surface. Effects of the surface treatments on surface morphology, surface film composition, and structure are shown in transmission electron photomicrographs and electron diffraction patterns. Roughened surfaces were produced, and surface films of titanium oxide (TiO) or titanium dioxide (TiO2) or both occurred on some specimens. Sodium titanate (NaO · xTiO2) occurred on the specimens washed in sodium hydroxide (NaOH) solution.

Open circuit potential versus time curves have been measured to show some electrochemical effects of various surface treatments. The results show that titanium alloys immersed in Hanks' physiological solution reach the same final open-circuit potential after approximately two weeks' exposure regardless of prior surface treatment. Measurements of the anodic polarization behavior of titanium alloys and other surgical implant alloys show the effects of alloy composition and the testing solution on the passive region and breakdown potentials of these materials. In general, for titanium alloys, the differences are not great, but the presence of nickel results in a significant lowering of the breakdown potential. The materials studied were titanium, Ti-6Al-4V, titanium-nickel (memory alloy), Ti-13Cu-4Ni, and Ti-4.5Al-5Mo-1.5Cr. In all cases titanium materials are more corrosion resistant in Hanks' solution than cobalt-chromium-molybdenum Type 316L stainless steel, or cobalt-nickel-chromium alloys. Repassivation measurements show the rapid formation and the high degree of stability of the protective film on titanium and titanium alloys.
Tensile Strength, Fatigue Life, and Corrosion Behavior of Ti-318 and Ti-550
Authors: Dobbs HS , Robertson JLM
Published: March 2009

Titanium alloy 318 (Ti-318) (Ti-6Al-4V) in both the annealed and solution-treated and aged conditions and titanium alloy 550 (Ti-550) (Ti-4Mo-4Al-2Sn) in the annealed condition were studied. Tension tests demonstrated that Ti-318 was little improved by heat treatment and that Ti-550 was slightly stronger than Ti-318. Corrosion fatigue tests were carried out in Ringer's solution at 50 Hz at a stress of 575 MPa using tapered cylindrical specimens with two surface finishes: (1) polished and (2) acid etched and shot peened. For Ti-318 the acid-etched, shot-peened condition reduced the scatter and revealed the slight superiority of the solution-treated and aged material. Forged material exhibited similar behavior to that of rolled material, and preliminary results suggested that Ti-550 was better than Ti-318 under any condition. Anodic polarization tests were carried out in deaerated buffered Ringer's solution at 37°C, with a pH of 7.4 and a sweep rate of 10 mV min−1. For passivated and steam-sterilized material there was little difference between Ti-318 and Ti-550. The effects of passivation and steam sterilization, anodization, and acid etch and shot peening were determined. It was concluded that, for joint replacement applications where high corrosion fatigue strength is required, solution-treated and aged Ti-318 offers a slight advantage over annealed Ti-318 and that Ti-550, on the basis of preliminary results, appears to offer an advantage over both.
Fracture Testing of Injection-Molded Glass and Carbon Fiber-Reinforced Thermoplastics
Authors: Mandell JF , Darwish AY , McGarry FJ
Published: March 2009

A study is reported of the application of linear elastic fracture toughness testing techniques to short glass and carbon fiber-reinforced injection-molded thermoplastics. The materials were typical of high-temperature engineering thermoplastics and included polycarbonate, polysulfone, nylon 6/6, polyphenylene sulfide, and poly-(amide-imide). Tests were run on specimens of various sizes and shapes with machined notches and fatigue cracks. Results are reported for modes of crack growth, applicability of linear elastic fracture mechanics, and test peculiarities. Attempts to correlate the matrix toughness and fiber length with composite toughness are discussed.
A Comparative Study of Composite Shear Specimens Using the Finite-Element Method
Authors: Herakovich CT , Bergner HW , Bowles DE
Published: March 2009

Four specimens for the in-plane shear behavior of fibrous composites are analyzed for elastic stress distributions. Rigid and elastic fixtures as well as mechanical and thermal loading are considered. Results are presented in the form of stress contours, stress profiles, and stress concentrations for [0], [0/90]s and [0/±45/90]s laminates. It is shown that the assumption of rigid-fixture rail shear specimens predicts regions of uniform pure shear, but that the inclusion of elastic fixture effects introduces normal stresses in the test section. These results also indicate that the shear stress in the test section may differ from the average value by as much as 10 percent, depending upon laminate configuration. Results are also presented for slotted coupon, crossbeam, and a double V-notched specimen.
Experimental Study of Compression-Compression Fatigue of Graphite/Epoxy Composites
Authors: Grimes GC
Published: March 2009

The objective of the study is to determine the static compression and R = 10 constant frequency compression-compression fatigue properties of Hercules AS/3501-6 tape graphite/epoxy composites. Environmental conditions selectively used are: (1) room temperature dry, (2) room temperature wet (1.1 percent by weight), (3) 103.3°C (218°F) dry, and (4) 103.3°C (218°F) wet (1.1 percent by weight). Ply orientations studied are [0]nt, [90]nt, [±45]ns, and [(±45)5/016/904]c. All fatigue testing is at room temperature with subsequent residual strength testing on survivors at 103.3°C (218°F). New test methods are developed. Degradation is observed in the 1.25 million cycle endurance limit stresses and the compressive residual strength values compared with static properties.
Bolted Joint Design
Authors: Ramkumar RL
Published: March 2009

Bolts are commonly used in many structures to transfer loads from one component to another. When the structural components are fabricated using heterogeneous, fiber-reinforced composite materials and the magnitudes of the load transferred directly through the bolt vary, concerns regarding structural integrity arise. A change in the failure mode due to a change in the bolt load could be detrimental to the strength of the bolted joint. Results are available in the literature for the extreme cases where the bolt load is zero (unloaded hole) and where the total applied load is resisted by a bolt. This paper summarizes the results from an experimental-analytical program that investigated the effect of transferring an arbitrary fraction of the applied load through the bolt. In the analytical part of the program, a two-dimensional finite-element analysis was carried out, using NASTRAN, to predict the stress state around the bolted joint and the average stress failure criterion used to predict the joint strength and failure modes. The experimental program was conducted under room temperature dry and wet (1.2 percent moisture by weight) conditions. Experiments were conducted on AS/3501-6 graphite/epoxy specimens in test fixtures designed to transfer variable loads through the bolt. Identical specimens were subjected to static tensile and compressive loads, and to two lifetimes of tension and compression-dominated F-5 fatigue spectrum load conditions. Design curves were generated for the different test cases.
Literature Survey of the Properties of Synthetic Fuels Derived from Coal
Authors: Flores FJ
Published: March 2009

This report describes and summarizes a literature survey of the properties of synthetic fuels for ground-based turbine applications, compiled up to October 1980. The major processes for coal liquefaction (solvent extraction, catalytic liquefaction, pyrolysis, and indirect liquefaction) and coal gasification (fixed bed, fluidized bed, entrained flow, and underground gasification) are described. Processes for upgrading coal-derived liquids are discussed, and some property data for some coal-derived liquid and gaseous fuels are presented.
Gas Turbine Fuel Processing Costs and On-Site Cleanup Options
Authors: Dunning JW
Published: March 2009

This fuel processing/quality study provides a data base that can be used for assessing trade-offs between advanced gas turbine technology and liquid fuel quality and to help guide the development of specifications for future synthetic fuels anticipated for use in the time period 1985 through 2000. The study has quantified the cost and energy efficiency required for achieving various fuel characteristics and purity levels in coalderived liquids, shale oils, and residual oils processed through modified existing refineries or new refineries. The study also has developed cost data associated with using onsite fuel treatment, such as blending, washing, and exhaust gas cleanup, which allows the turbine user to make use of low-quality fuels. Minimum cost paths have been identified considering the trade-offs between refinery processing and on-site treatment. This paper highlights the results, methodologies, and assumptions of two contracted studies managed by the National Aeronautics and Space Administration for the U.S. Department of Energy. The work was performed under Interagency Agreement DE-AI01-77ET-13111.
Future Distillate Fuel Trends in Canada and Some Preliminary Gas Turbine Test Results on Tar Sand Products
Authors: Whyte RB , Grimsey RG , Glew CAW
Published: March 2009

The forecast for distillate fuels in Canada projects a trend towards lower quality brought about by the falling demand for gasoline and heating oils and the increasing demand for aviation jet fuel and diesel fuel. The problem is compounded by the increasing aromaticity of the crude supply and the increasing volumes of heavy crudes being processed. The changes in quality predicted include a lower flash point, higher viscosity, broader distillation range, and lower cetane number, smoke point, and hydrogen content.

There is an urgent need to evaluate the power plant performance of such fuels, and as a first step, the Canadian Forces (Navy) have compared the performance of a Solar Saturn gas turbine when burning blends of tar sand crude fractions and a conventional diesel distillate.

No abnormal carbonization of the fuel injectors, or hot-end components, occurred when the engine was running on the tar sand blends. However, there was an increase in fuel consumption of between 4% at no load and 2% at full load, and associated decreases in combustion efficiency and increases in exhaust smoke level.

The combustor liner metal temperature increased by 30 deg Celsius at full power when the engine was running on either of the tar sand blends. These performance changes are attributed to the high aromatic content of tar sand products, and it may prove necessary to derate slightly certain types of gas turbines if they are required to operate on highly aromatic fuels.
Properties of Synthetic Fuels Evaluated for Combustion Turbines
Authors: Streed CW , Mulik PR , Ambrose MJ , Cohn A
Published: March 2009

Under a comprehensive synthetic fuels program sponsored by the Electric Power Research Institute, Westinghouse Electric Corp. has evaluated the turbine combustion properties of over twelve coal-derived liquid (CDL) fuels, three shale-derived liquid (SDL) fuels, and six petroleum-derived surrogate fuels.

The combustion performance effects have been reported elsewhere. This paper compiles the properties of the various classes of synthetic fuels that were combustion-tested and discusses the significance of the analytical methods utilized by the Mobil Research and Development Corp. to characterize the physical and chemical properties, trace metal content, and aromaticity of these test fuels. The authors have concluded that certain modifications to the current ASTM turbine fuel specification tests will be required to accommodate CDL and SDL fuels.
Effect of Sodium and Potassium on the Hot Corrosion of Gas Turbines
Authors: Haskell RW , Doering HvonE , Grzybowski DF
Published: March 2009

The determination of a specification for trace metal corrosion-causing contaminants in coal-derived fuels depends on the corrosion resistance of gas turbine hot gas path materials to the deposits produced during the combustion of such fuels. The contaminants of principal concern are compounds of sodium and potassium, which produce deposits of sodium and potassium sulfate.

This report gives the results of small burner rig (SBR) accelerated corrosion tests with state-of-the-art alloys and coatings for the combustion of distillate fuel doped with sodium and potassium chlorides. The SBR data on the deposit chemistry and corrosion rates are analyzed to give corrosion data for turbine hot gas path components as a function of fuel trace metal contamination. The modes of corrosion attack when sodium and potassium are present in comparison with those when only sodium is present (distillate case) are discussed.
A Projection of Coal Gas Properties Considered from the Viewpoint of a Coal Gas Combined-Cycle Plant
Authors: Marlow JH , Pavel J , Vidt E
Published: March 2009

Four factors affect the quality of coal gas in the type of total gasification plant used for generation of electricity. The coal gas properties investigated here are considered in relation to the effects of these four factors: (a) coal type, (b) fluidized-bed type of gasifier, (c) wet (cold) and dry (hot) gas cleanup systems, and (d) gas turbine requirements.

The properties given are for gases having a heating value range of 3.4 to 11.3 MJ/m3 (90 to 300 Btu/ft3) and include gases from both air-blown and oxygen-blown gasifiers.

The chemical makeup of the gases is considered in terms of the nitrogen gas, hydrogen gas, carbon dioxide, carbon monoxide, and water content. Also the trace material content is given in both quantity and size of particles. The amounts of sodium and vanadium and both the size and the concentration of potentially erosive particles are discussed.

The measurement methods required for these types of fuels are also briefly discussed.
Tissue-Culture Methods for Determining Biocompatibility
Authors: Fehn J , Schottler D
Published: March 2009

Tissue-culture test methods are used as acute screening for biocompatibility testing of materials and solutions used in the manufacture of our biomedical devices at Medtronic, Inc. Presently, we are capable of performing three methods, they are: agar overlay, minimal essential medium (MEM) elution, and low cell density. In all the test methods performed we use L-929 mouse fibroblasts as our cell line.

Tissue-culture procedures are used for screening the safety of materials that are being evaluated in the following situation: (1) new material and vendor qualification, (2) process change or qualification or both, (3) vendor audit, and (4) incoming inspection. Medtronic basically follows the guidelines of the Health Industry Manufacturers Association (HIMA) Report 78-7, which classifies devices into four categories based upon usage. These are intended to be guidelines, but ultimately the criteria to classify materials and the testing done on the material are dependent upon (1) the intended end use of the material and its application, (2) whether it has direct or indirect body tissue, or fluid contact or both, (3) whether it will be short term or long term or both, and (4) if the material is put through a process that may change or affect the material or both.

The decision as to which tissue-culture method to use by which to screen a material is determined by (1) the nature of the material, (2) information required of testing, and (3) history of material and which test method is most applicable. The results of tissue-culture testing are meant to be screening and do not replace in vivo testing. If the results of a tissue-culture test are questionable, it is the decision of the study director of how to proceed. Medtronic has been doing tissue-culture testing for more than ten years and has a good data base to support our test methods.
Availability and Standardization of Cell Lines at the American Type Culture Collection: Current Status and Prospects for the Future
Authors: RJ Hay
Published: March 2009

Procedures in use at the American Type Culture Collection (ATCC) for standardization of cell-culture lines are summarized with illustrations. Comments on the total holdings and distribution are included with a listing and brief description of representative cell lines that may be of use in materials testing. The development of new technology for isolation and propagation of potentially useful functional human and other animal cell lines is discussed and referenced. The advantages in the use of standardized cell lines for materials testing are listed and emphasized.
A Laboratory Test Method for Evaluating the Efficacy of Glueboards for Trapping House Mice
Authors: Frantz SC , Padula CM
Published: March 2009

A laboratory test method developed for evaluating glueboard efficacy against house mice is described. The test method involves two different procedures for exposing mice to a particular glueboard product. The first procedure is to establish if mice captured by all four feet on glueboards will remain captured. During this 24-h study, individually caged mice are placed by hand on glueboards and observed at ten present intervals for changes in glueboard holding ability and for changes in the health condition of captive mice. Positive results (regarding holding strength) from this screening technique leads to a second procedure to establish if “free-ranging” mice will go onto glueboards and be captured. In this case, the mice are tested as a social group in a 32-m2 colony room where they make a choice of whether to enter a specially designed test apparatus (containing the food and water supply) via an open route or via a route containing a glueboard. Activity is monitored automatically, and food consumption is recorded daily over this twelve-day procedure (four days = pretest, four days = test, and four days = posttest), which allows social interaction and other behavioral factors to affect product efficacy. With the occasional appearance of new and modified glueboard traps on the market, a comparative basis for efficacy evaluation is desirable. Both testing procedures offered here yield useful information, though the first method could be simplified to ease data collection. The second procedure, by itself, may be sufficient for some purposes, and the results may be more applicable to field interpretation. Field application of glueboards, product design, and consumer considerations are discussed.
Plot Occupancy for Indicating Pocket Gopher Abundance and Conifer Damage
Authors: Anthony RM , Barnes VG
Published: March 2009

Pocket gopher (Thomomys mazama) sign (mounds and earth plugs) was inventoried at 48-h and one-month intervals in study areas in central and south-central Oregon. Similar counts of 48-h and three-month accumulations of sign made by T. mazama and T. talpoides were taken in California, Idaho, and Oregon. Plot occupancy—the frequency at which sign occurred on circular, 81-m2 plots—was strongly correlated with counts of individual signs and gopher depredation of planted conifer seedlings. For one area, we also determined that plot occupancy was significantly related to gopher density. We recommend the 48-h plot occupancy count—done in late summer or early fall, when gophers are most actively producing mounds—as the most useful index for forest management.
Methods Used in the Field Evaluation of Anticoagulant Rodenticides in India
Authors: Mathur RP , Prakash I
Published: March 2009

Field evaluation to establish the relative efficacy of three anticoagulant rodenticides for the control of desert rodents was made employing three census methods: active burrow counts, census baiting, and live trapping. The field testing was conducted in three phases: pretreatment population estimation, random placement of the candidate poison baits, and posttreatment population estimation. It is indicated that the burrow count method of population estimation is more reliable than the census baiting and live trapping methods.
Characterization of Microplasticity Developed During Fatigue
Authors: Field JL , Behnaz F , Pangborn RN
Published: March 2009

X-ray line-broadening studies and stress analyses were employed to characterize quantitatively the fatigue-induced lattice deformation and change in the residual stress prior to crack initiation. Measurements were made after surface layer removals to evaluate surface and subsurface microplasticity, and X-rays with different penetration capability were used in order to facilitate a similar comparison nondestructively. At high maximum stress amplitudes imposed by bending fatigue, rapid distortion of the surface layer followed by an extended period of recovery contrasted with a more steady accumulation of lattice imperfection in the subsurface region. Concomitant modification of residual stresses during the cycling included the development of a maximum compressive stress early in the life and a transition to tension during the intermediate life fractions, reaching a peak tensile stress when the line breadths for the near-surface and subsurface converged. The differentiation in surface and subsurface line broadening during cycling at high and low maximum stress levels was accredited to the operation of different crack initiation mechanisms, and the potential for postponing crack initiation through surface layer removal was investigated.
Physical and Mechanical Measurements of Damage in Low-Cycle Fatigue: Applications for Two-Level Tests
Authors: Pluvinage GC , Raguet MN
Published: March 2009

Physical and mechanical measurements of damage during low-cycle fatigue are made on steel by eight different methods. The decrease in load at constant strain amplitude is chosen as damage parameter to predict the cyclic life during two-level temperature and strain tests.
Statistical Aspects of Fatigue Failure Due To Alloy Microstructure
Authors: Morris WL , James MR
Published: March 2009

The elements of a methodology are described to calculate the scatter in fatigue lifetime which arises from statistical variations in alloy microstructure from sample to sample within a uniform heat of material, and from variations in mean grain size and in the ductility of the alloy surface from heat-to-heat. The modeling is formulated for certain structural aluminum alloys for which the dominant mode of crack initiation is by fracture of constituent particles near the alloy surface. For one of these, an Al 2219-T851 alloy, small amounts of internal hydrogen at contents less than 1 ppm are found to affect surface ductility and both crack initiation and early growth. The application of models of crack initiation and short crack growth to predict the combined effects of grain size and hydrogen on fatigue lifetime is demonstrated for smooth bar specimens of two heats of Al 2219-T851. Experiments confirm predictions that fatigue lifetime is increased by decreasing both grain size and alloy hydrogen content.

The models used to predict fatigue lifetime are discussed individually and deal with both the initiation and the early growth of surface fatigue cracks. They are evaluated by comparing predicted and measured mean and stochastic trends in rates of initiation and growth in Al 2219-T851 and Al 7075-T6. The paper concludes with a short treatment of the implication of the statistical nature of the fatigue failure process to prediction of the occurrence of failures of low probability, very early in the service lifetime.
Measurement of Fatigue Damage by Randomly Distributed Small Cracks Data
Authors: Kitagawa H , Nakasone Y , Miyashita S
Published: March 2009

During the fatigue process of unnotched smooth materials, small surface cracks often initiate, grow, and coalesce; these cracks are randomly distributed over the material surfaces in terms of size and location. This paper investigates the probabilistic laws these cracks follow, and proposes a quantitative method for the fatigue damage evaluation and residual-fatigue-life prediction of the materials. This method can be carried out in two ways. One is based on the variation of the statistical parameters (for example, the mean etc.) of the crack surface-length distribution with the number of load cycles. The other is based on the growth rate of the distributed small cracks and on the crack length distribution function.

The procedures of the method are described by taking the example of corrosion fatigue of a weldable structural steel, HT 60. The first step is the preparation of specimens having small cracks randomly distributed over their surfaces; the second step is the sampling of statistical data on the cracks from these specimens and from real structures; and, finally, the third step is fatigue damage evaluation and residual-life prediction based on various statistical treatments of the data obtained.

For the test of the goodness of the model and data in the present study, a Monte Carlo simulation analysis was made, which can deal with the initiation, growth, and coalescence behavior of distributed cracks.

Finally, the characteristic features and the scope of application of the method are described, and some comments are made on its applications to other fatigue fracture processes.
Short Fatigue Cracks
Authors: RA Smith
Published: March 2009

Short fatigue cracks are the linkage of the initiation stage to the long crack growth which can be described by linear elastic fracture mechanics. Because some cracks can initiate then cease to grow, short cracks are important in the definition of fatigue limits. This paper reviews the fatigue limits of plain and notched components and concludes that this particular short crack problem can be overcome by macroengineering parameters. So far as the growth of short cracks is concerned, their interaction with microscopic metallurgical features can be treated quantitatively only in a local sense. However, their growth in large plastic strain regions, which typically occur at a notch root, can be described by semiempirical macromechanics parameters. Finally, it is shown that in many practical circumstances the bulk of the fatigue life can be considered to be either initiation or long crack propagation, thus bypassing the short crack problem.
The Plastic Zone Ahead of a Fatigue Crack in 316 Stainless Steel
Authors: Loye C , Bathias C , Retali D , Devaux JC
Published: March 2009

After a short review of different experimental methods used for studying the plastic zone ahead of a crack tip, the capabilities of the microhardness method are analyzed in detail. A finite-element calculation, which takes the cyclic hardening of 316 stainless steel into account, permits a thorough study of plastic deformation at the crack tip. The microhardness technique is a good method of studying the shape of the plastic zone and the deformation around the tip of the crack.
Quantitative Measurements in the Plastic Zone Caused by a Single Overload in Air and Vacuum
Authors: Ranganathan N , Petit J
Published: March 2009

Plastic deformations near the crack tip following overload tests in air and vacuum on 2024-T351 aluminum alloy were measured by interferential-contrast, interferometry, and microhardness methods. The evolution of the plastic zone sizes in the overload-affected zone is described. Quantitative analysis of the results obtained show that plastic zone sizes are higher in vacuum and the distribution of plastic strains are different than in air. Differences in plastic zones between plane stress and plane strain conditions are also shown. These results, complemented with macrofractographic and microfractographic measurements and the calculation of the J-integrals, suggest an explanation for the differences in material behavior in air and vacuum.
Interaction of Gage and Hardenability on the Properties of Quenched and Tempered 2¼Cr-1Mo Steel Plate
Authors: Swift RA
Published: March 2009

A study of the hardenability of 2¼Cr-1Mo steel shows that the strength of this steel in the quenched and tempered condition can be correlated with the calculated hardenability, as defined by the ideal diameter, D1, but not with an inflection point in the Jominy end-quench hardness-distance curve, J1, for plates in gages from 140 to 214 mm. No correlation is found for plates 76 to 91 mm in gage or when the heavier plates are tempered to a Holloman-Jaffee parameter of 20.7 × 103. These trends are explained by the degree of through hardening and the sequence of precipitations that occur when the quenched steel is tempered.

The 50 percent martensite microstructure in an end quench test has been found to correlate with J1 but not D1. This, and the lack of correlation between J1 and D1 are explained by the methods used to develop each indicator. Both are indicators of 50 percent martensite. J1 indicates the location of the 50 percent martensite microstructure in an end quench bar regardless of the second constituent. D1 calculates the diameter for 50 percent martensite-50 percent pearlite. Since 2¼Cr-1Mo is bainite hardenable, a straightforward correlation is not expected.
Variation in the Microstructure of Electrodeposited Black Chrome Solar Coatings
Authors: Pettit RB , Sweet JN , Sowell RR
Published: March 2009

Electrodeposited black chrome solar coatings have been found to degrade thermally when used at temperatures near 300 °C. This degradation is evidenced by a large (∼ 10 percent) decrease in the solar absorptance for these coatings. The solution of the thermal degradation problem has led to a detailed study of the dependence of the coating microstructure and composition on the plating process variables and how these film properties change after thermal aging. The areal density, ρs, of coatings deposited on steel substrates reaches a constant value as the plating time increases. For thermally unstable coatings, ρs ≈ 2.6 × 10−5 g/cm2, while for thermally stable coatings, ρs ≈ 11 × 10−5 g/cm2. Scanning electron microscope studies of both unstable and stable coatings show that the films are composed of roughly spherical chromium/chromic oxide (Cr/Cr2O3) particles with diameters in the range of 90 to 150 nm. In the stable coatings, the particles tend to form clusters. This microstructure does not change upon heating, although the metallic chromium in the film oxidizes to form fine crystalline chromic oxide (Cr3O3). These data, together with previously published results, have been utilized to develop a model of the black chrome coating. This model is used to calculate the reflectance properties as a function of the average Cr2O3 percentage by volume within the film. The calculated reflectance curves are compared with experimental data for coatings aged for various times at 450 °C in air. Both the model and experimental data show that the solar absorptance initially decreases only slowly as the amount of Cr2O3 increases; however, a rapid decrease occurs when the Cr2O3 content exceeds ≈ 70 volume percent. Thus the authors have concluded that the decrease in solar absorptance with heating can be explained by oxidation of metallic chromium in the films to Cr2O3. It is believed that the clustering of particles in the more stable films decreases the effective exposed surface/volume ratio and thereby tends to inhibit the chromium oxidation. As a result of these investigations, it has been determined that careful control of the film morphology, through careful control of the plating process, is necessary to produce thermally stable black chrome coatings.
Flowable Pesticide Formulations: Development, Process, and the Need for Standard Testing Procedures
Authors: Halliday CG
Published: March 2009

Over the period of the last decade, numerous flowable (suspension concentrates) pesticide formulations have been developed using various manufacturing processes.

This paper deals briefly with the reasons for development of this type of formulation and the process and development problems encountered by the author and outlines the physical test procedures.

Physical tests such as specific gravity, particle size analysis, viscosity, and pH are mentioned, along with sampling problems which have been encountered in the field after these products were stored in a warehouse for some time. The need for standardization of physical test methods is mentioned.
Properties and Characteristics of Vibratory-Compacted Bituminous Mixes
Authors: Ali GA , Al-Jarallah MI
Published: March 2009

The purpose of this research was to investigate the feasibility of employing vibratory compaction to bituminous mixtures under laboratory controlled conditions, as a step in the direction of designing mixes utilizing dynamic properties determined by vibratory techniques. Three parameters are defined to characterize vibratory-compacted bituminous mixes: compaction force, Fc; mix stiffness factor, k, and mix damping coefficient, c. Use was made of the ASTM vibrating steel deck [ASTM Test for Relative Density of Cohesionless Soils (D 2049-69)] employing different surcharges and vibration amplitudes. The scope of testing included dense and open-graded mixes with asphalt contents, respectively, of 4.5 to 7.0 and 3.0 to 4.5%. On the basis of the analysis of the experimental data, it was concluded that bituminous mixtures can be characterized by dynamic parameters that are influenced by variations in amplitude and surcharge. These parameters are comparable to conventional Marshall properties and may be used as criteria for rational design of bituminous mixtures. For the purpose of developing final mix design criteria for a wider range of application using vibratory compaction in the laboratory, it is recommended that a vibrating system with varying frequencies, amplitudes, and surcharges be standardized.
Effects of Stress Ratio, Frequency, and Loading Time on the Tensile Fatigue of Glass-Reinforced Epoxy
Authors: Mandell JF , Meier U
Published: March 2009

The interaction of time under load and number of tensile fatigue cycles has been investigated for 0°/90° E-glass/epoxy laminates. The frequency was varied from 0.01 to 1.0 Hz, and the stress ratio was varied from 0 to 1.0 (static fatigue). Square wave and spike loading data indicate a higher initial strength but also a higher rate of loss of initial strength per decade of cycles for waveforms with less time at maximum stress. S-N curves tend to converge at low stress to the same number of cycles to failure, regardless of waveform. Long-term results are reported for fiberglass box beams fatigued for up to 108 cycles at relatively low loads, where matrix cracking and delamination damage were studied. A brief description is also given of field failures involving crack growth in a brittle mode, normal to the fibers.