bluuebunny/crossref_metadata_2025 huggingface dataset:
A Finite Element Analysis for Stress Distribution in Gripped Tubular Specimens
Authors: Rizzo RR , Vicario AA
Published: March 2009

A new elastic finite element program is implemented. The analysis can account for general anisotropy and the three-dimensional nature of axisymmetric composite bodies. Attention is directed to characterizing the anomalous stress distributions which can occur in certain anisotropic tube specimens. For axial- and hoop- wrapped tubes accurate principal properties data can be obtained using classical shell theory and assuming uniform stress at the midlength cross section of the tube. For helically laminated tubes, the degree of accuracy is highly influenced by the geometry. A substantial inaccuracy could occur in strength predictions even for what normally are considered thin tubes. The study also identifies the stress distribution, including interlaminar effects, under the gripped area, which is not possible with any known closed form solutions.
Mechanical Behavior of Carbon/Carbon Filamentary Composites
Authors: Bert CW , Guess TR
Published: March 2009

The paper reports on uniaxial, biaxial, and shear loading tests on filament wound carbon/carbon composite tubes and rings. Circular cylindrical tubes were loaded in axial tension and compression, in hoop tension (by a pressurized bladder), and in combinations of these to obtain biaxial loading. Shear data were obtained primarily by means of out-of-plane loading of split rings, although limited data were also obtained from torsion tube tests. In reducing the test data to obtain the basic orthotropic elastic properties of a thin ply, it was found that the stiffness matrix was significantly unsymmetric, that is, the fundamental reciprocal relation involving the two in-plane Young's moduli and the two in-plane Poisson's ratios was violated. Thus, anisotropic elasticity and shell equations should be derived without assuming that symmetry holds. The implications of the results obtained are discussed in the light of thermodynamics, tests conducted by other investigators, and stress analysis.
A New Theory to Predict Cumulative Fatigue Damage in Fiberglass Reinforced Plastics
Authors: Broutman LJ , Sahu S
Published: March 2009

Two-stress level cumulative fatigue damage was studied on a cross-plied E glass fiber/epoxy laminate (Scotchply type 1002). Tests were performed in fluctuating tension with the minimum value of cyclic stress equal to 5 percent of the maximum value of cyclic stress (R = 0.05). The results show that for a high-low stress cumulative damage test the Miner's sum, (n1/N1)+(n2/N2), is greater than unity and for a low-high stress test less than unity. The deviation from unity depends on the difference between the high and the low stress levels. These observations can be explained on the basis of a theory proposed here which takes into account the reduction of the tensile strength of the material due to cyclic loading. The residual strength of the composite at a given stress level has been determined as a function of number of cycles or fractional life spent. The predicted values of Miner's sum based on strength reduction curves agree qualitatively and quantitatively with the experimental values.
The Engineering Properties of Polymer Matrix Composite Materials by a Pure Moment Test
Authors: Hill RG , Anderson WE
Published: March 2009

A pure moment test fixture is described for examining the engineering properties of materials through bend deflections up to 180 deg. Specimen configurations are described for applying flexural, tensile, and compressive loads to the gage section. The method may be applied to any symmetrical specimen which can be gripped in the load heads of the fixture. Dual-element beam configurations for tensile and compressive loading of polymer matrix composites are described, and test data are provided. A method for determining interlaminar shear properties, using a multi-element beam specimen and the pure moment fixture, is suggested.
The Preparation and Testing of Miniature Carbon Fiber Reinforced Composites
Authors: McLoughlin JR
Published: March 2009

A method for preparing small carbon fiber reinforced composite test specimens is described which results in high quality specimens of high fiber volume fraction. The method consists of impregnation of the carbon fiber bundles with a solution of a resin, partial drying, careful loading in a mold which is tight in the long dimensions but loose at the ends, and treatment of the mold and contents under heat and vacuum to completely remove solvent and air before mold closure. The mold is closed and heat and pressure are applied without breaking the vacuum. The bars produced have excellent mechanical properties, which is shown to be due to good composite preparation rather than as a result of size. The small composites serve as standards against which larger composites with their various imperfections can be compared. They are also useful for evaluating new fibers, new resins, fiber surface treatments, and molding conditions.
Toughness of Filamentary Boron/Aluminum Composites
Authors: Hancock JR , Swanson GD
Published: March 2009

An exploratory study was carried out to determine whether, in terms of the definitions and test procedures developed for alloys, valid fracture toughness values could be measured for highly anisotropic and heterogeneous boron/aluminum composites. The mechanical test results were correlated with acoustic emissions from filament breakage, with fractography, and with high-speed movies of surface deformation and crack growth.

The plane strain fracture toughness, KIc, parallel to the filament axis of center notched specimens of 6061 aluminum-30 volume percent boron was determined to be ∼30,000±4000 psi √in. Filament pullout contributed negligibly to the fracture toughness of the composite. The minimum plate thickness, in terms of the plastic enclave size factor (KIc/σy) necessary to achieve plane strain conditions is about the same as that recommended for metals. The results indicate that conventional concepts of fracture toughness can be applied to filament reinforced metals to provide engineering design data.
Pendulum Impact Resistance of Tungsten Fiber/Metal Matrix Composites
Authors: Winsa EA , Petrasek DW
Published: March 2009

The impact properties of copper, copper-10 nickel, and a superalloy matrix reinforced with tungsten fibers were studied. In most cases, the following increased composite impact strength: increased fiber or matrix toughness, decreased fiber-matrix reaction, increased test temperature, hot working and heat treatment. Notch sensitivity was reduced by increasing fiber or matrix toughness. The effect of fiber content depended on the relative toughness of the fibers and matrix. Above 530 K a 60 volume percent superalloy matrix composite had a greater impact strength than a turbine blade superalloy, whereas below 530 K a hot worked 56 volume percent composite had a greater impact strength than the superalloy.
Reinforced Cutouts in Graphite Composite Structures
Authors: Kocher LH , Cross SL
Published: March 2009

A 1-in.-diameter, unreinforced hole in a 6-in.-wide, multidirectional, graphite composite laminate test specimen is shown to reduce the gross section strength by a factor of two. This stress and strain concentration effect is more severe than with most metals because of the nonyielding behavior of the composite but is not as severe as with typical brittle materials. Integral composite reinforcements around holes in several tension specimens are shown to carry loads efficiently, that is, they develop 80 to 90 percent of the strength of a specimen without a hole. For the particular metallic and composite reinforcement designs considered, the composite reinforcements are three to six times as light as metallic ones giving approximately the same load carrying capability. Although these reinforcements are not of an optimum configuration, they demonstrate a capability for reinforcing cutouts in composite structures. Strain responses and ultimate loads compare reasonably well with predictions based on discrete element analysis. A technique of lightweight reinforcement for a cutout in a stiffened compression panel is successfully demonstrated by fabrication and structural testing.
Off-Axis and Transverse Tensile Properties of Boron Reinforced Aluminum Alloys
Authors: Swanson GD , Hancock JR
Published: March 2009

Tension specimens of boron reinforced 7075 and 6061 aluminum were tested at angles of 0, 30, and 90 deg to the unidirectionally aligned filaments. Metallurgical structures in the matrix and at interfaces were correlated with stress-strain curves, with acoustic emission from boron filament breakage during the tests, and with fractographic studies. Differences in composite strength after various heat treatments were attributed to changes in the properties of the matrix rather than to any difference in properties of the filament-matrix interface. Transmission electron microscopy of boron/ 7075 aluminum composites revealed (1) precipitate segregation to interfaces for all heat treatments, (2) that subzero thermal treatments provide a new means of developing desired microstructures in composites, and (3) the presence of a narrow surface layer in the filaments in boron/7075 aluminum composites. This surface layer is believed to be a result of diffusion during composite fabrication.
The Initiation and Growth of Fatigue Cracks in Filament Reinforced Aluminum Alloys
Authors: Hancock JR
Published: March 2009

The low cycle fatigue behavior of filamentary composites of beryllium/1235 aluminum, beryllium/6061 aluminum, and boron/7075 aluminum were compared. The effects of the strength and ductility of the filaments and matrix, and the role of interfaces on fatigue crack initiation and growth were evaluated to develop guidelines for the design of fatigue resistant composites. Generally, brittle filaments, a low yield strength ductile matrix, weak interfacial bonds, and a large modulus difference between constituents are the factors which lead to greater fatigue resistance in filament reinforced metals. The observed modes of fatigue crack growth confirmed the theoretical predictions of the effects of stress distribution at a crack tip at an interface and extended the applicability of these predictions to filamentary composites.
Neutron Irradiation Effects on a Metal Matrix Composite
Authors: Kvam KC , Jones RC
Published: March 2009

The study examined the effects of nuclear irradiation on the mechanical properties of a metal matrix composite to update composite theory to include nuclear effects and to determine the feasibility of nuclear applications of metal matrix composites. An NS 355 stainless steel fiber/2024-T6 aluminum matrix composite was cut into specimens which were then divided into four sample groups. Three of these groups were irradiated to fast neutron dosages of 1.56, 2.84, and 4.68 × 1018 n/cm2. Microhardness and flexure tests were performed on each of the four sample groups. Fracture surfaces of all sample groups were viewed by scanning electron microscopy.

Strength increases and ductility decreases with increasing dosages are generally observed in the aluminum matrix and the stainless steel fibers. The high degree of matrix hardening and subsequent saturation with increasing dosage, leading to changes in the relative failure strain of matrix and fiber, is identified as the controlling mechanism of the composite strength changes in flexure. Existing composite theory is concluded to be applicable to nuclear irradiated composites without modification. Nuclear applications are most feasible in fast reactors, where the tailorability of a metal matrix composite might provide the technical breakthrough needed to combat the severe materials problems inherent to fast reactors.
The Transverse Strength of Boron Fibers
Authors: Kreider KG , Prewo KM
Published: March 2009

A fiber crushing test which relates to previous testing procedures for brittle materials was developed. The test is used to determine the tensile strengths of fibers, particularly with respect to the propagation of preexisting flaws. The transverse strength of 4-mil (0.010-cm)-diameter boron and Borsic fibers was surprisingly low (30,000 psi) indicating severe anisotropy. This strength anisotropy was related to the residual stress pattern retained from manufacture and preexistent flaws in the fiber. Boron and Borsic fibers 5.6 mil in diameter did not suffer such severe strength anisotropy and demonstrated excellent transverse strength properties in the fiber crushing test. Both observations are confirmed in tests of metal matrix composites.
Carbon/Carbon Composites—Solid Rocket Nozzle Material Processing, Design, and Testing
Authors: Laramee RC , Canfield A
Published: March 2009

One hundred and one ring shapes (2 to 16 in. in diameter) of carbon/carbon composites have been tested and evaluated to determine the processing cycle, the design properties, the ablative performance in a solid rocket nozzle environment, and the reinforcement tailoring for design applications. A carbon/carbon composite with a carbon or graphite reinforcement (cloth, fiber, felt, yarn, or granular) and a carbon or graphite bonding matrix (pitch, resin, or pyrolytic graphite) has demonstrated a capability to replace a warm standard nozzle ablative (carbon or graphite cloth phenolic) and room temperature structural (steel or aluminum) shells with a single hot material nozzle design. The carbon/carbon material provides an improved nozzle and missile performance through a lower nozzle weight volume and simpler design. The carbon/carbon material uses a 5500 F maximum processing cycle and develops a room temperature ultimate strength and modulus ranging from 3 to 88 ksi and 1.2 to 17.0 × 106 psi, respectively, an ablation erosion rate of 0 to 10 mil/s, and a reinforcement orientation of 0 to 90 deg with respect to the nozzle center line. In addition, the material offers good mechanical properties, dimensional stability, and structural integrity for a nozzle operating temperature of 5500 F and a pressure of 500 psi. The carbon/carbon limitations are longer procurement time, a need for additional processing and material properties, a high cost per pound in development quantities, and a greater design application analysis time than with existing standard ablative and structural materials.
Twenty-Year Atmospheric Corrosion Investigation of Zinc-Coated and Uncoated Wire and Wire Products
Authors: Reinhart FM
Published: March 2009

Description

Nine papers describe the state-of-the-art in mixture design, laboratory testing, and field evaluation of compacted bituminous aggregate mixtures designed for fatigue resistance.
Chapter 2—The Babcock & Wilcox Company Reactor Vessel Surveillance Programs
Authors: Lowe AL , Palme HS
Published: March 2009

Throughout the lifetime of a reactor vessel, the impact and tensile properties of the ferritic beltline region materials change because of neutron irradiation. These changes require periodic adjustments of the reactor vessel pressure-temperature relationships for heatup and cooldown during normal operating, upset, and testing conditions.
Chapter 5—The Westinghouse Electric Corporation Reactor Vessel Radiation Surveillance Program
Authors: Mager TR , Anderson SL , Yanichko SE
Published: March 2009

Westinghouse recognized that the disruption of the atomic lattice of metals by collision from energetic neutrons could alter the properties of the metals to such an extent that the changes could be of engineering significance. Furthermore, it was recognized that a physical-metallurgical phenomenon such as aging, both thermal and mechanical, also could alter the properties of a metal over its service life. Because of the potential changes in properties, reactor vessel radiation surveillance programs to monitor the effect of neutron radiation and other environmental factors on the reactor vessel materials during operational conditions over the life of the plant were initiated for Westinghouse plants with the insertion of reactor vessel material radiation surveillance capsules into the Yankee Atomic Company's Yankee-Rowe plant in 1961 [1–3].
Chapter 6—The General Atomic Company High-Temperature Gas-Cooled Reactor Surveillance Program
Authors: Hildebrand JF , Roberts DI
Published: March 2009

The Fort St. Vrain Nuclear Generating Station at a site in Colorado, about 56 km (35 miles) north of Denver, is the first nuclear-powered unit of the system of the Public Service Co. of Colorado. Gulf General Atomic Inc., constructed this station under the U.S. Atomic Energy Commission's Power Reactor Demonstration Program. The high-temperature gas-cooled reactor (HTGR) steam supply system provides 16.5-MPa (2400-psig), 538°C (1000°F) steam and 538°C (1000°F) reheat steam to a 3600-rpm tandem compound turbine generator to produce a net electric output of 330 MW.
Chapter 8–Review and Analysis of Reactor Vessel Surveillance Programs
Authors: Steele LE
Published: March 2009

The problem of neutron radiation embrittlement of reactor pressure vessel steels has been addressed in earlier chapters by direct review of specific vessel surveillance programs. To end this study, all available surveillance results are summarized and analyzed within the context of current codes, rules, and standards. The results provide bases for certain modifications of future surveillance programs, surveillance analysis procedures and, possibly, for guiding criteria for developing Federal regulations and voluntary consensus standards and codes.
Electron Fractography—Tools and Techniques
Authors: McCall JL
Published: March 2009

Electron fractography has recently become a valuable tool for studying the topographic features of fractures, and from it much new theoretical and applied information regarding the micromechanisms of fractures has been obtained. Prior to the use of electron microscopes, the unaided eye, optical microscopes, and metallographic cross sections were used to study fractures. These methods, however, have distinct limitations such as low resolution and small depth of field. Both of these limitations have been overcome with the electron microscope. Other tools are now being applied to fracture studies to complement the electron microscope. These include deep-focusing microscopes, electron microprobe analyzers, and scanning and reflection electron microscopes. The combination of all these tools has provided much new information, but it must be realized that electron microscopy as a tool for studying fractures is still essentially in its infancy, and it offers tremendous opportunities which, as yet, have not been fully explored.
Symposium on Masonry Testing
Authors: Committee C-12  , Committee C-15  , Committee E-6
Published: March 2009

Description

An informative report on some of the most important testing, research and development work done on masonry materials and construction is presented in the seven papers comprising this publication.
Cleavage Phenomena and Topographic Features
Authors: Burghard HC , Stoloff NS
Published: March 2009

Cleavage fractures have been widely studied in body-centered-cubic and certain hexagonal-close-packed metals and alloys as well as ionic crystals. It is shown that the theoretical treatments due to Stroh, Cottrell, and Petch have successfully accounted for the effects of yield strength, grain size, and mode of deformation on crack nucleation and propagation. The results of these studies are summarized, and their application to the prediction of the ductile-to-brittle transition temperature is described. In addition, theoretical studies which have led to the prediction of cleavage planes and to an explanation of the influence of dispersed particles are reviewed.

Fractographic studies have established topographic features characteristic of cleavage fracture; namely, steps and river patterns, cleavage tongues, and herringbone patterns. Examples of these features are presented, and factors associated with their formation are described. It is shown that steps and river patterns are formed by secondary cleavage, slip, or plastic fracture and are influenced by crystallographic imperfections and microstructural discontinuities. Tongues and herringbone patterns are shown to be associated with deformation twins formed ahead of the advancing crack. In addition, a discussion of “cleavage-like” features observed in quenched and tempered steels, face-centered-cubic materials, and in certain environmentally induced fractures is presented.
Fracture by Microscopic Plastic Deformation Processes
Authors: Beachem CD , Meyn DA
Published: March 2009

The various fracture surface features formed by fine-scale plastic flow processes are discussed, and the mechanisms by which they are formed are discussed where they are known.

Glide plane decohesion, as it has been used in the literature, is shown to be misleading, and a more descriptive term, “stretching,” is used in its place. The use of “ductile cleavage” to describe the same process is also misleading.

Since brief, descriptive, nonmisleading terminology is necessary for immediate communication, several terms have evolved to describe the surfaces created by unknown processes. Glide plane decohesion, serpentine glide, ripples, stretching, and three kinds of microvoid coalescence are shown to be parts of a spectrum of plastic rupture.
Application of Electron Fractography to Fatigue Studies
Authors: McMillan JC , Hertzberg RW
Published: March 2009

A review of the application of fractography to fatigue studies is presented that covers fatigue fracture appearance, the occurrence of striations, and qualitative and quantitative aspects of the fracture surface microdetails. Recent experimental results in three areas are also discussed: (1) the effect of prior loading history on subsequent crack propagation, (2) the smallest observable crack growth increments, and (3) the effect of environment on fatigue crack growth.
Engineering Applications of Fractography
Authors: Brothers AJ , Yukawa S
Published: March 2009

To date the primary use of microfractography has been qualitative. For this purpose the characteristic features of a specific fracture mechanism are compared with those of the service failure to be identified. However, the optimum use of fractography is that of both a quantitative and qualitative tool. This paper illustrates its usefulness in interpreting quantitatively the microfractographic features of various failure mechanisms, and suggests some currently speculative but promising areas for future work.

The incidence of fatigue striations and their association with cyclic alternating loads provide the basis for quantitative interpretation of fatigue failures. It is shown that fractographic determination of microscopic crack growth rates, coupled with currently available analyses for macroscopic crack growth rates, permits one to estimate relative failure stress or strain level, approximate number of failure cycles, and, in some cases, the relative stress gradient and mode of loading. The general stress dependence of fatigue striations, if determined from component tests, can be used directly for estimating relative operating stress levels of service failed parts. However, the influence on crack growth rate of geometrical factors suggests caution in comparing service failures with fractographic features of laboratory specimens. For this general case the correlations of crack growth rate with Griffith-Irwin fracture mechanics concepts are recommended. Since these analyses consider both component and crack geometry and mode of stressing, they are more generally applicable to a service consideration.

The high magnification used in electron microfractography and its use of replica techniques are shown to be useful in interpreting quantitatively the metallurgical features associated with creep microvoid formation. It is shown that fractography, in combination with standard electron diffraction techniques, permits one to isolate and identify the distribution, size, and content of specific metallurgical phases.
Deterioration of Wood by Marine Fungi in the Deep Sea
Authors: Kohlmeyer J
Published: March 2009

Wood panels exposed for 13 to 35 months at three Pacific and Atlantic Ocean locations at depths between 1616 and 2073 m were attacked by cellulose digesting fungi. Degradation was limited to the outer layers of the wood and was identical with the “soft rot” decay caused by terrestrial, fresh-water, and marine shallow water fungi.

Two new organisms were discovered belonging to the Ascomycetes and Deuteromycetes. Growth of fruiting bodies was slow, requiring more than 1½ years for development. One additional abyssal Ascomycete was collected with deep-water driftwood from 3710 m in the Gulf of Panama. No fungi were found on panels of seven wood species exposed at a Pacific site (722 m depth) with a low dissolved oxygen content. Cellulolytic bacteria developed in this “minimum oxygen zone” and also in two other test sites. Wood deterioration by bacteria differs distinctly from that caused by fungi. Influence of microorganisms on the settlement of wood boring molluscs is discussed.
Effect of External Hydrostatic Pressure on Damaged Glass Hydrospheres
Authors: Outwater JO , Austin LE
Published: March 2009

As the external hydrostatic pressure around a hollow glass vessel is increased, the damage to the vessel that may result from point-impact loads is reduced. The effect of hydrostatic pressure on conical cracks in the shell of hollow glass spheres is dependent on the magnitude of the pressure, the time under load, and the depth of the initial flaw. It is relatively independent of the pressurizing medium. Bare conical cracks may initially spall under compressive stresses in the glass of 45,000 psi, whereas sealing the surface of the cracks by adhesive cellulose tape prevents spalling at stresses as high as 148,000 psi. The compressive stress needed to initiate flaking in a damaged glass hydrosphere is approximately the same as that needed to cause flaking in a glass rod under compressive end load.
The Information Background in the Field of Biological Deterioration of Nonmetallic Materials
Authors: Wessel CJ
Published: March 2009

Important in the consideration of biological agents is the role of chemical and physical factors such as moisture, heat, light, oxygen, and salts. Crucial in determining the existence of the biological agents at the site of the deteriorative action, they also influence the rates of reaction of biological agents on their substrates. For the subsequent discussions of rubber, plastics, paint, textiles, and other nonmetallics, this paper will sketch the development of science in this field. A secondary goal will comprise outlining methods for obtaining published information on the subject.

There are many antecedent instances of biological deterioration of nonmetallic materials, but World War II assembled circumstances where the subject rose to the attention of the government. Environments of battle theaters and the need to concentrate immense amounts of materiel under primitive storage conditions caused the deterioration by biological agents to become critical. This paper will provide some history and describe events during and after World War II associated with the development of the field.

To perform biodeterioration research and development, it is essential to know the work done in the past. It is important to have under control that little bit of the information reservoir pertinent to the biodeterioration field. The paper, therefore, will identify the information resources which developed concomitant with the needs of research, development, test, and evaluation in the biodeterioration field. The intent is to leave the audience with a picture, not only of the subject matter highlights of this fascinating field, but also the sources where he can gain additional information.
Uptake and Assimilation of Nitrogen in Microecological Systems
Authors: Ehrlich GG , Slack KV
Published: March 2009

A study of biological effects on water quality utilized recirculating laboratory streams. The sole nitrogen source in one stream was Ca(NO3)2 and in the other was yeast extract. Soluble organic nitrogen from the yeast extract decreased rapidly accompanied by large increases in bacteria and in ammonia. Nitrite and nitrate increased slightly. Bacteria and combined nitrogen decreased rapidly after the initial rise. In the stream with the inorganic nitrogen medium, about half of the nitrate disappeared in two weeks, and nitrate was undetectable after the third week. Bacterial counts were relatively low and constant. Periphyton increased in both streams as nutrients decreased, reaching quasi steady states after about four weeks. The rate of biomass increase was greater in the inorganic medium. Chlorophyll increased rapidly in both streams, reached a maximum the third week, then decreased.

Nitrogen assimilation followed characteristic patterns. Nitrate was directly assimilated by algae. A slight denitrification occurred at high-nitrate concentrations. Organic nitrogen was converted to ammonia by proteolytic bacteria, during which process some nitrogen might have escaped as gaseous ammonia. Ammonia from organic compounds was partly assimilated by algae and partly nitrified by bacteria. Nitrate of bacterial origin was assimilated by algae. Nitrification apparently was not of major importance in converting organic nitrogen to algal biomass.

Laboratory streams simulate natural streams in diurnal cycles of pH and dissolved oxygen, in periphyton growth rate and biomass, and in assimilation of nutrients. Use of model systems to study natural processes under controlled conditions appears justified.
Determination of Phenols in Surface Waters by Thin-Layer Chromatography
Authors: Smith D , Lichtenberg JJ
Published: March 2009

Thin-layer Chromatographic procedures for the determination of phenol and certain substituted phenols are applied to raw surface waters. Both water grab and carbon adsorption samples are analyzed. The concentrated solvent extracts of the samples are chromatographed on silica gel G thin layers and developed in benzene/cyclohexane/diethylamine (5:4:1) or chloroform. The first system provides for selective determination of the alkylphenols, since the chloro-, nitro- and aminophenols remain at or near the origin. Phenols developed with this system are detected with p-nitrobenzenediazonium fluoroborate. Those developed with chloroform are detected with Gibbs' reagent. Specific phenols are characterized by their Rf values and the color of the spots produced. A wide variety of phenols are detected at the 0.1 to 10 μg level with the Gibbs' reagent and at the 0.5 to 25 μg level with p-nitrobenzenediazonium fluoroborate.
Fluorescence Techniques in Detection of Organics in Water
Authors: Christman RF , Arnquist JL
Published: March 2009

The fundamental objective of the authors' continuing research in this area is to increase our understanding of the chemical structures of natural product organic molecules responsible for color in natural water and the mechanism of their interaction with salts of Al3+ and Fe3+. Previous research has resulted in the isolation and identification of seven aromatic oxidation products of the parent color producing macromolecules. In this paper the research results of interaction studies using model flavonoid compounds and controlled concentrations of coagulant metal ions, alkalinity, and ionic strength are presented.
Determination of Trace Amounts of Molybdenum
Authors: Armstrong R , Goldman CR
Published: March 2009

Molybdenum is determined directly in solutions containing above 100 ppb. A spectrophotometric method using the extractable complex with diacetyldithiol was found to be the most convenient and the least subject to interference of a number of methods.

Preconcentration of dissolved molybdenum by coprecipitation with hydrated MnO2 followed by spectrophotometry of the dithiol complex allows the determination of a 1 μg of molybdenum in a 5 liter sample (0.2 ppb) with a relative error of 3 percent.

Particulate matter may be removed from water samples by HA Millipore filtration or by continuous flow (150 ml/min) centrifugation at 28,000 g. The latter method is more convenient for processing the large (10L to 50L) water samples needed for estimating the trace metal content of suspended particles in unpolluted waters.

Molybdenum is most conveniently released from organic materials by wet oxidation with perchloric acid, the residue being taken up in 3-N hydrochloric acid. Hydrofluoric acid digests of silicate samples were found to give higher recoveries than perchloric acid digests and were found to be more reproducible than fusion methods.
A Code Official's View of Requirements for Noncombustible Building Materials
Authors: Bihr JE
Published: March 2009

The traditional definition of noncombustible has given way to a performance oriented approach. Comparing the various model code treatments, it is apparent that they are leading this trend. The motivation stems from the development of new products such as plastics and composites as well as the ability to significantly change the combustible characteristics of older products such as wood. Potential heat tests appear to be a realistic method of separating materials with respect to levels of combustibility.
Perspective on Methods of Assessing Fire Hazards in Buildings
Authors: Ryan JE
Published: March 2009

Present fire protection regulations are based on fire classifications of materials obtained from standard laboratory tests and on simplified methods of estimating building fire loads. The history of, and philosophy behind, present fire resistance test methods are examined and the relevancy of the fire load and noncombustibility concepts to conditions actually encountered in the field are discussed. Information needed to improve methods of assessing fire hazard and to achieve more effective fire protection regulations is identified.
Heat Release Rate of Building Materials
Authors: Smith EE
Published: March 2009

Equipment and procedures for determining rate of heat release versus time for building materials and furnishings are being developed. The object is to obtain data which can be used in the design of rooms and their furnishings that will be safe from catastrophic fires. A description of the equipment is given and the significance of the data obtained is discussed. Rate of heat release versus time curves at different levels of exposure are used to describe burning characteristics of various materials. The use of this information as the basis for assigning fire hazard classification is examined.
Development of a Heat Release Rate Calorimeter at NBS
Authors: Parker WJ , Long ME
Published: March 2009

The heat release rate calorimeter being developed at the National Bureau of Standards measures the rate of heat release for building materials exposed to radiant fluxes up to 10 W/cm2 with a response time of a few seconds. The calorimeter and its operation are described and preliminary results are presented on the maximum one minute average heat release rates for a variety of building materials. Also given is the effect of irradiance on the maximum one minute average heat release rate of a wood fiber insulating board. The total heat generated by a pine specimen is compared with its heat of combustion measured with an oxygen bomb calorimeter. This heat release rate calorimeter has adequate sensitivity, accuracy, and time response to provide useful information on the heat release characteristics of building
A Low Cycle Fatigue Testing Facility
Authors: Hirschberg MH
Published: March 2009

The equipment and methods for low cycle fatigue testing used at the National Aeronautics and Space Administration (NASA) Lewis Research Center are presented. These include the design of the specimens, grips, and loading frame, as well as the hydraulic system and console which are capable of operating several testing machines simultaneously. The methods of measuring and controlling load, strain, and temperature are also included. Emphasis is placed on those items or procedures used in our laboratory but not commonly used by others.
Elevated Temperature Testing Methods
Authors: Wells CH
Published: March 2009

Techniques of axial strain-controlled fatigue testing at elevated temperature are described. The specimen design incorporates thin ridges for attaching the extensometer arms; details of the design are provided to avoid premature failure at these discontinuities. Special problems of specimen gripping, alignment, and break detection at high temperature are discussed for both mechanical and closed-loop hydraulic testing machines.
High Temperature Material Behavior
Authors: Lord DC , Coffin LF
Published: March 2009

The purpose of this paper is to describe the equipment and procedures developed at the General Electric Research and Development Center for testing and evaluating materials at elevated temperature under uniaxial controlled cyclic strain. Items considered include specimen design and surface finish, grip design and specimen assembly, extensometer design and operation, instrumentation, heating and temperature control, test operation, and failure interpretation and data reduction.
Thermal Fatigue Evaluation
Authors: Carden AE
Published: March 2009

A test method for performing uniaxial low cycle thermal fatigue tests on ductile metals is described. The test method is built around the Instron testing machine. Both temperature and crosshead extension are programmed and the test cycle can be designed for either tensile or compressive loading at the maximum temperature.

The test method is described for hollow, tubular, threaded-end specimens, resistance heating and compressed air cooling, linear heating and cooling rates, and air environment. The stress dependence of the thermal coefficient of expansion causes no special problem in the determination of the strain values.

A strain measuring system is described that eliminates the thermal component of strain from strain record. Employment of such a system allows a direct recording of load versus mechanical deformation. From these hysteresis loops the pertinent information of the cycle can be determined.
Relation of Strength and Toughness to Fine Structures in a Beta Titanium Alloy
Authors: Banerjee BR , Hauser JJ , Capenos JM
Published: March 2009

Although a great deal of mechanical properties data on titanium alloys have appeared in the literature, no attempt has been made to relate the fine structures in beta titanium alloys to strength and fracture toughness. Therefore, strength and fracture toughness properties of B-120VCA—obtained through a variety of thermal and thermomechanical treatments—were related to fine structures by transmission electron microscopy, electron fractography, etc. Effects of (1) prior solution-treating temperatures, (2) cold working after solution treating, and (3) cold working both before and after solution treating were evaluated in terms of strength and fracture toughness, and parallel fine structure studies. The double cold-work treatment, without aging, produced σt with a fracture toughness of 115 ksi√in. and may be promising for certain high-strength applications. Also short aging times produce unique combinations of strength and fracture toughness (σt ≈ 190 ksi, Kc ≈ 70 ksi√in. The kinetics of β→ α transformation were characterized and related to fracture toughness and strength properties. Precipitation of omega was suggested in the solution-annealed material during cooling to room temperature; further growth of this phase upon prolonged aging at 600 F was established. At 900 F, omega growth was limited, being replaced by alpha precipitation first in a discontinuous and later in a general dispersion.
Plane Strain Fracture Toughness and Mechanical Properties of 5Al-2.5Sn ELI and Commerical Titanium Alloys at Room and Cryogenic Temperatures
Authors: Carman CM , Katlin JM
Published: March 2009

An investigation was performed to determine the engineering properties and plane strain fracture toughness characteristics at cryogenic temperatures for ¼, ½, and 1-in.-thick plates of 5Al-2.5Sn ELI (extra low interstitial) and commercial grade titanium alloys. These results were then translated into design information data applicable to liquid-fueled rocket booster tanks for service at -320 and -423 F. The tensile properties of these materials were determined at room temperature, -110 F, -320 F, and -423 F using small round tension specimens. The plane strain fracture toughness was determined using an instrumented precracked bend specimen. The dimensions of these specimens were such that the criterion (crack length and specimen thickness are equal to 2.5 (KIc/σys)2) was met at testing temperatures of -320 and -423 F. These data may be considered valid values of plane strain fracture toughness. The commercial 5Al-2.5Sn titanium alloy gave values of KIc of approximately 25,000 and 24,000 psi √ in. at testing temperatures of -320 and -423 F, respectively. On the other hand, the 5Al-2.5Sn ELI titanium alloy gave values of KIc of 65,000 and 55,000 psi √in. at these testing temperatures, respectively. These data show a superiority of approximately 1.5 in terms of critical crack size for the ELI grade. The relative level of texture hardening in this material was estimated by measuring the R values of these plates. The predicted biaxial yield strength of tanks fabricated from this material was compared with experimental data.
Metallurgical and Mechanical Aspects of the Sea-Water Stress Corrosion of Titanium
Authors: Lane IR , Cavallaro JL
Published: March 2009

Results of concentrated investigations on the sea-water stress corrosion of titanium indicate that the behavior is dependent on certain mechanical factors and on the metallurgical structure. The mechanical factors include a requirement that localized plastic deformation induce the formation of a coarse slip step. A possible further requirement is that the slip step occurs under crevice conditions. Recent work on the titanium-aluminum system, including kinetics of reactions occurring in the system, add to the evidence that stress corrosion is associated with the presence of the coherent Ti3Al precipitate. The most effective method for control of stress corrosion in titanium alloys containing aluminum is inhibition of the formation of Ti3Al by control of composition and heat treatment.
The Influence of Composition and Heat Treatment on the Aqueous-Stress Corrosion of Titanium
Authors: Seagle SR , Seeley RR , Hall GS
Published: March 2009

Chemical composition and heat treatment were found to have an effect on the aqueous-stress corrosion of titanium. Aluminum contents greater than 5 per cent and oxygen contents greater than about 0.3 per cent caused appreciable sensitivity to stress corrosion. The additions of beta-isomorphous type alloying elements, such as molybdenum, were beneficial for titanium-aluminum alloys but showed no improvement for titanium-oxygen alloys. The amount of oxygen that could-be tolerated was reduced substantially by the addition of aluminum.

Heat-treatment effects were very pronounced and not similar for the alloy systems investigated. The heat-treatment temperature for maximum sensitivity to stress corrosion increased from 1000 F for Ti-6Al alloys to 1200 F for Ti-8Al alloys. This corresponds to about 150 F below the estimated Ti3Al transus. The stress-corrosion resistance of Ti-6Al-4V alloy was reduced as a result of long annealing times prior to exposure in the Ti3Al region. Long annealing times also promoted stress corrosion in titanium-oxygen alloys. Microscopic examination did not reveal significant changes with annealing time. This finding indicates the metallurgical factors affecting the stress corrosion resistance are related to submicroscopic changes.
Effects of Heat Treating Environmental Conditions on the Stress-Corrosion Cracking Resistance of Several Titanium Alloys
Authors: Howe DG , Goode RJ
Published: March 2009

The effects of heat treating environmental conditions on the stress-corrosion-cracking resistance of several titanium alloys have been studied. The alloys studied in this investigation were the Ti-8Al-1Mo-1V, Ti-7Al-1Mo-1V, Ti-6Al-4V, and Ti-7Al-2.5Mo alloys. Precracked cantilever type specimens were heat treated in either an inert atmosphere or in vacuum and tested in a 3.5 per cent salt water solution. A comparison of the stress intensity required for failure in salt water with that required for “dry” mechanical fracture indicates that all of these alloys become essentially insensitive to the aqueous environment when vacuum solution annealed and helium gas cooled. Similar heat treatments in argon or helium developed a wide range in level of stress-corrosion-cracking resistance for these alloys; the level was dependent upon the temperatures used. The environmental conditions associated with aging treatments at 1200F following the solution anneal appear to have little effect on the stress-corrosion-cracking resistance of these alloys. Comparison of the stress-corrosion-cracking data with hydrogen content before and after treatment indicates a close connection between stress-corrosion-cracking sensitivity and hydrogen content in the material even at very low hydrogen levels. These results suggest that hydrogen contained in the metal may play an important role in the stress-corrosion cracking process of titanium alloys.
Crevice Corrosion of Titanium
Authors: Jackson JD , Boyd WK
Published: March 2009

Crevice attack of titanium and its alloys has been observed in high-temperature chloride solutions, chlorine gas, and certain acid environments. In chloride solutions, the attack becomes more severe as concentration and temperature increase. For chlorine gas, water is found to be an effective inhibitor.
Lubricants and Wear Coatings for Titanium
Authors: Kostman SJ
Published: March 2009

Titanium has poor resistance to wear and galling and is among the most difficult of metals to lubricate. This condition is attributable to the nature of the adsorbed gas film on the metal's surface. Emphasis has been placed on modifying the surface to improve wear and lubrication properties. Liquid lubricants were found to have little effectiveness on untreated titanium, but solid lubricants such as molybdenum sulfide (MoS2) applied to properly roughened surfaces can give useful wear life. Chemical and electrochemical conversion coatings combined with mechanical or chemical roughening provide the optimum pretreatment for bonding solid lubricants to titanium. Surface hardening processes such as nitriding and oxidizing produce wear resistant surfaces which may be lubricated by standard liquid lubricants, even at high loads. Platings of chromium or nickel on titanium are promising from the standpoint of wear resistance, but poor adhesion limits their usefulness. The most practical treatments for improving the wear resistance of titanium involve spraying of metallic or ceramic compounds such as molybdenum, titanium oxide, chromium oxide, and tungsten carbide.
Surface Treatment of Ti-6Al-4V for Impact-Fatigue and Wear Resistance
Authors: Weltzin RD , Koves G
Published: March 2009

Tests have shown that the Ti-6Al-4V alloy performs best under impact-fatigue loading conditions. This type of test best simulated actual loading conditions in many components in electro-mechanical devices. While the desired impact-fatigue performance is obtained with Ti-6Al-4V, the tendency of the alloy to gall and seize in wear indicated the desirability of some means of surface treatment for improved wear resistance. The combination of improved or unimpaired fatigue performance, along with improved wear, are not necessarily complementary results of surface treatment. Three basic types of surface treatments were investigated: (1) nonmetallic compound or gaseous diffusion coatings, (2) intermetallic-compound coatings, and (3) diffused metal coatings. After eliminating a number of surface treatments on the basis of hardness testing and microstructural examination, the following were selected for impact-fatigue and wear testing: (1) nitriding, (2) heat treatable titanium-chromium alloy layer, (3) heat treatable titanium-chromium alloy layer plus nitriding, and (4) oxygen-saturated alpha-titanium layer. The impact-fatigue testing showed that it is possible to obtain a surface treatment which results in improved fatigue life of Ti-6Al-4V. The results of all impact-fatigue testing will be presented, along with a discussion of subsequent wear testing of each surface treatment.