bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermal Expansion Characteristics of Graphite Reinforced Composite Materials
Authors: Freeman WT , Campbell MD 
Published: March 2009

The high modulus and negative thermal expansion coefficient of graphite filaments provide the potential for fabrication of laminated composites exhibiting negligible thermal sensitivity. Advanced satellite and space antenna applications requiring structurally efficient materials that are distortion free over a wide range of thermal gradients and local thermal conditions are now practical. The paper describes an investigation to determine the thermal expansion characteristics of graphite composites. Thermal strain measurements over a wide temperature range, -320 to 550 F(-196 to 288 C), were made by General Dynamics using a modified Leitz dilatometer. The feasibility of measuring thermal strains with strain gages is discussed.
Measurements of the longitudinal and transverse dilatation of five composite systems containing high modulus and high tensile strength graphite fibers in three different resin binders are reported. Moisture content was found to have a significant effect on thermal strain versus temperature hysteresis characteristics of both neat resins and composites. Moisture removal at high temperature was manifested as a shrinkage in the material length, and the thermal expansion coefficient remained constant over a given temperature range after sufficient drying. With the exception of unidirectional composites, the thermal coefficient increased nonlinearly with temperature. The practical aspects of stress relaxation effects and hysteresis characteristics on unidirectional laminates are discussed. Data obtained on quasi-isotropic laminates, 0/± 60 and 0/±45/90, indicate that low expansion coefficients are obtainable.
The Embedded Strain Gage Technique for Testing Boron/Epoxy Composites
Authors: Daniel IM , Mullineaux JL , Ahimaz FJ , Liber T 
Published: March 2009

An embedded strain gage technique for measuring subsurface strains in boron/epoxy composites was successfully developed and tested. Preliminary tests to establish the feasibility of the technique demonstrated that conventional foil gages do not produce local thickening of the specimen when a patch of scrim cloth is removed, do not change the average material properties, and do not reduce the strength of the specimen. The technique was used to determine surface and subsurface strains in three-, five-, and seven-ply boron/epoxy tension coupons of three different layups. In preparing these specimens an area of scrim cloth corresponding to the gage area was removed and the gages were laid down without any adhesive. Two- and three-element rosettes were used. Ribbon leads were soldered to the gages and taken out from the sides of the specimen. The assembled specimen with the embedded gages and leads was then cured in the autoclave, tabbed, and tested to failure.
Results are presented first in the form of stress-strain curves for each ply and then as strain variations through the thickness with applied stress as a parameter. Values of modulus, Poisson's ratio, and strength were obtained from these tests. Deviations of varying degrees were observed in the strain readings through the thickness. The diagonal (45-deg) strain deviations were higher than those of the transverse strains, which in turn were higher than those of the longitudinal strains. It was also observed that deviations tended to be smaller when the gages were oriented in the direction of the fibers than when they were oriented transverse to them.
A Fractographic Analysis of the Relationships Between Fracture Toughness and Surface Topography in Ultrahigh-Strength Steels
Authors: Spitzig WA , Pellissier GE , Beachem CD , Brothers AJ , Hill M , Warke WR 
Published: March 2009

Fracture surfaces of fatigue precracked, notched tension test specimens of experimental oil quenched and tempered (800 F)0.45C-Ni-Cr-Mo steels of different residual sulfur contents, and of two 18Ni maraging steels (250 and 300 grades) were investigated, using electron fractography, by a task group composed of various members of Subcommittee II on Fractography of ASTM Committee E-24 on Fracture Testing of Metals. Sulfur levels of 0.008, 0.016, 0.025, and 0.049 weight per cent in the 0.45C-Ni-Cr-Mo steels corresponded to fracture toughness values (K1c) of 65.3, 55.6, 51.0, and 42.8 ksi√in., respectively. The 250- and 300-grade maraging steels exhibited K1c values of 68 and 42 ksi√in., respectively. The investigation was carried out to determine whether the differences in fracture toughness could be related to changes in fracture surface topography.
The differences in fracture toughness among the quenched-and-tempered 0.45 carbon alloy steels of different residual sulfur contents could be accounted for by differences in the frequency (or spacing) of the sulfide inclusions. These particles seemed to have nucleated microvoids in advance of the crack tip, which coalesced and resulted in dimple rupture. The particle spacing in each steel was equivalent to a process zone size based on the Krafft model. A similar correlation was not found for the two grades of 18Ni maraging steel having different toughness levels, possibly because the mechanism of fracture is more complex than for the 0.45 carbon alloy steels. Another fractographic feature, namely, the extent of a “stretched” zone between the fatigue-cracked and overload regions of the fractures, did appear to show some correlation with the KIc levels for both classes of steels, and may be related to the size of the process or plastic zone at the crack tip. This feature, and its significance in terms of planestrain fracture toughness, is being more extensively investigated by Subcommittee II of E-24.
Environmental Effects on Fracture Morphology
Authors: Nielsen NA 
Published: March 2009

The utility of fractography can be greatly increased if the technique can be applied on a broader basis to provide unambiguous interpretation of fracture surface morphology (and thereby, identification of the fracture mode) resulting from specific environmental exposure of stressed metals and alloys.
This paper reviews the present status of electron fractography in this area of expanded application. High-strength steels, martensitic and austenitic alloys, and titanium and zirconium alloys are considered with respect to the effects chemical environment, including high energy irradiation, induces in the fracture characteristics of the alloys.
Effects of Hydrostatic Pressures on Electrolytic Hydrogen in Iron
Authors: Nanis L , DeLuccia JJ 
Published: March 2009

The permeation of hydrogen in iron under high hydrostatic pressures has been studied using an electrochemical source and sink for hydrogen in a pressurized cell. The drumhead arrangement of the electrochemical cell marks a breakthrough in techniques for the study of corrosion mechanisms under high pressures. Studies on pure iron at 21 C clearly indicate a positive deviation from Sieverts' square root relationship between pressure and hydrogen solubility.
Hydrogen solubility and diffusion coefficient in iron have been determined at pressures up to 8250 psig (18,400 ft depth) in an overall study of hydrogen embrittlement.
The nature of permeation and related electrochemical factors (cathodic overpotential) are considered in terms of anticipated deep submergence corrosion problems.
Effects of Marine Environment on High-Strength Steels
Authors: Wacker GA 
Published: March 2009

This investigation summarizes the general and stress-corrosion cracking behavior of several classes of high-strength steels in the marine environment. Eleven experimental heats of maraging steel were evaluated for resistance to stress-corrosion cracking in seawater. Those alloys containing 10 and 12 percent nickel were found to be susceptible to pitting attack and stress-corrosion cracking, while 18 percent nickel maraging steels were found to be highly resistant to pitting attack.
The corrosion characteristics of 5Ni-Cr-Mo-V HY-130 steel were also investigated in natural seawater. The stress corrosion threshold stress for HY-130 was determined utilizing the criteria of no failure after six months of exposure in natural seawater under sustained stress in the precracked cantilever test. A major portion of the investigative work was concentrated on answering the question of whether long-term continuous cathodic protection of HY-130 in natural seawater will lead to eventual problems associated with hydrogen embrittlement. Preliminary work utilized precracked cantilever specimens, which were precharged with hydrogen at several high-current density levels and then step loaded to failure while still being cathodically protected. Cathodic protection tests were also carried out utilizing two-point loaded bent-beam specimens stressed to 90 percent of the 0.2 percent yield strength which were cathodically protected at 13 and 130 mA/ft2 current densities for one year in low-velocity flowing seawater. The effect of cathodic protection on the low-cycle corrosion fatigue behavior of HY-130 was also determined.
Aluminum Alloys After Five Years in Seawater
Authors: Ailor WH 
Published: March 2009

Eight aluminum alloys and panels of high-purity aluminum were exposed for five years in seawater at Harbor Island, N. C. Replicate 4 by 12-in. panels of each material were exposed in half-tide immersion and full immersion. Removals in triplicate were made at the end of one-, two-, and five-year exposures.
Other than the 1199 aluminum (99.99 percent purity), seven aluminum-magnesium alloys (5000 series) and one aluminum-zinc-magnesium-copper alloy 7079 were tested. Panels were degreased prior to exposure and were cleaned ultrasonically in a chromic-phosphoric acid solution after exposure. After depth of pitting was measured, tension specimens were cut from each panel, and the ultimate tensile and yield strengths and elongations were determined. All panels were heavily fouled with barnacles and other marine growth for all exposure periods. The fouling apparently had some effect on the pitting depth of the aluminum in tidal immersion.
Little change in tensile properties after five-years' exposure was noted for the 1199, 5083-O, 5086-O, or 5454-H32. Tensile losses were recorded for several alloys as follows: 5086-H112 (4.8%), 5154-H38 (6.2%), and 5457-H34 (4.3%). The high-purity 1199 and alloys 5154-H38, 5086-H112, and 5456-H321 showed losses of 6 to 10 percent in elongation while the change in elongation for the 5457-H34 was a decrease of about 16 percent.
The 7079-T6, which can only be used in seawater when protected, had severe exfoliation corrosion. Confirming other work, we found the corrosion rates to be greater for the full-seawater immersion than for the tidal immersion. The lowest five-year corrosion rate in the half-tide location was 0.07 mdd (milligrams per square decimeter per day) for the 5083-O, and the highest rate for the aluminum-magnesium 5000 series was 0.11 mdd for the 5454-H32 alloy. In full-immersion tests the lowest rate was 0.12. For comparison, the rates for the 7079-T6 alloy were 0.79 mdd in tidal and 3.4 mdd in full immersion. Corrosion weight losses and depth of pitting had reduced rates of growth over the interval between two years and five years. Maximum depth of pitting for an alloy was generally at least four times the magnitude of the average of the twenty deepest pits.
The deepest pit found for any alloy after five years was 33.0 mils for 5456-H321 in half-tide immersion and 38.0 mils for the same alloy in full immersion. Least pitting depth occurred in 5457-H34 (less than 4.5 mils for both exposures).
Analysis for Organic Pesticides in Aquatic Environments
Authors: Faust SD , Suffet IH 
Published: March 2009

The detection of organic pesticides in aquatic environments represents an unique analytical problem. It is unique in the context that specificity is required under extremely sensitive conditions as opposed to gross analysis for trace organics in water. First, there is the problem of pesticide identity. Second, direct measurement is not feasible because of sensitivity and specificity requirements. Extraction, concentration, and cleanup techniques must be employed prior to qualitative analysis and quantification. Third, natural waters may contain such organic interferences as aromatic and aliphatic compounds from industrial waste waters, and naturally occurring colored compounds. These impurities are often present in concentrations greater than the pesticide.
Two objectives are offered herein: (1) a brief critique of extraction, cleanup, identification, and quantification techniques is given in order to highlight limitations fallacies, and pitfalls, and (2) a model system for the recovery, separation, and confirmation of organophosphate pesticides, oxons, and their hydrolysis products. This model system provides the basic needs of pesticide methodology; namely, simplicity and minimum sample handling. The problems of recovery from water by liquid-liquid extraction, separation by gas-liquid chromatography, and subsequent confirmation by micro-ultraviolet absorption spectrophotometry are discussed.
Freeze Concentration of Microorganics in Water
Authors: Baker RA 
Published: March 2009

Organic contaminants at concentrations of parts per billion or less may modify water quality significantly. However, even the most sensitive of the available analytical procedures are not capable of quantitative identification at these trace levels. Thus, the organics must be concentrated prior to analyses. Freezing was evaluated as a concentration technique. As solute-containing aqueous solutions are frozen, the ice which crystallizes initially is very pure. The solutes are rejected into the unfrozen liquid. If the process is interrupted prior to complete solidification, the residual liquid will be considerably enriched.
Recovery of micrograms per liter and milligrams per liter concentrations of various organics from aqueous solutions was studied. In the absence of dissolved inorganic salts mixing rate is not a factor. Organic dissociation potential; molecular size and weight; and nature, location, and number of substituent groups have no effect. However, dissolved salts impair organic solute rejection and in this case higher mixing rates promote recovery. An interrelationship between total dissolved salt content, mixing rate, and efficiency of organic solute recovery was demonstrated. Most important, for the systems studied, it was shown that although complete organic recovery was not achieved, all components of complex mixtures were recovered with equal efficiency. Thus, an analytical procedure making use of additions of known organic materials to serve as internal standards is suggested.
Mechanics of Materials in Low Cycle Fatigue Testing
Authors: Raske DT , Morrow J 
Published: March 2009

The purpose of this paper is to outline a method for evaluating the low cycle fatigue resistance of a metal from the mechanics of materials viewpoint. This includes a discussion of the fatigue properties and the effect of repeated plastic straining on the mechanical properties of metals. The cyclic stress-strain curve is defined as the locus of tips of several stable hysteresis loops obtained at different cyclic strain ranges. An expression is presented for mathematically representing the locus of their tips, and a number of experimental methods are discussed for determining the stable cyclic stress-strain properties.
Experimental techniques for low cycle fatigue testing and methods of interpreting results are presented. The equations which relate the elastic and plastic components of cyclic strain amplitude to fatigue life are developed. A means of approximating the strain-life curve using these relations is presented.
Nonlinear Dynamic Response of Soft Clay
Authors: Krizek RJ , Franklin AG 
Published: March 2009

A series of approximately 40 controlled-deformation, torsional shear tests in sinusoidal oscillation was performed on a Georgia Kaolin clay at moisture contents ranging from slightly below to considerably above the liquid limit. The tests were done with a rotational viscometer using a cone-and-plate sample holder to provide reasonable homogeneity of strains and stresses. The results are expressed in terms of complex viscoelastic response parameters, and some aspects of the limitations and usefulness of viscoelastic relations to describe soil response are examined by (a) study of the strain dependence of the response parameters and (b) comparison of energy dissipation as calculated by viscoelastic relations with that measured directly from hysteresis loops.
The magnitude of the complex modulus was found to vary exponentially with the moisture content and to vary as the -1.3 power of the strain amplitude. The phase lag between stress and strain had no discernible dependence on the moisture content for moisture contents above the liquid limit, but was found to vary as the 0.4 power of the strain amplitude. Despite the marked nonlinearity of the material, the calculation of energy dissipation according to viscoelastic relations agrees comparatively well with the observed data.
Soil Studies for Seismic Design of San Francisco Transbay Tube
Authors: Aisiks EG , Tarshansky IW 
Published: March 2009

The Transbay Tube, currently under construction, is a 3.6 mile sunken tube railroad tunnel under San Francisco Bay between San Francisco and Oakland. The Tube traverses a stratum of nonuniform silty clay with pockets of sand, shell, and organic matter, known locally as San Francisco Bay Mud.
Earthquake resistant design requirements involved investigation of dynamic soil properties in order to: (1) evaluate potential loss of soil shear strength during an earthquake and (2) determine deformations and loads imposed on the Tube by ground deformations during earthquake.
The investigation included an underwater field seismic survey, installation of an earthquake sensing and recording system in the Bay sediments, and dynamic testing of undisturbed soil samples. The dynamic tests were triaxial compression tests under alternating strains and simple shear tests under confining pressure with alternating strains. Soil properties used in analysis were derived from experimental stress-strain curves of a hysteretic type and consisted of shear moduli and viscous damping coefficients. The soil properties established in this manner were used to estimate free-field responses and soil-structure interaction.
It was concluded that in these soils significant loss of strength will not occur under earthquake strains and durations. Stresses imposed on the Tube by ground deformation are not of significant magnitude. Differential movements between the Tube and the ventilation buildings at either end required provision of a special universal sliding joint.
Stress-Strain Behavior of Clays in Dynamic Compression
Authors: Yong RN , Japp RD 
Published: March 2009

Instability of earth structures and yielding and flow in soils due to earthquake loadings may be traced quite often to the problem of large displacements directly relatable to the resultant dynamic load condition occurring in the soil. This study examines the problem of large strain performance of clays under impulsive-type loadings, where the ultimate objective is to assess material behavior with a view to specification of pertinent and significant material parameters.
The formulation of a flow rule relying upon a base value at particular strains and strain-rates and additive strength performance is shown, and further study of the contribution to strength arising from increased strain-rates is examined. At the higher rates of sample straining, the significant increases in strength of the clay soils cannot be totally accounted for by linear extrapolations of rate effects and the contribution from coupled inertia terms. It is shown that these contributions, can be due to nonlinearity in rate effects at the higher end of the strain-rate spectrum, coupled with the formation of a quasi shock front. It appears that the rate of impulsive loading is higher than the ability of the specimen to deform plastically in the region adjacent to the loading front. Hence, a moving shock front is created and significant increases in strength are realized because of the change in material properties in the presence of this moving shock front.
In the problem of loading arising from impulsive mechanisms, instability in yield surfaces can be realized, and hence the problem of definition of a critical time-dependent yield surface as a function of strain-rate becomes apparent. This concept is also examined and discussed in this paper in relation to the previously described material characteristics.
Atmospheric Exposure of Nonferrous Metals and Alloys—Aluminum: Seven-Year Data
Authors: McGeary FL , Summerson TJ , Ailor WH 
Published: March 2009

This report describes the results of weathering tests on 34 wrought aluminum alloys exposed seven years at four ASTM sites in the United States. Also included, for comparison, are data on three additional aluminum alloys exposed six years at five sites in England.
The British industrial atmosphere exposures at Sheffield and London were found to produce the most corrosion, particularly on the sheltered sides of these panels which were exposed at an angle of 30 deg from the horizontal. The self-limiting corrosion characteristics were observed on weather surfaces at all test sites in both countries.
The test will be continued and again reported after twenty years, as was the case in a previous ASTM B-3 test (ASTM STP 175) on older aluminum alloys.
Copper and Copper Alloys
Authors: Mattsson E , Holm R 
Published: March 2009

In 1958 exposure tests were started in Sweden to gain knowledge of the natural patination and the corrosion behavior of copper and copper alloys when used outdoors. The investigation covered 36 alloys in sheet or rod form: 5 coppers, 20 brasses, 5 phosphor bronzes, 1 silicon bronze, 1 aluminum bronze, 1 cadmium bronze, 2 nickel-silvers, and 1 free-cutting phosphor bronze. Specimens were exposed in rural, marine, and urban atmospheres. After two- and seven-years' exposure, specimens were examined.
During the first years of atmospheric exposure the copper and copper alloys acquired a dark surface coating consisting mainly of copper oxide (Cu2O). In urban and marine atmospheres, signs of green patina appeared on copper after about six to seven years; the basic copper salt causing the green color being sulfate in the urban, chloride and sulfate in the marine atmosphere. The average penetration as calculated from the weight loss during 7-years' exposure was: in rural atmosphere 0.2 to 0.6 μm per year, in marine atmosphere 0.6 to 1.1 μm per year, in urban atmosphere 0.9 to 2.2 μm per year. The corrosion rate decreased with the time of exposure. The losses in mechanical properties were in most cases of negligible importance.
The dezincification of brass was of significant degree only in β-brass and in certain (α + β)-brasses when exposed to the urban or the marine atmosphere. Dezincification was observed also in α-brass, even with as high copper content as 92 per cent, although the depth of attack was not very great. It should also be mentioned that arsenic was consistently effective as a dezincification inhibitor for α-brass only in the marine atmosphere. This indicates that the mechanism of dezincification is different in the presence and in the absence of chloride.
The tests described here are continued and further examinations will be carried out after 20 years of exposure.