bluuebunny/crossref_metadata_2025_split huggingface dataset:
Finite Element Analysis of Biaxial Stress Test Specimen for Graphite/Epoxy and Glass Fabric/Epoxy Composites
Authors: Marloff RH 
Published: March 2009

Finite element analyses of a diametrally loaded circular test specimen proposed for biaxial stress testing of composite materials are described. Two orthotropic material systems were investigated: unidirectional graphite/epoxy and glass/epoxy woven fabric. For the former, the stress distributions in the gage section were obtained for various loading angles. In general, the stresses did not agree with the uniform stress assumption based on force equilibrium except for the case corresponding to pure shear. Probable failure locations on the specimen boundary rather than in the gage section were identified for all loading angles by using a tensor polynomial failure criterion. Test results for the pure shear loading case confirmed the predicted failure location. Two geometry modifications were investigated as to their effect on this failure location. One of these, consisting of the removal of the small radius at the end of the gage section, warrants further investigation.
Examination of the E-glass/epoxy woven fabric material for the pure shear loading case showed a more uniform stress state in the gage section and the absence of a potential failure point on the boundary. Thus the test specimen shows promise for the determination of shear properties for such materials.
Stiffness Reduction as an Indicator of Damage in Graphite/Epoxy Laminates
Authors: Camponeschi ET , Stinchcomb WW 
Published: March 2009

Changes in the stiffness of graphite epoxy laminates were experimentally investigated as indicators of fatigue damage. Five laminate orientations were considered: [0]4, [90]4, [±45]8, [0.90]8, [0.90,±45]8, and four inplane stiffness properties were monitored for each. The stiffness components were Exx, Eyy, Gxy, and , and vxy and were measured using a longitudinal tension test, a rail shear test, and a transverse bend test. Nondestructive testing techniques such as C-scan and edge replication were also performed to aid in the observation of damage development.
Results describe the response of each laminate orientation in tension-tension fatigue, including a record of changes in the stiffness properties at intervals during fatigue.
Longitudinal stiffness (Exx) and shear stiffness (Gxy) were shown to significantly decrease for the [0.90,±45]8 laminate following fatigue loading. The inplane stiffness properties for the other four laminates remain essentially unchanged following fatigue loading. Matrix cracking and delamination appear to contribute to the stiffness reductions that occur in the [0.90,±45]8 laminate, although the damage state and attendant stifness changes are not simple functions of the response of the constituent laminae.
Influence of Frequency and Environmental Conditions on Dynamic Behavior of Graphite/Epoxy Composites
Authors: Putter S , Buchanan DL , Rehfield LW 
Published: March 2009

The purpose of this research is to experimentally determine the combined influence of frequency and environmental conditions on dynamic behavior of graphite/epoxy composites. The new additions to the data base on dynamic behavior facilitate confident use of these composites in applications.
This objective has been accomplished by performing flexural vibration tests on graphite/epoxy beams. Dynamic behavior in the dry room-temperature state of 25°C (77°F) is contrasted with four elevated-temperature states: (1) 82°C (180°F), dry; (2) 60°C (140°F), moisture saturated; (3) 82°C (180°F), moisture saturated; and (4) 93°C (200°F), moisture saturated. The properties determined are an effective flexural modulus and damping for frequencies from 10 to 1000 Hz. Specimens are of four distinct ply layups manufactured from Narmco 5208/T300 unidirectional tape.
Overall, the modulus and damping results indicate that frequency effects are quite small in all cases. They are a bit greater for matrix-controlled modes of response at the higher frequencies. At the same temperature, damping increases with moisture saturation. For dry specimens, however, damping decreases with temperature.
Long-Life Damage Tolerant Jet Transport Structures
Authors: Goranson UG , Hall J , Maclin JR , Watanabe RT 
Published: March 2009

Criteria and procedures used in commercial aircraft design over the last two decades have produced long-life damage tolerant structures with a credible safety record. This has been achieved through diligent attention to detail design, manufacturing, maintenance, and inspection procedures. Recent updates of federal regulations governing fatigue and fail-safe strength evaluation of transport category airplane structures and advancements in the capability to analyze damaged structure have spurred new technological developments. Adaptation of traditional fatigue and fracture mechanics technologies plus a large test and service experience data base have led to development of technology control methods suitable for nonspecialist engineers.
Detection of damage before it becomes dangerous is the ultimate control in ensuring damage tolerance throughout the economic service life of the structure. Traditional damage growth and residual strength evaluations fail to incorporate damage detection parameters which influence maintenance planning. New technology is under development for proper recognition of damage detection opportunities in a fleet of aircraft with possible multiple cracking events and subjected to a multitude of inspections. Emerging damage tolerance rating systems provide efficient measurements of inspection activities and permit coordinated manufacturer/operator/certifying agency actions necessary to ensure continued structural airworthiness of existing and future jet transport fleets.
Geotechnical Properties of Two Calcareous Oozes
Authors: Valent PJ , Altschaeffl AG , Lee HJ 
Published: March 2009

The geotechnical properties of two deep-sea calcareous oozes are discussed. The first ooze, a clayey silt with 56 to 75 percent calcium carbonate, was subjected to laboratory vane shear, one-dimensional compression, and triaxial shear testing. The void ratio-log pressure relationship obtained from one-dimensional compression tests, for a pressure increment ratio of 1, was found to be continuously plunging, a curve form possibly characteristic of the calcareous oozes. The failure envelope determined from triaxial shear tests defined a decreasing effective friction angle with increasing confining stress (34 deg, decreasing to 28 deg). Efforts toward establishing a connection between these phenomena and grain crushing in the sediment at engineering loads were not conclusive.
The second ooze, a fine sand-silt with 77 to 86 percent calcium carbonate, was tested both in-place (vane shear) and in the laboratory (vane shear and triaxial). In-place vane strengths are quite high, 10 to 30 kPa (1.5 to 4.5 psi), while laboratory vane strengths are near zero. The ooze exhibits high in-place vane strength sensitivities (5 to 10).
Heat-Transfer Model for Fibrous Insulations
Authors: Bhattacharyya RK 
Published: March 2009

A model has been developed that describes the insulation property of fibrous insulation. The assumptions necessary for the derivation and possible limitations are discussed.
Analysis of the model shows the effect of mean temperature and the effect of the insulation thickness on the effective thermal conductivity. The model provides a convenient way of predicting the thermal resistance at full thickness. Implementation of the technique, however, requires further tests with standardized equipment.
Further extensions of the model and modifications of the standard measuring techniques of the standard calibration specimen have been outlined. Areas requiring further research are indicated.
Use of Low-Cycle Fatigue Data for Pressure Vessel Design
Authors: Lawton CW 
Published: March 2009

Pressure vessels are usually designed for only a few thousand stress cycles and seldom for more than 105 cycles. For fatigue analysis to be practical for most of the ASME Code applications, a concept has been developed different from the practice used in machine design for high-cycle fatigue in rotating machinery. The concept uses fatigue design curves developed for the different materials. The curves account for most of the factors that reduce fatigue life as shown by a comparison with fatigue data generated with laboratory specimens. Because most pressure vessels are of welded fabrication, the fatigue design curves have full corrections for tensile mean stress in the applicable region to account for tensile residual stresses. For corrosive conditions, the fatigue design curves may require further corrections. A modified concept of strain range partitioning has been developed for the analysis of the creep and fatigue interaction for high-temperature design. The concept uses the strain difference range to calculate creep and fatigue damage, which is similar to the shear stress failure used in lower temperature design.
The use of the fatigue design curves is demonstrated with the evaluation for fatigue life of two fossil-fuel boiler components. One of these components illustrates the difference in use of the fatigue design curves when creep is a further consideration.
Atmospheric Corrosion of Copper Alloys Exposed for 15 to 20 Years
Authors: Costas LP 
Published: March 2009

Copper alloys were exposed for 15 to 20 years at two marine, one industrial, and one rural location. Based on average corrosion rates for 13 alloys, the industrial corrosion rate was 1.4 µm/year whereas the rate for the other sites was approximately 0.7 µm/year. As expected, alloying agents affected the corrosion rates by a factor of 2 to 3.
General attack was the predominant form of corrosion. Dezincification was positively identified in C260 alloy and intergranular attack was noted in C642. Pitting was not a factor for any alloy.
Atmospheric Corrosion Test Results for Metallic-Coated Steel Panels Exposed in 1960
Authors: Tonini DE 
Published: March 2009

Results of an ASTM-sponsored 20-year exposure of corrugated metallic-coated steel panels at five locations in the United States are reported. A total of 19 panels was placed at each exposure site, including at least one specimen from each of six types of continuous galvanizing lines in use when the test was initiated, five sheets galvanized using equipment similar to that used to prepare specimens for a similar test series initiated in 1926, one panel coated with pure aluminum, one panel coated with an aluminum-silicon alloy, and one panel coated with terne metal.
The analysis of the galvanized coatings data suggests the presence of nonlinear effects in the performance of the coatings. However, it was not possible to establish whether these effects were the result of nonlinearities in the coating performance itself or if they were the consequence of uncontrollable external factors which occurred during the exposure period.
The aluminized sheets were found to be essentially without failure at all test locations. In general, coating degradation beyond minor pinholing was not found.
The terne-coated sheets evidenced early rusting at all except the most aggressive of the test sites. Despite nearly total coating depletion, none of the test sheets have perforated.
Corrosion Performance of Decorative Electrodeposited Nickel and Nickel-Iron Alloy Coatings
Authors: DiBari GA , Hawks G , Baker EA 
Published: March 2009

The corrosion performance of chromium-electroplated, decorative nickel and nickel-iron alloy electrodeposits has been studied in marine and industrial atmospheres and by means of copper-accelerated acetic acid-salt spray testing (CASS). Decorative nickel coatings, 15 and 30 μm thick, gave better overall corrosion performance than comparable decorative nickel-iron alloy coatings. Because of the rapid staining that occurs in marine and industrial atmospheres, nickel-iron alloy deposits are not suitable for decorative applications involving moderate and severe corrosion service. Decorative nickel-iron alloy deposits, 7.6 µm thick, appear suitable for mild corrosion service on the basis of CASS test results, but results were affected by iron content and type of electrodeposited chromium. The relatively good performance of thin alloy deposits accounts for established applications in mildly corrosive environments.
The performance of the decorative electrodeposited nickel coatings was influenced by the activity of bright nickel. Low-activity single-layer bright nickel (15 μm) performed better than high-activity bright nickel when used with microporous or microcracked chromium. High-activity double-layer nickel (30 µm) protected low-current-density areas of contoured steel panels better than low-activity double-layer nickel, either with microporous or microcracked chromium. Microporous chromium was more effective in this program; microcracked chromium was more effective in a previous study.
Calibration of Atmospheric Corrosion Test Sites
Authors: Baker EA , Lee TS 
Published: March 2009

Inherent in the ability to accurately assess the performance of a material exposed in the atmosphere is an understanding of the relative corrosivity of that environment. The most reliable of present test methods for ranking materials' corrosion behavior have necessarily utilized long-term exposures to the natural environment in question. Given the variable nature of many atmospheric factors, it becomes important to determine the relative stability in the corrosivity of an atmospheric exposure site. Only in this way can the desired credence be given to atmospheric corrosion data generated for a variety of materials over an extended duration.
A review is provided of the major factors which must be considered in establishing a program to monitor and calibrate an atmospheric test site. These factors include both environmental assessments and corrosion evaluations. Consideration is given to the specific environmental parameters which could be monitored as well as experimental procedures which affect the atmospheric corrosion behavior of materials.
Reproducbility of Electrochemical Measurements of Atmospheric Corrosion Phenomena
Authors: Mansfeld F , Tsai S , Jeanjaquet S , Meyer E , Fertig K , Ogden C 
Published: March 2009

A brief discussion is given of recent efforts to use electrochemical techniques for monitoring of atmospheric corrosion phenomena. Problems existing with the interpretation of time-of-wetness measurements are identified, and the finding that electrochemical sensors in their present design and application determine only fractions of the true corrosion rate is discussed. In order to resolve some of these difficulties, a statistically designed experiment is being carried out to evaluate the reproducibility of electrochemical measurements of atmospheric corrosion phenomena and to determine the effects of sensor design on time-of-wetness and cell efficiency. Results are presented for the first phase of this project, in which 15 atmospheric corrosion monitors (ACM) of the copper/steel and 15 ACM's of the steel/steel type, have been fabricated with steel and copper from three different heats. These ACM's have been tested in triplicate runs by exposure to aqueous 1-mM sodium chloride at a relative humidity of 45 percent until the surface had dried out, followed by additional exposure to either a moist air environment at three levels of relative humidity (65, 80 and 95 percent) or a sodium dioxide (SO2) test at three levels of SO2 ≈ 0, 0.2, and 1.1 ppm. During each test, steel plates from each heat were exposed to determine weight loss data. At present, only the drying-out data have been analyzed by statistical methods. It has been found both from electrochemical and weight loss data that the heat of the steel plays an important role, with one heat corroding at a higher rate than the other two which have equal corrosion rates. No differences were found between the five sensors of one heat. Additional factors that influence the measurement are day-to-day variations of the environment in the test chamber and to some extent the position of the ACM's in the test chamber. By comparing the electrochemical and weight loss data, a cell efficiency of about 20 percent was found for copper/steel and about 7 percent for steel/steel. This low cell factor is considered to be due mainly to local cell action on individual plates and to uncompensated ohmic drop in the electrolyte.
The copper/steel and steel/steel ACM's are being exposed on the Rockwell International Science Center roof for an aging period of three months, after which another series of laboratory tests will be conducted.
Effect of Atmospheric Pollutant Gases on the Formation of Corrosive Condensate on Aluminum
Authors: Byrne SC , Miller AC 
Published: March 2009

As part of a program to develop predictive methods to estimate the long-term durability of aluminum parts, a methodology was developed to calculate the chemical composition of condensates formed on aluminum exposed to polluted air.
In this study, it is proposed that the maximum concentrations of ionic species in a condensate must be limited by the equilibrium condition established between the dissolved ions and the gases from which they formed.
Development of a Teflon Helix Continuous Liquid-Liquid Extraction Apparatus and Its Application for the Analysis of Organic Pollutants in Drinking Water
Authors: Yohe TL , Suffet IH , Grochowski RJ 
Published: March 2009

A continuous liquid-liquid extractor (CLLE) applicable for isolation and enrichment of trace organic constituents found in drinking water is described. The CLLE is automated for unattended operation and accomplishes the mixing, separation, and solvent recovery operations sequentially. Solvent recycle is employed to minimize solvent usage. The optimization procedures and evaluative criteria for the CLLE are presented along with two specific examples of drinking water applications.
The variability of the final evaporation step for highly volatile organics limits the use of this system for quantification of “low boilers”; however, purge and trap analyses can be utilized to quantify these compounds.
Response of Infrared Transmitting Materials to High-Velocity Impact by Water Drops
Authors: Hackworth JV , Kocher LH , Snell IC 
Published: March 2009

An experimental and analytical program was performed to investigate the response of zinc selenide, zinc sulfide, and gallium arsenide to water drop impact. The experiments consisted of single-drop impact (0.7, 2.0, and 2.5-mm-diameter drops and impact velocities of 222 and 341 m/s); overlapping drop impacts (2.0-mm drops at 222 m/s); and exposure at 222 m/s to the standard rainfield (1.8-mm drops, 2.54-cm/h rainfall rate). An analytical model was used to compute stresses induced in the materials by a single water drop impact.
Within the conditions tested, each single-drop impact produced a ring fracture pattern characteristic of the material. Resistance to damage increased in the order zinc selenide, gallium arsenide, and zinc sulfide. The superior performance of zinc sulfide with respect to zinc selenide is attributed to the order-of-magnitude smaller grain size of zinc sulfide. Comparison with experimental results showed the analytical model to be a reasonable representation of the drop impact process.
The rainfield test of zinc sulfide showed that transmittance loss at short wavelengths (0.5 to 2.1 μm) was linear with exposure time, indicating a dependence on the extent of subsurface damage. At wavelengths above 2.5 μm, there was an incubation period before loss of transmittance. The end of the incubation period and the start of transmittance loss were associated with the nucleation of surface pits.
Influence of Crystal Structure on the Failure Mode of Metals by Cavitation Erosion
Authors: Preece CM , Vaidya S , Dakshinamoorthy S 
Published: March 2009

The cavitation-induced deformation and erosion of metals of the three common crystal structures, face centered cubic, body centered cubic, and hexagonal close packed (fcc, bcc, hcp), have been investigated. It is shown that the shock-loading conditions encountered by the metal during cavitation enhances the effects of different deformation modes and strain-rate sensitivity arising from differences in crystal structure. This, in turn, results in a complex crystal orientation and grain size dependence of erosion rates.
These factors, which are highlighted under cavitation conditions and minimized under quasi-static loading, are considered responsible for the lack of any correlation between erosion rates and conventional mechanical properties such as strength and hardness.
Influence of Test Paraments in Vibratory Cavitation Erosion Tests
Authors: Matsumura M 
Published: March 2009

A series of tests on iron and steel in a water tunnel system, which simulated field conditions quite closely, showed that each material has its own process of erosion, and that in general the fracture of metals by cavitation turns from ductile to brittle with the lapse of testing time.
Fractures of iron and steel in the vibratory method turned, as in the water tunnel, from ductile to brittle. It was found also that the ductile-brittle transition is decisively influenced by experimental parameters such as temperature of the test liquid, frequency of the vibration, and corrosiveness of the test liquid.
Based on these experimental results, it was concluded that, in the vibratory test, the process of damage of a material can be changed to a great extent by choosing appropriate conditions of the test.
Low-Cycle Fatigue Damage Mechanisms at High Temperature
Authors: Sidey D , Coffin LF 
Published: March 2009

Observed effects of wave shape on low-cycle fatigue resistance and on concomitant fracture appearance at elevated temperature are summarized. Additionally, previously unreported tests on oxygen-free high conductivity (OFHC) copper at 673 K, as well as available published results, are examined using unequal strain rates to produce the wave shape. For OFHC copper, the fatigue lifetimes decreased by an order of magnitude as the tensile-going strain rate was reduced from 1.7 × 10 -3 s -1 to 1.7 × 10 -5 s -1 with a constant cyclic period. Accompanying this reduction in lifetime, the fracture mode changed from a transgranular fracture for the fast-slow wave shape to an intergranular single-crack fracture for equal ramp rates to interior cavitation for the slow-fast test.
Based on these findings and related work of other investigators, a qualitative model is presented to predict the ranking in fatigue resistance and in fracture mode as a function of wave shape and environment, for a given temperature, strain range and overall frequency. Essential features of this model include the assumption of grain boundary cavity size variability depending on the magnitudes of the tensile-going and compressive-going strain rates of the hysteresis loop and recognition of the important role of environment in degrading life and affecting fracture mode, especially when tensile- and compressive-going strain rates are equal.
Factors Affecting the Design and Implementation of a Workable Community Noise Ordinance
Authors: Gatley WS 
Published: March 2009

Municipal governments have the power to restrict the operation and use of many noise sources within their areas of jurisdiction. The success of programs to regulate community noise depends upon a number of factors: (a) identification of major noise sources; (b) training of personnel; (c) funding available for implementation and continued enforcement; (d) success in overcoming legal challenges; and (e) education of and support from the public.
This paper summarizes the types of noise legislation available to communities and describes their primary features. Design of effective and enforceable noise regulations for smaller communities with limited resources is emphasized. Methods for avoiding community noise problems, including prediction of noise levels, land-use planning, and zoning ordinances, are discussed briefly.