bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of Zircaloy Oxidation Films
Authors: Urquhart AW , Vermilyea DA
Published: March 2009

Capillary condensation measurements of the pore size distribution, transmission electron microscopy using ion micromilling to thin the oxide, and a–c impedance measurements in aqueous electrolytes have been used to obtain information on the porosity and grain structure of post-transition oxide films grown in oxygen at 600°C on Zircaloy-2. The results indicate that the films contain important amounts of very fine porosity which is interconnected to the exterior surface. The impedance measurements suggest the presence of a nonporous sublayer near the oxide-metal interface. The oxide has a fine columnar grain structure at some distance from the metal and an extremely fine structure or substructure near the oxide-metal interface.
Fracture of Zircaloy-2 in an Environment Containing Iodine
Authors: van der Schaaf B
Published: March 2009

Many Zircaloy cladding failures and the results of out-of-pile iodine stress corrosion tests are so similar as to suggest that fission of uranium produces enough iodine to attack the cladding locally. This paper presents a study of the effects of iodine on the fracture of Zircaloy-2 sheet being stressed very locally. Discs produced from Zircaloy-2 sheet were bent biaxially by pressing an indentor into the center of the disc. The force necessary to penetrate the discs decreased when either the initial amount of iodine or the temperature was increased, for cold-worked as well as recrystallized Zircaloy-2. Uniaxial short-time creep tests and tests with stressed slotted rings, both performed in environments containing iodine, did not result in stress corrosion cracking.

Microprobe analysis of the regions adjacent to cracks revealed deposition of iodine compounds on the walls of narrow cracks or near the crack tips. The propagation of the cracks in cold-worked material is affected by the manufacturing process of the sheet. The main conclusion of this investigation is that a high degree of local deformation is needed before biaxially stressed Zircaloy-2 suffers from stress corrosion by gaseous iodine.
Bureau of Reclamation Procedures for Conducting Uniaxial Jacking Tests
Authors: Misterek DL , Slebir EJ , Montgomery JS
Published: March 2009

The Bureau of Reclamation's present method of conducting uniaxial jacking tests incorporates the desirable features and techniques developed over many years of testing. Successful tests yielding usable data are attributed to thorough pre-test geologic exploration; careful site preparation; special drilling and explosive excavation techniques; and well-planned procedures for installation and removal of specialized equipment. Non-engineering factors, such as good contractor-test team relationship, also play a critical role in a successful test program. The process where hydraulic flatjacks are used to apply desired loads to prepared rock surfaces within a tunnel is described. Instrumentation to measure resulting displacement is referenced within the rock mass and is independent of the loading system. Details of all phases of conducting the tests are presented. In addition, a discussion is given of some of the problems, solutions, and philosophies that evolved while tests were being planned or conducted. This discussion is of value to those conducting in situ jacking tests or those preparing standards for the tests.
Weather Factors Affecting Corrosion of Metals
Authors: Sereda PJ
Published: March 2009

Various weather factors are assessed in relation to corrosion of metals. Published data are discussed and new results presented to show that time-of-wetness is a very important factor and that reasonable values may be obtained from analysis of meteorological records. These are applicable for predicting long-range corrosion effects. For short-term corrosion, data must be collected for the particular exposure conditions. Results are presented to show the effect of orientation on time-of wetness, and recommendations are made for increasing this type of study.

A summary of data on pollution by SO2 in major cities of Canada is presented and the distribution in Metro Toronto given. It indicates that pollution by SO2 has been decreasing in many areas of the world. The effects on corrosion of chlorides, corrosion products, and temperature are also discussed.
Selecting Testing Conditions Representative of the Atmospheric Environment
Authors: Stanners JF
Published: March 2009

The main environmental factors that affect atmospheric corrosion of metals are examined and their range and distribution are related to steel utilization. From the data available, recommendations are made for the selection of exposure sites in Great Britain likely to be more representative of conditions in which steel is used than are present sites. A method is suggested for examining pollution data in this context. The implications for natural atmospheric exposure testing are discussed.
Corrosion Aggressivity of Model Regions of Czechoslovakia
Authors: Knotková-Čermáková D , Bošek B , Vlčková J
Published: March 2009

A comprehensive research program was started in Czechoslovakia five years ago for a systematic investigation of the corrosion aggressivity of selected industrial regions. The corrosion tests were performed on 19 corrosion stations in the North-Bohemian model region. Principal technical metals were tested.

The characteristics of climate and air pollution and also the combined index of the corrosion aggressivity were suggested and numerically expressed.

The hyperbolic function has most closely approximated the law of the time-dependent course of the corrosion process of metals. The regression analysis was performed with the use of various forms of the climate characteristics, and the most favorable function was expressed.

The cybernetic model of the atmospheric corrosion process was suggested.
Technical Note: An Evaluation of Titanium Panels After Seven Years' Exposure in a Marine Atmosphere
Authors: Covington LC
Published: March 2009

An evaluation was made of test panels of four titanium alloys that were exposed to a marine atmosphere for seven years at Point Reyes, California as part of the ASTM B-3V1 1957 test program. No evidence of corrosion or significant change in physical properties was found. It was concluded that titanium is virtually immune to corrosion under most atmospheric exposure conditions.
Corrosion of Copper Alloys in Hydrospace
Authors: Reinhart FM
Published: March 2009

A total of 1050 specimens of 46 different copper alloys were exposed in the Pacific Ocean at two depths, 760 and 1830 m, for periods of time varying from 123 to 1064 days in order to determine the effects of deep-ocean environments on their corrosion resistance.

Most of the copper-base alloys corroded uniformly and their corrosion rates were low, 25 μm per year or less after one year at a depth of 760 m and after two years at a depth of 1830 m. A few of the alloys containing zinc, aluminum or silicon were attacked by parting corrosion. They were not susceptible to stress corrosion cracking. Only the mechanical properties of the alloys attacked by parting corrosion were adversely affected.

The aggressiveness of the seawater and of the bottom sediments on the copper alloys was about the same, except for the copper-nickel alloys, where the bottom sediments were less aggressive.
Galvanic Corrosion of Ferritic Stainless Steels in Seawater
Authors: Baboian R , Haynes GS
Published: March 2009

Galvanic behavior of stainless steels in seawater is difficult to predict because of their susceptibility to localized corrosion. This susceptibility can be either enhanced or eliminated depending on the particular galvanic couple.

This paper deals with seawater corrosion of several ferritic stainless steels in galvanic couples. Methods of predicting their behavior are described based on electrochemical polarization measurements, various laboratory tests, and actual immersion in seawater.

Results of electrochemical and laboratory tests are compared with those obtained in seawater. The validity of each of the test procedures is discussed with regard to alloy development and designing materials systems.
Relationship of Accelerated Test Methods for Exfoliation Resistance in 7XXX Series Aluminum Alloys with Exposure to a Seacoast Atmosphere
Authors: Lifka BW , Sprowls DO
Published: March 2009

Accelerated corrosion tests are necessary and an invaluable aid to research and quality control engineers, provided that the test has adequate discriminatory ability and the test results relate to serviceability of the metal. An inherent problem associated with accelerated exfoliation tests is the definition of different degrees of susceptibility and the interpretation of borderline performances. The concern in the present instance is that truly insignificant exfoliation tendencies may be magnified out of proportion by the very rapid exfoliation tests now being used in materials specifications for exfoliation resistant 7XXX-T7 alloy products.

Correlation of accelerated tests with service environments or the equivalent is necessary, and it is highly desirable that the range of performances observed in the accelerated test be related to a similar range of performances under service conditions. This paper contains the results of relatively long exposures of test panels to the salt atmosphere at a location about 100 yd from a stony beach at Point Judith, Rhode Island, where the corrosive conditions are representative of other very corrosive environments. These extended exposures are of particular interest because they furnish a basis of evaluating indications of borderline susceptibility to exfoliation revealed in the accelerated corrosion tests.

Four- to eight-year exposures to this aggressive seacoast atmosphere have demonstrated the excellent resistance to exfoliation of 7075-T73 and T76 and 7178-T76 products, whereas exfoliation susceptible T6 temper materials displayed considerable exfoliation after short exposures, sometimes after only three to six months. Both the EXCO immersion test (ASTM G 34-72) and the salt spray test (modified ASTM acetic acid salt intermittent spray) developed the same basic type of corrosion that occurred in the seacoast atmosphere. It was shown, however, that the accelerated tests, especially the spray test, tend to magnify slight indications of susceptibility to exfoliation that are of doubtful practical consequence. Suggestions are made for determining more realistic visual acceptance criteria in 7XXX-T7X materials specifications.
Effect of Alloy Composition on the Atmospheric Corrosion Behavior of Steels Based on a Statistical Analysis of the Larrabee-Coburn Data Set
Authors: Legault RA , Leckie HP
Published: March 2009

In 1962 C. P. Larrabee and S. K. Coburn published an extensive collection of atmospheric exposure data showing the effect of variations in copper, nickel, chromium, silicon, and phosphorus content on the corrosion resistance of low-alloy steel. Two hundred and seventy steel alloys of different composition were exposed for 15½ years at three separate locations representing industrial, semirural, and marine atmospheres. Among these experimental steel compositions there were five levels of copper concentration, two levels of nickel concentration, three levels of chromium concentration, three levels of silicon concentration, and three levels of phosphorus concentration represented. A statistical analysis of these data has been conducted and the results of the analysis are presented and discussed.
Dynamic Response and Fatigue Characteristics of Asphaltic Mixtures
Authors: Saraf CL , Majidzadeh K
Published: March 2009

This investigation deals with the influence of several mix variables in respect to asphaltic concrete on its fatigue response.

The investigation was based on a simple model representation comprising a beam supported on elastic foundation subjected to sinusoidal repeated loading, thus providing a two-dimensional simulation of actual pavement conditions under traffic loads. The dimensions of the beam were designed such that plan strain conditions prevailed during fatigue loading.

Fracture mechanics concepts using linear elastic theory were employed to analyze test data, including stress and deformation near the crack tip. It was also hypothesized that the parameter, A, in the rate-of-crack-growth equation, dc/dN = A K4 would adequately reflect the changes induced in the fatigue response of the mix by the selected mix variables.

The effect of mixture variables such as the amount of binder, density, aging, and viscosity on the parameter A is investigated.
Procedures and Problems Associated with Reliable Control of the Instrumented Impact Test
Authors: Ireland DR
Published: March 2009

The inherent characteristics of the instrumented impact test are discussed. The hammer energy is reduced by deforming the test specimen, accelerating the specimen from rest, Brinell-type deformation at the load points, vibrations of the hammer assembly, and elastic deformation within the machine. The limitations of the electronic components can affect the test results. The superimposed oscillations on the apparent load-time signal derived from the instrumented tup are best controlled by varying the initial impact velocity. Dynamic load cells must be calibrated by dynamic loading and then be checked by comparisons of dynamic and static test results for a strain-rate insensitive material. The analysis of instrumented tup signals for determination of various energy, deflection, and load values must be done with a clear understanding of dissolution of hammer energy, electronic limitations, and superimposed oscillations.
An Analysis of Charpy Impact Testing as Applied to Cemented Carbide
Authors: Lueth RC
Published: March 2009

In an effort to better understand the nature and the limitations of impact testing, the Charpy impact test was studied in detail via instrumentation of both the tester and the specimen. It was found that the energy associated with the impact testing of cemented carbide consists mainly of elastic bending energy and absorption of energy by the testing machine. The vibrational and plastic components are insignificant. The toss energy and energy necessary to create new surfaces can be fairly well calculated from other considerations. The tests have shown no rate effects in cemented carbides, and the state of stress in the beam is uniaxial tension. Thus the test does not describe the material's propensity for cleavage or brittle failure, but rather describes mainly the modulus and strength of cemented carbides (which are routinely and more easily measured in other ways), and the stiffness of the testing machine—all of which have very little bearing on the toughness of the cemented carbide. The components which describe this are the energy of plastic work and the energy necessary to create two new surfaces, and these consist of only a few percent of the total measured energy. The amount of energy which the machine absorbs will vary with the modulus and strength of the material being tested. In the case of a hard low-strength grade like Carboloy Grade 320, the anvil sees very little load before failure and thus the energy partitioning will be significantly different than that for a stronger grade.

The Charpy test conducted with the conditions in this study has little value in ascertaining the toughness of cemented carbide; in fact, results from it may be misleading. When cemented carbide is evaluated for toughness by impact testing of any kind, careful attention must be given to the aforementioned factors because they are encountered to a large extent in most, if not all, types of impact tests. Charpy impact-type tests on cemented carbide are essentially fast transverse-rupture strength tests on a “soft” test machine.
Cavitation Erosion—Corrosion Modeling
Authors: McGuinness T , Thiruvengadam A
Published: March 2009

Due to the increased occurrence of cavitation erosion in hydrodynamic systems operating in an ocean environment, there is a need to study the role of corrosion on the process of cavitation erosion. Previously, for noncorrosive systems, correlation of experimental data with the theory of erosion resulted in a time-scale modeling law of erosion. The changes in this scaling law due to corrosion were then investigated. A high-frequency, 20 kHz, piezoelectric vibratory apparatus was employed to generate erosion time history data for HY-130, HY-80, SAE 1020 steels, and Al 5086 H117 at several different erosion intensities in sea and distilled water. Results indicated that the relative erosion rate curves for materials susceptible to corrosion were different, and that the changes due to corrosivity increased with increasing erosion intensities. By coupling changes in corrosivity with maximum erosion rate increases, and times to the maximum rates, it is possible to make prototype performance predictions for either seawater or distilled water conditions. Qualitative relationships were found between the relative erosion rates and galvanic potentials of tested materials. A mechanism was proposed to account for the corrosive influence on erosion based on hydrogen-generated micropit destruction of a material surface that accelerates cavitation erosion.
Cavitation-Induced Deformation of Aluminum
Authors: Vyas B , Preece CM
Published: March 2009

A metallographic study has been made of the damage produced in pure aluminum by cavitation at ultrasonic frequencies. Scanning electron microscopy and transmission electron microscopy of eroded specimens indicate that the extensive slip steps and massive undulations produced on the surface result from shock deformation. It is proposed that shock loading is caused by the pressure pulse of a cloud of cavities collapsing in concert. It is apparent that fatigue (in the conventional metallurgical sense), corrosion, or localized melting cannot be considered responsible for the observed cavitation damage.
A Model for Rain Erosion of Homogeneous Materials
Authors: Springer GS , Baxil CB
Published: March 2009

In this report the behavior of homogeneous materials subjected to repeated impingements of liquid droplets was investigated. Based on fatigue theorems, a model was presented for describing both the incubation period ni (that is, the time elapsed before the mass loss of the material becomes appreciable), and the mass loss past the incubation period m. The parameters were established which govern the length of the incubation period and the subsequent mass loss rate, and simple algebraic expressions were developed relating ni and m to the properties of the impinging droplets and the material. The limits of applicability of the model was also established.

The results obtained were compared to available experimental data. Reasonable agreement was found between the present results and the data, indicating that the model developed can be used to estimate the incubation period and the mass loss of the material.
Effects of Fatigue and Dynamic Recovery on Rain Erosion
Authors: Conn AF , Rudy SL
Published: March 2009

The latest results from a study of the dynamic behavior of rain erosion-resistant coating and substrate materials are described. The correlations between rocket sled erosion data and fracture stresses determined from single-impact tests with a split Hopkinson pressure bar facility have been extended to include polyurethane. The results of tests within a small-scale erosion facility, and analyses of large whirling-arm studies, have shown that a fatigue type of behavior, already found to be applicable for an acrylic plastic, may also be used to describe the rain erosion resistance of elastomeric coatings such as polyurethane, and the glass fiber-reinforced epoxy composite substrates which are frequently utilized for radome construction. The importance of the “dynamic recovery rate” or relaxation time, and stress wave interactions, in understanding the rain erosion phenomenon is described in this paper. The applicability of the elastic-plastic, uniaxial stress wave theory for making rain erosion predictions is also discussed.
Wear Characteristics of Modified Plasma-Deposited Aluminum Bronze
Authors: Tucker RC
Published: March 2009

Plasma-deposited aluminum bronze coatings (Cu-10 Al) have been shown to be superior to wrought aluminum bronze (AMS 4640) when mated against steel with a hydraulic oil lubricant. In this study a series of compositional changes of the plasma-deposited aluminum bronze resulted in another order-of-magnitude reduction in wear rate. This was achieved without an increase in the hardness of the material so the embeddability and conformability of the materials were not degraded. The coefficients of friction of the plasma-deposited materials were much lower than their wrought counterpart, but there was little further change in the coefficients as a function of compositional changes in the plasma-deposited materials.

The coating parameters and compositional studies were based on unidirectional wear tests with the Dow Corning Alpha Wear Test Machine LFW-1 using hydraulic fluid Mil H5606A at loads from 30 to 450 lb at constant speed. The wear scars and debris were examined using scanning electron microscopy and microprobe analyses, and these observations correlated with the microstructures of the deposits. Differences between the various plasma deposits were correlated with microstructural and compositional variations.
Acoustic Emission in the Frequency Domain
Authors: Graham LJ , Alers GA
Published: March 2009

A means for quickly and easily determining the broadband frequency content of acoustic bursts as short as 20 μs in duration has been developed using a video tape recorder and a standard spectrum analyzer. It is shown by examples from several tests on laboratory specimens and on large structures that the frequency content of an acoustic burst is related to the mechanism which produced it and is not affected substantially by the specimen size or by mode conversion due to multiple reflections in the structure. The frequency content of the burst can be changed in two ways, however: by the frequency-dependent attenuation of the propagation medium and in the cases where the medium is dispersive. Results of measurements on the effect of these factors in a variety of structures are given. Although acoustic emissions from many materials tend to be “white noise,” several examples of acoustic emissions and extraneous background noise bursts having distinctive frequency spectra are given which suggest possibilities for discriminating true acoustic emission signals from background noise on the basis of frequency content alone.
Evaluating the Stability of Geologic Structures Using Acoustic Emission
Authors: Hardy HR
Published: March 2009

This paper describes the application of acoustic emission to the study of geologic structures. Evaluation of the overall mechanical stability of large-scale geologic structures such as underground and open-pit mines, highway and waterway cuts, petroleum reservoirs, and underground gas storage reservoirs is extremely complex. Acoustic emission appears to be one of the most suitable techniques available for such purposes.

A brief review of the associated literature is presented along with a description of a mobile monitoring facility developed by the writer for field use. Two current field projects, associated with underground gas storage and longwall coal mining, presently underway by the writer are described.
Industrial Use of Acoustic Emission for Nondestructive Testing
Authors: Drouillard TF , Liptai RG , Tatro CA
Published: March 2009

The industrial use of acoustic emission is presented. Emphasis is given to the characteristics of acoustic emission as a unique nondestructive testing method for use in the evaluation of the structural integrity of materials, components, and engineering structures. Several applications of acoustic emission testing are discussed.
Industrial Application of Acoustic Emission Analysis Technology
Authors: Parry DL
Published: March 2009

Acoustic emission analysis technology as a nondestructive testing tool is being applied in industry to a wide variety of structures. Its acceptance, however, has been more rapid in industries where it is applied to metallic pressure containment structures. These applications include pipelines, piping systems, storage vessels, pressure vessels, and even complex pressure containments such as the primary coolant systems of large nuclear power plants.

The application techniques used and a description of typical results obtained during field applications provides additional insight into a new powerful testing tool that is rapidly gaining acceptance throughout the industry.
Establishing Structural Integrity Using Acoustic Emission
Authors: Morais CF , Green AT
Published: March 2009

Acoustic emission techniques have advanced from laboratory use to applications such as establishing the quality of pressure containment and many other structures. The authors discuss the statistical relationship between acoustic emission data and the structural integrity of a series of production pressure vessels. In this application, acoustic emission data obtained from the first 25 percent of a required hydroproof test determined the bursting strength of the vessel. Additional information contained in the data is shown to establish the mode of structural degradation.

At least seven ways of utilizing acoustic emission data to establish the quality of pressure vessels are presented. Use of acoustic emission techniques to detect and locate a growing defect in a structure, while under a relatively severe environmental condition, is presented.

Various methods of data processing are described and the relations to parameters which may indicate the degree of quality of the structure are shown. Data from materials such as glass-reinforced plastics, concrete, glass, and metallics are presented. References to less well known efforts show the universal nature of the technology.
Acoustic Monitoring Systems to Assure Integrity of Nuclear Plants
Authors: Gopal R
Published: March 2009

A comprehensive program is underway at the Westinghouse Electric Corporation to develop and evaluate acoustic monitoring systems as a nondestructive testing tool for nuclear power plants that will assure structural integrity with minimum interference to normal power plant activities. A prime requirement for instrumentation for nuclear reactors is that it should function reliably in severe environments for several years. Sensors and instrumentation for source location and display developed for this application are described. Results of tests performed in major test facilities for vessel flaw growth, vessel rupture, and pipe rupture under various operating conditions are summarized. Evaluation performed in nuclear power plants both during hydro tests and operation of plant is presented. Laboratory tests for studying relationships between acoustic emission and fracture mechanics technologies are presented along with a summary of wave propagation results. Measurements, to date, indicate that an acoustic monitoring system has practical applications in nuclear power plants for improving safety and availability of plants.
Background and Perspective
Authors: De Simone D
Published: March 2009

With every other major nation converted to the metric system or committed to conversion, eventually the United States will also adopt this system as the predominant common language of measurement. Developing trends in international trade indicate such a course, and a growing majority of U. S. businessmen and educators favors conversion to the metric system. The key decisions now facing the United States pertain to planning and timing. The changeover, most people agree, should be carefully coordinated and could take place over a transition period of ten years, more or less, under reasonable guidelines designed to encourage maximum voluntary participation by all sectors. If the changeover to predominant metric usage is guided by a “Rule of Reason,” the costs and difficulties of conversion can be minimized. Immediate steps should be taken to stress the teaching of the metric system in our schools and to promote a more vigorous and influential role by American industry in the setting of international engineering standards.
Changeover to Metric—Timetable and Government Role
Authors: Barbrow LE
Published: March 2009

The changeover to the metric system in the United States is motivated by our manufacturing industry. The basic reason for the changeover is economic necessity, which dictates also that changes to metric be made only where they are advantageous. In the transition timetable, our manufacturing industry and our educational institutions are already well started. Now, then, is the time also for the development of national metric engineering standards to supersede or supplement our customary engineering standards. Government procurement will keep in step with industry changeover. Consumer products will be changed some years hence, the specific time being dependent on the enactment of national metric legislation, but early programs should be initiated to keep our public informed as to why the changeover is taking place and how it is progressing. The principal role of Government in the changeover is to keep SI, the modernized metric system, as clean as possible. When metric legislation is enacted, a National Metric Conversion Board will have the responsibility for coordinating the changeover. Meanwhile the American National Metric Council has undertaken this role.
International Standards—Impact on American Metrication
Authors: Peyton DL
Published: March 2009

This paper is an account of why metric engineering standards are essential to metric conversion; why these standards must be based upon international agreement to avoid technical barriers to trade; and why the United States must participate fully in their development if good U. S. standards and engineering practices are to gain proper recognition in international metric standards. National and international trends in and attitudes toward international standardization are described, problem areas identified, and a national metric standards strategy proposed.
Metrication in the United Kingdom— The Industrial Bonus
Authors: Feilden GBR
Published: March 2009

This paper reviews the British industrial program for metrication and the provision of metric standards which were the cornerstone for the changeover. British experience in the practical use of SI units is detailed, and examples are given of the opportunities metrication provides for simplification and variety reduction.
Going Metric—To What Standard
Authors: Doebereiner JE
Published: March 2009

This paper generally relates the considerations required in accessing the implications of developing a metric product standard. It describes the case study of the Timken Company and the requirements necessary to establish changes in an international standard.
Metrication in the United Kingdom Construction Industry
Authors: Clarke AB
Published: March 2009

In May 1965 The United Kingdom Government announced its decision, following representations by industry, that it was desirable that British industry on a broadening front should adopt metric units. A metric program for the construction industry was published in February 1967. This industry thus became one of the first major British industries to commit itself to metrication.

From the beginning the main organizations connected with construction saw the need for maximum interchange of information on individual plans and specialist programs. Arrangements were made to monitor the changes, identify existing and potential difficulties, and coordinate the various timetables. Government departments and local authorities with building programs adopted a policy of supporting the industry in its determination to go metric by specifying and designing in metric themselves. Central and local government requirements for their building projects constituted the greatest single motive force for the change during the early part of the program. Trade associations representing the manufacturers of the industry's supplies announced early programs designed to make metric sized supplies generally availabe during the period of 1970 to 1972.

The change is now well on the way to completion but it is likely that part of the industry will continue to do some work in imperial units for some years. The structure of the industry and the nature of the work it carries out go far to account for this; for example, some maintenance work is likely to continue in imperial even when all new work is in metric.
Metric Packaging
Authors: Li M
Published: March 2009

In recent years, Great Britain, Australia, and Canada have adopted the metric system as their measurement standard. Although the U. S. government has considered going metric since James Monroe's administration, legislative efforts to convert the nation to the metric system over a ten-year period have so far been unsuccessful. Prospects for Federal legislation are now uncertain.

Metric conversion will have a significant impact upon the packaging and its allied industries. There is no doubt that metrication represents a monumental task to the suppliers and users of packaging materials, but they almost all agree that, despite those recognized problems and high cost of conversion, adoption of the metric system as the U. S. measurement standard is inevitable.
A Metrication Case History: Ford's 2.3-Litre Engine
Authors: Mallen SE
Published: March 2009

This illustrated report covers Ford's experience in engineering and manufacturing the first mass-produced, metric automotive engine in the United States. Some conversion problems are identified, and techniques used to minimize short-term costs of going metric are described. The metrication trend is briefly reviewed, along with a reference to the opportunity for potentially minimizing final product costs in the long run as a result of metrication.
Probabilistic Design of Composite Structures
Authors: Maxwell RE , Toland RH , Johnson CW
Published: March 2009

The method of statistical trials (Monte Carlo simulation) in combination with a sensitivity analysis by variance separation is presented as an efficient design and analysis system for each specific mode of failure. The method has several advantages: (1) it provides a realistic reliability prediction for each failure mode of a composite structure; (2) it determines the material, geometrical, and manufacturing variables which have a significant role upon the structure's reliability with respect to each failure mode; and (3) it determines which material, geometrical, and manufacturing variables should be controlled in order to manufacture the structure at minimum product assurance costs. Application is made to the graphite-epoxy truss tubes of NASA's applications technology satellite.
Spectrum Analysis of Acoustic Emissions from Boron-Aluminum Composites
Authors: Henneke EG , Herring HW
Published: March 2009

Acoustic emissions were monitored from unidirectional tension specimens of boron-aluminum composites. It is shown that a sudden increase in count rate presages final failure. This sudden increase, however, occurs at a variable point relative to final failure load. Spectrum analysis in the range to 1 to 100 kHz was performed on the emissions with the result that no immediately obvious recognition pattern exists to distinguish between types of failure mechanisms. Thus, it is suggested that either acoustic emissions cannot be used to distinguish different failure modes in boron-aluminum composites in the frequency range studied or else the specimens used here had only one failure mode operating with sufficient energy release to be detected. The spectrum analysis did show, however, that the acoustic emissions had frequency components much higher than the frequencies for the fundamental modes of natural vibration of the specimen.
Creep Analysis of Laminates
Authors: Foye RL
Published: March 2009

Results are presented for an analytical investigation of the creep response of laminated composites. This analysis relates the creep response of the composite to the fiber-matrix creep properties. First, the method of predicting the biaxial creep response of a unidirectional composite is described and some qualitative results given. Some interesting effects are the time dependence of the coefficients of thermal expansion of the composite and the pseudo-primary creep stage in a composite whose constituents only exhibit secondary creep. The analysis is then extended to symmetric laminates and the creep response of boron-epoxy and boron-aluminum composites are investigated.
Composite Matrix Fatigue Crazing—Detection and Measurement
Authors: Schwabe JE
Published: March 2009

Crazing has recently become of interest in composite materials having organic matrices, and the development of crazes has been suggested as a failure criterion in the fatigue testing of susceptible composites.

This paper reports the results of an experiment to find a practical means of detecting and monitoring the development of crazing during fatigue testing of fiber-reinforced epoxy matrix composite materials. A specimen of such material was strain-gaged with one 2-in.-long (0.051 m) foil gage, and with thirty 2/100-in.-long (0.508 mm) gages. The apparent strain of each gage was monitored during displacement control tension-tension fatigue testing.

The experimental results demonstrated that the maximum difference between apparent strains as measured by the small strain gages provided a sensitive means of detecting crazing. It was concluded that thirty small strain gages with appropriate instrumentation could provide a practical means of automatically detecting crazing during such fatigue tests of composite materials.
Impact Damage Effects on Boron-Aluminum Composites
Authors: Carlisle JC , Crane RL , Jaques WJ , Montulli LT
Published: March 2009

The foreign-object damage problem associated with jet engines was investigated by impacting both titanium (6Al-4V) and boron-aluminum specimens with either steel or room-temperature vulcanizing rubber spheres to simulate the two principal types of ingested foreign objects. To simulate engine operating conditions, some specimens were impacted while under a tensile load. Results indicate that a prestressed composite suffers much greater damage than simple cantilevered specimens. Ti-6Al-4V exhibits excellent impact resistance, loosing only 10 percent of its ultimate tensile strength up to the highest prestresses and impact velocities. Composite specimens react much differently depending on the type of impactor. Steel spheres cause severe damage at very low impact velocities. Room-temperature vulcanizing rubber, on the other hand, causes little damage up to a velocity threshold. Above this point, specimen failure was observed at some prestresses upon impact. The residual tensile and low-cycle fatigue strength of both boron-aluminum and titanium was documented for various impacting velocities and prestresses. A fracture-mechanics analysis is presented which successfully predicts the effects of room-temperature vulcanizing rubber impact on boron-aluminum composites.
Use of Highly Active Pozzolans for Reducing Expansion in Concretes Containing Reactive Aggregates
Authors: Mehta PK , Polivka M
Published: March 2009

Since it takes only a small amount of reactive aggregate to cause deterioration of concrete due to the alkali-silicate reaction, vast deposits of aggregates throughout the world are in danger of being rejected as undesirable for use in concrete unless acceptable corrective measures are found. Although addition of commonly available pozzolans can effectively reduce the expansion associated with the alkali-silicate reaction, the quantity of pozzolan needed for this purpose is generally large enough to influence adversely the water demand and thereby the concrete quality.

In this study the use of a highly active pozzolan, namely, rice hull ash, is compared with a normal pozzolan for reducing the alkali-silicate expansion. Whereas 25 percent of the latter by weight of the cementing material was required to reduce the expansion in the ASTM Test for Effectiveness of Mineral Admixtures in Preventing Excessive Expansion of Concrete Due to the Alkali-Aggregate Reaction (C 441-69) mortar by 90 percent, only 10 percent of the former was sufficient to obtain the same degree of effectiveness in reducing the expansion. Laboratory tests on concrete mixes containing the corresponding proportions of the pozzolans showed that, when compared with the control concrete, the mix containing the rice hull ash did not show strength loss at three and seven days whereas the mix containing the normal pozzolan showed severe strength loss at early ages.
Characteristics and Utilization of Coarse Aggregates Associated with D-Cracking
Authors: Stark D
Published: March 2009

Primary considerations in the selection of materials for coarse aggregate are those pertaining to freeze-thaw durability and the development of D-cracking in highway and airfield pavements. Two aspects of the problem are of particular importance: moisture movements and critical saturation of the aggregate, and the response of the aggregate to cyclic freezing and thawing in concrete.

Laboratory studies of coarse aggregates have indicated that nondurable materials are generally of sedimentary origin and may reach critical saturation when the concrete is in direct contact with either free water or capillary-held water. Absorption-adsorption and mercury intrusion studies have revealed differences in the pore structure of durable and nondurable materials, while laboratory tests of aggregates in concrete differentiate performance during freezing and thawing in line with field service records.

The most feasible method of utilizing potentially nondurable coarse aggregates is to reduce maximum particle sizes. The needed reduction can be determined from laboratory freeze-thaw tests and is found to vary with source. Gravel sources have the option of crushing oversize material for using naturally finer material to improve durability, while crushed stone sources may use alternatively selective quarrying to produce higher quality aggregates. Proper evaluation of aggregate materials is contingent on establishing laboratory procedures directed expressly to the problem of D-cracking.
Reef Shell-Beach Sand Concrete
Authors: Popovics S
Published: March 2009

Several years ago the Alabama State Highway Department decided to investigate the applicability of reef shell as aggregate for concrete. Considerable difficulties were encountered in the investigation in attempting to produce a shell concrete with acceptable technical properties. The main problem was the inadequate workability of the shell concretes. Finally, a combination of crushed reef shell and beach sand was found that appeared to provide adequate concrete for selected structural purposes.

These results indicate that concrete of suitable strengths for certain purposes can be produced from reef shell and beach sand aggregates even though these aggregates do not meet the usual requirements concerning grading, particle shape, and abrasion loss. Concrete with a compressive strength of 2500 psi, flexural strength of 550 psi, and adequate workability can be obtained by combining 40 percent (by weight) of sand, 60 percent (by weight) crushed reef shell, 6 bags/yd3 (564 lb/yd3 = 335 kg/m3) cement, and suitable amounts of fly ash and air entraining agents.

The reef shell and beach sand are available in areas where there is a scarcity of suitable aggregates for concrete. The use of reef shell and beach sand in these areas would be less costly than “imported” aggregates to produce concrete for uses where high strength and high abrasive resistance is not required. These uses could include retaining walls, structure foundations, subpavements, and construction involving massive concrete.
Calibration of Stack Gas Instrumentation
Authors: Chapman RL
Published: March 2009

Experience in stack gas instrumentation calibration is presented, based on a study involving the measurement of sulfur dioxide in the stack of a power plant and in the exit gases from a Claus sulfur recovery incinerator. Calibrations were performed by the use of analyzed cylinders of gas. The method of presenting the calibration gas to the analyzers is described, and data are presented to provide comparisons of the resulting instrumental readings with correlated, independant determinations made by the standard reference (manual) method for sulfur dioxide in stack gas.
Preparation of Stable Pollution Gas Standards Using Treated Aluminum Cylinders
Authors: Wechter SG
Published: March 2009

The use of gas cylinder calibration standards is becoming an increasingly important tool for use in pollution analysis methods requiring a known reference. There are problems, however, in the preparation of pollution gas standards using high pressure steel cylinders. Researchers have documented these problems in the literature, especially in recent months. When reactive gases such as the oxides of nitrogen, carbon monoxide, or sulfur dioxide are blended in a steel cylinder with an inert balance gas, the concentration that the cylinder delivers can vary with time, pressure, and temperature. The nature of the blend's instability is random and a function of the absorption or reaction with the walls of the cylinder. These disturbing features lead to an obvious question. Can the specialty gas industry provide a stable and accurate pollution calibration standard in a cylinder? This paper deals with that question and describes experience gained using treated aluminum cylinders as a solution to the problem. Included in the discussion are: (1) instrumental and analysis method evaluation, (2) calibration and correlation of internal standards, (3) effects of various cylinder types on the stability of reactive gas mixtures, (4) effects of preconditioning as a means of deactivating cylinder walls, (5) effects of variables such as temperature and pressure on cylinder concentrations, and (6) long-term stability data.