bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrahigh-Strength Steel Fasteners
Authors: Hood A. C. , Sproat R. L.
Published: August 2009

Bolts with tensile strengths as high as 300,000 psi are being produced and reliably used. The manufacturing and application of these bolts are a challenge owing to the basic design of threaded fasteners. There are severe stress concentrations caused by the notches of the threads and the abrupt change in cross section of the head-to-body fillet area. In order to maximize both notch toughness and fatigue strength, large fillet radii are used in both of these critical areas. For additional fatigue strength, the head-to-shank fillet radius is prestressed and the threads are rolled after heat treatment. The material selected for bolting must have a high degree of notch toughness as well as strength. H-11 hot-work die steel has the greatest application for bolts with tensile strengths over 220,000 psi. Corrosion-resisting materials such as A-286 and Inconel 718, which are cold worked prior to aging, are also used. Care must be exercised during the heat treatment of the bolts to prevent carburization or decarburization, both of which reduce fatigue strength. Stresses caused by grinding are removed by retempering prior to fillet stressing and thread rolling. Alloy steel bolts are coated for corrosion protection with electroplating or vacuum-deposited cadmium. Through the use of these methods, hydrogen embrittlement is avoided. Application and environmental conditions greatly affect the life of a bolt in actual usage. Fatigue failures may be caused by corrosion. The performance of the bolt is influenced by the configuration of a nut or tapped hole. The design of the joint and conditions of tightening must also be considered.
Introduction
Authors: Dietz A. G. H.
Published: August 2009

This Symposium on Application of Advanced and Nuclear Physics to Testing Materials, sponsored jointly by RILEM (Reunion Internationale des Laboratoires D'Essais et de Recherches sur les Materiaux et les Constructions—International Union of Testing and Research Laboratories for Materials and Structures) and by the American Society for Testing and Materials was part of the First International Conference on Materials held by ASTM in Philadelphia, Pa., Feb. 3–6, 1964. The papers in this symposium, although directed primarily at building materials, in actual fact present some insights into advanced physical processes and measurements as well as their applications to the investigation of materials. Included are extremely short electromagnetic waves and their absorption by moisture; spectrochemical analysis of materials by X-rays; an examination of neutron diffraction, its similarities to and differences from X-ray diffraction, the resulting relative limitations and advantages of the methods, and a discussion of the types of measurements possible with neutron diffraction as compared with X-rays; and irradiation by nuclear fission products including the use of radioactive isotopes. These physical and nuclear processes are used to determine moisture contents, thicknesses, densities, and other properties of materials in situ; to make a variety of difficult measurements such as the constituents of hardened portland cement; to study effects of irradiation on organic and inorganic materials; to follow manufacturing processes; and to make a considerable number of other determinations, some heretofore unavailable, slow, or uncertain.
Applications of Centimetric Radio Waves in Nondestructive Testing
Authors: Boot A. R. , Watson A.
Published: August 2009

The dipolar relaxation phenomena and attendant absorption displayed by water in the microwave region of the spectrum has been used as a basis for the nondestructive testing of the moisture content of building materials. Because of this relaxation effect, the dielectric properties of moist materials at these frequencies depend sensitively on the quantity of moisture present, and thus the macroscopic electromagnetic parameters, and in particular the transmission attenuation, associated with a building structure at a particular frequency are characteristic of the water content. A practical method of assessing the moisture phase of materials is thus available. Further, observation of the dielectric behavior of the water-material mixture can yield information about the distribution of moisture in porous media. The theory of these new methods of testing, based on electromagnetic theory and dielectric mixture studies, is presented in some detail, followed by a description of the apparatus and experimental procedure. Problems of calibration and accuracy are discussed and results compared with other work in the field.
Nondestructive Estimation of Cement Content of Hardened Concrete
Authors: Yaltkaya E. R. , Enüstün B. V. , Urkan S. , Sentürk H. S. , xKöksal S.
Published: August 2009

This paper describes a method to estimate the cement content of hardened concrete specimens based on the determination of the water content of ovendried powdered concrete specimens by neutron scattering. The cement content could be computed on the assumption that the percentage of water of hydration is approximately constant for all cements. To justify this assumption, a systematic investigation of hydration value was carried out with cement specimens of various Turkish origin. The method involved dehydration of the hydrated cement specimens at 100 C in an atmosphere of oxygen and absorbing water in calcium chloride. A value of 14.1 was found for the mean percentage of hydration water with a standard deviation of 0.5. Because it is impossible to eliminate capillary water in situ—a requirement for adapting this technique to a nondestructive method—attempts were made to estimate this water by measuring electrical conductance of concrete. The over-all water content, that is, capillary water plus hydration water, is determined by neutron scattering, and the hydration water content is found by substraction. The cement content is then calculated from the mean hydration value of cement.
Influences of Modern Physics on the Properties of Wood and Their Evaluation
Authors: Youngs R. L.
Published: August 2009

Recent developments in physics provide a basis for modifying the physical and mechanical properties of wood and the techniques by which those properties are evaluated. Ionizing radiation from radioactive isotopes may affect the characteristics of wood formation as well as the properties of mature wood. Such radiation may also provide new possibilities in modification of wood properties by in situ polymerization of monomers impregnated into the wood. Developments in several areas of nuclear physics may provide a promising basis for the more effective evaluation of wood properties by nondestructive methods, a significant step toward the more efficient use of wood as an engineering material. Consideration of these developments and possibilities leads to an interesting study of the relationship between a classical engineering material and new developments in science.
Applications of Modern Physics to Materials Tests
Authors: Lachaud R. , Paquet J.
Published: August 2009

This paper reports the results of studies carried out at the Centre Expérimental de Recherches et d'Etudes du Bâtiment et des Travaus Publics (CEBTP) since 1953 on the application of radioactivity to measurements of density and water content, stressing more particularly certain difficult points, such as the influence of the surface state and the problems of calibration. The results of studies on the possibility of batching bitumen in road surfacing by neutron diffusion, the results of an X-ray study of the composition of baked clay for building, and the measurements of the dielectric constant are discussed.
Introduction to Session II
Authors: King R. W.
Published: August 2009

As Harold Smith mentioned in his opening remarks, the purpose of this symposium is to provide the opportunity and, hopefully, the stimulus for petroleum analysts to reflect on “WhereWe Are”, “How We Got There”, and most important of all, “Where We Are Going”. We all recognize that many of tomorrow's problems will not yield to today's tools. If we acknowledge that, as competent scientists, we are obligated toanticipate what some of these problems may be, it follows that we should also appraise the trends in the development of analytical methods, so that we can develop a feeling for what tomorrow's tools may be like. Over the past two decades instrumental methods have become more and more important to the petroleum analyst, until today it's almost like losing your right arm if a filament burns out in a mass spectrometer or in a gas chromatograph.
NMR Analysis of Hydrocarbons and Related Molecules
Authors: Zimmerman J. R.
Published: August 2009

Some of the more recent contributions in nuclear magnetic resonance instrumentation, structure determinations, and characterizations pertinent to petroleum and petroleum products are reviewed. A projection of future analytical developments is made with detailed discussions on, (1) the application of molecular interactions to extend identification and characterization of liquid hydrocarbons, and (2) the possible uses of pulse resonance methods.
Absorption Spectroscopy of Hydrocarbons
Authors: LeTourneau R. L.
Published: August 2009

Infrared and ultraviolet-visible spectroscopy are important in the identification of individual hydrocarbons and have important uses in identifying certain types of hydrocarbons in mixtures. The development of these techniques and uses over the past 20 years is briefly reviewed, the important current uses for which there are not simpler competing methods emphasized, and further developments are forecast as far as possible. The related techniques of Raman spectroscopy and fluorescence are also mentioned. In the future, absorption spectroscopy will be used increasingly in integrated methods of analysis and will complement data from mass spectrometry and nuclear magnetic resonance.
Introduction to Session III
Authors: Herman Jack
Published: August 2009

We tried to find a concise heading and the right words for describing the set of talks that you will hear this morning. With some misgivings, both technical and sociological, we put down the words “Integrated Methods Approach”. However, I think it isn't a bad title. It was mentioned several times yesterday afternoon and a couple of examples have already appeared on some phases of what is meant by this approach. For instance, Stewart Kurtz mentioned ES-45 which was adopted as an ASTM emergency method in World War II. That was really, I think, a primary example of an early integrated method. He mentioned six or eight separate methods which have come out of that and for the long range, one wonders whether in the end the separated methods might not again be put together in one comprehensive approach to a request for a hydrocarbon type analysis of a petroleum distillate. One thing about a combination of methods, the individual deviations or errors of each step are perhaps bound to be compensating in the course of applying the total analysis; whereas, when you look at one particular method, the limit of precision stands out.
Aromatic Hydrocarbons in High-Boiling Fractions
Authors: Mair B. J.
Published: August 2009

Research Project 6 of the Am. Petroleum Inst. is summarized. An integrated approach was used to, as far as possible, isolate, identify, and determine the amounts of the aromatic hydrocarbon components present in petroleum. Methods of analysis and compounds identified in four portions of the reference petroleum are reviewed: (1) The mononuclear aromatic portion of the light gas oil fraction, 230 to 305 C, (2) The dinuclear aromatic portion of the light gas oil fraction, 255 to 275 C, (3) The dinuclear aromatic portion of the light gas oil fraction, 275 to 300 C, (4) The trinuclear aromatic portion of the heavy gas oil and light lubricating distillate.
The Molecular Complex Comprising Heavy Petroleum Fractions
Authors: Erdman J. Gordon
Published: August 2009

Present knowledge of the skeletal structure of the asphaltene and resin portions of the heavy oil fraction of petroleum is reviewed. This fraction consists primarily of graphite-like clusters of condensed aromatic rings joined together by alkyl groups. Infrared studies show condensed naphthalenic ring systems are also present. The naphthalenic ring systems are usually not fused to the aromatic clusters. Within the aromatic clusters are sites of free radicals and sites where a nickel or vanadium ion can be coordinated with heteroatoms present in the aromatic rings. Detailed information about aromaticity, intermolecular distances, and the methods of analysis used for structural determinations are presented.
Control of Bituminous Shoulder Construction for the Northern Illinois Toll Highway
Authors: Waddell Joseph J.
Published: August 2009

The Northern Illinois Toll Highway consists of 187 miles of four- and six-lane limited access tollway, providing a belt-line highway around Chicago. Branches extend to the Indiana line, to Wisconsin at Beloit and Kenosha, and west past Aurora. To provide adequate safety for the motorist, the road was designed with wide, asphaltic concrete shoulders on both sides (Fig. 1). These shoulders provide a safe space for disabled vehicles to stop off the main pavement. A total of 602,000 tons of hot plant-mixed bituminous concrete was required for the 3,664,000 sq yd of shoulder. The Marshall test method was used to design the asphaltic concrete and to control its proportioning, mixing and compaction. Because construction on some 50 individual contracts was to be administered by 23 different section engineers, this method was selected because it was considered to be capable of producing consistent results in the hands of many different operators and to lend itself to easy demonstration and explanation to persons unfamiliar with control of bituminous pavement. It was also felt that the method selected must have a satisfactory history of use and provide a satisfactory degree of control, yet be relatively simple in application.
Triaxial Testing of Bituminous Mixtures
Authors: Goetz W. H. , Schaub J. H.
Published: August 2009

For approximately twenty-five years the attention of paving design engineers has been directed in part towards the use of a triaxial shear strength method of test to evaluate the properties of bituminous mixtures. Interest in this form of test, particularly as a means of evaluating fundamental strength properties of bituminous mixtures, has become increasingly great. At the present time there are several techniques in use that utilize the principles of triaxial shear testing for the design and strength evaluation of bituminous concrete mixtures. The purpose of this paper is to summarize the status of triaxial testing as a mix design and research tool and to present a résumé of the various triaxial test procedures that are in use.
Void Requirements for Dense-Graded Bituminous Paving Mixtures
Authors: McLeod Norman W.
Published: August 2009

The void properties of compacted dense-graded bituminous paving mixtures are at least as important as their stability insofar as pavement performance is concerned. It is shown that the most significant void requirements for compacted bituminous mixtures are air voids and voids in the mineral aggregate (VMA). The values obtained for air voids and VMA for any given paving mixture depend upon whether the aggregate's ASTM bulk, ASTM apparent, or effective specific gravity has been employed to calculate them. For the design and control of dense-graded paving mixtures, it is recommended that requirements for air voids and VMA be based on the aggregate's ASTM bulk specific gravity, and that loss of bitumen by absorption into the internal capillary porosity of the individual aggregate particles must be allowed for when determining the air voids value. A useful chart for illustrating specification void requirements, and for assisting the design and control of bituminous paving mixtures, is described. By means of a graph, a tentative procedure is suggested for relating the mimimum VMA requirement of a compacted paving mixture to the nominal maximum particle size of the aggregate it contains. A general method for controlling the VMA value of a paving mixture by modifying the gradation of the aggregate is illustrated.
Use of the Immersion-Compression Test in Evaluating and Designing Bituminous Paving Mixtures
Authors: Goode Joseph F.
Published: August 2009

The background of the immersion-compression test and some of the important uses of the test in evaluating bituminous paving mixtures are given, followed by a discussion of the more important factors to be considered in designing bituminous mixtures. Illustrations are given showing how these factors are treated in the Bureau of Public Roads method of design.
Practical Significance of Tests on Asphalt Cements
Authors: McLeod Norman W.
Published: August 2009

The practical significance of each of the usual tests for asphalt cements, and of their specification limits, is critically examined from the point of view of the highway or airport engineer who is responsible for the design, construction, and maintenance of asphalt surfaces. Based on the results of this review, it is recommended that specifications for asphalt cements should be limited to flash point by the Pensky-Martens closed tester; penetration at 77 F; ductility at either 77 F or 60 F; either loss on heating to 325 F, or the U. S. Bureau of Public Roads Thin Film Oven Test, but restricting tests on the residue in either case to penetration at 77 F; solubility in carbon tetrachloride; and statements requiring the asphalt supplier to provide the specific gravity 77/77 F and the viscosity temperature curve for each asphalt cement furnished under the specifications.
Fundamental Viscosity Versus Saybolt Furol Viscosity for Refinery Control of Cut-Back Asphalt
Authors: Levy D. F. , Fassnacht F. E. , Hibler G. P. , Umbach R. D. , Gagle D. W.
Published: August 2009

In asphalt manufacture, viscosity is of primary importance to product quality control. It is the one test which, more than any other, is necessary to establish the limits of consistency and workability for both manufacture and end uses. At the present time, 12 grades of cutback asphalts are specified by the American Society for Testing Materials. Viscosity specifications are based on Saybolt Furol values, but because of the nature of the test method and the number of grades of asphalt, viscosities must be obtained at four different temperatures. In an effort to simplify viscosity testting, three Phillips Petroleum Co. refineries started using a kinematic capillary viscometer as a control instrument in conjunction with automatic asphalt blend plants. Two and one-half years' experience have demonstrated its practical ability to measure asphalt viscosity in fundamental kinematic units. Use of Saybolt Furol equipment has been discontinued. Equivalent Saybolt Furol values are now obtained by conversion.
Introduction
Authors: Clapper R. B.
Published: August 2009

The title of this Symposium “Newer Structural Materials for Aerospace Vehicles,” is, I think, adequately expressive. We are experimenting here with the idea of giving a broad brush treatment to a variety of materials which are believed by many to have an important future as structural materials in aerospace vehicles. None of these materials are available today as “off-the-shelf” items, and not even on a special order basis. In aerospace environments, a host of new design requirements must be successfully determined and then solved by optimization of many materials to design a vehicle structure with 99.9 per cent reliability. The factors of tremendous cost of advanced structures and protection of human life with reliability in space vehicles requires knowledge of a whole new spectrum of materials properties as compared to the relatively narrow band of property requirements required for the subsonic low-altitude aircraft.
New Ductile Beryllium-Aluminum Wrought Alloys
Authors: Fenn R. W. , Crooks D. D. , Pasternak R. C.
Published: August 2009

The properties of a new series of ductile beryllium-aluminum alloys, which were specifically designed for use in aerospace vehicles, are described. Young's modulus, bend, and tensile properties of sheet and extrusion alloys containing between 24 and 43 per cent aluminum are presented. The elevated-temperature tensile properties to 1000 F (540 C) are given for both rolled and extruded material containing 36 per cent aluminum. The effect of temperature on Young's modulus of an extruded Be-31.4 per cent Al alloy is also given to 1000 F (540 C). Structural efficiency comparisons are made between beryllium and competitive materials, in some cases, to 1000 F (540 C). The improved ductility, machinability, weldability, and formability of these new alloys, as well as the lack of brittleness and freedom from chemical etching requirements, as compared to currently available commercial purity beryllium, should result in significantly lower installed cost than for beryllium. Substitution of beryllium-aluminum alloys for currently used HM21A-T8 and HK31A-H24 magnesium alloys could result in weight savings on the order of 40 per cent.
Testing 1-Mil Molybdenum-Faced Foil Sandwich up to 1800 F
Authors: Hunter A. R.
Published: August 2009

This paper presents techniques for testing foil-gage honeycomb sandwich structures at elevated temperatures. Also included are the results of tests that were used to determine edge compressive strength, core shear strength, and core crushing strengths of a particular sandwich construction. These results are compared with empirical design values to show that refractory foil sandwich structures are practical and that further development work would be desirable.
Nonmetallic Materials for High-Temperature Structural Applications
Authors: Kendall E. G. , McClelland J. D.
Published: August 2009

The urgent need for high-temperature aerospace materials is spurring the development of the refractory nonmetallic materials, including the carbides, graphites, oxides, borides, and beryllides. The materials are discussed with emphasis on high-temperature structural applications. A detailed compilation of property data is presented, aerospace applications described, limitations of the materials reviewed, and promising areas of research outlined. These include the prestressing of oxides for rocket nozzle inserts and the carbide-graphite eutectics for improved thermal shock resistance.
Thermal-Structural Composites for Aerospace Applications
Authors: Beasley R. M. , Clapper R. B.
Published: August 2009

Advanced aerospace applications require combinations of property characteristics which cannot be met by monolithic materials. New materials and processes combined to contribute specific properties offer the most promise for satisfying these requirements. Property evaluation of both material components and final composites is difficult and is a limiting factor in optimizing the design and utilization of such heterogeneous structures. Inorganic bonded refractory fiber-based composites have been developed to meet specific requirements of varied applications. Examples representative of several thermal-structural applications are presented with attention directed to factors considered in the design; for example, thermal, mechanical, and electrical property evaluations as influenced by construction. Difficulties encountered in tests to define and control variables affecting these properties are indicated. Examples of simplified test methods for evaluation of variables of construction are given.
Continuous Measurement of Rubber Vulcanization with the Agfa Vulcameter
Authors: Gehman S. D. , Ogilby S. R.
Published: August 2009

The Agfa Vulcameter was the forerunner and inspiration for more elaborate types of instrumentation now used to follow the course of vulcanization of laboratory test specimens. Procedures are described which enable the Vulcameter to fulfill most of the purposes of such instruments. The temperature control system has been modified so that the temperature rise in the specimen corresponds rather closely to that of a standard test sheet in a mold. The most serious objection to the Vulcameter has been the absence of pressure on the specimens allowing porosity to develop. This difficulty has been mitigated by using thinner specimens, about 0.04-in. thick, and practically eliminated by containing the specimen in a specially designed, low-pressure cell. Suitable calibration curves permit the conversion of the recorded traces to plots of shear modulus. The capabilities of the instrument for determining pertinent vulcanization and processing parameters are illustrated. Activation energies were determined for the vulcanization of a variety of rubber compounds. Vulcameter measurements of the shear modulus of uncured compounds and of scorch times correlated rather well with values from the Mooney viscometer.
Vulcanization Measurement Using the Instron Tester
Authors: Rowley A. C.
Published: August 2009

With the dual objective of economy in laboratory man-hours, and more comprehensive evaluation of elastomer vulcanization compounding, a technique has been developed which combines the Curometer and the Instron tester. By mounting the vulcanizing chamber assembly of a standard Curometer vertically on the face of a compression load cell of an Instron tester, and the Curometer paddle vertically in the Instron crosshead, measurements of vulcanization activity at temperatures of current commercial interest can be made by the proposed method. This method takes advantage of recognized valuable features of both instruments, including: 1. wide range of chart operating speeds, 2. small specimens, 3. easy and rapid changes in temperature, 4. rapid oscillatory movement, 5. heavy-duty mechanical actuation of the strain applicator (paddle) and reliable electronic programming and instrumentation, and 6. measurement of stress resulting from constant strain applied repeatedly (analogous to conventional physical test procedures). Sample Instron charts are displayed and their interpretation discussed. A statistical evaluation of the technique is included, as well as suggestions for its application.
A Guarded-Hot-Plate Thermal-Conductivity Apparatus for Multilayer Cryogenic Insulation
Authors: Karp G. S. , Lankton C. S.
Published: August 2009

A guarded-hot-plate apparatus is employed by the General Electric Spacecraft Department for measuring the thermal conductance of multilayer insulation under vacuum conditions. The physical arrangement of the test apparatus, the range of operating temperatures, the methods employed in achieving these temperatures, and the method of measurement of heat flow and the method of control, are described. The basic sources of error in the measurement of the effective thermal conductivity, primarily the effects of pressure, temperature gradients, and edge effects, are identified, and results are given for some insulation configurations. The effect of the use of slit and unslit insulation on the measurement accuracy, the criteria for an equilibrium condition, and techniques for reducing the required test time are evaluated.
Cryogenic Thermal-Conductivity Measurements of Insulating Materials
Authors: Coston R. M. , Zierman C. A.
Published: August 2009

Two methods of determining the thermal conductivities of cryogenic insulation systems over a wide range of variables are presented and discussed. Both methods are similar in that thermal-conductivity determinations are made calorimetrically by measuring the boiloff rate of the liquid cryogen in the test section. One method utilizes a modified National Bureau of Standards type of cryostat whose capabilities include variation of the external boundary temperature from 212 to −320 F, while the inner boundary temperature is dependent upon the choice of cryogen. Interstitial pressures can be varied from 10−7 torr to 1 atmos. A second method is provided by a flat-plate calorimeter which consists of two isothermal boundaries, one of which is a warm boundary whose temperature can be varied from −320 to 1500 F. The cold boundary consists of two cryogen reservoirs, the calorimeter reservoir and the guard reservoir, whose temperatures are dependent on the cryogen choice. The effect of residual-gas conduction on the thermal conductivity of the insulation can also be determined, as well as the effect of compressive loads on the insulation. Both devices have measured thermal conductivities in the 10−1 to 10−5 Btu/hr ft deg R region.
An Apparatus for Thermal Conductivity at Cryogenic Temperatures Using a Heat Flow Meter
Authors: Hollingsworth Marion
Published: August 2009

This paper describes a heat-flow-meter apparatus capable of rapidly measuring thermal conductivity of flat insulation specimens under cryogenic temperatures. It has been used successfully with various types of insulations, including rigid and flexible fibrous glass or mineral fiber materials, rigid and flexible foamed insulations, loose-fill granular or powder specimens, and the super insulations. A single 12 by 12-in. test specimen is sandwiched between a copper plate cooled by liquid nitrogen and a heat flow meter maintained near the 80 F ambient. The apparatus is built into a standard vacuum bell jar to allow for testing in controlled atmospheres or under high vacuum. Calibration of the heat flow meter is accomplished using specimens whose conductivities at elevated mean temperatures are accurately known from guarded-hot-plate measurements. The validity of the calibration assumption is borne out by apparent good agreement between data from this apparatus and published data on similar materials from other types of equipment. The simplicity of its construction and rapidity of operation recommend this type of apparatus to anyone contemplating such measurements.
A Simple Multilayer Insulation Calorimeter
Authors: De Haan J. R.
Published: August 2009

An inexpensive calorimeter for comparing and evaluating the performance of evacuated multilayer insulation materials between ambient and cryogenic temperatures for varying thicknesses is described and discussed. Simply stated, the calorimeter comprises an easily dismantleable dewar which provides for convenient replacement of insulation and thus incorporates in the measured k-value the influence of overlapping of joints which commonly exists in practical applications. The heat-transfer rate is measured by boiloff of cryogenic fluid. Utilizing a completely wrapped dewar eliminates or minimizes the edge effects which are a major factor in the testing of anisotropic multilayer insulation. Estimated errors and design considerations which reduce the errors to a minimum are discussed. The chief advantages of this type of calorimeter are its low cost, simple operation, and the fact that it most nearly duplicates, in many cases, the expected use conditions of the insulation. Principal limitations are the difficulty of measuring the thermal conductivity at variable temperatures on the warm side and the impossibility of measuring thermal conductivity of insulation as a function of compressive load. Selected results for some of the more common multilayer insulations with temperature interval from ambient to LN2 and LH2 for various thicknesses of insulation and layer densities are presented.
Introduction
Authors: Grosskreutz J. C.
Published: August 2009

Crack propagation is the one phase of fatigue failure which can be treated quantitatively without the added complication of statistical fluctuations. Moreover, in many materials, and especially in notched structures, the crack propagation phase occupies a major fraction of the useful fatigue life. There is, in fact, one school of thought which views all of fatigue damage as the growth of cracks; cracks which grow from preexisting flaws in real structures. In recent years an enormous amount of effort has been devoted to the study of fatigue crack propagation. Some of the first fruits of this effort were reported at the Crack Propagation Symposium held in Cranfield, England, in 1961. Since that time several powerful techniques for the study of crack growth have been developed more fully. Electron fractography has been applied to a wide variety of materials, and the distinguishing “fatigue striation” has been studied in detail. Transmission electron microscopy has been used for the observation of localized damage in the vicinity of cracks. The science of fracture mechanics, which treats the stress concentration, energy balance, and plasticity at crack tips, has found fruitful application to the fatigue problem. Careful microscopic observation of growing fatigue cracks has led to semiquantitative models for the crack extension process. Test apparatus for application of random loads has been developed, and crack growth under these service-simulated loads has been observed. Finally, the results of crack propagation research are becoming useful tools which the engineer can use in designing real structures. In the light of these significant advances, the members of Committees E-9 and E-24 of ASTM felt that the Society could perform a valuable service to the scientific and engineering community by bringing together representative people to review recent accomplishments in this field. This book, which details the proceedings of the Fatigue Crack Propagation Symposium, is divided into four sections. The first three sections, Fatigue Crack Growth in Structures, Microstructural Aspects of Fatigue Crack Growth, and Continuum Approach to Fatigue Crack Growth, are each introduced with a review paper which is followed by several shorter papers which report current research activities in the field. The last section of the book contains a comprehensive paper by J. Schijve, who, through his broad knowledge of the field, manages to bring together the diverse elements of crack growth research into a coherent whole. Dr. Schijve also concludes the volume with a critical survey of the results of the symposium, in which he defines those areas most in need of additional work. The last section also includes papers which report very recent experimental results which became available after the original Symposium Program had been finalized.
Limitations of Fatigue-Crack Research in the Design of Flight Vehicle Structures
Authors: Christensen R. H. , Harmon M. B.
Published: August 2009

This paper surveys the current state of fatigue-crack research and the effect of this work on structural design. The subject areas discussed include: (1) fatigue-crack growth equations, (2) multiaxial strain effects, (3) temperature effects, (4) frequency effects, (5) anisotropic effects, (6) variable stress field effects, (7) fractography, (8) crack growth under random loads, and (9) critical elements and fracture modes. The current limited application of the available fatigue information to design is recognized. Practical objectives for fatigue research from the standpoint of structural design are itemized.
Effect of Environment on Fatigue Cracks
Authors: Achter M. R.
Published: August 2009

In this review of the fatigue of metals in controlled gaseous environments, particular emphasis is placed on the mechanism of crack propagation as it is affected by the test variables. The crack growth rates of some metals are accelerated more by oxygen than by water vapor, while for others the reverse is true. Increases of cyclic frequency and of stress decrease the magnitude of the effect of environment. It is generally agreed that the mechanism is more an increase of the rate of crack propagation than of crack initiation. Of the two explanations proposed, the process of corrosive attack of the crack tip is favored over that of the prevention of rewelding of crack surfaces by the formation of oxide layers. Curves of fatigue life, or of crack growth rate, versus gas pressure show regions of little or no dependence, connected by a transition region of steep slope. In a quantitative treatment of the shape of the curve, the significance of the location of the transition region is discussed.
Fatigue Fracture Surface Appearance
Authors: Hertzberg R. W.
Published: August 2009

The macroscopic and microscopic appearance of fatigue fracture surfaces is strongly affected by the prevailing stress intensity conditions at the moving crack tip. The nature of the fatigue striation found during plane strain propagation is examined and crystallographic considerations introduced to explain different topographical striation arrangements. Program loading studies reveal the importance of stress intensity factor range and maximum or mean values in the determination of striation spacing. Evidence of fatigue damage accumulation is presented. “Elongated dimples” found in the plane stress region of crack propagation are not related to stress intensity conditions or macroscopic growth rate.
Mechanics of Crack Tip Deformation and Extension by Fatigue
Authors: Rice J. R.
Published: August 2009

This paper surveys the continuum mechanics of deformation near cracks and its application to propagation by fatigue loadings. Results of various elastic-plastic models are summarized and compared in relation to hardening behavior, size effects, and large scale plastic yielding. The role of the elastic stress intensity factor variations in governing local plastic flow, and thus crack growth rates, is emphasized for the common high-cycle low-stress fatigue situations. General features of crack propagation are discussed, and theories are examined which seek to relate continuum analyses to separation mechanisms.
Crack Propagation in Clad 7079-T6 Aluminum Alloy Sheet Under Constant and Random Amplitude Fatigue Loading
Authors: Swanson S. R. , Cicci F. , Hoppe W.
Published: August 2009

This paper presents the results of a comprehensive experimental study, mainly using square panels, of a recently introduced high-strength aluminum alloy sheet material and its resistance to the propagation of fatigue cracks. An axial-load fatigue machine, applying both constant and Rayleigh random loads, was developed for the test program, and fatigue cracks in the panels were continuously monitored by a new servo-controlled eddy-current crack follower. The resulting traces of crack length permitted the study of several crack growth laws, by manipulation of the loads to maintain a theoretically constant crack growth rate. From the tests where the load levels were not altered, an optimum thickness of sheet (yielding a minimum average crack growth rate) was indicated. Load-shedding, a phenomenon inherent in the failure of elements in redundant (fail-safe) structures, was simulated in many of the tests. It was found that appreciably different load-shedding histories still yielded the same instantaneous crack growth rate for a given instantaneous level of stress intensity factor. It was found that fracture mechanics provided the most effective approach for the study of fatigue crack propagation, either by constant amplitude or by Rayleigh random amplitude loading.
Application of a Double Linear Damage Rule to Cumulative Fatigue
Authors: Manson S. S. , Freche J. C. , Ensign C. R.
Published: August 2009

The validity of a previously proposed method of predicting cumulative fatigue damage in smooth ƈ-in.-diameter specimens based upon the concept of a double linear damage rule is investigated. This method included simplified formulas for determining the crack initiation and propagation stages and indicated that each of these stages could be represented by a linear damage rule. The present study provides a critical evaluation of the earlier proposal, further illuminates the principles underlying cumulative fatigue damage, and suggests a modification of the original proposal. Data were obtained in two stress level tests with maraged 300 CVM and SAE 4130 steels in rotating bending. Two strain level tests were conducted in axial reversed strain cycling with maraged 300 CVM steel. The investigation showed that in most cases the double linear damage rule when used in conjunction with originally proposed equations for determining crack initiation and propagation predicted fatigue life with greater or equal accuracy than the conventional linear damage rule. An alternate viewpoint of the double linear damage rule is suggested. This requires that a limited number of simple two-stress level tests be run to establish effective fatigue curves for what may be defined as Phases I and II of the fatigue process. These fatigue curves may then be used in the analysis of any spectrum of loads involving as loading extremes the two stresses used for their determination. Only limited verification of the new method has been obtained to date, and it must presently be limited to the study of smooth, ƈ-in.-diameter specimens. However, it may be considered as a first step in the direction of eventually predicting the effect of a complex loading history on the life of more complex geometrical shapes.
Significance of Fatigue Cracks in Micro-Range and Macro-Range
Authors: Schijve J.
Published: August 2009

The fatigue phenomenon can be described as a sequence of four phases: (1) crack nucleation, (2) microcrack propagation, (3) macrocrack propagation, and (4) final failure. The last phase is not discussed. Technical problems related to the other phases are indicated. The continuum mechanics approach is discussed, including the application of the stress intensity factor to microcracks and macrocracks. Several factors are mentioned that cannot be accounted for by continuum mechanics. Questions regarding the microstructural aspects of crack growth are analyzed, and a tentative model for crack growth is outlined. The discussion is illustrated by results of recent NLR investigations regarding the growth of microcracks and the influence of several factors on the propagation of macrocracks, including mean stress, variable amplitude loading, sheet thickness, sheet width, heat treatment, manufacture, batch, rolling direction, environment, and frequency. All data apply to aluminum alloys and mainly to 2024-T3. The main results are summarized in a number of conclusions, and problems for further research are listed.
The Effect of Grain Size on Fatigue Crack Propagation in Copper
Authors: Hoeppner D. W.
Published: August 2009

A study was made of the influence of grain size on the propagation of fatigue cracks in electrolytic tough pitch copper. Copper specimens possessing grain sizes ranging from 0.060 to 7 mm were produced by annealing at various temperatures for preselected periods of time. Center-notched specimens were subjected to a positive mean stress and an alternating stress superimposed. Measurements of crack length were taken continually throughout the test to determine fatigue crack length as a function of number of cycles. Observations were made, using optical and electron fractography, on the mode of propagation and the influence of grain boundaries on the crack as it extends through the matrix. At a given stress level the initiation period of a fatigue crack at the starter notch was observed to increase with decreasing grain size. However, grain size was observed to have little effect on the propagation rate.
Municipal Water from Western Rivers
Authors: Cecil L. K.
Published: August 2009

Western rivers are modified by construction of reservoirs to serve irrigation, flood control, and power production. Municipal supplies from these sources must be taken as is and treated to meet the varied requirements of the users. Return irrigation water, natural brine pollution, and contamination from pesticides, herbicides, and fertilizing nutrients from agricultural land runoff introduce purification problems that require adoption of new technics such as activated carbon filtration and ionic irradiation. More sophisticated analytical tools are needed to help the purification plant operator control treating systems.
Industrial Water for Cooling and General Purposes
Authors: von Frank A. J. , Fawcett R. L.
Published: August 2009

Quality criteria for industrial cooling waters have received little industrial attention in the context of use for source standards. The reasons given for this passivity are: (a) a history of industrial adaptation to a wide variety of water supplies without stress in most cases; (b) an awareness that other beneficial uses, both public and private, involve quality limits more stringent than those reasonably required for cooling water supply; and (c) the practical problems in isolating meaningful threshold concentrations in those multivariant technico-economic systems. The common parameters of biological growths, carbon dioxide, chlorides, dissolved oxygen, dissolved solids, iron, manganese, and pH are discussed briefly against this background.
Water Quality Requirements of Estuarine Organisms
Authors: Katz Max , Woelke C. E.
Published: August 2009

The disposal of industrial and domestic wastes into the estuarine and marine environment is feasible and practical. Properly designed disposal systems can distribute wastes so that the other beneficial uses of the aquatic environment are not harmed. A prerequisite to the planning of the disposal system is a knowledge of the life history and ecological requirement of the important aquatic species which utilize these environments. The estuarine environment is an extremely variable one, and the organisms that utilize this habitat have specialized life histories that have enabled them to adapt to these conditions. Some fish, the salmonids, migrate throught the estuary at certain limited times of the year, and water quality must not impede free migration. Shrimp reproduce in the open ocean and feed in the estuaries. Some fish species use the estuaries only for a spawning and nursery area for their young, and only utilize the estuary at certain times of the year. Oysters remain in the estuary throughout the year; the shelled adults can close their shells and survive a toxicity episode, but their free-swimming larvae are very sensitive, and a population can be destroyed readily by toxic effluents. A good deal of material on the ecological requirements of the important marine species is available and should be applied by those responsible for waste discharges in the estuarine and marine environment in order to protect the important biological communities.
What Do We Really Know About Stream Quality Criteria and Standards?
Authors: Clarke F. E.
Published: August 2009

Generally speaking, quality standards for streams are aimed at insuring maximum practicable utility of water resources for all intended users. Thus, the basic criterion in setting stream quality standards has been to insure absence of those quality factors which are dangerous or otherwise objectionable to the users. Lack of accurate information on effects of many pollutants hinders standardization, as does inability to perform accurate analysis for certain pertinent water components. Even if one could analyze accurately and be sure of the quality he desires in a river, the complex interactions of flow, water composition, seasonal variations and aquatic processes would make it quite difficult to set a single quantitative standard for any quality parameter. In some cases, efforts to reduce pollution are opposed by almost immovable forces of nature and thus are impracticable, if not almost impossible. The proper approach to setting stream quality standards under these circumstances is to accept arbitrary limits or ranges for the most pertinent solutes, suspended materials, and aesthetic factors, while performing the data collection and research necessary to place standardization on a firmer basis.
Moisture Flow and Equilibria in Unsaturated Soils for Shallow Foundations
Authors: Richards B. G.
Published: August 2009

The performance of engineering structures on shallow foundations in Australia is largely dependent on moisture movement and equilibria in soils which are unsaturated. No suitable theory for the foundation design of these structures exists, and this paper outlines briefly a rational design approach based on considerable experimental evidence. This approach is suggested, not as one that has been tried successfully in many instances and therefore one which can be used without reservation, but rather to convince practical engineers that there is a rational solution to this problem which should lead to adequate design techniques in the near future. Techniques for the measurement of the required soil moisture properties are also mentioned and briefly discussed.