bluuebunny/crossref_metadata_2025 huggingface dataset:
Life Testing of Nickel-Chromium Alloys
Authors: Starr CD
Published: February 2009

An evaluation of the life test for 80Ni-20Cr alloys specified in ASTM B 76 has been made. It is shown that the emissivity of the wire is not constant after the pretreatment but requires about an additional four hours at the test temperature. The convection coefficient increases continuously during the life test causing more power to be dissipated by convection as the test progresses.

The small resistance change during the test is a balance between relatively large changes in both the resistivity and the dimension of the sample. A unique expression is developed that enables the change in resistivity to be determined from electrical data. Calculated decreases in chromium and in the diameter of the wire are compared to experimental values. Failure occurs after the alloy has lost about 6 percent chromium and about 10 percent of its cross-sectional area.
Experimental Determinations of the Thermal Conductivity of Fluids by Coaxial-Cylinder Apparatus
Authors: Tsvetkov OB
Published: February 2009

A coaxial-cylinder apparatus has been designed for steady-state and for non-steady-state measurements. The cell was calibrated by using several gases of known thermal conductivity (air, helium). The thermal conductivity of Refrigerant 12 (R 12) in the liquid and gaseous states at temperatures up to 0.95 Tcr and at pressures to 16 MPa has been determined. Erratum to this paper appears in 3(1)
Computer Optimization of Hydraulic System Pressure for Development and Qualification Testing
Authors: Goldenberg K , Collins DG
Published: February 2009

A computer program has been developed to optimize hydraulic pressure system selection for use in the structural testing of aeronautical vehicles. This program will select the minimal number of pressure systems, using available hydraulic cylinders, to match all the simulated flight loads which are applied during a test. Programs were written for Fortran and Advanced Basic language users of the IBM 360/67 time-sharing system or the Varian 620/i stand-alone system. Various options are present in the programs to adjust for unique testing conditions. Since the number of pressure system combinations for large-scale testing can be astronomical, this program has eliminated what was formerly a frustrating, time-consuming, and highly subjective task.
A Spectrophotometric Technique for the Fabric Analysis of Monomineralic Kaolinitic Soils
Authors: Sheeran DE , Krizek RJ
Published: February 2009

A technique for identifying the fabric of kaolin clay by measurement of the monochromatic light intensity emanating from the analyzer of a polarizing microscope is described and evaluated analytically and experimentally. This technique is based on the variation of light intensity with the degree of retardation in an optical compensator. Actual fabrics are simulated by super-imposing the optical properties of 2000 individual kaolinite crystals comprising hypothetical fabric models in which the individual c-crystallographic axis directions are normally distributed about a mean direction with respect to the microscope optics. The intensities are computed for models with different mean c-axis directions and degrees of fabric randomness, which is characterized by the standard deviation of the normal distribution, and these intensities serve as a reference to which experimentally obtained intensities for thin sections of kaolinitic soils with unknown fabric are compared. An appreciation of the fabric homogeneity over the area of a thin section can be obtained by use of an equal area spherical projection plot.
Waste Glass as Coarse Aggregate for Concrete
Authors: Johnston CD
Published: February 2009

The paper reports on the performance of 34 different concrete mixes containing glass crushed to ¾-in. (19-mm) maximum size as coarse aggregate and six reference mixes made with gravel of the same size. Two cements of alkali equivalent 0.58 and 1.13, classifiable as low and high alkali (ASTM C 150-72), in amounts ranging from 400–900 lb/yd3 (237–534 kg/m3 were used in combination with glass both with the fines removed and in the as-crushed condition. Partial cement replacement with fly ash and mixing of glass with gravel aggregate were included in an attempt to find a suitable method of overcoming the expected adverse effects of the reaction between glass and cement alkalis.

On the basis of compressive strength, flexural strength, expansion, and visible surface deterioration recorded up to an age of one year, the results show that in many cases the direct combination of glass with portland cement yields concrete which exhibits marked strength regression and excessive expansion due to alkali-aggregate reaction. The conditions under which performance is satisfactory appear to relate to limiting maximum values of cement content and alkali equivalent. Replacement of 25 to 30 percent by weight of the cement, whether low or high alkali, appears to be an effective and widely applicable method of ensuring good long-term concrete performance, although the minimum required in any given case may be related to cement composition.
Fracture of Rocket Grain Models Subjected to Cooldown: A Study of Temperature-Initiated Fractures of Two-Dimensional Rocket Grain Models
Authors: Francis EC , Deverall LI , Zitzer HJ
Published: February 2009

A method is presented for evaluating two-dimensional crack behavior resulting from thermal cooldown loading of rocket motor configurations in which the grain is bonded to a stiff case. The associated analytical solution used to quantitatively interpret the data is also presented. For three different grain geometries of a brittle epoxy tested, comparison was quite good between analytical predictions (using elastic fracture mechanics methods) and experimental observations. The results of this study can be applied to fracture analyses of solid propellant rocket grains and other structures containing cracks extending partially through the thicknesses of the structures.
Computer-Aided Interpretation of Stress-Strain Curves
Authors: Goodman ML , Jorgensen GJ , Wonsiewicz BC
Published: February 2009

A computer scheme for interpreting stress-strain curves has been developed using two basic algorithms. The first locates the initial linear portion of the curve by comparing the fit of linear and quadratic curves to the data. The second determines the intersection of the offset line with the data. The scheme was tested by comparing computer results with manual results obtained by skilled observers. Results were good: tensile strength and 0.2 percent offset yield strength showed small differences, less than 2 percent. For the modulus and yield strength at 0.01 percent offset, the differences between the various observers were more significant than the differences between the computer results and the observers. For 32 samples (95 specimens) the computer results for the modulus were generally within ±2 percent of the average of the results from four observers and within ±10 percent for the 0.01 percent yield strength. Based on these results, a standard computer program has been developed which generates graphical summaries of the mechanical properties in a form suitable for permanent records.
The Dynamic Response of Metals in Evaluating Stress Corrosion Cracking
Authors: Hochrein AA , Thiruvengadam A
Published: February 2009

An experimental investigation of stress corrosion cracking in metals is reproted for several alloy-corrodent systems. Internal damping measurements are made on the metals in the as-received condition and after they have been exposed to a corrosive environment. Data curves are reported for different grain sizes of 2024-T4 aluminum in a mercury-corrodent environment and for 304 stainless steel in boiling MgCl2. Considerable changes in the diffusion peaks of these alloys are observed following their exposure in a stressed state to the environment in which they are known to be susceptible to stress corrosion cracking. Corroborative tests on electrolytic copper stressed in a corroding environment of air-saturated synthetic seawater indicate no changes in its internal damping characteristics. This material is immune to stress corrosion cracking in the seawater environment.

This study is developed from the idea that metals which are susceptible to stress corrosion cracking exhibit changes in their damping properties after environmental exposure. From the experimental evidence obtained, susceptibility to stress corrosion cracking is associated with decreases in the peak amplitudes of the internal damping curves. The decrease occurs across either the thermal diffusion peak associated with the specimen thickness or with the grain size of the metal. Moreover, for alloys immune to stress corrosion cracking, it is shown that the peak amplitudes remain unchanged after environmental exposure and when compared to the same data curve for the as-received material.

From these studies it is concluded that the decreased amplitudes of the internal friction peaks indicate the susceptibility to stress corrosion cracking. This decrease results from the thermal diffusion effects associated either with the specimen thickness or with the grain size. For nonsusceptible systems, the peak amplitudes remain unchanged after environmental exposure.

The specific aluminum alloy and stainless steel are used in order to demonstrate a basic phenomenon. It should not be construed that neither aluminum alloys nor stainless steels are useful marine alloys.
Interlaboratory Evaluation of ASTM E 84-70 Tunnel Test Applied to Floor Coverings
Authors: Lee TG , Huggett C
Published: February 2009

Results of an interlaboratory evaluation of the American Society for Testing and Materials (ASTM) Test for Surface Burning Characteristics of Building Materials (E 84-70), involving eleven laboratoires and nine materials including four carpets, are reported. Data on flame spread, smoke, and fuel contribution were analyzed statistically to determine the reproducibility and repeatability of the test method. Selected physical characteristics of each tunnel are tabulated and compared relative to specifications in the test method. The between-laboratory coefficient of variation (reproducibility) in flame spread classification (FSC) was found to range from 7 to 29% for the four carpets and from 18 to 43% for the other materials tested. The between-laboratory coefficients of variation for smoke developed and fuel contribution ranged from 34 to 85% and from 22 to 117%, respectively, for all materials tested. The causes of higher variability in smoke and fuel contribution measurement between laboratories are not definitely known but may reasonably be attributed to variations in tunnel construction, instrumentation, and operation in different laboratories.
Spectral Energy Distributions and Aging Characteristics of Fluorescent Sunlamps and Blacklights
Authors: Mullen PA , Kinmonth RA , Searle NZ
Published: February 2009

The spectral energy distributions of commercially produced 20-W fluorescent sunlamps and blacklights designated for use in the revision of the American Society of Testing and Materials (ASTM) Recommended Practice for Exposure of Plastics to Fluorescent Sunlamp (D 1501-71), were measured between 250 and 600 nm at 3-nm intervals. Two types of blacklights with the same designation (F20T12B1), but with different emission characteristics, are manufactured. The decrease in emission intensity with hours of use varies with type and source of lamps. The best simulation of sunlight in the ultraviolet region below 360 nm is given by the combination of one sunlamp with one of each type of blacklight.
Finite Element Modeling of Magnetic Field/Defect Interactions
Authors: Hwang JH , Lord W
Published: February 2009

Defect modeling and the prediction of magnetic field/defect interactions is of importance to the further refinement of electromagnetic methods of defect detection and categorization. Finite element methods are particularly suited to the analysis of field distributions within magnetic structures having complex boundary geometries and nonlinear B-H characteristics. This paper describes operational aspects of the finite element technique and shows how such methods can be applied to the analysis of electromagnetic methods of nondestructive testing, by predicting the magnetic field distribution around a rectangular slot in the surface of a circular ferromagnetic bar carrying an axial magnetisation current.
Effect of Specimen Thickness on Delay in Fatigue Crack Growth
Authors: Shih TT , Wei RP
Published: February 2009

The effect of specimen thickness on delay in fatigue crack growth, produced by load interactions in variable-amplitude loading, was examined. Experiments were carried out on 7075-T6 aluminum alloy sheets. The results indicate that delay is a function of specimen thickness. This influence of thickness, along with variations in behavior among different materials, suggest that extensive extrapolation of existing data should not be made.
Inverse Method for Determining Approximate Stress-Strain Behavior of Soils
Authors: Farzin MH , Corotis RB , Krizek RJ
Published: February 2009

A new approach is advanced to analyze and interpret experimental data from a compression test on a cylindrical soil specimen. With a knowledge of the applied axial and radial pressures, the overall axial deformation, and radial deformations at several discrete points on the boundary, a piecewise linear continuum model is used to calculate approximate secant and tangent values for the modulus and Poisson's ratio of two different soils. Although soil moduli are found to be highly stress dependent and significantly influenced by the dry density of the specimen, values of Poisson's ratio are relatively insensitive to these variables. Results obtained by use of this new approach can be used to evaluate the assumptions that are frequently incorporated into simpler interpretation procedures. In particular, a comparison of secant and tangent moduli determined by the proposed method with other modulus values determined by commonly used procedures reveals substantial differences and suggests the use of extreme caution when selecting values of soil parameters for use in mathematical models of soil mechanics problems.
Stress Relaxation in Tension of CA 172 Copper-Beryllium
Authors: Goel RP
Published: February 2009

Stress relaxation data on commercially available copper-beryllium alloy 172 are presented. Test samples were subjected to strains of up to 2% and temperatures from 25 to 181°C. The data show that a high degree of relaxation occurs at higher temperatures and relaxation was found to be independent of the initial stress levels. Time-temperature plots of stress relaxation are presented for designing accelerated relaxation tests on the copper-beryllium alloy tested. The material in the tested condition is generally not used in spring applications and thus results of Austen which compare stress relaxation characteristics of copper-beryllium alloy 172 in the aged and unaged conditions are also presented.
The Strength of Concrete Subjected to Compression-Compression-Tension Stress Systems
Authors: Mahmood N , Hannant DJ
Published: February 2009

An experimental investigation into the failure of a particular concrete subjected to stress fields varying between biaxial compression, compression-compression-tension, and uniaxial tension is described. The results are compared with published data for related stress systems, and the shape of the failure surface in the compression-tension quadrants of stress space is shown to be of the simple hexagonal pyramid type.
Evaluation of an 80Ni-20Cr Alloy in an Enclosed Heating Element
Authors: Starr CD
Published: February 2009

Accelerated life tests on enclosed heating elements were conducted using a constant power cyclic type of test that caused failure in about 500 h. The results were compared to those on a cyclic test run near rated power of the element where failure occurred in approximately 5000 h. The change in both the hot and cold resistance of the heater wire in the accelerated test was about five times greater than in the rated power test. This correlated with a much larger loss in chromium and silicon from the heating coil tested under accelerated conditions.

The cold resistance of the MgO was always over 100 Mω during the test. The hot resistance of the MgO decreased during the test but was always over 3000 times the resistance of the heater coil. This correlated with X-ray fluorescence analyses of the MgO which disclosed no chromium in the midpoint of the MgO to form a continuous conductive path.

The emissivity and convection coefficient of the sheath were essentially constant during the test at rated power.

The accelerated test method selected for range-type enclosed elements is not suitable for predicting the service life of an enclosed element. It is usable as a quality control test.
An Ultrasonic Technique for the Measurement of Residual Stress
Authors: Noronha PJ , Wert JJ
Published: February 2009

An ultrasonic shear wave technique to measure stress in metals is described. The technique utilizes a pulse-echo system operating at 7 MHz to measure changes in the time of travel of the ultrasonic shear wave to 1 part per million. Linear changes in the velocity of a shear wave occur with stress and are dependent on the higher order elastic constants of the material. The linear change in velocity with stress allows the definition of a constant called the stress acoustic constant for the material. The amount of birefringence in a specimen is measured, and after accounting for the portion caused by anisotropy of the material, the remainder gives an accurate measure of the residual stress in the material. The amount of birefringence caused by anisotropy is a constant for specimens having the same nominal mechanical and thermal treatments. Measurements using the ultrasonic technique of simulated residual stress, introduced by bending of a 6-ft (1.8-m) section of A-36 steel I-beam, yielded values in the vicinity of those measured using strain gage and O-ring techniques. Application of this technique to the measurement of other simple states of stress is suggested, along with the precautions to be observed for measuring stress.
Interlaboratory Test for Wool Fineness Using the PiMc Particle Measurement Computer System
Authors: Pohle EM
Published: February 2009

The application of a particle measurement computer (PiMc) system for measuring average fiber diameter and variability of wool and other animal fibers has been demonstrated. Three lots of wool top and three lots of scoured wool cores representing fine (19 to 20 µm), medium (27 to 28 µm), and coarse (34 to 35 µm) grades were used. Preparation of slides of cut wool fibers and different mounting media were tested. Based on analyses from results of two laboratories, testing six lots of wool, only one had a difference in average fiber diameter between methods that was significant at the 0.05 probability level. This difference was 0.32 µm. Also, the analysis did not detect any bias or systematic error attributable to the PiMc system, nor was the difference between laboratories using different machines significant. The system reproduced its measurement results very closely. In this study, there were 24 comparisons and all differences were within theoretical differences due to chance.

The PiMc procedure of measuring fibers is over twice as fast as the microprojector and takes one less person. Alternative sampling procedures are presented showing how the sampling error can be reduced with a fixed number of fibers analysed. Based on these results, a standard computer program can be developed which generates summaries of the diameter and variability properties for wool and other animal fibers in a printout form suitable for a permanent record.
Note on Performance of Tapered Grip Tensile Loading Devices
Authors: Jones MH , Brown WF
Published: February 2009

Alignment results are presented in terms of percent bending for a quick release, tapered grip, tensile loading device that has been proposed for testing sharply notched specimens of aluminum and magnesium alloys by a Task Group of the ASTM Committee E-24 on Fracture Testing of Metals. The results show that the bending introduced by the fixtures is strongly dependent on their relative rotational positions in respect to the loading rods which adapt them to the tensile machine. For one set of tapered grips the highest bending was about 15%. Recommendations are made for improvement in the design of the tapered grips which should reduce the bending stresses substantially.
Determination of Low Levels of Chloride in Hardened Portland Cement Paste, Mortar, and Concrete
Authors: Berman HA
Published: February 2009

Errors occur in the analysis of cement and concrete samples containing less than 0.02% Cl when the potentiometric ion electrode titration method published earlier is used (Journal of Materials, JMLSA, Vol. 7, No. 3, 1972, pp. 330–335). Slow nucleation of AgCl and slow equilibration produce large initial voltage increments which may be mistaken for the end point. A preliminary addition of 1 or 2 ml of 0.01 N NaCl delays the end point and places it in a nonambiguous region of the titration. Examples are given of titrations with and without the NaCl addition and a technique for handling millivoltmeter needle instability is described.
Long-Term Dosimetry
Authors: Morgan WC
Published: February 2009

It should be assumed that the shape of the neutron energy spectrum and the neutron flux intensity will change during a long-term materials irradiation. The neutron dosimetry effort should have three primary goals: (1) dosimetry should be concentrated on the range of neutron energies of most importance for the radiation damage process; (2) the effective half-lives of the dosimeters should be less than the irradiation duration; and (3) appropriate corrections should be made for changes in the neutron spectrum and flux intensity during the irradiation.
Damage Function Analysis
Authors: McElroy WN , Simons RL , Doran DG , Odette GR
Published: February 2009

This paper reviews the current status and procedures associated with damage function analysis as it applies to the development, design, and operation of nuclear reactors. Damage function analysis provides a systematic applied engineering approach for estimating fluence limits and their uncertainties for neutron-induced property changes for reactor materials and components. A summary of derived, quasi-empirical damage functions is provided and emphasis is placed on the need for standardization in their definition and application. Included is a discussion of the calculation and use of displacement production as an energy-dependent measure of exposure and displacement cross sections for damage function analysis. A brief review is given of the current and projected status of the neutron flux-fluence spectra characterisation that is essential for damage function analysis.
Cycle-Dependent Softening in Notched Steel Specimens
Authors: Czoboly E , Sandor BI
Published: February 2009

The results of experiments on Society of Automotive Engineers (SAE) 1043 steel show that the cyclic stress-strain response in small regions of a notched specimen is not necessarily the same as that obtained in tests on smooth specimens of the same metal. At the roots of notches (two different notch radii were used) plastic flow occurs at the same cyclic lives as in unnotched specimens, when the longitudinal total strains are similar. Cyclic plasticity develops in many fewer cycles near the notches than in smooth specimens under the same longitudinal total strains. The more sharply notched specimens soften more rapidly at locations near the notches than the less severely notched ones under identical longitudinal strains.
Evaluation of Deformation Phenomena of Metals for Fatigue Analysis
Authors: Jhansale HR
Published: February 2009

Simple calculations for estimating extremes in fatigue life of metals, with or without accounting for cycle-dependent hardening, softening, and mean stress relaxation, are presented. These calculations aid in assessing the importance of cyclic deformation properties in cumulative damage procedures. An SAE 1045 quenched and tempered steel is considered for illustration. In general, cycle-dependent deformation phenomena may be important only in intermediate and long life situations. The sensitivity of predicted life to cyclic hardening or softening depends on the degree of hardening or softening a material exhibits, whereas in the case of mean stress relaxation it depends on the shape of the cyclic stress-strain curve or the strain hardening exponent. However, the need for a proper accounting of cyclic history, recognized as the “cycle counting problem” in fatigue literature, is the most important requisite of a cumulative damage analysis. Two alternative approaches of dealing with the cycle counting problem are discussed.
Polymeric Materials for Concrete
Authors: Idorn GM
Published: February 2009

Session III-9 of the VI International Congress of the Chemistry of Cement (held in September 1974 in Moscow) dealt with cement-polymer materials, or, as it appears from the papers presented, with various types of composites using ordinary cements and organic monomers together as binding materials.

Both the manufacture and the characteristics of these materials open up new potentials and problems to technology and construction development: potentials, because the excellent functional capabilities that can be attained with these composites will be much needed in further technical development; problems, because civil engineering has come to know ordinary cements and concrete quite well over a period of about 150 years' evolution, but is not as familiar as yet with these materials' development based upon modern scientific research.

This paper presents the “pros and cons” of this entirety, based upon the contents of the principal paper “Cement-Polymer Materials,” by G. M. Idorn and Z. Fördös, presented to the above session of the Cement Chemistry Congress.
Fatigue of Ferrocement
Authors: McKinnon EA , Simpson MG
Published: February 2009

Ferrocement is a composite of reinforcing wire and cement mortar that is used in thin shell construction. Several layers of wire are impregnated with the cement mortar, resulting in a material that behaves synergistically. Ferrocement is becoming widely used for private and commercial boat hulls because of its formability, economy, fire resistance, and low maintenance. In this study, several variations of ferrocement were fabricated and subjected to constant amplitude cyclic loads up to ten million cycles. Stress versus cycles-to-failure plots were developed and comparisons between the data for various ferrocement modifications were made.
Connected Air Voids Content in Permeable Friction Course Mixtures
Authors: Alvarez Allex E. , Epps Martin Amy , Estakhri Cindy
Published: February 2009

Current hot mix asphalt (HMA) mix design procedures used to determine the optimum asphalt content for permeable or porous friction course (PFC) mixtures are based primarily on total air void (AV) content. Durability and functionality of PFC mixtures are also related to the total AV content. However, the connected AV content (defined as the proportion of AV that form connected pathways for air and water transport through PFC mixtures) may provide more insight into the mixture structure in terms of the AV content directly associated with functionality and durability properties and constitute an alternative parameter to conduct PFC mix design and evaluation. This study evaluated two laboratory methodologies (vacuum and dimensional analysis) for determining water-accessible AV content and two types of analysis to compute interconnected AV content based on X-ray Computed Tomography (X-ray CT) and image analysis techniques. Although both the interconnected AV content and water-accessible AV content constitute determinations of connected AV content, different nomenclature was used to differentiate the origin of the calculation. Dimensional analysis with application of vacuum and X-ray CT and image analysis with inclusion of surface AV are recommended for determining water-accessible AV content and interconnected AV content, respectively. Future work should focus on investigating the use of connected AV content as an alternative parameter to integrate in mix design and laboratory and computational evaluation of PFC mixtures.
Computer Simulation of the Tension Test: Effect of Testing Conditions
Authors: Baptista AA , Fortes MA
Published: February 2009

Tension tests performed at constant crosshead speed have been simulated in a computer, and stress-strain, load-displacement, and strain rate-strain curves in uniform deformation under various testing conditions were obtained. Hart's phenomenological description of the plastic deformation was used together with a simple form for the stress and strain rate dependence of the material parameters that appear in this description. Various materials were simulated and the effects of crosshead speed, initial “hardness” state, specimen dimensions, and machine stiffness were studied in each case. The implications of these results in the specification and interpretation of tension tests are discussed. Particular attention is given to the relation between the onset of plastic instability and the point of maximum load in the tension test.
Relationships Between Low-Cycle Fatigue and Fatigue Crack Growth Rate Properties
Authors: Kaisand LR , Mowbray DF
Published: February 2009

A fracture mechanics model is developed to describe crack growth in a low cycle fatigue test specimen. The model involves a J integral analysis and a growth rate hypothesis in terms of ΔJ. A relationship for low cycle fatigue is derived that has strain energy density as the controlling variable. This relationship reduces to well-known low cycle fatigue equations in terms of elastic and plastic strains for the limiting conditions of fully elastic and fully plastic strain fields. These equations in turn define relationships between the material properties commonly employed to describe low cycle fatigue and fatigue crack growth rate data. The latter are used to demonstrate the facility of predicting fatigue crack growth rate curves from standard low cycle fatigue properties.
Nondestructive Evaluation of Hygrothermal Effects on Fiber-Reinforced Plastic Laminates
Authors: Bar Cohen Y , Meron M , Ishai O
Published: February 2009

Ultrasonic tests were performed on glass-, carbon-, and Kevlar®-fiber-reinforced plastic laminates that had been exposed to varying hygrothermal ambient conditions. Results reveal similar trends between ultrasonic attenuation measurements and the degree of material degradation as reflected by laminate strength characteristics. A slow decrease in attenuation with almost no degradation was found to be common in all laminates exposed to cold water immersion. Hot water immersion seems to affect significantly glass-fiber-reinforced and Kevlar-fiber-reinforced plastic laminates, which exhibited an increase in attenuation with exposure time. Such a trend is attributable to the degradation process found to be significant in glass-fiber-reinforced plastics and almost nonexistent in the carbon-fiber-reinforced plastic systems.
A Rapid Technique for Estimating Fiber Lengths of Mineral Wools and Other Staples
Authors: Atkinson AW , Lancaster JM
Published: February 2009

A rapid and reproducible technique is described for estimating the mean length of staple fiber. A pad or felt prepared from the fiber is separated into two parts giving a torn edge, the diffuseness of which is proportional to the mean fiber length. This diffuseness may be quantified by illuminating the torn edge and measuring the changing light attenuation in a direction perpendicular to the line of separation. Absolute estimates of length are made by reference to calibration standards. The method is of particular value with brittle fibers such as mineral wools, for which it can otherwise be difficult to obtain reliable length data.

The techniques described in this paper form the basis of patent applications in several countries.
The Effect of Varying Mean Stress on the Dimpled Loaded-Hole Fatigue Strength of 2024-T3 Aluminum Alloy
Authors: Kuc AP , Shewchuk J
Published: February 2009

The effect of mean stress on the fatigue strength of notched and unnotched metal components is well known. Recently, a residual stress technique known as dimpling has been developed and used for improving the zero-to-tension fatigue strength of loaded holes in thin sheet material. Experiments were conducted to investigate the effect of varying stress ratio on the dimpled loaded-hole fatigue strength.

In tension-tension fatigue tests on nominally 1.6-mm thick 2024-T3 (Unified Numbering System [UNS] A92024) aluminum alloy specimens, dimpling gave fatigue strength improvement factors of 3.67, 2.78, and 1.5 at ratios of minimum to maximum stress of 0.0, 0.5, and 0.9, respectively, all at 107 cycles to failure. The strengthening effect of dimpling is found to decrease with decreasing life (higher maximum stress) and tends to become independent of stress ratio at low values of life.
Rate Sensitive Tensile Impact Properties of Fully and Partially Loaded Unidirectional Composites
Authors: Hayes SV , Adams DF
Published: February 2009

An instrumented tensile impact test system with partial loading capabilities has been developed and tested. Hardware development included a low mass gripping system for tensile impact and a vibration-damped base and load cell. A standard pendulum type impact testing machine was modified for use. The rate sensitive material properties of unidirectional glass/epoxy and graphite/epoxy composite materials were investigated. The micromechanics of fracture within the composite caused by impact were studied, using partially loaded impact test specimens and scanning electron microscopy.
Explanation of the Empirical Factor Recommended in the Permanganate Titration of High Chromium Stainless Steel from Tristumulus Chromaticity
Authors: Bhuchar VM , Majumdar AK
Published: February 2009

Excess results of 0.6% are obtained for chromium in high chromium steels when analyzed according to the ASTM Chemical Analysis of Steel, Cast Iron, Open-Hearth Iron, and Wrought Iron (E 30). The excess results have been explained on the basis on the tristimulus chromaticity of the human photocell, that is, the eye. It is concluded that the 0.6% excess results are necessary because: (1) 6% of the excess is for the permanganate pink to show itself in colorless solution, (2) 30% of the excess is for the permanganate pink to overcome the green hue of the chromium and nickel sulfates present in the solution, and (3) the balance 64% of the excess is needed because of the oxidation of trivalent chromium by permanganate. The trichromatic coordinates of nickel sulfate and chromium sulfate solutions have been calculated both according to Commission Intérnationale d' Eclairage (CIE) 1931 recommendations, namely, x,y coordinates and also according to a perceptually more uniform chromatic system of color matching, that is, u,v coordinates.
A Dispersant Effectiveness Test Based on the Drop-Weight Interfacial Tension Test Method
Authors: Rewick RT , Sabo KA , Smith JH
Published: February 2009

A simple apparatus has been developed for evaluating the effectiveness of surfactants in dispersing No. 6 fuel oil. The measurement, obtained by the drop-weight method and expressed in terms of the critical micelle concentration, is based on reduction of the interfacial tension between oil and water. The procedure described here is faster and less costly than other dispersant test methods.
Effect of Temperature on Brick Suction
Authors: Davison JI
Published: February 2009

A brief study has been carried out on the effect of temperature on brick suction or initial rate of absorption (IRA), which is a factor in determining the amount of water extracted from mortar placed between bricks. This is important during cold weather construction when the amount of water extracted determines the pore space available for expansive forces if the remaining water freezes at an early age.

The study included extruded clay and shale, dry-press clay, sandlime, and concrete bricks selected to include a range of control IRA (suction) values. Values were determined at 20, 10, −1.5, and −10°C with water at 20°C and at 20°C with water at 10°C.

Results indicate a small reduction in suction with dropping temperature for low absorption bricks and a substantial drop for high absorption extruded and dry-press clay bricks at temperatures below 0°C. It is concluded that bricks should be at temperatures above 0°C to ensure maximum potential for reducing the moisture content of mortar during winter construction.
Measuring the Abrasion of Transparent Materials with Hazemeters
Authors: Ladson JA , Evans RE
Published: February 2009

Assessments of the amount of light scattering or haze caused by the abrasion of transparent plastics when measured with a collimated beam hazemeter at reduced beam diameter are shown to be affected by differences in amount of beam reduction. The data presented illustrate that most of the light scattered from a sample abraded with a Taber Abraser® is found in the angular cone between 0 and 2.5°. This is also the region subtended by the 1.3° annulus between the lightbeam and the exit port of a hazemeter conforming to ASTM Test for Haze and Luminous Transmittance of Transparent Plastics (D 1003). For this reason, measurement of abraded specimens is very sensitive to the beam geometry of the hazemeter.

Since conventional (nonabraded) specimens produce very diffuse scattering patterns, changes in beam diameter and thus the size of the annulus do not significantly affect haze readings. However, to obtain reproducible results on abraded specimens, modification is required to the geometry of the hazemeter so that the image of the entrance window is focused at the exit port of the sphere. Good interlaboratory agreement was obtained when suitably modified hazemeters were used to measure a set of polymethylmethacrylate (PMMA) specimens. Modifications that have been made to ASTM Test for Resistance of Transparent Plastics to Abrasion (D 1044) are discussed.
Development of a Scratch-Test Instrument for Thick Wall Coverings
Authors: Jaegermann C , Becker R , Relis M
Published: February 2009

While establishing performance specifications for building elements, the authors have recognized the fact that there is no available test method for the direct investigation of scratch resistance of thick wall coverings. This has led to the development and manufacture of a prototype scratch-test instrument. Verification tests have been carried out on 18 types of laboratory samples and three existing walls. The research included investigation of repeatability of results, influence of speed of operation, influence of operator, performance fitness, and accuracy of results. Finally grading of the “degree of damage,” according to the depth of scratch has been deduced. Acceptance criteria for different functional uses are suggested.
A Microcomputer-Based System for Instrumented Impact Testing
Authors: Crawford RJ , McFerran NV , Ali A
Published: February 2009

As part of a program of research to study the influence of processing conditions on the impact strength of injection moldings, a relatively inexpensive modification has been made to an Izod type impact test machine so that fully instrumented tension impact tests may be carried out. The principle of operation of the system is described in detail. Basically a quartz load cell in the base of the test machine sends the impact signal through a charge amplifier to a transient recorder. Having thus stored the signal, the data is passed to a microcomputer where it is transformed from force-time to force-deformation. The trace is integrated to provide the impact strength of the test sample. This value is then printed out along with characteristic details of the sample, including a graph showing the shape of the force-deformation relationship.

The main improvement this type of system offers over conventional single value impact testing lies in the convenience of use and increased amount of information available on the type of fracture that has occurred. This is supported by typical system printouts and photographs of fractured samples.
Dynamic Effective Young's Modulus of Thin Adhesive Layers in Bonded Joints
Authors: Ramakrishnan N , De AK , Suryanarayan S
Published: February 2009

In recent years, adhesive bonding has shown promise in replacing or supplementing conventional methods of joining such as riveting, welding, mechanical fastening, and so forth. To evaluate the dynamic characteristics of bonded structures, it is necessary to know the dynamic characteristics of bonded joints. This paper presents the development of an experimental technique to evaluate the dynamic effective Young's modulus (DEYM) of a thin adhesive layer sandwiched between metallic adherends. Considering the difficulties in measuring the strain across the adhesive layer, it was decided to avoid the measurement of strain in this technique. The joint is introduced in a cantilever beam, which causes its resonant frequency to drop because of the lower modulus of the adhesive layer. An analytical technique has been developed to evaluate its modulus from the drop in resonant frequency.

Experiments were conducted on two types of adhesives. It was observed that the DEYM is significantly influenced by the thickness of the adhesive layer. A thin adhesive layer has a higher modulus, which is less sensitive to change in the frequency. A thick adhesive layer, on the other hand, permits wider tolerances on the joint surfaces and makes fabrication easier. An optimum adhesive layer thickness has to be chosen as a compromise depending on the various joint parameters. The technique described in this paper can be used for such studies.
Introduction to Papers Presented at the Symposium on Ultrasonic Measurements of Stress
Authors: Proctor TM
Published: February 2009

Ultrasonic measurements of the variation of elastic modulus with stress have been done for more than 30 years. The inverse problem of measuring residual stress by ultrasonic means is still poorly understood. As a result, the measurement of residual stress by ultrasonic means has not been a successful engineering method. A symposium describing the present state of the art has been held and the written record of some of the contributors to it is presented by the following set of papers.
Ultrasonic Measurement of Axial Stress
Authors: Heyman JS , Chern EJ
Published: February 2009

Several applications of ultrasonic techniques are gaining acceptance for accurate preload determination of critical fasteners. In this presentation, one class of techniques based on continuous wave ultrasonics is examined in detail, with benefits and limitations discussed as they apply to accurate determination of fastener preload. The theory of acoustic propagation in strained media is reviewed as it applies to bolt geometries. Propagation measurements in these geometrics require an understanding of guided-wave effects which can influence stress determination. However, studies of the acoustic spectra of rods identify diffraction and resulting mode conversion as the main artifact for such a measurement. The acoustic spectra, obtained with a novel tone burst spectroscopy method, clearly show mode conversion effects at low frequencies to be absent at high frequencies.

Changes in the acoustic spectra are shown to accompany applied stress and suggest an instrument technique for measuring changes in fastener strain. The method, called a Reflection Oscillator Ultrasonic Spectrometer (ROUS), is discussed with an improved technique called Pseudo Continuous Wave Method (PCW) described. Data presented are obtained with the PCW for strain in several engineering materials.

Bolt geometry is shown to have an influence on the stress measurements. In particular, percent fastener length under load is evaluated for its effect on material strain measurements. A computer model predicting a linear dependence on the percent of fastener under load is verified using the PCW technique. Other aspects of bolt geometry are discussed including poor geometry bolts, bolts with transverse holes, and bolt-loading anisotropy. Experimental techniques for performing measurements on fasteners with poor geometry are discussed.
Ultrasonic Measurement of Residual Stress in Textured Materials
Authors: Arora A , James MR
Published: February 2009

A method is developed that determines the state of stress in a test piece in the presence of texture, that is, preferred grain orientation. This method uses frequency domain analysis of the acoustic birefringence by which an ultrasonic shear wave propagating in a material travels at slightly different velocities in the polarizations parallel and perpendicular to the axes of texture or stress. Results obtained from a Ti-6%Al-4%V block confirm that the velocity shift is linearly dependent on the amount of stress, but is independent of frequency in the case of stress as opposed to the texture. Experimental considerations involving transducer characteristics, bond (transducer to specimen) characteristics, specimen size, and signal processing are discussed in relation to the reliability and repeatability of the data.
Anharmonic Properties of Solids from Measurements of the Stress Acoustic Constant
Authors: Cantrell JH
Published: February 2009

The description of anharmonic properties of solids, such as thermal expansion or the interaction of thermal and acoustic phonons, involves generalized Grüneisen parameters that describe the strain dependence of the lattice vibrational frequencies. In the Debye model of specific heats the lattice vibrations are approximated by long wavelength acoustic standing-wave modes of a dispersionless elastic continuum in which the generalized Grüneisen parameters are frequency independent. Recently, a new ultrasonic measurement technique has been developed which uses such long wavelength acoustic modes to monitor axially induced accumulated static loads in threaded fasteners from a state of zero initial stress. A fundamental calibration parameter of the new technique is the stress acoustic constant defined as the fractional change in the resonant standing-wave frequency in the solid cavity per unit applied axial stress. We generalize the equations of elastic wave motion and their solutions to include nonzero homogeneous initial stresses and redefine the stress acoustic constants to include the effect of initial stress. The relationship between the newly defined stress acoustic constants and the strain-generalized Grüneisen parameters is derived, and the implications to material anharmonicity and nonlinear thermoelasticity discussed.
High Temperature Cyclic Oxidation Furnace Testing at NASA Lewis Research Center
Authors: Barrett CA , Lowell CE
Published: February 2009

A standardized method of testing the cyclic oxidation resistance of various alloys in static air up to 1200°C has been developed and routinely used at the National Aeronautics and Space Administration (NASA) Lewis Research Center. Test specimens are automatically raised and lowered into a resistance wound furnace for a series of fixed-interval heating and cooling cycles. Spall catchers collect the accumulated spall from each specimen. The specimens are weighed intermittently to generate specific weight change with time data. At various test times the specimens and the accumulated spall are analyzed by X-ray diffraction. A computer program is used to print out the specific weight change versus time data and the X-ray data in tabular form and to plot the specific weight change versus time data in a publishable format. The data are also organized and indexed. So far several hundred iron-, nickel-, and cobalt-base alloys have been tested using this basic procedure and will form the basis of a series of cyclic oxidation handbooks to be published by NASA. Such specific weight change/time data have been used to estimate the oxidative metal consumption by several computer modeling techniques both to rank alloys and to estimate life.