bluuebunny/crossref_metadata_2025 huggingface dataset:
Computerized Near-Threshold Fatigue Crack Growth Rate Testing at Cryogenic Temperatures: Technique and Results
Authors: Liaw PK , Logsdon WA , Attaar MH
Published: December 2008

A computerized near-threshold fatigue crack growth rate (FCGR) test method has been applied at cryogenic temperatures. Near-threshold FCGR tests were conducted at room and cryogenic temperatures as low as 4.2 K (−452°F) on JBK-75 (modified A-286) stainless steel (base and autogenous gas-tungsten arc weld metal). Near-threshold crack growth rates in both the base and weld metal tended to decrease with decreasing temperatures from 297 to 4.2 K (75 to −452°F). At each temperature, the JBK-75 base material typically demonstrated a higher threshold stress intensity range than the weld material. Unlike the room temperature results, at 77 and 4.2 K (−320 and −452°F) near-threshold crack propagation rates were insensitive to load ratio (R = Pmin/Pmax). The decreased dependence of near-threshold FCGR data on load ratio at low temperatures appears to be in agreement with a crack closure model.
Low Temperature and Loading Frequency Effects on Crack Growth and Fracture Toughness of 2024 and 7475 Aluminum
Authors: Abelkis PR , Harmon MB , Hayman EL , Mackay TL , Orlando J
Published: December 2008

An experimental program was conducted to investigate the effect of low temperature (219 K [−65°F]) on the crack growth and fracture toughness of two aluminum alloys, 2024-T351 and 7475-T7651. Crack growth tests were performed with center-cracked panels and constant-amplitude and spectrum loadings. The spectrum represented a transport wing lower surface. The results show the 2024 alloy properties at low temperature to be equal to or better than the properties of that alloy at room temperature (RT), whereas some of the 7475 alloy properties decreased. In addition, tests were performed at RT and low temperature on 2024-T3 to evaluate the effect of loading frequency on crack growth. The results indicated a faster crack growth rate at lower frequencies.
Fatigue Crack Growth Behavior in Mild Steel Weldments at Low Temperatures
Authors: Kitsunai Y
Published: December 2008

Fatigue crack growth rates for the base metal and welds of SM50A steel weldments were determined at temperatures ranging from room temperature down to 123 K. For the base metal, crack growth rates between room temperature and 188 K decreased slightly with decreasing temperature. At 123 K, the growth rate of the base metal increased markedly because of cyclic cleavage during striation growth. For the welds, no systematic correlation can be made between temperature and growth rate. The growth rates of the welds were lower than those of the base metal regardless of temperature because the crack tips in the weld specimens always existed in the field of compressive residual stresses. Therefore the growth rates of the welds were dominated by residual welding stress rather than temperature. The crack growth rates of the base metal and the welds with residual stresses under low temperatures were closely correlated with the effective stress intensity factor range (ΔKeff), estimated based on crack closure measurements, when the crack growth mechanism was dominated by striation formation.
A Concise Feature Set for the Pattern Recognition of Low-Temperature Luminescence Spectra of Hazardous Chemicals
Authors: Sogliero G , Eastwood D , Gilbert J
Published: December 2008

As computer libraries of corrected, digitized, low-temperature luminescence, and fluorescence spectra are expanded, it becomes increasingly important to specify a succinct and pithy set of features that will accelerate the library search for a matched spectrum to an unknown sample spectrum. While feature sets for other types of spectra have been investigated extensively, feature sets for fluorescence and luminescence spectra have not been fully explored as yet. Using a specially generated library of lowtemperature luminescence spectra of approximately 60 hazardous chemicals, a feature set consisting of only six components (the first four noncentral sample moments of the spectrum, the approximate normalized area under the spectral envelope, and the wavelength corresponding to the location of the maximum intensity) performs exceptionally well in a test using a cluster analysis involving over 2000 pairwise comparisons of the feature sets.
Load Concentration Factors in a Chain-of-Bundles Probability Model
Authors: Fukuda H
Published: December 2008

A chain-of-bundles probability model is often used to predict the strength of unidirectional composites. In this model, it becomes necessary first to calculate stress redistribution due to fiber breakage. A rather simple estimation of this stress redistribution has hitherto been conducted. This paper examines it in a more precise manner by adopting a shear-lag assumption. Both ordinary composites and hybrid composites are analyzed. Two idealized models are chosen in the analysis: (1) an infinite model in which a group of broken fibers is embedded in an infinite number of continuous fibers, and (2) a repeating model in which broken fibers appear repeatedly. Actual load concentration factors will fall in between the above two extreme cases. Results of load concentration factors are presented in terms of the number of fractured fibers. The present analysis provides data for a statistical calculation of the strength of composites.
Effect of Graphite Fiber/Epoxy Matrix Adhesion on Composite Fracture Behavior
Authors: Drzal LT , Rich MJ
Published: December 2008

Very little fundamental information is known about the mechanism by which surface treatments and surface finishes influence fiber-matrix adhesion and composite properties. This study is directed at elucidating the molecular mechanisms by which surface treatments affect fiber-matrix adhesion and composite properties.

A polyacrylonitrile based graphite fiber and epoxy matrix were chosen as a model system. Substantial changes were detected in the value of the interfacial shear strength attainable for this fiber-matrix system when only the interphase region was altered. Observation of the interphase under load and high resolution transmission electron microscope (TEM) of ultramicrotomed sections were able to discriminate between various failure mechanisms operating at the fiber-matrix interphase.

An untreated graphite fiber possesses a weak structural layer that can not support high shear loads. When this fiber is stressed in shear the fiber separates from the matrix. Failure analysis shows that the interfacial fracture path involves some fiber fracture in the outer layers as well as along the interface. Surface treatment removes this defect laden outer layer of the fiber and also adds surface chemical groups which increase the interaction with the matrix by a factor of two. The fracture path becomes purely interfacial with no fiber failure. Both mechanisms, that is, surface chemical interactions and morphological changes in the outer layers of the fiber contribute to the increased interfacial shear strength attainable with the surface treated fiber in the same matrix.

Application of a fiber surface finish increases the interfacial shear strength. The mechanism by which this can occur is through the creation of a brittle interphase around the fiber. The original finish layer devoid of crosslinking agent receives some through diffusion from the surrounding resin mixture. This results in a layer more brittle than the matrix. Stress analysis shows that this brittle layer promotes better shear transfer resulting in an increased interfacial shear strength. However, at the fiber breaks, matrix cracks grow perpendicular instead of parallel to the fiber surface under shear loading because of this brittle layer.

Small composite specimens containing the fibers with various surface treatments and possessing the various failure modes were fractured in order to determine if the interphase effects had an influence on composite properties. Results indicate that the single filament behavior is observable in the composite.
Fracture Toughness of Fiber-Polymer Cement Concrete System
Authors: Horiguchi T
Published: December 2008

Fracture mechanics parameter and energy absorption capacity of fiber-polymer cement concrete are experimentally evaluated and then KIc, JIc, toughness index, modulus of toughness, impact toughness, and bending toughness are examined by means of an analysis of factorial experiments.

Five factors—namely, steel fiber geometry, volume fraction of fiber, unit polymer content, water-cement ratio, and relative notch depth—are assumed to affect these fracture mechanics parameters and toughness parameters.

Experimental scatter of the test method of these fracture parameters is discussed in order to determine the testing method of toughness property of the fiber-polymer cement concrete composite. The confidence interval and significant factors effect are also calculated. Finally, the usefulness and the limitation of fracture mechanics for the application of the cementitious concrete design are discussed.
Knee Point and Post-Failure Behavior of Some Laminated Composites Subjected to Uniaxial Tension
Authors: Ohira H , Uda N
Published: December 2008

To investigate the phenomenon of initial failure, the post-failure behavior and the behavior under unloading and reloading, uniaxial tension tests were conducted on three kinds of laminated carbon fiber reinforced plastic coupon specimens, that is, ±30-deg, 90-deg laminates, ±45-deg, 90-deg laminates and 0-deg, 90-deg laminates. The test results are compared with the authors' theory. In the experimental stress-strain diagram, the notable incremental strain at a constant stress level was observed at the knee point, that is, the point of initial failure. This indicates that the assumption of the brittle matrix of the composite is adequate for the specimens tested, and the assumption of the ductile matrix is invalid. An inverse method is presented which makes it possible to estimate the failure stresses of constituent layers and also the effective curing temperature of an individual laminate from the experimental stress-strain diagram. The experiment showed that the unloading path is in agreement with one of two possible theoretical predictions. The reloading path coincided with the unloading path.
Fatigue Behavior of Alumina Fiber Reinforced Aluminum Composites
Authors: Tsangarakis N , Slepetz JM , Nunes J
Published: December 2008

The fatigue behavior of two different batches of an alumina fiber reinforced aluminum composite (FP/Al) was investigated. Both batches had a nominal 55% fiber volume fraction with fibers uniaxially oriented in the test direction. Tension-tension fatigue tests were conducted on flat, untabbed, contoured specimens in a 90 KN MTS axial fatigue test machine at R = 0.1. The cyclic frequency of the fatigue tests was 30 Hz except for a limited number conducted at various frequencies to determine if fatigue behavior was frequency dependent. Some specimens were strain gaged so that load-strain response could be monitored during fatigue tests. Metallographic and fractographic examination of specimens was conducted to evaluate failure modes and damage mechanisms.

Preliminary static and fatigue tests showed a significant difference in mechanical properties of the two batches of FP/Al investigated. The first batch had an endurance limit of 410 MPa compared to 330 MPa for the second batch. Static strength and modulus were correspondingly higher for the first batch than the second. Microstructural differences were also observed, such as a significantly higher number of debonded fibers in the second batch of FP/Al, that could account for the difference in mechanical properties. There was no decrease in secant modulus with fatigue cycling for either batch of material, contrary to reported behavior for boron/aluminum composites. In spite of observed fabrication defects, the ratio of endurance limit and residual strength to ultimate tensile strength was greater than 60% for both batches tested. Fiber failure was found to dominate the fatigue life of FP/Al, and failure of the composite generally occurred after a sufficient number of fibers fractured at a given cross section.
Residual Stresses In and Around a Short Fiber in Metal Matrix Composites Due To Temperature Change
Authors: Mura T , Taya M
Published: December 2008

Residual stresses in and around short fibers in metal matrix composites due to temperature change are evaluated. An analytical result for the residual stress in the fiber is obtained by use of Somigliana dislocations at the matrix-fiber interface. These dislocations are introduced to accommodate the misfit of the thermal expansion difference between fibers and the matrix. These dislocations are responsible for the residual stresses after the composite material is cooled down to room temperature.
Finite-Element Analyses of Saint-Venant End Effects for Composite Materials
Authors: Okumura H , Watanabe K , Yamada Y
Published: December 2008

Stress eigenstates at the loaded end in composite materials are discussed. It is shown that a characteristic matrix equation for end effects can be obtained by the usual finite-element formulation based on the principle of virtual work and, through several examples, that Saint-Venant end effects can be easily analyzed by the method developed. The rate of attenuation of nonuniform stress distribution in composite materials is slow in comparison with isotropic materials, and it is emphasized that the evaluation of this decay by the numerical method is important in relation to the estimation of the strength of composite materials.
Stability of Nonlinear Circumferential Waves in an Accelerated Spinning Rectilinearly Orthotropic Disk
Authors: Ohnabe H , Funatogawa O , Itoh M
Published: December 2008

A system of two coupled nonlinear differential equations of the second and fourth order, respectively, governing motions of an accelerating membrane-like disk, made of a rectilinearly orthotropic material, is derived. A harmonic-type nonlinear transverse vibration and wave representing the gravest mode in the linear case is then studied. The membrane is assumed to be free, and its deflection is represented by a simple monomial. Free nonlinear vibrations represent the familiar decrease of period of vibrations with an increase of amplitude and show a dependence on the degree of anisotropy. By imposing temporal perturbations on the deflections, the equations for stability of the vibration and the forward and backward traveling waves are derived and discussed.
Fabrication and Spin Tests of Thick Laminated S2-Glass Flywheel Disks
Authors: Nimmer RP , Torossian KA , Hickey JS
Published: December 2008

Flywheels have been used to store and supply energy in a wide range of applications. In transportation-related applications, a primary design consideration is to store the maximum amount of energy per unit weight of the flywheel. Based upon this criterion, the high strength-to-density ratios of composite materials make them attractive materials for an efficient design. This investigation reports on a program to develop a composite flywheel consisting of a laminated S2-glass/epoxy central disk and a filament-wound graphite/epoxy outer ring. It is shown both analytically and experimentally that the presence of the outer ring significantly improves the energy density available in a simple laminated disk. Consideration is given to the subjects of fabrication, failure criteria, and experimental determination of ultimate speed and strength of prototype flywheels.
Effect of Coatings on Interfacial Reaction in Tungsten/Nickel and Tungsten/316L Composites
Authors: Umekawa S , Lee CH , Yamamoto J , Wakashima K
Published: December 2008

Effects of the fiber coating on interfacial phenomena in tungsten/nickel and tungsten/SUS316L (AISI 316L type stainless steel) composites were studied with special emphasis on the diffusion and the chemical reaction. A combination of tungsten fiber without doping and nickel matrix, in which recrystallization easily takes place at elevated temperature, was tested as a preliminary experiment. The combination is rather an extreme example with the recrystallization and interfacial reaction. Then, a composite with the tungsten fiber and 316L stainless steel matrix which would be more adoptable than pure nickel matrix for practical application was employed.

Oxides, carbides, and nitrides of such elements as aluminum, titanium, chromium, zirconium, and tantalum were examined as coating materials. The materials were selected on the basis of the chemical free energy of formation. The composites were exposed under the different kinds of thermal conditions. Effects of coating on the interfacial phenomena were evaluated by such characteristics of the composites as microstructure and mechanical behavior after the exposure.

Among all the coating materials tested, some of zirconium compounds were most effective in tungsten/nickel composites. Accordingly, zirconium dioxide and zirconium nitride coatings were mostly examined in a tungsten/316L stainless steel system. These coatings worked well as the reaction barrier at elevated temperature.
Assessing the Corrosion Resistance of Metal Matrix Composite Materials in Marine Environments
Authors: Aylor DM , Kain RM
Published: December 2008

The corrosion resistance of graphite/aluminum (Gr/Al) and silicon carbon/aluminum (SiC/Al) metal matrix composite (MMC) materials and composite corrosion protection methods were investigated in marine environmental exposures ranging from 30 to 365 days. Accelerated corrosion of the Gr/Al resulted from galvanic interactions between the graphite fibers and the aluminum matrix. Corrosion of the SiC/Al was due to pitting, which was oriented at the silicon carbide-aluminum interfaces in the discontinuous forms of silicon carbide reinforcement. Differences in surface foil alloy and composite structure for the Gr/Al or type of silicon carbide reinforcement for the SiC/Al did not affect the materials' overall corrosion resistance. A variety of corrosion control coatings was found to be suitable for protection of the MMC, including organic and thermal-sprayed coatings.
Elevated-Temperature Internal Friction in an Oxide Dispersion-Strengthened Nickel-Chromium Alloy
Authors: Shioiri J , Satoh K
Published: December 2008

Internal friction in an yttrium oxide dispersion-strengthened nickel-chromium alloy (Inconel MA 754 alloy) was measured at temperatures ranging from 15 to 1200°C and at frequencies from 1 to 35 Hz. Measurements were made also for Nimonic 75 alloy, which has essentially the same chemical composition as the matrix of MA 754 alloy. In both alloys, the internal friction plotted against temperature is composed of a peak component and a background component. The activation energy of the grain boundary viscosity obtained from the peak component was 360 and 310 kJ/mol for MA 754 alloy and Nimonic 75 alloy, respectively. The background component was discussed in terms of the behavior of dislocations.
Thermal Expansion Coefficients of Misoriented Short-Fiber Reinforced Composites
Authors: Takao Y
Published: December 2008

This paper examines the thermal expansion coefficients αc of hybrid composites containing two- or three-dimensionally misoriented transverse-isotropic short fibers under the assumption that in the thermal expansion problem the transverse-isotropic fiber can be characterized by its longitudinal Young's modulus, Poisson's ratio, longitudinal thermal expansion coefficient, and transverse one—that is, isotropic mechanical properties and transverse-isotropic thermal ones. The analysis is based upon the Eshelby's equivalent inclusion method and average induced strain approach, which can take into account the interaction among all fibers at different orientations. It is therefore suitable for intraply hybrid systems. Numerical results are presented to demonstrate the effects of the distribution of fibers on αc in the cases of carbon/glass/epoxy and carbon/Kevlar/epoxy composite. The effects of material constants on αc are presented in detail.
On High-Velocity Brittleness and Ductility of Dual-Phase Steel and Some Hybrid Fiber Reinforced Plastics
Authors: Kawata K , Hashimoto S , Takeda N , Sekino S
Published: December 2008

First, the one-bar method developed by the present authors for the characterization of materials in high-velocity uniaxial tension up to breaking is stated. Second, the results of high-velocity tension ranging up to 1.4 × 103 s−1 on a dual-phase steel (shown in Table 1), pure iron A and B (shown in Table 2), and carbon/glass hybrid composites (shown in Table 3) are stated, comparing with the data of static tension. The dualphase steel shows the tendency of high-velocity ductility, differing from the pure irons. Three types of carbon fiber/glass fiber hybrid composites tested show the tendencies of high-velocity ductility with varying increasing rate according to the hybrid ratio, in contrast to the fact that carbon fiber reinforced plastic is strain-rate insensitive or high-velocity brittle.
Measurement of Permeability at Elevated Stresses and Temperatures
Authors: Voegele MD , Brace WF
Published: December 2008

Laboratory measurements of the permeability coefficients of various rock types suggest that the permeability coefficient is sensitive to the temperature and the stress state at which it is measured; the effects become more pronounced as the temperature or stress state is increased. This paper presents a summary of data in the literature to support this statement and describes some laboratory techniques used to obtain the data base.

Laboratory observations indicate that the permeability coefficient is temperature sensitive and that it is affected in many different ways as the temperature is increased. Temperature might be expected to affect the permeability coefficient through purely physical effects such as thermal expansion or thermal cracking. However, a variety of fluid-rock interactions apparently play a role, evidently through pore geometry alteration, which can have profound effects on the value of the permeability coefficient. The changes in permeability coefficients caused by temperature reviewed in the paper were large but not quantitatively predictable.

The permeability of rock is known to depend upon pore dimensions and fracture geometry. Either one, or a combination of the two, can control the measured permeability depending on the type of rock and its stress-strain history. Pore dimensions, particularly the aperture and the fracture width, change with stress so that it is not surprising to find that the permeability coefficient of various rock types can be quite stress dependent. The paper discusses general trends in stress related behavior changes for both low and high porosity unjointed rocks as well as for some jointed rocks.
Influence of Various Nondisease Factors on the Response to Pollutant Exposure (Age, Sex, Circadian Rhythm, Season, Temperature, Humidity, Adaptation)
Authors: Folinsbee LJ
Published: December 2008

When evaluating the modest effects of low concentrations of air pollutants, it is necessary to control the influence of as many variables as possible. In this review, the effects of temperature and humidity, circadian rhythms, gender, and age are discussed. The influence of “adaptation” through repeated ambient exposure or laboratory exposure, or both, is also considered.
Design and Measurement Considerations for Exercise Protocols in Human Air Pollution Inhalation Studies
Authors: Horvath SM
Published: December 2008

The impact on pulmonary functions of exercising at different intensities during pollutant exposures was evaluated. It was apparent that there was considerable variation in exercise protocols. These variations occurred in the magnitude of the exercise load, the duration of the exercise period, and the timing of the exercise during exposure. It was also apparent that ventilation during rest and exercise was not always determined; in many instances ventilation was estimated based on other criteria, such as heart rate. The influence of ambient temperature conditions was frequently not considered. Determinations of pulmonary functions were also made at various time intervals following exercise or subsequent rest periods. All of these factors could result in some degree of misinterpretation of the consequences of pollutant exposure.
The Inspiratory Path to the Lungs
Authors: Proctor DF
Published: December 2008

Environmental air and its pollutants must ordinarily pass through the nasal or oronasal airway. During its inspiratory passage, the physical nature of the air is modified, and many pollutants are removed. Considering these facts, it is essential that studies of the pulmonary effects of air pollutants be conducted under circumstances which allow free breathing through the upper airways. In evaluations of toxicological investigations in experimental animals, the comparative anatomy and physiology of the nose is a necessary component.
Measurement of Airway Responsiveness in Studies of Health Effects of Air Pollution
Authors: Sheppard D
Published: December 2008

Measurement of airway responsiveness is commonly included in studies of the adverse health effects of air pollutants. These measurements are important in characterizing the study population when patients with asthma are studied. In addition, an acute increase in airway responsiveness may be a sensitive marker indicating acute airway injury. In this review, some of the important technical factors that affect measurement of airway responsiveness are discussed.
Use of Aerosols for Measuring Airway and Air Space Sizes and Tracheobronchial Mucociliary Clearance Rates
Authors: Lippmann M
Published: December 2008

Physiological and pathological changes in lung conductive airways can be studied in clinical pulmonary laboratories using noninvasive measurements of particle deposition efficiency and rates of mucociliary clearance. These techniques, reviewed herein, can provide very sensitive indices of (1) the average effective sizes of small airways, (2) the presence of airway obstructions, and (3) defects in clearance function. Serial measurements in the same individuals can be used to determine responses to and recovery from short-term exposures to airborne chemicals. The aerosol techniques provide evidence for physiological responses to irritants such as cigarette smoke and submicrometre-sized droplets of sulfuric acid at exposures which, in many cases, are much lower than needed to produce changes in respiratory mechanical function. Furthermore, transient changes in mucociliary clearance function following single exposures in humans and animals lead to persistent changes in function and airway structure after repetitive exposures of animals. Thus, aerosol techniques should be more widely utilized in clinical pulmonary studies on criteria pollutants.
Air Pollution Exposure Studies in Smokers and People with Chronic Obstructive Pulmonary Disease
Authors: Linn WS , Hackney JD
Published: December 2008

People with chronic obstructive pulmonary disease (COPD) are often thought to be especially at risk from air pollution and thus are prime candidates for clinical exposure studies. However, scientific, ethical, legal, and practical problems must be faced in studying individuals with COPD. To deal with these problems, the following priorities of concern are suggested: (1) the safety and welfare of subjects, (2) scientific rigor of the experiment, (3) relevance of the experimental results to “real-world” health concerns, that is, to air quality regulatory decisions, and (4) improved general understanding of physiology or toxicology. Smoking often complicates interpretation of the results of clinical exposure studies; in many cases, smokers should be excluded to maximize scientific rigor. However, smokers may be viewed as a group with early or mild COPD: most have at least slight chronic bronchitis. Thus, in some investigations, smokers might be appropriate surrogates for diseased population groups. Care should be taken to distinguish between the effects of the experimental pollutant and the effects of recent smoking on smokers' experimental responses. Only a few of many potential ambient-air hazards have been investigated in people with COPD; no clear differences in responses from healthy people have been found. Only a few studies have attempted rigorous comparisons between smoking and nonsmoking subjects, either healthy or with lung disease. Their results have been inconclusive.
Initial Studies on the Effects of Droplet Size and Electrostatics on Spray Deposition Efficiencies
Authors: Hall FR , Reichard DL
Published: December 2008

Equipment and instruments have been assembled and are being used to study the deposition of spray droplets on leaves. High-speed motion pictures show that a large portion of the droplets rebound from cabbage and lambsquarters leaves after the first impaction. To improve the deposition efficiency of sprays, we are continuing to study the effects of droplet size and velocity, electrostatic charge, and type and concentration of surfactant on the rebound of spray droplets from various types of leaf surfaces.
Efficacy of Insecticides Applied Ultra-Low Volume in Vegetable Oils
Authors: Luttrell RG
Published: December 2008

Increased use of vegetable oils as carriers for insecticide sprays has stimulated additional research related to the efficacy of aerial application of insecticides. The efficacy of insecticides applied as ultra-low-volume (ULV—2.34 L/ha [0.25 gal/acre]) vegetable oil sprays was compared with standard volume (SV—18.71 L/ha [2 gal/acre]) water sprays in field experiments involving a complex of cotton insect pests at several locations in Mississippi during 1981 to 1983. Results suggest that insecticides applied as ULV-vegetable oil and SV-water sprays are equally efficacious against cotton insect pests.

Bioassay data and spray deposit characterizations were used to study more accurately differences in ULV-vegetable oil and SV-water sprays. Spray droplets associated with ULV-vegetable oil sprays tend to be smaller and deposited in a less dense pattern than those of SV-water sprays. Bioassay and residue analyses data indicate that ULV-vegetable oil and SV-water sprays deposit comparable amounts of active ingredient on the target area.
Control of Spruce Budworm by Ultra-Low-Volume Application of an Insecticide Suspension
Authors: Shafer JG
Published: December 2008

The spruce budworm, a native insect in the Eastern United States and Canada, can cause defoliation severe enough to kill a tree within a year. For a number of years, Matacil has been used to control the insect. The formulation is a true solution containing 180 g of Matacil per litre (1.5 lb/gal). It is mixed with diesel oil and applied ultralow volume (ULV).

It was desired to have a formulation that could be mixed with water as well as oils. This was accomplished by changing the formula from a true solution to a suspension in oil. The suspension can be mixed directly with oil or after addition of an emulsifier, with water.

Biological efficacy data supported the formula change. Spray patterns and droplet size counts showed that ULV application of the suspension by fixed-wing aircraft was feasible.
Effect of Formulation and Pressure on Spray Distribution Across the Swath with Hydraulic Nozzles
Authors: Krueger HR , Reichard DL
Published: December 2008

Various types of hydraulic atomizing nozzles were used to study the spray distribution across the swath with water and emulsions at pressures of 138, 276, and 552 kPa (20, 40, and 80 psi). The nozzles sprayed onto a spray table divided into troughs 3 cm (1.2 in.) wide. The results indicate that composition of the material sprayed, type of nozzle, and operating pressure greatly influenced distribution of deposits across the swath. A computer program was used to determine the coefficient of variation (COV) and mean deposit for 3-cm increments of various distances between nozzles. The optimum distances between nozzles (lowest COV) were dependent on spray mixture and operating pressure.
Water Dispersible Granule Development Process and Equipment
Authors: Holley CA
Published: December 2008

This paper provides a review of the problems involved in selecting agglomeration equipment compatible with the formulation. It discusses the choice of agglomeration equipment and provides equipment cost estimates for many capacities of plants.
New Developments in Automated Materials Testing Systems
Authors: Miller NR , Dittmer DF , Socie DF
Published: December 2008

This paper traces the development of automated materials testing systems over the past ten years. The rapid reduction in computing hardware costs in recent years, coupled with fundamental improvements in computing systems design, has led to the development of a new generation of test control systems. The paper focuses on recent developments in this area at the University of Illinois at Urbana-Champaign.

The paper describes in detail a microcomputer-based controller designed to be used with a standard servohydraulic test frame. The controller uses menu-driven software which permits the operator to set up and execute tests, sample and store data, and transfer the collected data to a host computer system for data reduction and archival storage. Currently, software exists to perform standard low-cycle fatigue tests and other related test procedures. The software is designed to permit ease of operation and reduce the chance of operator error. In addition, numerous checks are performed during the course of a test to assure that the test is carried out in accord with ASTM specifications where applicable.

The paper contains a discussion of digital communications as they relate to the materials testing laboratory. The growing array of computing hardware in the testing laboratory necessitates the careful selection of communication techniques to match the needs of each application and the laboratory as a whole. The paper concludes with a discussion of the impact of new testing techniques on testing standards.
Development of an Automated Fatigue Crack Propagation Test System
Authors: Vecchio RS , Jablonski DA , Lee BH , Hertzberg RW , Newton CN , Roberts R , Chen G , Connelly G
Published: December 2008

An automated fatigue crack growth rate test system was developed to characterize the crack growth response of engineering materials as a function of the applied stress-intensity range. The test system utilizes DEC PDP 11 series minicomputers and a software feedback control loop to control testing at frequencies up to 100 Hz. Additional system flexibility is provided in its three control modes: constant-load amplitude, constant ΔK, and variable-ΔK test capabilities.

A comparison of crack growth rate data obtained using this automated system is made with data generated under manually controlled test conditions, for aluminum and steel alloys, and for engineering plastics.
An Automatic Fatigue Crack Monitoring System and Its Application to Corrosion Fatigue
Authors: Kondo Y , Endo T
Published: December 2008

A measuring system that automatically detects fatigue crack initiation and propagation behavior has been developed. This system is based on calculating and recording automatically the change of compliance due to fatigue crack growth using an analog circuit.

The authors applied this system to fatigue testing in an aqueous environment and succeeded in detecting a part-through semi-elliptical crack as small as 0.2 mm deep initiating from the notch root.

Using this system, the crack initiation and following propagation behavior in the vicinity of a notch root in 3.5Ni-Cr-Mo-V steel in an aqueous environment were investigated.
Experience with Automated Fatigue Crack Growth Experiments
Authors: Van Der Sluys WA , Futato RJ
Published: December 2008

The experience of the authors with the automation of the fatigue crack growth experiment is described. The system is described from both the hardware and the software standpoints.

The approach used in automating the fatigue crack growth experiment was to make as much use of the computer as possible by writing large, user friendly, multipurpose program systems. The approach has been very successful based on four years of experience in conducting experiments. High quality results have been obtained from experiments conducted by personnel not skilled in computer programming.
Potential-Drop Monitoring of Cracks in Surface-Flawed Specimens
Authors: VanStone RH , Richardson TL
Published: December 2008

A direct-current potential-drop crack monitoring technique has been modified for use with test specimens having rectangular cross sections and semicircular crack starting notches, with radii as small as 0.075 mm (0.003 in.). An experimental program was conducted to evaluate an analytical model which predicts the crack depth from the potential drop, crack aspect ratio, and potential probe spacing. The fatigue crack growth rates of Rene'95, an advanced nickel-base superalloy, were determined at room temperature for three levels of gross section stress. There was extremely close agreement between the crack depths determined experimentally through post-test fractography and those predicted by the analytical potential-drop model. The critical barrier for fully automated monitoring of surface flaw crack growth with potential drop is the development of relationships to predict the crack aspect ratios as a function of material and testing parameters.
A Microprocessor-Based System for Determining Near-Threshold Fatigue Crack Growth Rates
Authors: McGowan JJ , Keating JL
Published: December 2008

A microcomputer-based system has been developed to perform near-threshold fatigue crack growth testing. The crack length is measured by both potential-drop and compliance techniques. The potential-drop technique has a resolution of 0.0005 W and is used for real-time load control. The compliance technique has a resolution of 0.002 W and is used for comparative reference. The potential-drop system uses d-c current and has multiple voltage probes (located remote from current input points) to minimize the effects of current variation and resistance changes. The potential-drop measurements are made with and without excitation to minimize thermal offset problems. Compliance and potential-drop measurements are determined at specified load points during a cycle to minimize the effects of crack closure.

The system is programmed to control the rate of ΔK change (for increasing or decreasing ΔK tests) to a user-selected value. As the applied load is changed, the sample points (for measuring compliance and potential drop) during the cycle are changed automatically. A real-time sliding-seven-point fatigue crack growth rate calculation is performed for each sample. The sampling frequency is adjusted by the system during the test to maintain measurement accuracy. The microcomputer records crack lengths, loads, cycle number, and specimen temperature on floppy disks for post-processing.

Near-threshold fatigue crack growth results are presented for Type 304 stainless steel at both 24 and 538°C.
A Computer-Interactive System for Elastic-Plastic Fracture Toughness Testing
Authors: Saario T , Wallin K , Saarelma H , Valkonen A , Törrönen K
Published: December 2008

A computer-interactive fracture toughness testing system is described. The system reliability is shown to meet the requirements of the proposed standard test procedure. Exemplary test results for compact testing, round compact testing, and three-point bend specimen geometries are presented. Based on the experiences gained, some minor additions are proposed to the standard test procedure.
Analysis of Errors in Guarded Hot Plate Measurements as Compiled by the Finite Element Method
Authors: Troussart LR
Published: December 2008

The object of this research was to study the effect of various design parameters of a guarded hot plate (GHP) on the error of measurement due to gap unbalance without having to resort to simplifying assumptions as has been the case in existing analytical studies. A better knowledge of this effect could lead to better national standards. It could explain some of the discrepancies often found between the results of round-robin tests. The method used is the finite element (FE) method applied to an axisymmetric GHP. The latter choice is justified by the fine discretization of the domain which is achievable without requiring a huge computer memory. This feature allows us to study the influence of thermopile wires crossing the gap.

The results show that for a given gap unbalance, one is not free to arbitrarily choose the thermopile wire diameter, nor the temperature drop across a given specimen thickness, if one seeks accurate measurements. One cannot achieve precise measurements with one apparatus and only one set of operating conditions that would apply to a broad range of thermal conductivities.

The value of the FE method to solve the differential equation of heat conduction while satisfying the operating boundary conditions of the GHP apparatus is also demonstrated.
Discussion of Heat Flow Meter Apparatus and Transfer Standards Used for Error Analysis
Authors: Bomberg M , Solvason KR
Published: December 2008

The need for thermal resistance measurements on thick specimens (100 to 180 mm) of low-density thermal insulation and subsequent changes in ASTM test standards have increased the need for the evaluation of precision and accuracy attainable with the heat flow meter (HFM) apparatus. Such an evaluation is usually performed with transfer standards established on a guarded hot plate. The Division of Building Research of the National Research Council of Canada (DBR/NRCC) has developed a transfer standard and calibrated specimen bank to be used in verifying HMF test procedures and instrument error evaluation. This paper discusses such calibration and the use of the HFM apparatus and reviews the transfer standards developed at NRCC.
A Review of Current Commercially Available Guarded Hot Plate and Heat Flow Meter Apparatus and Instrumentation
Authors: Coumou KG
Published: December 2008

Equipment for the measurement of thermal performance is commercially available from a number of sources. Specifications of the various apparatus are compared, and unique features of each model are described briefly in the text. Future requirements for commercially produced thermal testing equipment are discussed.
Field Measurements of Steady-State Thermal Transfer Properties of Insulation Systems
Authors: Larson DC
Published: December 2008

A technique to assess the thermal performance of building envelope systems in the field has been developed. The thermal resistance of these systems is measured with a 1.22-m-square temperature-controlled test plate to which heat flow sensors and thermocouples are attached. The plate is placed on top of an insulated roof system or against an insulated wall system, and thermocouples are attached to the opposite surfaces of the envelope systems. Measurements can be made without disturbing the structure of the envelope systems by using test plate temperatures approximating normal outside surface temperatures. The test plate is either heated or cooled and temperatures and heat flows are measured after equilibrium is achieved. The method provides reliable thermal resistance values for envelope components which are laterally uniform and useful thermal transfer property information for more complex envelope systems. The application of the method to a single-ply expanded polystyrene insulated roof, sprayed-on polyurethane roof insulation systems on both metal and concrete decks, and an insulated metal-stud wall system is described.
Engineering Application of Heat Flux Sensors in Buildings—The Sensor and Its Behavior
Authors: Trethowen HA
Published: December 2008

The factors affecting the measurement accuracy of (perfectly calibrated) heat flux sensors in buildings are discussed. A preliminary attempt is made to quantify this measurement error using dimensionless parameters. This attempt indicates that the method offers some promise and that some previously little-discussed items, such as the absolute size of the sensor, may have a great effect on the accuracy. An additional heat flux sensor is described, and a simple calibration method using a heater foil is outlined.
Heat Flux Sensor Calibration Technique
Authors: Bligh TP , Apthorp DM
Published: December 2008

A new heat flux sensor calibration technique has been developed that is traceable to the National Bureau of Standards. It can be used to calibrate sensors at the temperature and heat flux levels typically found in the field, without requiring any expensive equipment or special experimental techniques. Sixty-four sensors have been calibrated with a mean precision of 2.2%. Three sensors were independently calibrated by Dynatech, and their calibration factors were all within 2% of the Massachusetts Institute of Technology (MIT) values, whereas the manufacturer's calibration factors ranged from 99 to 151% of the respective MIT values and so are effectively useless. There is evidence that the thermal conductivity of a sensor may vary by as much as a factor of two from sensor to sensor, and therefore a technique for measuring this is discussed.
Heat Flux Sensor Applications for Below-Grade Energy Studies
Authors: Shipp PH
Published: December 2008

The use of heat flux sensors for energy studies of below-grade building envelopes and soil heat transfer is discussed. In a two-year study of three basements, heat flux sensors provided valuable information about local variations over the envelope surfaces. For complex building geometries, experimental designs that combine calorimetric monitoring of energy consumption with envelope heat flux profiles from heat flux sensors offer the most efficient means of determining building thermal performance.

The results from heat flux sensors buried in the soil were less satisfactory as the measurements were difficult to interpret because of the variability of soil thermal properties and the sensors' inability to detect vapor transport phenomena. Localized distortions caused by differences between the thermal conductivities of the sensors and their surroundings were found to affect heat flux sensor output significantly.

Significant differences between locally determined and factory supplied calibration values illustrate the need for improved standardization and disclosure of calibration procedures.
Thermal Resistance Measurements with Heat Flow Sensors—Application to Spray-Applied Insulation Systems
Authors: Larson DC
Published: December 2008

Heat flow sensors are often attached to the inside surfaces of building envelope systems to determine the thermal resistances of these systems in the field. In this paper an alternative method for using heat flow sensors for this application is described. The heat flow sensors are attached, along with thermocouples, to a temperature-controlled test plate. The plate is generally placed against the outside surface of the building, and thermocouples are attached to the opposite surface. The plate is either heated or cooled for summer or winter conditions, respectively, and the heat flows and temperatures are measured after equilibrium is achieved. The method provides reliable thermal resistance values for envelope systems which are laterally uniform and useful approximate thermal resistance values for nonuniform systems. The application of the method to nonuniform building envelope systems is described, and experimental results are reported for insulation systems consisting of polyurethane, fiberglass, and cellulose spray-applied to metal decks.
Calculation of Thermal Conductance Based on Measurements of Heat Flow Rates in a Flat Roof Using Heat Flux Transducers
Authors: Hedlin CP
Published: December 2008

Heat flow rates through 60-mm-thick rigid mineral fiber insulation mounted in the flat roof of an outdoor test facility were measured with heat flux transducers. The temperature differences across the insulation were measured simultaneously with thermocouples.

Three different analytical procedures were used to calculate the thermal conductance of the insulation: (a) the ratio of heat flow rate to temperature difference, (b) the slope of heat flow rate as a function of temperature difference and mean temperature, and (c) transfer functions. The results obtained with these three methods are compared.

The effect of ignoring thermal lag was estimated for the first two methods.