bluuebunny/crossref_metadata_2025 huggingface dataset:
Atomizer Design for Agricultural Air Shear Applications
Authors: Akesson NB , Steinke WE , Yates WE
Published: March 2009

The nozzle-atomizer on most agricultural pesticide applications must perform two basic functions. First, the spray liquid must be atomized or broken up into small drops for dispersal to plant surfaces, and secondly, the amount of liquid discharged must be controlled or metered to obtain the proper plant coverage and dosage.

Most atomizers used today on agricultural sprayers produce a wide range or spectrum of drop sizes approximating a Gaussian or somewhat skewed Gaussian (skewed towards small drops) range. While no one has conclusively determined that a single drop size sprayer would produce the most desirable coverage of plant surfaces, it is widely understood that a narrowed spectrum which cuts off both the small and large end of the range, would be a desirable step forward in nozzle design, thereby, reducing the amount of spray in small drift-prone drops as well as reducing the very large drops which do not provide good plant coverage.

Several new designs of nozzle atomizers have been examined in our wind tunnel drop size analyzer specifically to examine their ability to reduce drift losses through production of larger drop size ranges as well as to check these for drop size range control. A few of these designs have been marketed for ground sprayer use, but we were particularly interested in how improvement in drift-control could be attained, while still maintaining adequate plant coverage with air carrier ground and aircraft spray equipment. Our studies have pointed out the drop size characteristics of certain of the available nozzles as well as developing some further lines of nozzle design that might be suitable for this purpose.
The Effect of Dynamic Surface Tension and High Shear Viscosity on Droplet Size Distributions Produced by a Flat Fan Nozzle
Authors: Downer RA , Cooper JA , Chapple AC , Hall FR , Reichard DL , Zhu H
Published: March 2009

Viscosity and surface tension are known to have a significant impact on liquid breakup into droplets. However, the droplet size data reported by many authors is more irregular than the data on physical properties. In this study, recent improvements to existing techniques were used to obtain the dynamic surface tension at young surface ages and viscosity at high shear rates, which more closely represents those conditions typically encountered at nozzle orifices. The surface tension and viscosity were measured for a selection of surfactants mixed with water, using an oscillating jet technique and a high shear viscometer, respectively. Droplet size and velocity data for the same mixtures, at known distances from the nozzle, were measured using an Aerometrics PDPA-100 1D. A simple correlation between the physical properties and droplet size distribution parameters was made and showed that droplet size (Dv0.5) increased with increasing surface tension. The range of viscosities tested was too small to obtain any meaningful correlation with droplet size. This study is not intended to provide data for rigorous statistical analysis and interpretation, but is a preliminary step in such an investigation.
Tristyrylphenol Surfactants in Agricultural Formulations : Properties and Challenges in Applications
Authors: Gubelmann-Bonneau IV , Mailhe PA , Perrin MA
Published: March 2009

Tristyrylphenols-based surfactants have been developed by Rhône-Poulenc for many years. For the first time, the EPA has approved tristyrylphenol surfactants for agricultural applications, respecting the new regulations required to exempt inerts from a tolerance limit. This paper reviews the nature of the tristyrylphenol surfactants in terms of chemical structure and the main interests of these surfactants. Interaction between phenylurea herbicides and tristyrylphenol surfactants was demonstrated by computational chemistry. Comparison with nonylphenol surfactants showed the unique affinity of tristyrylphenol-based surfactants for organic molecules. This specificity makes this class of surfactants particularly well suited for agricultural formulations. Their abilities to form a strong structure in concentrated dispersions, and to stabilize concentrated suspensions were studied by dynamic rheology. Examples of formulations (Suspension Concentrates, Microemulsion and Water Dispersible Granules ) are given in regards of these properties. Opportunities to optimize formulations using synergy values with other surfactants are proposed.
Composition Effects on Hydrocarbon Physical Properties
Authors: Sorensen WL , Lachocki TM
Published: March 2009

Kerosene-derived solvents that are substantially free of aromatic hydrocarbons and normal-paraffins provide useful solvent properties. Kerosene, a petroleum derived distillation fraction, is a complex hydrocarbon mixture of both aromatic and aliphatic hydrocarbons (normal-, iso-, and cyclo-/naphthenic-paraffins). Kerosene-derived solvent properties are a function of the kerosene and the crude-oil source. Despite kerosene variability, kerosene-derived solvents can be modified by physical and chemical means to tailor their properties for different formulation needs. The resultant solvents are useful in many applications, including pesticide formulations. This paper relates some key solvent properties to the general chemical classes of hydrocarbons contained in kerosene-derived solvents and gives an example using commercially available products.
Polymers for Instant Dispersions for the Herbicide Metolachlor and Other Chloroacetanilides
Authors: Narayanan KS
Published: March 2009

The pesticide metolachlor (a member of Chloracetanilide family) which is a liquid at ambient conditions was converted to a solid product by coprecipitation with Agrimer VEMA H-240, maleic acid methyl vinyl ether copolymer. This solid at 1–2% in water instantly produced a dispersion stable for > 24 hours and showed 100% recovery on standing over a period of 24 hours. This technology is extendable for other members of the pesticide family and other modifications of the polymer. This simple technique also offers several formulation variables such as: hydrophilic-hydrophobic balance of the backbone effect of counter ions effect of pH effect of crosslinking in the polymer and others (use of additional dispersing agents) Other commercial advantages are the capacity to formulate into solid forms that can be packaged in water-dispersible bags. Such packaging would reduce container disposal problems.

A working hypothesis is provided showing the unique backbone-spacing requirement for the polymer and its capacity to instantly disperse the active ingredient in water.
Water Soluble and Water Dispersible Granules with Spreader-Sticker Incorporated
Authors: Fu E , Narayanan KS , Hall FR , Downer RA
Published: March 2009

Agrimax™3 adjuvants have been shown in field tests to enhance the efficacy of pesticides. These adjuvants act as spreader-sticker-penetrants, which increase the uptake of pesticide by the target species. Conventional adjuvants are added to the tank mix separately from the active ingredients. Incompatibility may result, and extensive tests with each active ingredient are necessary to avoid such problems. Incorporating the adjuvant into the formulation directly ensures compatibility and carries other benefits, such as product differentiation and lower total costs, and also offers a proprietary position.

This study has demonstrated the technical feasibility of using Agrimax adjuvants as granulating fluid for water soluble and water dispersible granule formulations. The majority of work was performed with phosphonomethylglycine. It was mixed with sodium bicarbonate in a 1:1 weight ratio to yield sodium salts which dissolved readily. The amount of adjuvant required to obtain an extrudable mass ranged from 14 to 20% (wet mix basis). Extruded granules had excellent friability resistance and good dissolution. Bioefficacy tests under greenhouse conditions were performed with an experimental granule formulation and a commercial formulation, Roundup®4. Phytotoxicity assessments on three weed species over a two week period produced statistically equivalent results under all conditions with one exception. Other active ingredients, such as 2, 4-dichlorophenoxyacetic acid and chlorothalonil, could also be granulated with Agrimax. Results indicate that Agrimax adjuvant can be readily incorporated into granule formulations, and such granules can be highly efficacious.
Validation of the Percent Suspensibility Test for Dry Flowables by Round Robin Testing
Authors: Munie LA
Published: March 2009

This paper discusses the validation of the proposed Standard Test Method for Percent Suspensibility of Dry Flowables. This validation consists of a round robin test conducted by member labs.
USDA Forest Service Spread Factor Technology Database
Authors: Teske ME , MacNichol AZ , Barry JW
Published: March 2009

Whenever drops impact on cards or foliage, estimates of their aerodynamic size rely heavily upon the spread factor expression assumed or developed. Uncertainties in spread factor may lead to erroneous estimates of aerodynamic drop size and subsequent calculation of mass and volume of spray material released. Over the last 40 years the USDA Forest Service and its cooperators have used witness cards (because they are inexpensive and easy to use) to collect and interpret spread factors for several hundred pesticide tank mixes, and have conducted extensive tests to quantify the relationship between deposit stain size and in-flight drop diameter. The typical approach has been to generate drops of known size, and observe the resulting stain size after drop settling, impact and drying. This technique first involved magnesium oxide (MgO) coated glass slides, where the size of the impacted drops could be measured by craters left in the coating. These sizes were then compared with stains on paper cards, produced from impaction of the same drop population. Spread factor relationships are known to depend on physical properties of the spray material, state of the drop before impaction, drying conditions, and the type of collector paper. These relationships are expressed mathematically as linear, polynomial, or power law curve fits. A database library of these factors, enabling the extension of existing information to untested conditions, is developed and reviewed in this paper. In place, this database provides an historical record that should benefit future field measurements and data reduction and interpretation.
Effect of Temperature Fluctuations and Storage Period on Pesticide Stability in Formulation Concentrates Used in Forestry
Authors: Sundaram KMS , Sundaram A
Published: March 2009

Pesticide formulation concentrates should maintain their physicochemical stability from the time of preparation until field application. Literature information on pesticide stability is lacking at present, especially after field storage under the conditions of the operational spray programs for forest pest control. The present study provides information on the influence of water hardness, pH, formulation ingredients, carrier media, storage periods, and temperature fluctuations, on phase separation, pesticide hydrolysis, degradation and metabolism, in some simple formulation concentrates prepared in the laboratory, and in some complex formulation concentrates obtained from pesticide companies.

The investigation indicated that the greater the hardness of water, the greater the stability of the active ingredients. Formulants increased the storage stability of pesticides. Polymeric formulants of larger molecular mass provided greater stability to pesticides than the surfactants of smaller molecular size. The longer the storage period, the lesser the stability of pesticides. Highly water-soluble pesticides degraded to a much greater extent than the sparingly soluble ones. Degradation occurred much more in aqueous media than in non-aqueous media, and the type of metabolites formed differed in the two media. Commercial formulation concentrates made up of several ingredients provided metabolites different from those found in the simple formulations prepared in the laboratory. Pesticide degradation occurred to a much greater extent after storage of the commercial formulation concentrates under outdoor conditions at extreme fluctuating temperatures, than after storage in the laboratory at a constant temperature.
Relation of Surfactant HLB to Glyphosate Phytotoxicity
Authors: Nalewaja JD , Koziara W , Matysiak R , Manthey FA
Published: March 2009

Research was conducted to determine the phytotoxicity of glyphosate [N-(phosphonomethyl)glycine] formulations (Roundup® and Honcho®) as influenced by calcium chloride or calcium chloride plus ammonium sulfate and surfactant hydrophilic:lipophilic balance (HLB). Roundup® and Honcho® phytotoxicity to wheat generally was maximized by octylphenoxy and nonylphenoxy surfactants with HLB of 15 to 16 but to kochia phytotoxicity increased linearly with HLB except the response decreased or was quadratic in the presence of CaCl2. Roundup® and Honcho® phytotoxicity to wheat increased with surfactant concentration regardless of HLB, but concentration did not overcome differences between surfactants. Surfactants within the optimum HLB range differed similarly in effectiveness with both Roundup® and Honcho®. Certain surfactant adjuvants reduced phytotoxicity to wheat by glyphosate with MON 0818, the surfactant in the Roundup® formulation. Surfactant effectiveness was dependent upon surfactant chemistry and HLB.
The Relationship of Spray Adjuvant Surfactant Properties to Pesticide Spray Application Volumes
Authors: Mack RE , Roberts JR , Volgas GC
Published: March 2009

Over 100 pesticide labels recommend the use of a spray adjuvant to enhance efficacy of the active ingredient. Many of these labels require the use of an adjuvant. Imazethapyr requires not only the use of a nitrogen-based fertilizer, but for some applications, the use of a crop oil concentrate. The crop oil concentrate requirement specifies a given volume of adjuvant per hectare. The wetting properties, and/or surface chemistry, play a vital role in the usefulness of the crop oil concentrate.

There are several methods of evaluating the surface activity of adjuvants. Contact angles at the liquid-solid interface, surface tension, both dynamic and static, and spread areas are among the methods that have often been used to determine the effectiveness of an adjuvant. While these measurements do not replace actual efficacy trials, they should be valuable in the screening of different adjuvants for suitability with any given pesticide spray.

A series of tests were designed to determine if surface chemical properties are appropriate indicators for predicting the usefulness of crop oil concentrates with the herbicide imazethapyr. A correlation between the various methods of evaluating surface activity and the actual efficacy enhancements was observed.

When spray volumes per hectare are decreased, the rate of adjuvant per hectare remains constant and the concentration of the adjuvant increases. Therefore, it was investigated whether the recommendation of a crop oil concentrate at a given rate per hectare was more beneficial with lower spray volumes.

In these tests, the increased rate of adjuvant did not improve surface activity, or herbicide efficacy.
Application of a Biotreatment Screening Test for Considering Bioremediation As a Treatment Option
Authors: Roy M , Gauger WK , Rehage JA
Published: March 2009

The purpose of this study was to validate a test procedure developed to be flexible but sufficiently focused to determine the biodegradation potential of organic contaminants in a waste. The biotreatability test provides a low cost screening tool to evaluate bioremediation as a treatment option for contaminated soil. The test measures microbial activity by collecting oxygen uptake and carbon dioxide evolution data. Pollutant removal is assessed by destructive sampling of the soil. We report the use of this test on hydrocarbon-contaminated silty sandy soil from an Air Force Station in central Alaska. Soils were incubated at 4°C and at various oxygen levels which were expected to exist during in situ treatment conditions. The incubation period for the test was 90 days. Results indicated that the test conditions incubated at the reduced oxygen levels (2–14%) had the most vigorous oxygen uptake and efficient hydrocarbon removal.
PAH Impact on the Sediment Bacterial Community
Authors: Pikett SF , McEldowney S , Knights B
Published: March 2009

The potential for bioremediating polycyclic aromatic hydrocarbons (PAHs), the major constituents of creosote, will depend on the response of the sediment bacterial community. The microbial community in sediments from a creosote-polluted freshwater lake was studied. The aim of this study was to assess the impact of PAH contamination on the sediment bacterial community. Sediment samples were taken at selected sites around the lake and upstream at an unpolluted site. Samples were analyzed for selected PAH concentrations. The numbers of aerobic heterotrophic bacteria isolated after growth on peptone yeast extract agar, peptone yeast extract with added creosote agar, and a minimal media with added creosote agar were determined for each site. The response of different bacterial physiological types to PAH contamination in sediment ecosystems was assessed through the use of a gel-stabilized model system. It was apparent that the PAH contamination had a marked effect on the bacterial community of these freshwater sediments. Such effects may influence the cycling of nutrients within sediments, e.g., the nitrogen and sulfur cycle, and the potential for in situ bioremediation.
Investigation of Soil Venting-Based Remediation at a UST Site in the Appalachian Piedmont
Authors: Widdowson MA , Ray RP , Reeves HW , Aelion CM , Holbrooks KD
Published: March 2009

The feasibility and effectiveness of soil vapor extraction (SVE) -based remediation technologies is being addressed at a petroleum-contaminated site in the Piedmont region of South Carolina through a multi-disciplinary research program. The program objective is to gain better understand of mechanisms governing remediation of contaminated soil by SVE-based techniques. Baseline data collection of physical, chemical, and microbial properties is augmented by mathematical modeling of the processes. A pilot-scale remediation system has been designed to allow evaluation of SVE-based systems within Piedmont materials. System off-gas and soil vapor will be monitored to delineate which physical and microbial treatment processes contribute to in situ voc removal.
The Elda Center -- An Innovative Concept in Soil Recycling Using Bioremediation
Authors: Hater G , Gillenwater PS , Li AY , Start J
Published: March 2009

Soil pile bioremediation is a simple and cost-effective method for remediating contaminated soils. This bioremediation technology uses vacuum to provide continuous aeration to contaminated soil that has been excavated and inoculated with nutrients and contaminant-specific bacterial cultures.

In this process, contaminated soil is generally placed on top of an impermeable plastic liner to control leachate and runoff. Vacuum is then pulled on the pile through a framework of perforated corrugated hose, while air is supplied to the pile through a separate network of inlet pipes. The blower exhaust exiting the pile is sent to vapor phase activated carbon to eliminate air emissions. The soil pile is covered with a black plastic liner to prevent odor and air emissions, evaporation, and loss of passive solar heat. During operation, nutrients, water, and additional bacteria are added as needed through a separate leach line inside the top cover.

Soil pile technology has been successfully used to remediate several non-RCRA petroleum contaminated sites. To take advantage of these field successes, WMNA and CWM decided to build a permanent facility that treats and recycles soil at WMNAs existing solid waste landfill in Cincinnati, OH. The net result is the ELDA Soil Center. To date, two soil piles, each with 15 000 cubic yard capacity, have been constructed at the ELDA landfill. The Soil Center is capable of recycling in excess of 250 000 tons per year of petroleum contaminated soils. This permanent facility uses a clay liner underneath the soil pile and perforated ABS pipe for air and vacuum lines. A biofilter was installed for controlling the VOCs prior to a 2-stage activated carbon system for air emissions control.

Soil treatment at the ELDA Soil Center provides several significant advantages. First, it enables contaminated soil that would normally be landfilled to be recycled as daily cover or as backfill offsite, thus saving landfill space and eliminating the liability associated with landfill disposal. Second, it effectively destroys organics through biodegradation resulting in nonregulated soil. Third, the ELDA Soil Center offers an off-site alternative to on-site remediation, particularly to space constrained sites that cannot perform on-site remediation. It also enables customers to take advantage of the low operating costs associated with a fixed site. The ELDA Soil Center is the first of its kind. Plans are underway to use the 128 WMNA solid waste landfill sites to develop a strategically located network of additional soil recycle centers throughout the United States. Soil treatment centers may also be developed for organic contaminated RCRA soils at CWM hazardous waste landfill sites in order to provide a cost-effective remedial option for these soils.
Field Application of Solid Oxygen Source for Bioremediation
Authors: Davis-Hoover WJ , Murdoch LC , Vesper SJ
Published: March 2009

A contaminated field site was created in the subsurface soil by introducing propylene glycol (PPG). The soil at the site is an overconsolidated silty clay of very low permeability (hydraulic conductivity about 10-7 cm/sec). After a period of acclimation, the soil was hydraulically fractured using a mixture of sand, encapsulated sodium percarbonate, and IBDU slow-release fertilizer. In the vicinity of the fractures, microbial metabolic rate increases were observed as well as increases in the microbial population of 10 to 100 fold. The PPG was observed at lower concentrations near the fractures compared to above the fractures by the end of the incubation. After four months in the soil, the rate of oxygen release from the fracture layer was still 2.6% of its initial rate of oxygen release.
Oxygen Dissolution Technologies for Bioremediation Applications
Authors: Storms GE
Published: March 2009

For aerobic biotreatment processes, oxygen transfer and volatile organic chemical (VOC) emissions can be important operational limitations. By using industrially pure oxygen rather than air as the dissolved oxygen source, higher oxygen transfer rates and significantly lower volatile emissions rates can be achieved. In addition, pure oxygen can eliminate foam formation, reduce the evaporative cooling effects, eliminate dependence on electrical power for aeration, and allow for greater oxygen demand variations.

Due to the cost of oxygen, it is generally more cost effective to use mixing technologies that have higher oxygen transfer efficiencies (and higher mixing energy costs) than are usually used with air-based aeration. These are usually mechanical mixing technologies, rather than diffusion technologies. Several such approaches are discussed.
Effects of Nonuniformities in Fasteners on Localized Vibration and Fatigue
Authors: Allaei D
Published: March 2009

The purpose of this paper is to report on an ongoing project that combines recent developments in the fields of vibrations and modeling to increase the service-free life and the quality of performance and reliability of fasteners and to reduce unnecessary maintenance and failure in aircraft structures. In this project, the feasibility of developing an efficient and effective mathematical model capable of incorporating the dynamic characteristics of fasteners, their interfaces with the host structure, and the host structure itself is being investigated. Such a combination will result in a significant gain in computational speed and an improvement in the accuracy of the numerical results, producing a better prediction. The model will be adaptive based on the closed-loop dynamic relation between fasteners and the host structure. The main contribution of this work is to include the effect of fasteners on vibration phenomena such as loci veering and mode localization and the application of the receptance method, which makes the model compatible with existing computer models, to the dynamics of fasteners.
Review of Factors That Affect Fatigue Strength of Low-Alloy Steel Fasteners
Authors: Skochko GW , Herrmann TP
Published: March 2009

Axial-load-cycling fatigue tests of threaded fasteners are useful in determining fastener fatigue failure or design properties. By using appropriate design factors between the failure and design fatigue strengths, such tests are used to establish fatigue failure and design parameters of fasteners for axial and bending cyclic load conditions. This paper reviews the factors that influence the fatigue strength of low-alloy-steel threaded fasteners, identifies those most significant to fatigue strength, and provides design guidelines based on the direct evaluation of fatigue tests of threaded fasteners. Influences on the fatigue strength of the thread manufacturing process (machining and rolling of threads) and the effect of fastener membrane and bending stresses, thread root radii, fastener sizes, fastener tensile strength, stress relaxation, mean stress, and test temperature are discussed.
Stress Intensity Factor Approximations for Cracks Located at the Thread Root Region of Fasteners
Authors: Cipolla RC
Published: March 2009

Nondimensional stress intensity factors have been numerically determined for a straight-fronted edge crack located at the thread root of a fastener. An influence-function or weight-function approach was used in determining KI for several fastener sizes: diameters ranging from 1 to 6 in. (2.5 to 15.2 cm) and thread pitches of 4, 8, and 12 threads per inch. Several analytical approximations are used in simplifying the stress analysis problem and the development of the weight function. The results for the nondimensional stress intensity factor, KI/σ(πa)1/2, are provided as a function of crack depth, bolt size, and thread pitch. The effects of bolt size and thread form play an important role only when cracks are relatively small. These results indicate that local differences caused by thread form and root radius are limited to crack depths within 2% of the net section. All major contributions to elevation in KI, caused by the presence of the threads appear to diminish for cracks extending beyond 25% of the minor diameter.
Early Stages of Fatigue Damage of Fastener Holes Monitored by Laser Speckle
Authors: Chiang F-P , Du M-L , Li S
Published: March 2009

The present work confines itself to the study of the initiation and early propagation of fatigue cracks emanating from simulated fastener holes using a laser speckle method that is a noncontact, nondestructive, and remote sensing technique. When illuminated by a narrow laser beam, the fatigue-induced surface roughness causes the laser beam to diffract into a halo modulated by a random speckle pattern. The fatigue damage information is contained in the speckle diffraction pattern. The half width and cross correlation coefficient of a speckle pattern are chosen to quantify this information. Two kinds of specimens, a thin plate with an open hole in the center and a thin plate with an oversized pin impacted into a central hole, were tested. The fatigue process was monitored by the laser speckle patterns. After crack propagation, the specimens were examined under a scanning electron microscope and their fractographic features correlated with the fatigue process.
Resolving Term Disputes with Weighted Onometrics
Authors: Gilreath CT
Published: March 2009

This article describes a system that brings greater rationality to the process of selecting preferred terms for senses or concepts. Since vocality disputes (term disputes) occur in every discipline and within every personal vocabulary, the principles covered here are useful to a broad audience. This article refines the term-evaluating formalism called onometrics, previously introduced by the author. Onometrics holistically focuses our attention on term qualities that otherwise might be overlooked. Weights of relative importance are assigned to 16 criteria, the top ones being: transparency, precision, unequivocalness, precedent, and conciseness. Each criterion is assigned a weight of importance. For each criterion suggestions are given for measuring (rating) compared synonyms. A template useful in forming comparative profiles for any term dispute is presented. For illustration, the template is applied to three disputes currently unsettled among terminologists: 1. glossary-vocabulary, 2. designator-designation, and 3. polysemic-polysemous. Approximately 64 terms are defined.
Content Analysis of Definitions
Authors: Strehlow RA
Published: March 2009

Terminology harmonization involves concepts, concept systems, definitions, and term-concept designations. Harmonization of concepts is the fundamental objective for many applications in terminology work, and the analysis of definition statements is a key to concept identification. Analyzing a definition requires knowledge of the definition type. Examples are given from the 1990 ASTM Compilation of Standard Definitions along with a systematic set of questions that should aid definition writers, standardizes, translators, and others who use definitions in identifying concepts or harmonizing meanings in terminology.
Bringing Aristotle into the 20Th Century: Computer-Assisted Definition Construction in a Terminological Knowledge Base
Authors: Eck KE , Meyer IE
Published: March 2009

In this paper, we describe an approach to computer-assisted definition construction using CODE, a knowledge management system developed at the Artificial Intelligence Lab, Department of Computer Science, University of Ottawa, Canada. Our approach, which we call definition-oriented concept analysis, tries to rectify some of the most common problems in intensional terminological definitions, namely inconsistency of genus and differentia from one coordinate concept to the next. We examine how various features of CODE can help terminologists carry out definition-oriented concept analysis. These features include textual and graphical browsers, along with the Characteristic Comparison Matrix (CCM), a special browser that lets users view and compare the characteristics of coordinate concepts in tabular form. The explanation of our approach includes practical examples taken from a terminological knowledge base (TKB) on lasers, and demonstrates how terminologists can use CODE to methodically carry out definition construction and create consistent definitions.
A Construction Industry Terminology Database Developed for Use with a Periodicals Index
Authors: Greenwald S
Published: March 2009

ArchiText has developed a terminology database for use with Construction Index, a periodicals index. This paper describes the database structure and how the database is used to improve consistency of indexing and precision of searching. The terminology database combines functions of a thesaurus and a classification system, and references sources of technical definitions. Terms are arranged in hierarchies that allow for up to three broader terms for each term. Synonyms can be classified by type, such as acronym, colloquialism, or British term. Terms map to subject headings for various report formats, including ICONDA and CSIMASTERFORMAT. The principal long term goal is to develop the database in a manner that facilitates accurate searching of the database by users who have varying degrees of knowledge of the technical terminology. Terminology mistakes and questions generated by indexers for Construction Index, who are architectural students, provide feedback for improving database content.
Experimental Development of a Mixed-Mode Fatigue Delamination Criterion
Authors: Sriram P , Khourchid Y , Hooper SJ , Martin RH
Published: March 2009

Interlaminar fracture (delamination) is the dominant failure mechanism in most advanced composite materials. The resistance of a material system to delamination failure is generally quantified in terms of the interlaminar fracture toughness, Gc. The recently developed mixed-mode bending (MMB) test is unique in that it facilitates measurement of the fracture toughness Gc under any combination of mixed-mode loading from pure Mode I to pure Mode II. This makes it a very attractive technique for developing interlaminar fracture failure criteria. This paper reports on an application of the MMB test to fatigue loading for the generation of G versus N curves and identification of applicable mixed-mode fatigue failure laws. Fatigue results from unidirectional IM7/5260 carbon/bismaleimide and IM7/8320 carbon/thermoplastic specimens are presented for mode mixes varying from pure Mode I to pure Mode II. Static test results are also presented for both materials. The static and fatigue results indicate different mixed-mode failure laws for the two materials. Further, the effect of fatigue is shown to be both material and mode-mix dependent. All tests were conducted using displacement-controlled loading under room temperature dry conditions.
Delamination of Carbon/Epoxy Laminates Under Cyclic Mode II Loading
Authors: Kussmaul K , Alberti Mv , Eisele U , Schneider T
Published: March 2009

The influence of fiber orientation and the location of a delamination within the laminate on the delamination behavior under fatigue loading has not yet been considered sufficiently. In this study, the growth of delaminations between plies of different fiber orientation and on different locations over the thickness of the laminate under cyclic Mode II loading was characterized using the end-notched flexure (ENF) test. Laminates made of HTA/6376, a toughened carbon/epoxy, with unidirectional and quasi-isotropic layups were tested. Experiments were performed in stroke control at a frequency of 5 Hz and a displacement ratio of 0.1. Delamination growth per fatigue loading cycle, da/dN, was related to the strain energy release rate (SERR) GII associated with the Mode II (forward shear) loading. G was determined by an experimental compliance calibration procedure, correlating observed crack length with measured specimen compliance. A complete characterization of the delamination growth from the threshold of detectability to unstable delamination growth is given. A Paris law was fitted to the data which describes the experimental results rather well. It was observed that delamination growth always occurred along plies of 0° orientation. Depending on the specimens' lay up and the location of the crack initiation insert, intralaminar crack growth occurred until the crack reached the next 0° ply. Delaminations then propagated from this point. Due to the coupling of deformation modes and the rather complex damage pattern, a mixed mode loading may occur. The resulting delamination growth curves were found to lie within or to the right (i.e., delamination growth is slower for a given SERR) of the scatter band found for the specimens with midplane delamination and 0° bounding plies, with only few exceptions. Specimens with delaminations close to the laminate's surface did not fail by delamination from the insert but due to bending or interlaminar shear close to the laminate midplane. An analytical expression for the distribution of the strain energy release rate, II, over the thickness of the specimen is derived which, within the rather large scatter that was observed, characterizes the SERR determined experimentally fairly well. The experimental results suggest that it may be sufficient to characterize delamination propagation behavior under cyclic Mode II loading in carbon/epoxy utilizing specimens with unidirectional layup and midplane delaminations. However, further investigations are needed to confirm this conclusion.
Mode III Delamination Using a Split Cantilever Beam
Authors: Sharif F , Kortschot MT , Martin RH
Published: March 2009

In this study, 48-ply AS4/3501-6 (carbon fiber reinforced epoxy) laminates were delaminated in essentially pure Mode III using a modified split cantilever beam (SCB) Mode III test. For this test, two loads are applied directly to each arm of a SCB specimen using a pair of identical grips. The complex loading configuration is necessary to reduce the Mode II loading which is dominant at the free edges when a single load is applied to each arm. Finite element analysis of a three-dimensional mesh confirmed that the strain energy release rate, determined using the virtual crack closure technique, was dominated by the Mode III component for the proposed loading configuration. Scanning electron microscopy of the delaminated surfaces revealed matrix cracking (analogous to Mode II shear hackles) at 45° to the plane of the delamination and parallel to the fiber direction. Crack stability, data reduction techniques, and the limitations of the new method are also discussed. Further work is required before the method could be considered for widespread use.
Improvement of Delamination Resistance with Carbon Nonwoven Mat Interleaves
Authors: Armstrong-Carroll E , Cochran R
Published: March 2009

Composites have been used in many structural applications throughout the aerospace industry. This popularity is due to the combination of lightweight and high-strength properties possessed by these materials. A common composite material system is unidirectional graphite-reinforced epoxy. Unidirectional composites possess a high fiber volume fraction and thus maximize strength and stiffness. However, laminates fabricated with unidirectional fiber layers are susceptible to delamination when subjected to impact testing or other out-of-plane loads.

In this study, AS4/3501-6 composites were interleaved with nonwoven carbon fiber mats. The mats increased composite delamination resistance as measured with edge notch flexure (ENF) testing. The Mode II fracture energy (GIIc) of a composite without an interleaf was 359 J/m2. The use of a 12 g/m2 aerial weight mat increased GIIc by 60% (574 J/m2). A mat having an aerial weight of 6.8 g/m2 increased GIIc by 130% (834 J/m2). The ENF failure surfaces were investigated to determine how the mat affects failure surface topography. The mat fibers close to prepreg fibers acted as obstacles in the crack path. The failure topography was similar for both mats. The 6.8 g/m2 mat was thinner when consolidated and possessed a higher fiber volume than the 12 g/m2 mat. These factors were responsible for the greater increase in delamination resistance achieved with the 6.8 g/m2 mat.

This study also examined the effect of the mat interleaf on composite tensile and compressive strength. Both tensile and compressive strength were unaffected by the mat interleaf.
Stress and Energy Based Fracture Conditions for Fiber-Wise Splitting in Composites
Authors: Suresh N , Wang ASD
Published: March 2009

This paper discusses the critical conditions for an interface-related fracture in epoxy-based graphite fiber-reinforced structural laminates. The specific fracture mode under consideration is that of a splitting crack along the fiber direction. Fiber-wise splitting often occurs in laminates that have holes, sharp notches, or cutouts due to stress concentration near these locations. The problem has been treated as an interface shear-dominated fracture, and methods of fracture mechanics are frequently employed for the purpose of analysis. Within this context, suitable mixed-mode fracture criteria are required. Past studies have used the strain energy release rates in the formulation of the desired criteria, and, depending on the test model used, the formulated criteria came in a variety of forms. Among several possible forms, the one form involving the total strain energy release rate (GI + GII) = constant has often been recommended. Recently, however, a form employing the stress intensity factors KI and KII has been deduced from a set of fiber-wise splitting test data. An apparent difference existed between criterion deduced based on G and that deduced based on K. Theoretically, of course, the two deduced criteria should be mutually equivalent.

This paper discusses the reasons for the apparent difference and offers a consistent interpretation of the respective set of test data. When this is done, a unified criterion, be it expressed in G or in K, can then be deduced without contradiction.
Stacking Sequence Effects and Delamination Growth in Graphite/Epoxy Laminates Under Compression-Dominated Fatigue Loading
Authors: Komorowski JP , Lefebvre D , Roy C , Randon C
Published: March 2009

The effect of free-edge stresses on the fatigue of graphite/epoxy laminates was evaluated numerically and experimentally. Reported are results of static and compression-dominated (R = -3.75) fatigue tests on AS4/3501-6 and IM6/5245C using unnotched specimens. Two different stacking sequences of 18-ply laminates were tested. The lamination was (0°/45°/90°) (44.4%, 44.4%, 11.1%). Damage development was monitored using ultrasonic C-scans, photoelastic coatings, and optical microscopy.

Stacking sequence had a significant influence on compressive failure strength. Differences in the fatigue lives of the two stacking sequences were close to two orders of magnitude. Damage always initiated at the edge and was related to the magnitude of interlaminar shear stresses. Well-defined stages of the fatigue process leading to final failure were observed.

A computer code was used to predict the life of the specimens. The code has yet to be calibrated for an unnotched delamination failure mode.
Fatigue and Fracture of the 767 Graphite Torsion Spring
Authors: Bliss RW , Wheeler DL , Maguire R
Published: March 2009

The effect of fiber tow waves on the static strength and in-service fatigue life of the Hercules Graphite Torsion Spring used in the Boeing 767 airline is presented. A concise process overview is given. Process variables affecting tow wave formation are identified. The design of quality control specimens is presented. Pictures of tow waves preceding translaminar fractures are shown. The functional relationship of nested tow wave amplitude and length to the maximum strain is briefly reviewed. Tow wave strength and in-service fracture cycle data are fit to regression curves. The potential fatigue life of the springs is predicted. Finally, no effect of fatigue on spring rate and permanent set was found.
Fracture of Glass-Epoxy Laminates Under Torsion and Combined Tension-Torsion Loads
Authors: Sen JK , Fish JC
Published: March 2009

An experimental program and a finite element stress analysis were conducted to study delamination failures in glass-epoxy laminates subjected to torsion and combined tension-torsion loads. Nine laminate configurations with three ply orientations and three stacking sequences were evaluated. The failures consisted of through-the-thickness shear cracks in off-axis plies, which promoted delaminations at adjacent 0° interfaces. The predominant stress in all cases is the interlaminar shear stress, σxz. Dispersing off-axis plies away from the laminate midplane increased the torsion load-carrying capability but did not significantly increase twist capability. The failure torque and twist angles were higher under combined tension-torsion loads than under torsion load alone due to the increased torsional rigidity and the compressive interlaminar normal stress induced by the tension load.
What is Accelerated in Accelerated Testing: A Framework for Definition
Authors: Roberge PR
Published: March 2009

Each failure or corrosion case is as specific as a human thumbprint or genetic make-up. There is often enough information generated by a failure analysis investigation to permit one to pinpoint the cause of failure to the role played by a few atoms located in a microscopic environment. The design and practice of accelerated corrosion testing for the purpose of ranking materials and processes would benefit greatly if the degradation modes caused by the tests being performed were better characterized and monitored. This paper reviews the acceleration factors commonly used in continuous and cyclic cabinet testing and discusses some of their impact on the results generated. The inadequacies of traditional salt spray testing is discussed in the light of a comprehensive framework of parameters leading to corrosion degradation. The importance in recognizing the presence of competing failure modes is examined in relation to the statistical characteristics of the underlying acceleration factors.
An Alternate Electrochemical Procedure for Testing Anodized Aluminum
Authors: Roberge PR , Halliop E
Published: March 2009

The quality control of aluminum anodizing with routine electrochemical measurements has become an acceptable and reliable replacement to salt spray testing. The electrochemical measurements can be performed a thousand times faster than classical salt spray exposure and be included in the routine daily operation of a plant. The sensitivity of the electrochemical testing techniques to intermediate surface conditions also means that these alternate techniques could be used to reveal trends in the anodizing process and help to fine tune its chemistry. This paper reviews the progress made with the new electrochemical procedure which has been recently developed to evaluate the quality of anodized aluminum coupons.
Cosmetic Corrosion of Painted Aluminum Automotive Body Sheet: Results from Outdoor and Accelerated Laboratory Test Methods
Authors: Moran JP , Ziman PR , Kipp TR
Published: March 2009

In recent years, increasing attention has been given to the need to develop an accelerated laboratory test method(s) for cosmetic corrosion of painted panels that realistically simulate in-service exposure [1,2]. Much of that work has focused on steel substrates. The purpose of this research is to compare the corrosion performance of painted aluminum sheet as determined from various laboratory methods and in-service exposure, and to determine the most realistic accelerated test method. Several aluminum sheet products from the 2xxx, 5xxx, and 6xxx alloy series have been tested. Steel substrates similar to those used in other programs [1,2] have also been included. The results indicate that of the laboratory test methods investigated, ASTM B117, Continuous Salt Spray provides the best correlation with outdoor data for aluminum alloys. For steel, however, ASTM B117 correlates poorly. In addition, there is considerable difference in the relative magnitudes and morphologies of corrosion, and occasionally in the relative rankings, as a function of test method. The influence of alloy composition and zinc phosphate coating weight are also discussed.
Use of ASTM Standard Practice for Modified Salt Spray (Fog) Testing G85, Annex A2 Cyclic Acidified Salt Fog Testing, for Rapid Screening of Inorganic Coatings on Aluminum 1100 Alloy Fins for Heat Exchangers
Authors: Lifka BW , Vandenburgh PK
Published: March 2009

Aluminum 1100 alloy fins in small heat exchangers are press fit onto copper tubing and require a protective coating to prevent excessive galvanic corrosion. This program was conducted to determine whether use of the ASTM Standard Practice for Cyclic Acidified Salt (Fog) Testing (G 85-A2), could effectively screen experimental, candidate coatings in a relatively short time. Two weeks of exposure, utilizing only unassembled panels, identified coatings that provided excellent protection. This compares very favorable with the existent quality control test that requires exposure of assembled units for 1000 hours (almost 6 weeks) exposure to the less corrosive, ASTM Standard Test Method of Salt Spray (Fog) Testing (B 117).