bluuebunny/crossref_metadata_2025_split huggingface dataset:
Criticality of Disbonds in Laminated Composites
Authors: Chatterjee SN , Pipes RB , Blake RA 
Published: December 2008

Usefulness of analytical methodologies and nondestructive tests for assessing criticality of disbonds in laminated composties is examined. Fracture mechanics approach and critical energy release rate concepts are employed for the prediction of catastrophic growth due to quasi-static transverse shear loading. Semi-empirical growth laws are considered for modeling slow growth under cyclic loading.
Brief descriptions of the analytical methods utilized for calculation of energy release rates are given. Sizes and locations of implanted disbonds in graphite/epoxy laminates are determined from ultrasonic C-scans. Analytical results and quasi-static destructive test data for beams subjected to three-point bending are correlated for determining the critical value of energy release rate. Effects of initial flaw size, location, sharpness of disbond tips, as well as mixed-mode (I and II) loading conditions are studied. Ultrasonic C-scans are also used for monitoring growth of disbonds in plate-type structures under cyclic transverse shear. Least square fits are attempted with the disbond growth rate data.
Vapors, Odors, and Toxic Gases from Landfills
Authors: Young P , Parker A 
Published: December 2008

Landfill gas from eight different sites in the United Kingdom was analyzed for trace constituents. Municipal, industrial, and liquid codisposal sites were included. A hazard assessment was made on the basis of the concentrations of potentially toxic components, and some of the causes of landfill odors were identified.
Three trapping methods were used to provide samples for analysis by gas chromatography/mass spectrometry. Supplementary techniques were employed to quantify the bulk gases, hydrogen sulfide, and metallic elements present.
Over 100 organic constituents were identified, but only 10 exceeded their individual recommended toxicity threshold limit values. Toxic compounds were more abundant at industrial sites. Odors were strongest from recently deposited waste, with methanethiol exceeding the odor threshold by a factor of more than 106. Hydrogen sulfide was not a significant cause of odor. Odors from the compounds identified and quantified depend more on the stage of decomposition than on the nature of the waste, and industreal wastes did not exacerbate the smell.
Chromium-Bearing Waste Slag: Evaluation of Leachability When Exposed to Simulated Acid Precipitation
Authors: Kilau HW , Shah ID 
Published: December 2008

Waste slag dumps constitute a large potential source of chromium contamination of groundwaters, particularly under the enhanced leaching action of acid precipitation. Laboratory leaching experiments were carried out to determine the composition factors controlling the chromium leachability of waste slags when exposed to acidic solutions designed to simulate acid precipitation.
Two critical slag composition factors were found to control the chromium leachability: (1) the calcium oxide (CaO)/silicon dioxide (SiO2) ratio and (2) the magnesium content. It was determined that above a 2.0 CaO/SiO2 ratio, chromium exists in slag as calcium chromite, which can be vulnerable to leaching by acid precipitation, especially if it is oxidized to calcium chromate when exposed to the environment over an extended period.
Experimental results showed that maximum chromium leachability from industrial slags occurred when the composition of the slag was at about a 2.0 CaO/SiO2 ratio. Between a 1.0 and 2.0 CaO/SiO2 ratio, in the presence of sufficient magnesium, picrochromite (MgO · Cr2O3) was formed, which is very stable towards oxidation and was resistant to dissolution by simulated acid precipitation.
Trace Metal Interactions Affecting Soil Loading Capacities for Cadmium
Authors: Baker DE , Rasmussen DS , Kotuby J 
Published: December 2008

The goal of this investigation was to establish a theoretically applicable model of, and develop an approach for, the direct measurement of cadmium loading capacities under laboratory conditions. Data from the literature were fitted to a model indicating a direct, linear relationship between the logarithm of the activity of Cd2+ in the soil solution and the logarithm of plant uptake of cadmium. These results support the model for passive absorption of cadmium by plants. It was postulated that the diffusion of Cd2+ from the soil-adsorbed phase to plant roots results from the electrochemical potential gmCd, gradient established between soil-adsorbed Cd2+ and that in solution, which is depleted as a result of passive absorption by plants.
Laboratory methods for relating the negative logarithm of the activity of Cd2+ in solution, pCd, to soil-adsorbed cadmium and plant-absorbed cadmium were developed, and test results for each are presented. It was concluded that this approach is theoretically valid and will provide routine laboratory methods for measuring soil loading capacities to protect the human food chain from undesirable concentrations of cadmium.
Disposal of Oil-Containing Sludges on Farmlands
Authors: Mucsy G , Kránicz-Pap E , Urbányi G 
Published: December 2008

The response of soils and plants to oil-containing sludges was studied by pot, small plot, and field experiments. The objective was to develop a simple method of farmland disposal without detrimental effects on the environment.
Dewatered sludge from a petroleum storage plant, in combination with nitrogen fertilizer, was found most suited to farmland disposal. The sludge was applied to sandy soil at rates from 3 to 8 g oil per kilogram of soil, and during a single growing season (six months) 60 to 90% of the oil was decomposed. No oil was detected below a 60-cm depth. Some physical properties of the soil, particularly the texture and water-retaining capacity, were improved. The plants were analyzed for protein, phosphate, and potassium oxide and found to have suffered no detriment and no loss in crop yield. The method of disposal by conventional agrotechnical operations proved environmentally safe and economically superior to other alternatives.
Management of Solid Wastes in the Iron and Steel Industry
Authors: El-Gohary F , El-Khouly MS 
Published: December 2008

Wastes from a local iron and steel factory are the subject of this study. The manufacturing operations in the plant under consideration are agglomeration of iron ore and sintering, pig iron manufacture, steel making, rolling mill operations, and pickling.
Liquid slag, produced in the blast furnace, is granulated in water and used as a concrete additive. Other wastes are directed separately to sedimentation tanks. The settleable solids are reused, and the treated effluents are pumped to a cooling tower for recycling.
As a result of the new manufacturing expansion, existing waste treatment facilities are not adequate, and it was found necessary to provide additional treatment techniques.
Departmental, as well as composite wastes were treated using plain sedimentation, centrifugal sedimentation, or chemical coagulation, or a combination of these methods.
The results obtained showed that the use of the hydrocyclone for solid-liquid separation is much more efficient than plain sedimentation. When this process was followed by coagulation, very promising results were obtained. The use of pickling liquor as a coagulant gave comparable results with alum and ferric chloride.
The Use of the Chevron-Notched Short-Bar Specimen for Plane-Strain Toughness Determination in Aluminum Alloys
Authors: Brown KR 
Published: December 2008

An extensive study of the use of the chevron-notched short-bar (CNSB) specimen for measuring plane-strain fracture toughness in high-strength aluminum alloys is reported. The toughness measured in a CNSB specimen, KSB, correlates closely with plane-strain fracture toughness, KIc, for toughnesses less than 35 MPa m1/2. At higher toughnesses KSB is higher than KIc for two reasons; first, sample heterogeneity causes the different sized specimens to sample different material, and second, an effect of rising crack growth resistance in the toughness range 40 to 55 MPa m1/2; these latter test results should be considered invalid; however, within this range the KIc, KSB correlation, although largely empirical, is still useful for screening purposes.The toughness in high-strength aluminum alloy rolled plate may vary markedly through the plate thickness. Examples of these variations are presented.
Fatigue Crack Propagation of 25Mn-5Cr-1Ni Austenitic Steel at Low Temperatures
Authors: Yokobori T , Maekawa I , Tanabe Y , Jin Z , Nishida S-I 
Published: December 2008

A study has been carried out on the fatigue behavior of a newly developed high-manganese steel intended for low-temperature applications in the range from 0 to −174°C. As-rolled and solution-treated high-managanese steel were tested. The fatigue behavior of commercial austenitic steel was also presented for comparison.
The fatigue life of high-manganese steel was found to increase with decreasing temperature from 0 to −174°C. Crack growth rates were expressed in terms of the Paris relation da/dN = C(ΔK)n, and the power coefficient n was shown to depend on temperature. The temperature dependence of crack growth rate and n, as well as the linear dependence of apparent activation energy of the fatigue crack growth rate on the logarithm of the stress intensity factor range, are explained by the dynamic theory of fatigue crack growth.
Fatigue fracture toughness (Kfc) was found to increase with decreasing temperature. The effect of welding on Kfc is also shown.
Evaluation of Asphaltic Pavements for Overlay Design
Authors: Deen RC , Southgate HF , Sharpe GW 
Published: December 2008

To evaluate projects involving approximately 200-route-miles of interstate and primary pavements in Kentucky and Tennessee in relatively short time frames, it was decided to test, analyze, and design overlays using test equipment (Road Rater®) and procedures developed by the University of Kentucky Transportation Research Program. This paper presents the analysis methodology and the evaluation and overlay designs for selected projects, including the before and after analysis of milling on one project.
The Road Rater applies a dynamic sinusoidal loading of known force and frequency. The velocity of the vibration waves are measured by sensors and integrated electronically to obtain surface deflections. An analysis of the shape and magnitude of the deflection bowl permits an assessment of whether the structure is performing as anticipated or whether some component is significantly weaker than designed. Analyses permit the determination of the “behavioral” or effective thicknesses of the asphaltic concrete layers and the in-place subgrade moduli. Strip charts of effective thickness and subgrade strength (or alternatively, overlay thicknesses) along the length of a project permit delineation of the project into relatively uniform segments. The arithmetic mean and standard error are determined for each segment to estimate design parameters. The required overlay thickness is the difference between the total thickness required for new construction to carry the anticipated traffic and the behavioral thickness of the existing pavement.
Pavement Friction Measurements and Vehicle Control Reparations for Nontangent Road Sections
Authors: Balmer GG , Zimmer RA , Tonda RD 
Published: December 2008

Several measurement systems were evaluated to determine their applicability for measuring wet-pavement friction on transitional roadway sections. It was found that the two-wheel trailer is capable of such measurements if it is instrumented to measure the vertical dynamic test-wheel load as well as the longitudinal drag force during locked-wheel braking. A less desirable approach is to use accelerometers to measure the lateral and vertical accelerations on the trailer and compute the wheel load from these measurements.
There is greater friction deterioration on curves, ramps, intersections, and other transitional roadway areas from traffic wear and the environment than on tangent sections. When these roadway sections become slick or have marginal skid resistance, they can be milled, grooved, resurfaced, or overlaid applying a sprinkle treatment to restore adequate friction characteristics. This paper addresses both the measurement and the restoration aspects of this problem.
The Use of an Asphalt Polymer/Glass Fiber Reinforcement System for Minimizing Reflection Cracks in Overlays and Reducing Excavation Before Overlaying
Authors: Rowlett RD , Uffner WE 
Published: December 2008

Many techniques have been used in an attempt to prevent reflection cracking in asphalt overlays including stress relieving membranes, fabrics, bond breakers, and changes in mix design. Glass fiber reinforcements have been used in the plastics industry for increasing the fatigue life and fracture toughness of plastic products for many years. This paper describes the successful development of the use of glass fiber reinforcement in conjunction with an asphalt polymer to minimize reflection cracks in an asphalt overlay. The system is also used to reduce excavation of deteriorated cracks and joints before overlaying.
The glass fiber reinforcement is a high strength woven glass with a tensile strength of 1750 N/cm (1000 lb/in.) width. The asphalt polymer was specially designed for use with the glass fiber reinforcement and has excellent properties of adhesion, low-temperature flexibility, and high softening point.
The combined properties of the system are the key to performance. The asphalt polymer adheres to the old road, the glass fiber reinforcement, and the new overlay, protects the glass fiber reinforcement, acts as a stress relieving membrane, and transfers the stresses to the reinforcement. The glass fiber reinforcement distributes the stress over the width of the repair to a level below the fracture point of the overlay. Laboratory tests were used to determine the physical properties and characteristics of the system, but no laboratory tests were found to predict the field performance. Evaluation of the system was performed through field trials. Over a five-year period 150 field trials were installed in 21 states. These trials included transverse and longitudinal cracks in bituminous roads and transverse joints, longitudinal joints, and interslab cracks in portland cement concrete base roads. Approximately 30 480 m (100 000 ft) of the repairs were monitored for crack reflection. The asphalt polymer/glass fiber reinforcement system was 89% effective in reducing reflection cracks. The average age of the trials was 21 months with a range of 6 to 56 months. All trials were exposed to a minimum of one winter.
In recent trials this system has been used to reinforce badly distressed areas around joints or cracks in lieu of partial or full depth excavation. Cost savings greater than ten to one have been demonstrated for the asphalt polymer/glass fiber reinforcement system with equivalent or better performance than excavation.
The Use of a Gyratory Testing Machine in the Evaluation of Cold-Recycled Asphalt Paving Mixtures
Authors: Tia M , Wood LE 
Published: December 2008

This study evaluated the feasibility of using the gyratory testing machine in the fixed roller mode for evaluating the long-term behavior of cold-recycled asphalt mixtures. Cold recycled asphalt mixtures were compacted with the gyratory machine, and gyratory strain indices were obtained from the gyrograph recorded during the compaction process. The resilient modulus, Hveem stabilometer R value, and Marshall stability were obtained on the compacted recycled mixes at various curing times and were correlated to the gyratory strain indices. The scope of study presented in this paper covered two types of pavement material and five types of added softening agents, which included a high-float asphalt emulsion AE-150, a foamed asphalt and the rejuvenating agents, Reclamite®, Mobilsol®, and Dutrex 739®.
The results of the study indicated that the gyratory stability index (GSI) and the gyratory elasto-plastic index (GEPI) could be used to detect unstable mixtures when the binder content was too high. The GSI and GEPI correlated fairly well with the Hveem stabilometer R value of the recycled mix. However, they correlated poorly with the resilient modulus and Marshall stability of the recycled mix. Similar to the R-value test, the gyratory testing machine can be used to determine the optimum binder content of a cold-recycled mix.
The scope of this study was limited to the use of the gyratory testing machine in the fixed roller mode. Tests using the oil filled roller mode had not been conducted in this investigation.
Vickers Indentation Curves of Elastoplastic Materials
Authors: Loubet JL , Georges JM , Meille G 
Published: December 2008

Studies of Vickers indentation curves of elastoplastic materials give information about the relationship between plasticity and elasticity. We have built equipment which gives a record of the applied depression depth, h, as a function of the carried load, P (range, 0.5 to 20 N).
Investigation of the Vickers indentation curves, P(h), during loading and unloading and microscopic observations shows that the phenomena occurring during indentation are complex. We first discuss the loading curve. A comparison with a theoretical analysis is made. Young's modulus, E, and the Vickers indentation pressure during loading can be calculated from the unloading and loading curves. The meaning of the different characteristic parameters of the depth-load graphs is debated. Their correlation with optical measurements of the remanent Vickers indentation is proposed.
Use of the Scanning Electron Microscope in Microhardness Testing of High-Hardness Materials
Authors: Westrich RM 
Published: December 2008

Thin coatings of titanium nitride (TiN), zirconium nitride (ZrN), and hafnium nitride (HfN) are difficult to measure for hardness by any technique other than microhardness measurement. The question of apparent hardness increase with decreasing load has been the subject of much discussion, and many explanations have been offered, such as those of Gane and Cox and of Bulter. Impressions measured at high and low loads on a single hardness standard typically show higher hardness readings with lower loads. Correction factors have been suggested, however, there is still some question concerning the absolute hardness at low loads.
The purpose of this work is to show a technique, using the scanning electron microscope (SEM) and a diffraction grating for a measurement standard, that produces more accurate microhardness readings. Further, data suggest that very thin coatings, on the order of 2 to 5 μm, can be measured for hardness. A hardness standardization and comparison technique was also developed to relate microhardness readings from different hardness scales more accurately. Computer techniques were utilized to fit the hardness data for hardness scale comparisons.
Polarization Studies on Surgical-Grade Stainless Steels in Hanks' Physiological Solution
Authors: Ogundele GI , White WE 
Published: December 2008

The corrosion resistance of a wrought Type 316L stainless steel (WSS316L) and a surgical-grade stainless alloy (SG2SA) were studied. The behavior of the alloys, as influenced by chloride (Cl−) and bicarbonate (HCO3−) ion concentrations, as well as pH and temperature in Hanks' physiological solution, were explored using electrochemical techniques.
The results show that SG2SA exhibited a more noble response and higher passive breakdown potential than WSS316L. Both materials were significantly affected by changes in Cl− and HCO3− ion concentrations. The corrosion and breakdown potentials shifted to more negative values with increasing Cl− ion concentrations, but to more positive values with increasing HCO3− ion concentrations. The alloys displayed most noble characteristics in neutral solutions and at higher temperature conditions.
The alloys were found to be active only in highly acidic solutions at potentials below −300 mV versus saturated calomel electrode (SCE). Furthermore, the materials were found to experience an early passive film breakdown at higher temperatures, indicating that the passive film is more stable at lower temperatures.
Cyclic polarization tests on WSS316L showed that the chance of repassivation of actively growing pits is very limited in environments containing variable Cl− and HCO3− ion concentration as well as at higher temperature.
As both of the test materials were determined, from chemical analyses, to conform to AISI Type 316L stainless steel, the observed differences in corrosion behavior are explained on the basis of different chemical composition and microstructural differences as observed by metallographic analyses.
Surface Fissuring of Polyurethanes Following In Vivo Exposure
Authors: Szycher M , McArthur WA 
Published: December 2008

Compared to standard silicone elastomers, polyurethanes offer enhanced mechanical properties, improved durability, and reduced wall thickness for pacing leads. These thinner-wall polyurethane leads can be used in smaller vessels, or will allow multiple leads to be introduced into a single vein.
Recent reports have shown that pacing leads made with Pellethane 2363-80A exhibit shallow surface fissuring; some pacemaker or lead constructions have failed, particularly at areas of chronic mechanical stress. Several mechanisms have been proposed as the cause of surface fissuring: protein absorption with associated swelling, leaching of low molecular weight substances to the surface, or lipid absorption. However, there is little evidence supporting any of these mechanisms.
Our studies suggest that polyether-based polyurethanes are susceptible to in vivo oxidation of the polyether chain. In this chain, the most susceptible group is the -CH2 group in the alpha position to the ether oxygen, which undergoes peroxidation, free radical dissociation, and, eventually, chain cleavage, possibly leading to a reduction in molecular weight averages. Attenuated total reflectance infrared (ATR-IR) studies at the surface of the fissured polyurethanes have shown the presence of oxidative byproducts such as hydroxyl end groups (-OH).
Based on these preliminary results, we hypothesize that progressive surface degradation is caused, in part, by stress-induced oxidation of the polyether macroglycol used in the synthesis of polyurethane elastomers. Our hypothesis has been reinforced by experimental evidence that surface cracking can be significantly reduced, if not eliminated, by using higher-durometer polyurethanes, because these polymers contain fewer polyether macroglycol chains in the molecular backbone.
Irradiation-Induced Swelling in AISI 316 Steel: Effect of Tensile and Compressive Stresses
Authors: Lauritzen T , Vaidyanathan S , Bell WL , Yang WJS 
Published: December 2008

Effects of bending stresses on the swelling behavior of 20% cold worked AISI 316 steel were studied in material irradiated to moderately high fluences in EBR-II. Specimens used in this investigation consisted of beams subjected to four-point bending during irradiation. Fluences as high as 1.5 × 1023 n/cm2 (E &gt; 0.1MeV) were accumulated at temperatures ranging from 412 to 458°C. The beams were subsequently sectioned to isolate regions of tensile, compressive, and neutral loading for examination by transmission electron microscopy. A complete characterization of swelling in each of the three regions was conducted to assess the influence of these stress states on the magnitude of swelling. A detailed microstructural evaluation of the material was also made to attempt to relate swelling differences with physical changes in the alloy.
The results of this investigation confirm earlier experimental data that showed swelling in AISI 316 steel to be enhanced by the application of stress during irradiation and that the magnitude of swelling is independent of the sign of the applied stress. The results also show that increases in swelling can be correlated with either more or larger voids depending upon the total strain incurred. This suggests that the mechanism for stress-enhanced swelling in this alloy may be a sensitive function of the magnitude of the applied stress.