bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bias and Precision of To Values Determined Using ASTM Standard E 1921-97 for Nuclear Reactor Pressure Vessel Steels
Authors: Kirk M , Lott R , Server WL , Hardies R , Rosinski S 
Published: April 2008

Recently ASTM adopted a Test Method for the Determination of Reference Temperature, To, for Ferritic Steels in the Transition Range (E1921-97). This test method quantifies the variation of fracture toughness with temperature throughout the transition regime based on limited replicate testing at a single temperature. Advances in elastic plastic fracture mechanics enabled adoption of size requirements in E1921-97 that permit testing of specimens as small as 10 mm cross section. Thus, E1921-97 presents the first opportunity to measure directly the fracture toughness of samples removed from surveillance capsules, rather than inferring toughness using RTNDT indexed KIC curve.
We assemble a database of fracture toughness values for reactor pressure vessel steels, including over 1,600 E1921-97 valid fracture toughness values for both irradiated and unirradiated steels. In this paper, we use this database to address concerns regarding the bias and pecision of To values determined by ASTM E1921-97, and regarding the use of To as an index temperature for the ASME KIC curve. When the requirements of E1921-97 are satisfied, neither the temperature at which the fracture toughness tests are conducted nor the level of deformation prior to fracture bias the estimate of To. Furthermore, the recently proposed To-based index for the KIC curve (RTTo ≡ To+ 35°F) reduces considerably the degree of scatter in facture toughness data, and contains implicit margins on toughness that are consistent for every steel considered. RTTo is superior to RTNDT as an index temperature for the KIC curve, and also provides for a more conservative assessment of vessel safety than does RTNDT.
Microstructure of the Neutron Irradiated VVER-type Reactor Pressure Vessel Steels
Authors: Kočík J , Keilová E , Procházka I , Čížek J 
Published: April 2008

Conventional transmission electron microscopy has been used to investigate the radiation-induced changes in the microstructure of VVER-type RPV steels. Specimens irradiated at ≈ 270 °C temperature in both the power light-water reactor (surveillance specimens) and the research reactor have been studied. In addition, the microstructure of the thermally aged specimens was analyzed too. Microstructural analysis has been supplemented by some preliminary results of the Doppler broadening and lifetime positron annihilation measurements.
Radiation-induced matrix defects visible by TEM in power reactor surveillance specimens consist of black dots, small dislocation loops and fine precipitates distributed heterogeneously with a dislocation substructure. Evolution of the radiation damage structure depends on the neutron fluence and the neutron flux. Only hardly discernible black dots were observed in specimens irradiated in the research reactor in NRI Řež. However, also in this case, the presence of a vacancy-rich component in the damage structure was suggested by positron lifetime measurements.
Mechanical Properties and Microstructure of HFR-Irradiated Ferritic/Martensitic Low-Activation Alloys
Authors: Materna-Morris EI , Rieth M , Ehrlich K 
Published: April 2008

Within the framework of the European Fusion Technology Programme, a series of ferritic/martensitic developmental alloys have been investigated after irradiation in the HFR (Petten, Netherlands). These new 7–10%CrWVTa alloys have been optimized towards long-term activation and the properties are compared with the conventional 9–12% CrMoVNb steels. The comparison contains two alloys from FZK (OPTIFER - type), the commonly investigated IEA alloy F82H and an ORNL - 9Cr2WVTa material. The irradiation was carried out in the temperature range of 250 – 450 °C up to an accumulated dose of 0.8 dpa.
The mechanical properties of the unirradiated and irradiated specimens were determined by tensile and impact tests. Radiation hardening, shift in DBTT to higher temperatures and partially a reduction of upper shelf energy were observed. Selected samples have been investigated by means of metallographic, SEM and TEM methods. The micro-structures developed during neutron irradiation showed irradiation-induced precipitates, dislocation loops and He bubbles or small voids. These microstructures contribute to the observed irradiation-induced hardening and the changes of the fracture mode from transgranular to intergranular fractures.
Measurement and Calculation of Helium Generation in Beryllium Pebbles Irradiated in EBR-II
Authors: Greenwood LR , Oliver BM , Gelles DS , Baldwin DL , Dalle Donne M , Kawamura H , Scaffidi-Argentina F 
Published: April 2008

Beryllium pebbles are being evaluated for their potential use as a neutron multiplier in fusion power reactors. Commercially available pebbles were irradiated in the Experimental Breeder Reactor II to study property changes and gas production. Helium production rates from fast neutron irradiation are significantly higher in beryllium than in other metals due to the low neutron energy threshold and large (n,2n)2α nuclear cross section. Furthermore, the 9Be(n,α)6He(β) reaction breeds 6Li, which has a high thermal neutron cross section for producing helium and tritium. Calculations of helium and tritium production were performed based on neutron dosimetry measurements.
Stepped-anneal and total helium release measurements were conducted on single and multiple beryllium pebbles, from two different suppliers, Brush Wellman and Nippon Gashi Co.-Japan. The measurements were conducted to determine the total helium content for comparison with predictions, and to determine the helium release characteristics as a function of time and temperature. These data are required for fusion reactor design. Sequential helium analyses were conducted over a temperature range from 500°C to 1100°C in approximately 100°C steps. Observed helium release in both beryllium lots was nonlinear with time at each temperature interval, with each step being characterized by a rapid initial release rate, followed by a gradual slowing of the rate over time. Fractional helium release as a function of temperature was observed to be substantially different for the two lots.
Comparisons of the measured and calculated total helium production in the beryllium agree within ±5%. This agreement validates our understanding of the reaction mechanisms, nuclear cross sections, and neutron dosimetry results, thereby demonstrating that we can confidently predict helium generation and release characteristics for the design of fusion reactors.
Activation Spectra: Techniques and Applications to Stabilization and Stability Testing of Materials
Authors: Searle ND 
Published: April 2008

The activation spectrum of a material represents the relative amount of damage caused by individual spectral regions of the source to which the material is exposed. Experimental techniques used to determine activation spectra include (1) narrow-band radiation utilizing interference filters or a grating or prism spectrograph and (2) polychromatic radiation with sharp cut-on UV/visible transmitting glass filters to define the relative effects of radiation by individual spectral regions during exposure to all wavelengths longer than the cut-on of the filter. The spectral effects of radiation on a material are determined by measurement of spectral changes, i.e., by UV, visible or infrared spectroscopy, and, if sample size permits, by changes in physical properties.
Applications of activation spectra include the development of light stable materials, the design of meaningful light stability tests, timing of exposures based on actinic radiation and prediction of service life by providing a means of determining effective dosage. Examples are given to demonstrate many of the applications of activation spectra and comparison is made with action spectra which represent the wavelength sensitivity of a material independent of the spectral emission properties of the radiation source.
Advances in Accelerated Weathering Instrumentation Technology Using Advanced Control Systems
Authors: Patel B , Tikhtman J , Lee F , Scott K 
Published: April 2008

For laboratory weathering instruments to be most useful, they must have, among other qualities, the ability to conduct tests repeatably and reproducibility. Repeatability is the measure of a specific instrument's ability to duplicate results from one test to another. Reproducibility is the measure of the ability of instruments of the same model to duplicate test results. As users become more sophisticated, the demand for instruments capable of very good reproducibility and repeatability increases. Thus, instrument manufacturers are constantly challenged to deliver suitable instruments to the testing community. For those tests that are influenced by multiple parameters, some of which are synergistic, while others are offsetting, the challenge is even more pronounced.
This paper discusses the concepts and features incorporated in a particular type of xenon weathering instrument to control critical test parameters, whether they are mutually compatible or not.
Estimating the Durability of Roofing Systems
Authors: Cash CG 
Published: April 2008

A method for the estimation of the durability of both steep and low sloped roofing systems is presented. The “thermal load” concept is defined. Each estimate is based on the thermal load at the exposure site, the presence of significant design, workmanship, and materials defects, and the generic roofing system proposed or selected. Examples show how to calculate the mean durability, and the durability adjusted for systemic defects for any of seventeen low- and steep-sloped roofing systems.
Thermal loads for many geographic locations and the thermal sensitivity factors for many roofing systems are provided.
Insights into the Use of Biocides in Silicones Sealants: Test Methods and Durability Aspects
Authors: de Buyl F , Gastaldi H 
Published: April 2008

Especially in humid or wet environments, such as bathrooms and kitchens, silicone sealants must be protected by the use of biocides from the growth of microbiological agents, i.e. fungi (mould or yeast), bacteria, or algae, to ensure longevity of the aesthetic aspect of sealing joints. Environmental aspects of using biocides, efficacy of active ingredients, and appropriate test methods to be used in order to assess ultimate performance and predict service-life durability under various weathering conditions (underwater leaching, UV exposure, outdoor) are all important aspects that require careful consideration.
Based on the experiences acquired in Rohm and Haas and Dow Corning laboratories, respectively, we have shown the importance of pre-conditioning the specimens, and selecting the appropriate test method to assess the anti-fungal protection of sealants. Among the various methods developed for that purpose, i.e., CAN2-19.0-M77, Wallhauser test method, NFX 41-514, ISO 846 and ASTM G21-96, we have shown that ISO846, method B, is the most appropriate for assessing the efficacy of biocides in protecting sealants against fungus growth in sanitary environments. We also discuss the choice of the appropriate inoculums and challenge testing conditions, as well as the key aspects that are important for proper interpretation of the ratings resulting from the challenge tests.
Comparative testing carried out with various silicone sealant systems enabled the identification of active ingredients adequate to provide durable protection of a cured silicone sealant, in particular after underwater leach-out conditioning, which for weatherproof sealing in residential glazing and sanitary applications is an important requirement. Comparison of the ratings obtained before and after underwater leaching provides therefore insights that allow estimation of the decrease of anti-fungal efficacy over time during service-life. Key selection criteria that an effective biocide needs to fulfill are also suggested.
Sealant Failure Morphology — The Important Criterion of Equipment Selection for Weathering Studies
Authors: Wypych G , Kuberski S , Lee F 
Published: April 2008

The objective of this study is to identify criteria for the selection of laboratory equipment for weathering studies of sealants that allow improvements in the correlation of accelerated weathering results with outdoor exposure results.
The Approach of the study is to compare physical-chemical characteristics of sealants, which were exposed to various laboratory methods and outdoors. Polyurethane, silicone, polysulfide, and Kraton®-based sealants were selected for this study. Sealants were exposed outdoors to wet (Florida) and dry (Arizona) climatic conditions. The laboratory studies were conducted in a fully equipped xenon-arc weather-ometer simulating wet climate conditions, a xenon-arc tabletop device, simulating dry climatic conditions, and a fluorescent UV condensation weathering device.
The degradation of the sealant surface on exposure to both natural and laboratory conditions was compared on the basis of morphological changes. The following methods were used to study chemical and morphological changes: TGA, DSC, polarized light microscopy, and image analysis. The results of physical-chemical studies are related to the esthetic performance of sealants measured by an image analysis to determine the rate of crack formation and the development of characteristic morphological features of crack formation in different sealants.
In this analysis, the exposure to natural conditions is used as the point of reference. The physical-chemical changes due to weathering in laboratory devices are compared with outdoor exposure results to verify similarity of the failure morphology. A valid laboratory weathering procedure is expected to result in the same degradation mechanism and induce similar modes of failure as outdoor weathering.
Design of a Learning Binding for Alpine Skiing
Authors: Gulick DW , Mote CD 
Published: April 2008

Advances in binding design for alpine skiing have been unable to eliminate injuries to the lower leg and knee. Studies to identify appropriate release settings have concluded that the maximum forces during skiing are not predictable using any measurable anthropometric parameters, and furthermore, that they are variable during skiing due to changes in snow conditions, skiing style, and other unmeasurable variables. This paper considers the feasibility of an alpine sking binding with variable release settings that adapt to changes in the force magnitudes during skiing. Release settings are determined according to difference equations involving previous and current force measurements. To facilitate comparison with contemporary commercial bindings, the learning binding design includes three release modes: external twist and internal twist governed by the lateral force component at the toe and forward lean governed by the vertical force component at the heel. Binding forces measured during more than 36 min of skiing experiments are used to determine values for the design parameters within the adaptive algorithm. Then the performance of the learning binding is judged by comparing the release settings to the settings recommended by ASTM Standard F 939-93.
The release settings of the learning binding algorithms are on average more than 22% less than the ASTM recommended settings for each skier, with a maximum reduction of 50% for one subject. No inadvertent releases are predicted throughout the skiing data. The reduced release settings adapt to temporal changes in forces and yield earlier releases in several falling scenarios experienced in the data. These results suggest that a learning binding can significantly improve the safety of alpine skiing.
Environmental Problems in Preserving Wooden Buildings at the Estonian Open Air Museum
Authors: Laht M 
Published: April 2008

The Estonian Open Air Museum was founded in 1957 on the shore of Kopli Bay near Tallinn, on the territory of the 19th-century Rocca al Mare summer residence. By 1966, 22 structures had been transported to the Museum grounds. At present the number of structures is 79. The Museum was established to collect, preserve, study, and exhibit typical and best examples of historical rural architecture. Every component of the exposition, including ensembles of farm structures designed as villages together with their furnishings, are meant to recreate an authentic reflection of folk culture.
The Estonian Open Air Museum has encountered several problems in preserving its exhibit buildings. The geographical and climatic location of the Museum is not ideal for an open-air museum. Increased general pollution and acid precipitation have contributed to wood deterioration. It has proven difficult to adapt old wooden buildings to new environmental conditions into which they are transported.
The location of the Museum is rather unfavorable for preserving the exhibits. As the Estonian Open Air Museum is situated near the sea, a very damp maritime climate dominates. The first years of the Museum were accompanied by the lack of knowledge on how to control mold and fungi growth. The chemical treatment of exhibit buildings was begun in 1966. Structures in the Museum were treated periodically between 1966 and 1995. The increase of general pollution and the awareness of its effects has diminished the desire to continue to use chemicals in preserving the exhibit buildings.
At present, an alternative to chemicals is being utilized. Temperierungsystem, a German method for regulating the temperature in the buildings, diminishes the rate of humidity as well as the instability of temperature. It is too early, however, to pass judgement on the efficacy of this method.
The Restoration of Sodankylä Old Church 1992–1995
Authors: Kairamo M 
Published: April 2008

In 1689 a wooden church was built in Lapland at Sodankylä. The building type, the horizontal log construction with block pillars, originates from the medieval times. Size of the church was 8.5 m × 13.5 m (28 ft × 44 ft), and the height, 8 m (26 ft). In 1778 the church was “modernized” by adding a wooden shingle roof and wooden panel cladding. Then, in 1859 the church was abandoned. In the 1920s a restoration was carried out by the National Board of Antiquities. In 1950 the roof was made of industrially sawn wooden shingles on bitumen felt. Some minor repairs took place in the 1950s, 1970, and 1985. The bitumen felt caused rotting of the shingles, and in 1972–95 a new wooden shingle roof and new wood panel were installed. The restoration principles considering authenticity were debated.
The work was financed mainly by the state employment program. It was done by traditional methods by hand. The shingles were carved by ax, the boards riven, handmade nails used and the bitumen felt was replaced by birch bark. Natural wood tar was used to protect the wood.
The total cost was about 2 million Fim (approximately $500,000). Knowledge of choosing, seasoning, working on and treating wood was gained during the building process.
Hydraulic Failure Analysis: Fluids, Components, and System Effects
Authors: Totten GE , Wills DK , Feldmann DG 
Published: April 2008

Description
41 papers provide a comprehensive overview of the problems and new technologies in hydraulic systems associated with hydraulic fluids and their interaction with component design, component metallurgy, and the design of the hydraulic system itself.
Six sections cover: Theory, Mechanism and Simulation • Failure Analysis • Materials • Components--Seals, Valves and Rolling Element Bearings • Fluids
Major issues addressed include:
• The effect of fluid chemistry on component failure as the result of oxidation, wear debris, viscosity loss, generation of corrosion by-products, and yellow metal wear.
• Metallurgy of the material, including material pair effects and physical properties.
• The effect of surface finish.
• Modeling wear mechanisms as a function of material pair contact loading, speed, and other factors.
• Dynamic versus static wear.
• Wear mechanisms including rolling contact fatigue, cavitation, lubrication failure, abrasive wear, and others, in addition to combinations of these mechanisms.
• Methods of failure analysis focusing on strategies to identify root caused of failure.
• Hydraulic component design and metallurgy of bearings, gears, slippers, and end-plates.
Modeling the Ductile to Cleavage Transition in Steels and Structures
Authors: Howard IC , Li ZH , Sheikh MA 
Published: April 2008

The process of ductile damage and subsequent crack growth and of cleavage in ferritic steels occur in steps whose controlling microstructural features are quite different. Useful models of these can, therefore, be attempted by associating the mechanisms of ductile damage or cleavage with an appropriate, microstructurally controlled, cell size. Furthermore, the cell size for ductile damage is typically too large to be used for the crack-tip finite elements that are required for accurate resolution of the large strain gradients in the continuum field that represents the deformation there prior to significant damage development. What is required is a finite-element code that allows (at least potentially) the presence of cells of more than one size.
These considerations have led to mesh-independent damage mechanics modeling, and a model of the ductile-to-brittle transition that has appropriate cell sizes for each failure mechanism. The complexity of these refined models demands very large computational times for technically interesting problems. Accordingly, our predictions of the outcome of engineering tests have used a compromise single-size cell model chosen to balance the conflicting requirements for each failure process. The paper describes the proving of this, and its use in predicting two of the large-scale spinning cylinder tests.
The work illustrates the potential conflict that may arise between the detailed accuracy required for rigorous physical representation and the pragmatism needed to capture the essentials of application-driven research programs. The paper ends with a discussion of the possible relations between these approaches and their areas of effectiveness.
Mechanisms and Modeling of Near-Threshold Fatigue Crack Propagation
Authors: Petit J , Henaff G , Sarrazin-Baudoux C 
Published: April 2008

First, this paper proposes a comprehensive framework for the modeling of the intrinsic FCP (i.e. after elimination of any environmental and closure effects). On the basis of numerous experimental data on Al alloys, steels and Ti alloys, three intrinsic crack growth regimes have been identified: i) stage I regime, observed in single crystals or in the early growth phase of short cracks; ii) stage II regime, commonly observed when the crack advance proceeds along a plane normal to the load axis and results from the activation of symmetrical slip systems; iii) crystallographic stage I-like regime which prevails near the threshold.
Second, this contribution is dedicated to the description of environmentally assisted propagation and specially focused on the understanding of the role of water vapor and the complex interactions existing between environment and microstructure. The effective FCP behavior is described by superimposing two distinct stage II regimes: i) a propagation assisted by water vapor adsorption which can be operative under very low partial pressure or at very low frequencies; ii) hydrogen-assisted propagation which is operative when some critical conditions are encountered.
Constitutive laws are proposed for both intrinsic propagation and water-vapor assisted propagation.