bluuebunny/crossref_metadata_2025 huggingface dataset:
Amateur Youth Ice Hockey Coaches' Views on Rule Infractions, Aggressive Play, and Injuries During Games
Authors: Gaumond S , Trudel P , Gilbert W
Published: April 2008

The purpose of this study was to examine the views of youth ice hockey coaches (n=12) when asked to discuss their game behaviors related to (a) rule infractions, (b) aggressive play, and (c) injuries. A total of 48 stimulated recall interview transcripts were analyzed. Results show that (a) rule infractions, aggressive play, and injuries became more salient issues as the level of ice hockey increased, (b) issues related to violence and aggression seemed to be more predominant in men's ice hockey than in women's ice hockey, (c) only 15% of the statements regarding officials were positive, compared to 50% that were negative, and (d) injuries were more frequently discussed by coaches at the levels that allowed body contact.
Influence of the Mechanical Strain Amplitude on the In-Phase and Out-of-Phase Thermo-mechanical Fatigue Behaviour of NiCr22Co12Mo9
Authors: Kleinpass B , Lang K-H , Löhe D , Macherauch E
Published: April 2008

In total strain controlled in-phase and out-of-phase thermo-mechanical fatigue (TMF) tests on NiCr22Co12Mo9 (Inconel 617, Nicrofer 5520 Co) with a maximum temperature of 1123 K, a minimum temperature of 473 K and different mechanical strain amplitudes the cyclic stress-strain response, the change of the microstructure and the development of damage were analysed. The initial values of the induced stress amplitudes and plastic strain amplitudes, and the amount of cyclic hardening increase with the total mechanical strain amplitude. The observed cyclic hardening results from strong dislocation-dislocation and dislocation-particle interactions during plastic deformation at lower temperatures the latter being enhanced by the precipitation of small semi-coherent carbides at elevated temperatures of the TMF cycles. For each type of TMF tests the lifetime behaviour can be adequately described by the combination of the relationships of Basquin and Coffin-Manson. At equal total mechanical strain amplitudes in-phase tests always yield smaller lifetimes than out-of-phase tests. The difference between the two types of TMF-tests rises with increasing lifetime. This behaviour is caused by different accumulation of creep damage which is favoured by tensile stresses at high temperatures.
Thermo-mechanical Fatigue Behavior of Al-Si-Cu-Mg Casting Alloy
Authors: Ikuno H , Iwanaga S , Awano Y
Published: April 2008

This paper describes the thermo-mechanical fatigue behavior of Al-Si-Cu-Mg casting alloy. The alloy is widely used for cylinder heads and pistons of automobile engines. Repeated cycling between driving and resting, or low-power and high-power driving cause thermal cycling in the engine materials. The thermo-mechanical fatigue property is therefore very important to develop high-performance engines. This study aims to characterize the cyclic stress-strain behavior of this alloy and to clarify the factors dominating the fracture life. Results obtained are : (1) The stress-strain behavior changes remarkably during thermal cycling. Cyclic hardening and cycling softening occur in the higher and lower strain ranges, respectively. (2) A thermo-mechanical fatigue fracture limit diagram is obtained by connecting fracture points on the inelastic strain range — number of cycles relationship. (3) Consequently, in 103 – 104 cycles, it is considered that poor ductility and inelastic strain increase due to overaging dominate the thermo-mechanical fatigue life of the alloy.
A European Round Robin in Thermo-mechanical Fatigue Behavior of a 9% Cr Low Activation Ferrite-Martensite Steel
Authors: Filacchioni G , Petersen C , Rézaï-Aria F , Timm J
Published: April 2008

Test blankets of a thermo-nuclear fusion reactor are subjected during service to alternating thermal and mechanical stresses as a consequence of the pulsed reactor operation. Of particular concern is the thermo-mechanical fatigue (TMF) endurance of 9% Cr low activation ferrite-martensite steels. To design such blankets operating under the above loading conditions, for the time being fatigue life is predicted using design codes based on isothermal fatigue material data, but these codes will be verified with TMF data. Within the European Materials Long Term Programme for fusion research several laboratories are involved in performing TMF experiments using different facilities and samples. Results of a TMF-round robin of four European laboratories will be reported. Comparison of the various test data obtained will give a better understanding for these kinds of tests and enable an in-depth discussion of the scatter of the results, of its reason and what the implications are in terms of a TMF standard.
On the Significance of Environment in Thermal Fatigue of a Unidirectional SCS-6/Ti-24Al-11Nb Metal Matrix Composite
Authors: Okazaki M , Nakatani H
Published: April 2008

Thermal Fatigue tests of a Ti-24Al-11Nb matrix composite unidirectionally reinforced with SiC fiber, SCS-6/Ti-24Al-11Nb, have been carried out without external load in air and in vacuum, under various thermal cycling conditions. The following characteristics of the material subjected to thermal fatigue and isothermal exposure were investigated: (i) crack nucleation and the change in density with thermal cycling; (ii) change of the fiber/matrix interface morphology by means of Electron Probe Micro Analyzer and Scanning Electron Microscope; (iii) change of the interfacial shear strength by fiber push-out tests, and (iv) effect of environment on the properties from (i) to (iii). Methodologies are also proposed for the characterization of damage due to thermal fatigue.
A New Technique for High Frequency Multiaxial Thermo-mechanical Fatigue Testing of Materials
Authors: Chieragatti R , Paun F
Published: April 2008

The proposed thermo-mechanical fatigue test rig is based on a rotating bending machine and employs a high and a low temperature sources. This permits imposing thermal and mechanical loading at relatively high frequencies on a portion of a surface generatrix of a tubular specimen. Using this rig, a series of experiments was carried out on superalloy test specimens.

These tests were conducted at various mechanical loadings with the temperature cycling between 600 and 1050°C in 10 seconds. The temperature distribution on the test specimen was measured under stabilized conditions and the same was calculated using a finite element code. Good correlation was found between the experimental and simulated temperature distributions. The thermal stress field, hence calculated, enables us to identify the critical crack initiation sites of the specimen and to calculate the appliedthermo-mechanical cycle. In this way, an equivalent constant temperature can be defined and fatigue life has been predicted using isothermal fatigue results only.
Construction Quality Control Testing of Compacted Fills: Optimum Moisture-Density Values
Authors: Scavuzzo R
Published: April 2008

Construction quality control testing is critical in ensuring that compacted fills are properly placed. One element in the successful implementation of compacted fill placement is the appropriate assignment of optimum moisture-density values for varying fill material types encountered during construction. For decades the U.S. Bureau of Reclamation (USBR) has acquired laboratory moisture-density test data for a variety of material types from the 17 western states in which the USBR operates. A comparison between optimum moisture-density data published by the USBR is made with laboratory test results obtained from years of quality control testing of compacted fills on commercial projects throughout the Denver-Metro area. Optimum moisture content-maximum dry density curves are presented which provide a visual representation of the variability in the data which can be anticipated for each soil type evaluated. This data provides confirmation of the USBR database and can be used in estimating appropriate moisture content-dry density values, evaluating the validity of laboratory compaction test results obtained, as well as assessing the state of compaction of in-place fill material.
Compaction Control Bermuda Sports Centre
Authors: Peaker KR , Lohse H , Ahmad SA
Published: April 2008

The new national sports centre in Bermuda encompasses numerous facilities, including playing fields, which are located in an area previously filled with up to 6 m of loose granular materials. It was decided to re-compact the upper 3 to 4 m of the fill in order to provide a serviceable playing surface. A geotechnical investigation, which included both test pits and sampled boreholes, found that the fill was composed of aeolinite bedrock, which is a weakly, cemented friable limestone. This was found to overlie undisturbed bedrock. The limestone was composed of about 60 percent solid particles of shell fragments, ooliths and pellets and about 10 percent calcite cement. The porosity was about 30 percent. Normal compaction testing was difficult since the only nuclear gauge on the island had not been calibrated for several years and the Proctor values for the excavated limestone gave results lower than those measured in situ. It was decided to determine the maximum density of the fill using trial test strips. The test strips were found to be the most suitable method of evaluating the compaction. It was found that the aeolinite could be compacted in 300 mm lifts with heavy vibratory compactors.
Dynamic Compaction of Surface Mine Spoils to Limit Settlements Within Commercial Developments
Authors: Satyapriya CK , Gallagher PE
Published: April 2008

Throughout the Appalachian areas of the Eastern United States, site developers face the task of constructing extensive cut and fill situations in order to obtain building sites. Along with the expense of large filling operations, oftentimes they are required by the geotechnical engineer to monitor the fills for settlements before the foundation work can begin. This monitoring period can at times extend for 18 months. A developer will incur severe financial burdens during this monitoring period. CTL Engineering has incorporated the use of a technique commonly known as “dynamic compaction” to precompress these fills such that the post — construction monitoring period is substantially reduced. Five case studies have been completed where the fills were conventionally constructed and the building pads dynamically compacted. Three of the sites were extensively instrumented to monitor settlements during and subsequent to construction. The data will show that the areas that received dynamic compaction did not differentially settle under very large cut-fill depths and comparative fills where conventional compaction techniques were used settled more than 7 inches. Settlement plates, standard penetration testing and various survey networks were used to evaluate the performance of the dynamic compacted sites. The sites have been in operation for up to five years and have not exhibited any signs of differential settlement.
Quality Control of Earth Fills Using Time Domain Reflectometry (TDR)
Authors: Lin C-P , Siddiqui SI , Feng W , Drnevich VP , Deschamps RJ
Published: April 2008

Measurement of soil density and water content in compacted fills is the principal means of quality control to assure adequate performance. Current testing methods have various limitations, including the use of hazardous materials, limitations in accuracy, the need for extensive calibration, or the test duration. A new technique using time domain reflectometry (TDR) to measure the water content and density of soil is introduced. The purpose of this paper is to present a historical and theoretical background of this new approach. Prototype equipment was developed for routine use in the quality control testing of compacted soils. The method was evaluated with theoretical study and laboratory experiments. The results of the TDR method are compared with results from conventional methods on actual construction sites. The advantages and limitations of this new method are also discussed.

A TDR device is used to transmit an electromagnetic wave into the soil and receive a reflected waveform. The dielectric constant of the soil can be calculated from the travel time of the waveform. Water content and density are the basis used to assess the quality of a compacted earth fill. These are the same factors that affect the dielectric properties of soil; so a relationship between them can be established. A procedure to measure soil density in-situ using TDR was developed. This procedure obtains results comparable in accuracy to existing methods such as the nuclear density gage and the sand-cone test. The test duration is approximately 15 minutes. A new approach is under development to interpret the reflected waveform and extract additional information regarding the electromagnetic soil properties. This approach appears to be very promising and has the potential to provide even more rapid and accurate test results for assessing the water content and density of compacted soils.
Quality Control of Compacted Layers with Field and Laboratory Seismic Testing Devices
Authors: Nazarian S , Yuan D
Published: April 2008

A procedure to measure the modulus and Poisson's ratio of each compacted layer shortly after placement is presented. Seismic technology has been used for this purpose. Simplified field and laboratory tests are suggested that can be performed and interpreted rapidly and nondestructively so that any problems during the construction process can be adjusted. The field and laboratory methods are incorporated in a manner that their results can be readily reconciled without any scaling or simplifying assumptions. Therefore, the laboratory tests can be used to develop the ranges of acceptable properties for a given material. Nondestructive field tests are performed to determine whether the contractor has achieved these levels. In this paper, the overall procedure and the field and laboratory devices are introduced, a procedure to establish the accuracy and repeatability of the methods is described, and several case studies are included to exhibit the preliminary uses of the procedure.
Novel Biodegradable Polyurethanes for Medical Applications
Authors: Gorna K , Gogolewski S
Published: April 2008

Biodegradable polyurethanes with various hydrophilic-to-hydrophobic ratios and potential application for nonadhesive barriers in surgery and/or scaffolds for tissue engineering and bone substitutes were synthesized from polycaprolactone diol, mixtures of polycaprolactone and polyethylene oxide diols, hexamethylene- and/or isophorone diiscocyanates, and 1,4-butane diol or 2-amino-1-butanol chain extenders. The polymers had viscosity-average molecular weights in the range of 24.000 to 130.000 dalton, tensile strengths at break of 4 to 60 MPa, Young's moduli from 7 to 72 MPa, elongation at break of 100 to 950%, and glass transition temperatures in the range of-116 to -41°C. The affinity of polymers towards proteins varied depending on the type of polyol and the chain extender used. The adsorption of proteins from whole blood was highest for the materials based on poly(ε-caprolactone) and those containing 2-amino-1-butanol chain extender. There was no protein adsorption on materials based on mixtures of caprolactone and ethylene oxide polyols independent of the poly(ethylene oxide) molecular weight and the chain extender used. The polymers could be processed into three-dimensional porous scaffolds (membranes and sponges) using a phase-inverse process from solutions consisting of a solvent-nonsolvent system and/or with salt crystals additives.
Modulation of Pore Topography of Tissue Engineering Constructs
Authors: Burg KJL , Austin CE , Swiggett JP
Published: April 2008

Absorbable materials can be used in tissue engineering to provide a porous template into which cells can be dispersed. The template not only serves as the delivery vehicle for implantation, but it also provides the form that the developing tissue will eventually take. The physicochemical properties of the material influence the development of cells within the template. This preliminary study assessed the effect of two template processing techniques on cellular attachment using sheep uterus smooth muscle cells and poly-1-lactide constructs. The results demonstrate that porogen selection in solvent cast, particulate-leached templates can radically change cellular attachment behavior.
In VitroCompression Testing of Fiber-Reinforced, Bioabsorbable, Porous Implants
Authors: Slivka MA , Leatherbury NC , Kieswetter K , Niederauer GG
Published: April 2008

Proper in vitro mechanical testing of medical devices requires consideration of many factors, including environmental conditions, implant characteristics, and nature of the test method. In this study, parallel plate compression testing of porous specimens composed of 75:25 poly(D,L-lactide-co-glycolide) reinforced with short polyglycolide fibers was used to show the effect of many factors on the compressive modulus and yield strength. Compressive properties were dramatically reduced when tested under physiological conditions (aqueous, 37 °C) versus ambient conditions. Predominant fiber alignment yielded superior properties when tested parallel to the fiber orientation, increasing the compressive properties proportionally with fiber content from 0% to 20%. With increasing strain rate over four orders of magnitude, compressive moduli increased logarithmically and yield strength increased in a semi-logarithmic fashion. After in vitro degradation for nine weeks, compressive properties decreased to less than 20% of their original values.
Design and Fabrication of a 3D Scaffold for Tissue Engineering Bone
Authors: Hutmacher DW , Teoh SH , Zein I , Ng KW , Schantz J-T , Leahy JC
Published: April 2008

Autogenous cell transplantation is one of the most promising new techniques being developed for bone generation as it eliminates problems of donor site scarcity, immune rejection and pathogen transfer. Osteoblasts obtained from an individual patient can be grown in culture and seeded onto a three-dimensional scaffold that will slowly degrade and resorb as the bone or cartilage structures grow and assimilate in vivo. The three-dimensional (3D) scaffold provides the necessary support for cells to maintain their differentiated state and defines the overall shape of the new bone and cartilage. The necessity of using a scaffold structure as the basic template of engineering tissues has encouraged the study the application of advanced manufacturing technologies in this field. For example, rapid prototyping (RP) technologies such as fused deposition modeling (FDM) can be used to fabricate complex 3D structures based on two- dimensional (2D) cross-sectional data obtained by slicing a computer-aided design (CAD) models. FDM is currently being applied in our laboratory to fabricate bioresorbable 3D scaffolds of various porosities and micro-architecture for tissue engineering bone.
Mechanical Properties of Degraded PMR-15 Resin
Authors: Tsuji LC , McManus HL , Bowles KJ
Published: April 2008

Thermo-oxidative aging produces a non-uniform degradation state in PMR-15 resin. A surface layer, usually attributed to oxidative degradation, forms. This surface layer has different properties from the inner material. A set of material tests was designed to separate the properties of the oxidized surface layer from the properties of interior material. Test specimens were aged at 316°C in either air or nitrogen, for durations of up to 800 h. The thickness of the oxidized surface layer in air aged specimens, and the shrinkage and coefficient of thermal expansion (CTE) of nitrogen aged specimens were measured directly. Four-point-bend tests were performed to determine modulus of both the oxidized surface layer and the interior material. Bimaterial strip specimens consisting of oxidized surface material and unoxidized interior material were constructed and used to determine surface layer shrinkage and CTE. Results confirm that the surface layer and core materials have substantially different properties.
Time Dependent Volume and Enthalpy Responses in Polymers
Authors: McKenna GB , Simon SL
Published: April 2008

Most users of polymeric materials have a good sense that the glass transition event is kinetic in nature, i.e., it depends on cooling or heating rate in conventional experiments, and that the glassy state is a non-equilibrium state. However, it is often not appreciated that the structural recovery which occurs as a glass attempts to reach equilibrium is non-linear (e.g., the rate of volume recovery depends on the instantaneous volume). The non-linear viscoelastic nature of structural recovery can lead to surprising behaviors in certain kinds of measurements. It results in, for example, the asymmetry of approach in up and down-temperature jumps. The features of enthalpy and volume recovery, including the sub-Tg peaks and excess enthalpy overshoots in differential scanning calorimetry, are well-described by models of structural recovery developed in the 1970's. The purpose of the present work is to describe structural recovery and physical aging and their impacts on material performance and measurement of material properties. In addition, we present new results from calculations using the structural recovery models in which we demonstrate that new analytical tools, such as Temperature Modulated Differential Scanning Calorimetry (TMDSC), need to be used with caution when glass-forming systems are studied because of the nonlinear viscoelastic nature of structural recovery.
Creep Behavior in Amorphous and Semicrystalline PEN
Authors: Cerrada ML , McKenna GB
Published: April 2008

Poly(ethylene-2,6-naphthalate), PEN, is a suitable candidate to replace poly (ethylene terephthalate), PET, in some applications. PEN can be produced in either the amorphous or semi-crystalline states, depending on the processing conditions. Here, we report on results from uniaxial tension experiments in creep conditions in which we probed the viscoelastic and physical aging responses for both amorphous and semi-crystalline forms of PEN. The data show the existence of overlapping β and α relaxations in the experimental creep time range studied. The β process is stronger in the amorphous than in the semi-crystalline material and, in both cases, shows different aging time and temperature dependencies. A model in which the α process is treated as a stretched exponential process and the β process as a Cole-Cole process is developed and its validity examined for both the amorphous and semi-crystalline PEN materials.
Implementation of Constitutive Model in FEA for Nonlinear Behavior of Plastics
Authors: Skrypnyk ID , Spoormaker JL , Smit W
Published: April 2008

The main elements of implementation into a finite-element analysis (FEA) package of the earlier developed model for nonlinear viscoelastic behavior of plastics are described.

The Henriksen scheme of discretization of the hereditary integral has been chosen for implementation. This scheme enables development of a fast procedure for modeling of viscoelastic behavior. As a result, the time necessary for calculation of problems of viscoelasticity is not much larger than the calculation time required for simulation of elasto-plastic behavior.

Several discretization schemes have been analyzed, implemented in FEA software MARC and verified. The numerical algorithm, which is chosen as a result of comparison, allows us to reach a total deviation of less than 8% to 10% for the modeling of creep and recovery of PMMA and HDPE for the broad range of loading levels.

The case study of a thick plate under distributed transversal loading is examined to compare the results achieved using the Schapery model with the newly proposed approach.
Tensile and Compressive Creep of a Thermoplastic Polymer and the Effects of Physical Aging on the Composite Time-Dependent Behavior
Authors: Veazie DR , Gates TS
Published: April 2008

An experimental study was undertaken to compare the effects of physical aging on the viscoelastic behavior of IM7/K3B [90]12 composite and the K3B neat resin loaded in tension and compression. The tests, run over a range of sub-glass transition temperatures, provided material constants, material master curves and aging related parameters. Comparing results from the short term K3B resin and the IM7/K3B [90]12 composite behavior indicated that trends in the data with respect to aging time and aging temperature for tension loading are similar; however, trends in the IM7/K3B [90]12 composite curves in compression appear more exponential than in the K3B resin curves, and show a more uniform creep rate as a function of temperature. Although most of the long term predictions made in this study physically aged with time as expected, the rate of aging in tension was more severely altered with increasing temperature than in compression.
Nonlinear Viscoelastic Behavior of Rubber-Toughened Carbon and Glass/Epoxy Composites
Authors: Bocchieri RT , Schapery RA
Published: April 2008

A previously-developed constitutive equation for nonlinear viscoelastic materials is first used to characterize mathematically the ply-level stress-strain behavior of a rubber-toughened carbon/epoxy composite. Emphasized are some practical aspects of carrying out such a characterization. Constant stress rate tests are used to derive first-loading material response in the dry state, at room temperature. It is found for a large portion of the loading curve that the shear and transverse compliances can be described by a quasi-elastic model expressed in terms of a single scalar function of stress state, a ratio of compliances, a time or rate exponent, and two elastic terms. This model offers a simple way to incorporate nonlinearity and time dependence in a material model for limited loading conditions. Results are then compared to those for a glass/epoxy composite with the same rubber-toughened resin system. Special considerations for using off-axis coupons are examined and unique tabbing is employed to derive material properties out to high stress levels. The consistency of the carbon/epoxy characterization is checked by comparing experimental stress-strain response to results not used in the characterization. Behavior of the two composite systems is compared and checked for consistency using a micromechanical model.
Durability and Damage Tolerance of a Polyimide Chopped Fiber Composite Subjected to Thermomechanical Fatigue Missions and Creep Loadings
Authors: Castelli MG , Sutter JK , Benson D
Published: April 2008

Although polyimide based composites have been used for many years in a wide variety of elevated temperature applications, very little work has been done to examine the durability and damage behavior under more prototypical thermomechanical fatigue (TMF) loadings. Synergistic effects resulting from simultaneous temperature and load cycling can potentially lead to enhanced, if not unique, damage modes and contribute to a number of nonlinear deformation responses. The goal of this research was to examine the effects of a TMF loading spectrum, representative of a gas turbine engine compressor application, on a polyimide sheet molding compound (SMC). High performance SMCs present alternatives to prepreg forms with great potential for low cost component production through less labor intensive, more easily automated manufacturing. To examine the issues involved with TMF, a detailed experimental investigation was conducted to characterize the durability of a T650-35/PMR-15 SMC subjected to TMF mission cycle loadings. Fatigue damage progression was tracked through macroscopic deformation and elastic stiffness. Additional properties, such as the glass transition temperature (Tg) and dynamic mechanical properties were examined. The fiber distribution orientation was also characterized through a detailed quantitative image analysis. Damage tolerance was quantified on the basis of residual static tensile properties after a prescribed number of TMF missions. Detailed micro-structural examinations were conducted using optical and scanning electron microscopy to characterize the local damage. The imposed baseline TMF missions had only a modest impact on inducing fatigue damage with no statistically significant degradation occurring in the measured macroscopic properties. Micro-structural damage was, however, observed subsequent to 100 h of TMF cycling which consisted primarily of fiber debonding and transverse cracking local to predominantly transverse fiber bundles. The TMF loadings did introduce creep related effects (strain accumulation) which led to rupture in some of the more aggressive stress scenarios examined. In some cases, this creep behavior occurred at temperatures in excess of 150°C below commonly cited values for Tg. Thermomechanical exploratory creep tests revealed that the SMC was subject to time dependent deformation at stress/temperature thresholds of 150 MPa/230°C and 170 MPa/180°C.
Hygrothermal Modeling of Polymers and Polymer Matrix Composites
Authors: Roy S
Published: April 2008

The theory of irreversible thermodynamics is applied to derive governing equations for history-dependent diffusion in polymers and polymer matrix composites from first principles. A special form for Gibbs free energy is introduced using stress, temperatures, and moisture concentration as independent state variables. The resulting governing equations are capable of modeling the effect of interactions between complex stress, temperature, and moisture histories on the diffusion process within an orthotropic material. Since the mathematically complex nature of the governing equations precludes a closed-form solution, a variational formulation is used to derive the weak form of the nonlinear governing equations which are then solved using the finite element method. For model validation, the model predictions are compared with published experimental data for the special case of isothermal diffusion in an unstressed Graphite-Epoxy symmetric angle-ply laminate.
Roadway Base and Subgrade Geocomposite Drainage Layers
Authors: Christopher BR , Hayden SA , Zhao A
Published: April 2008

The Maine Department of Transportation (DOT) in conjunction with the University of Maine and the U.S. Army Cold Regions Research Laboratory evaluated the use of a special geocomposite drainage net as a drainage layer and capillary barrier (to mitigate frost heave) on a section of road plagued with weak, frost-susceptible subgrade soils and poor pavement performance. The special geocomposite drainage net that is being used has a higher flow capacity than conventional geonets and, based on tests performed by the University of Illinois, does not deform significantly under heavy traffic loading. For the 425-m-long test section, the geonet drainage geocomposite was placed horizontally across the entire roadway but varied in vertical location to form three separate subsections for evaluating drainage of 1) the base coarse aggregate, 2) the asphaltic concrete pavement, and 3) the subgrade to allow for a capillary break in order to reduce frost action. An integral drainage collection system was installed to collect the water flowing in the geonet. This paper includes a project description, material and construction specifications, installation procedures, instrumentation, and test results based upon two seasons of monitoring. Laboratory characterization and performance testing initially used to evaluate the geocomposite are compared with the monitored results.
Full-Scale Laboratory Testing of a Toe Drain with a Geotextile Sock
Authors: Swihart JJ
Published: April 2008

This paper describes the full-scale laboratory testing (pipe box testing) of a 380-mm-diameter, corrugated, polyethylene toe drain with a knitted geotextile sock, backfilled with a sand envelope material. The test results are compared with previous small-scale and full-scale pipe box tests using pipe with 3-mm and 6-mm perforations, but no geotextile. Use of the geotextile optimized toe drain performance both with respect to flow and with respect to loss of the sand envelope. The long-term flow rate was 260 liters per minute per linear meter of pipe, which was significantly higher (by a factor of 3 to 12) than the earlier tests without geotextile. The total loss of sand envelope was only 165 grams per linear meter of pipe, which was significantly lower (by a factor of 4 to 17) than the earlier tests without geotextile. The test with geotextile was run for 31 days at a constant head of 0.75 m above the pipe invert with no indication of clogging. Based on these results, use of geotextile sock in conjunction with a sand envelope is recommended for future toe drain installations in areas with fine-grained native soils.
Opportunities for Standardization of Beryllium Sampling and Analysis
Authors: Brisson MJ , Ekechukwu AA , Ashley K , Jahn SD
Published: April 2008

Since the U. S. Department of Energy (DOE) published the DOE Beryllium Rule (10 CFR 850) in 1999, DOE sites have been required to measure beryllium in air filter and surface wipe samples for purposes of worker protection and for release of materials from beryllium-controlled areas. Measurements in the nanogram range on a filter or wipe are typically required. Industrial hygiene laboratories have applied methods from various analytical compendia, and a number of issues have emerged concerning sampling and analysis practices. As a result, a committee of analytical chemists, industrial hygienists, and laboratory managers was formed in November 2003 to address the issues. The committee developed a baseline questionnaire and distributed it to DOE sites and other agencies in the U.S., Canada, and the U.K. The results of the questionnaire are presented in this paper. These results confirmed that a wide variety of practices was in use in the areas of sampling, sample preparation, and analysis. Additionally, although these laboratories are generally accredited by the American Industrial Hygiene Association (AIHA), there are inconsistencies in execution among accredited laboratories. As a result, there are significant opportunities for development of standard methods that could improve consistency. The current availabilities and needs for standard methods are further discussed in a companion paper.
Opportunities for Development of Reference Materials for Beryllium
Authors: Watters RL , Hoover MD , Day GA , Stefaniak AB
Published: April 2008

Reference materials provide the foundation for assessment of analytical chemistry methods, accurate quantification of occupational and environmental exposures, and conduct of in vitro and in vivo toxicology studies for health effects research. Although the National Institute of Standards and Technology (NIST) supplies industry, academia, government, and other users with over 1300 reference materials of the highest quality and metrological value, the number of beryllium reference materials is limited. Currently available beryllium reference materials include standard spectroscopy solutions of beryllium and copper-beryllium alloy in the form of blocks, chips, and rods. Beryllium is present as a trace element in some standard soil-sludge, coal fly ash, and urine reference materials. Beryllium on filter media was available at one time, but is not currently available. A number of opportunities exist for identification and development of needed beryllium reference materials for beryllium-containing ores, beryllium oxide, beryllium metal, beryllium metal-matrix materials, beryllium-containing alloys, and beryllium in biological samples. These opportunities will require multi-disciplinary and multi-organizational collaboration. Needed actions include consensus on the relevant chemical and physical forms of beryllium; market analyses of demand for the materials; identification of candidate industrial or laboratory-produced samples of the materials; selection of samples that meet criteria for uniformity, physical form, measured quantities, and continued availability; development of production protocols for collection and preparation of the materials, including adequate provisions for occupational health and environmental protection; incorporation of these materials into a supply, distribution, and cost-recovery infrastructure; and continued feedback and information sharing to ensure that the reference materials are meeting user needs or are modified as necessary. Lessons from other major initiatives for reference materials of lead, silica, and similar materials provide guidance on how to optimize and implement an enhanced program for beryllium reference materials.
Study of Nb and Fe Precipitation in α-Phase Temperature Range (400 to 550°C) in Zr-Nb-(Fe-Sn) Alloys
Authors: Toffolon-Masclet C , Barberis P , Brachet J-C , Mardon J-P , Legras L
Published: April 2008

This work is aimed at improving our knowledge of the Nb and Fe precipitation in the low α-temperature range as a function of Fe and Sn contents in ZrNb based alloys. Several experimental variants, with Nb contents ranging from 0.3–0.8 wt%, Fe from 0.01–0.5 wt% (and also Sn additions), have been studied, with special attention paid to the residual Nb content in the matrix, and to the SPP crystallographic nature and chemical composition as a function of the nominal alloy composition, annealing time/temperature, and initial metallurgical condition.

For ZrNb alloys, recent studies have pointed out the necessity of performing long term annealing treatments in order to avoid the persistence of metastable phases, and to reach a thermodynamic equilibrium state of precipitation. For that purpose, experimental alloys were annealed for up to 2 years at 400, 470, and 550°C. The evolution of SPP chemical compositions with temperature and annealing time was first quantified. For the longer annealing times, i.e., for conditions close to thermodynamic equilibrium, the results suggest an existence of a composition range for the SPP phases under equilibrium conditions. This specific point is currently taken into account to improve the thermodynamic description of the ZrNbFe phase diagram.

Also, the influence of preliminary cold work on the precipitation kinetics of equilibrium βNb phase has been investigated. This study was conducted on two Zr-1%Nb alloys containing initially metastable βZr precipitates. It was observed that cold work significantly accelerates the precipitation of equilibrium βNb phase, mainly for annealing treatments too short to allow significant recovery of the dislocation network, i.e., between 1 and 100 h of annealing.

Finally, all of these experimental results are discussed with regard to their consequences on the thermodynamic modeling of the equilibrium phase diagram and precipitation kinetics.
Microstructural Stability of M5™ Alloy Irradiated up to High Neutron Fluences
Authors: Doriot S , Gilbon D , Béchade J-L , Mathon M-H , Legras L , Mardon J-P
Published: April 2008

The present paper is focused on the microstructural stability of the Framatome-ANP M5™ (Zr-1%NbO) alloy. Thin foils were cut from M5 cladding tubes irradiated from 1 to 6 annual cycles in EDF PWRs, and examined by analytical transmission electron microscopy (TEM). The results show that within the wide range of irradiation conditions investigated, the initial β-Nb particles undergo no amorphisation and only minor evolutions in size distribution, number density, and composition. Finally, very few ⟨c⟩ component basal loops were detected, so that no sign of accelerated growth regime has to be feared for the fuel burn-ups currently considered (∼70 GWd/t) for PWRs.

In the second part of this paper, other industrial or experimental alloys (Zy-4, M4, Zr-2.5%Nb, ZrNbSnFe) are considered to improve our knowledge about the irradiation-induced evolution of β-Nb and other minor SPP. Thin foils were cut from specimens irradiated in PWRs or MTRs (OSIRIS, SILOE) and also examined by transmission electron microscopy. In addition, Small Angle Neutron Scattering (SANS) was used to provide quantitative and statistical information on the radiation-enhanced precipitation of β-Nb needles and possible other defects or solute clusters. All these results allow a general discussion of evolution of SPP with regard to their initial structure and composition, and of the noteworthy irradiation stability of the M5™ up to high neutron fluence with respect to other alloys.
Microstructure and Growth Mechanism of Oxide Layers Formed on Zr Alloys Studied with Micro-Beam Synchrotron Radiation
Authors: Motta AT , Yilmazbayhan A , Comstock RJ , Partezana J , Sabol GP , Lai B , Cai Z
Published: April 2008

The structures of oxides formed in water and lithiated water on three Zr-based alloys with varied corrosion behavior were studied with micro-beam synchrotron radiation and optical microscopy. Micro-beam synchrotron radiation (0.2 μm spot) has a unique combination of high elemental sensitivity (ppm level) and fine spatial resolution that allowed the determination of various oxide characteristics such as phase content, texture, grain size, and composition as a function of distance from the oxide-metal interface.

Micro-beam X-ray fluorescence shows that the oxides formed in lithiated water have increased levels of Fe absorbed from the autoclave environment indicating greater oxide porosity in these oxides. The phase content, texture, and grain size of oxides were studied in detail using synchrotron radiation micro-beam diffraction for samples corroded in water and lithiated water. A remarkable periodicity was observed in the oxide structures using various techniques including X-ray peak intensities for both monoclinic and tetragonal zirconia, texture, and optical microscopy. The periods were similar to the transition period and were less visible in the oxides that behaved worse in lithiated water. These results are discussed in terms of models of oxide growth and of the differences between alloys.
Simulation of Cold Pilgering Process by a Generalized Plane Strain FEM
Authors: Horada M , Honda A , Toyoshima S
Published: April 2008

In order to attain a defect-free operation in the cold pilgering process, one must understand the material behavior through both experimental and computational study, optimization of the tool profile (mandrel and rolls), and appropriate selection of the tool material. Until now, several simplified computational methods have been presented, because 3-dimensional analysis is still far away in such a complicated forming process. In this paper, a generalized plane strain model has been employed for the simulations of cold pilgering of fuel cladding for nuclear applications. In this model, the tube material is considered to be viscoplastic at the loading stage of pilgering and totally elastic after every stroke. Therefore, considering the tube springs back after each stroke, it can be investigated how the tube shape affects deformation in the next pilgering stroke. A cold pilgering of zirconium alloy by two types of tools has been computed and compared. Moreover, computed results are compared with experimental results. Throughout the studies, the effect of tube spring back and the effect of design parameters on the deformation behavior are demonstrated.
Role of Iron for Hydrogen Absorption Mechanism in Zirconium Alloys
Authors: Kakiuchi K , Itagaki N , Furuya T , Miyazaki A , Ishii Y , Suzuki S , Terai T , Yamawaki M
Published: April 2008

The latest PIE results of Zry-2 and HiFi alloy (0.4 %Fe-Zry2) showed that iron addition reduces the hydrogen pick-up ratio. In order to clarify this lower hydrogen absorption mechanism, three types of experiments were carried out for both alloys: (1) Measurements of the hydrogen pick-up ratio in the pre-transition region using an autoclave. (2) CPD (Contact Potential Difference) and FBP (Flat-band Potential) measurements of oxide film using a High Temperature Kelvin system and Photocurrent system. (3) Investigation of hydrogen absorption properties by Sieverts system and corrosion properties by autoclave for intermetallic compounds simulating SPP's Fe/Cr and Fe/Ni ratio in Zry-2 and HiFi.

Autoclave tests showed that the corrosion behaviors of both alloys were similar. However, the hydrogen pick-up ratio depended on not only iron addition but also surface treatment (with and without pickling). Iron addition and non-pickling (as-received) reduced the hydrogen pick-up ratio.

ΔCPD and FBP shifted to the positive side as the result of iron addition, and FBP changed with and without pickling. This difference in surface potential might be caused by the existence of anion vacancy concentration in the oxide film and furthermore may affect the electrochemical potential gradient over the oxide film. This potential gradient might control the proton diffusion in the oxide film.

In the results of the hydrogen absorption tests on intermetallic compounds, Zr(Fe,Cr)2 with a higher Fe/Cr ratio showed lower hydrogen absorption, and Zr2(Fe,Ni) showed higher hydrogen absorption than Zr(Fe,Cr)2. In the results of corrosion tests on intermetallic compounds, Zr2(Fe,Ni) showed a much larger corrosion rate than Zr(Fe,Cr)2. It is considered that Zr2(Fe,Ni)-type precipitate might be oxidized easily in the oxide film, thus it might not contribute to the window for hydrogen absorption, and Zr(Fe,Cr)2 with a higher Fe/Cr ratio would reduce the amount of hydrogen penetrating through SPP at the oxide/metal interface.

Based on these results, a tentative hydrogen absorption mechanism is proposed, explaining both roles of the electrochemical potential gradient over oxide film and the SPP window for the hydrogen absorption.
In-Situ Studies of the Oxide Film Properties on BWR Fuel Cladding Materials
Authors: Bojinov M , Hansson-Lyyra L , Kinnunen P , Saario T , Sirkiä P
Published: April 2008

The pre-transition oxides formed on five different types of Zircaloy-2 alloys have been characterized in-situ using electrochemical impedance spectroscopy (EIS) in high-temperature water simulating BWR conditions at 300°C. The contribution of the oxide film properties to the impedance spectra has been distinguished from the contribution of the corrosion reaction by performing additional EIS measurements in a gas atmosphere. To obtain a correlation between the oxide film thickness, the oxide growth rate, and the impedance parameters, the EIS data have been fitted to the transfer functions derived from the Mixed Conduction Model for oxide films. As a result, the oxide growth rate of each alloy has been calculated assuming that the growth rate is proportional to the flux of oxygen vacancies through the film. The values of the oxide film thickness based on the model calculations have proved to be in good agreement with the values measured from the cross-section micrographs of the specimens using scanning electron microscopy (SEM). The measured corrosion properties have been qualitatively correlated to the secondary phase particle distributions of the five fuel cladding materials. However, to establish a quantitative correlation between the corrosion rates and the second phase particle distributions of these alloys, more data on the microstructure of the metal-oxide interface are needed.