bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Influence of Test Parameters and Procedures on the Tensile Modulus of Stiff Geogrids
Authors: Austin DN , Wu KJ , White DF 
Published: March 2009

Geogrid tensile strength at low strains is difficult to determine due to the non-linear, viscoelastic behavior of thermoplastic polymers. Their response to applied tensile loads is profoundly different from that of elastic materials including elastic structural metals. The stress-strain properties of plastics are not constant, varying greatly and nonlinearly with the test parameters. Therefore, if testing conditions are not controlled and accounted for, they can be inaccurate predictors of tensile performance. The measurement of tensile modulus is affected by such factors as temperature, sample length, gauge length, extension rate, and tension and strain measuring equipment.
It is not easy to define the effect of the numerous variables involved with the tensile testing of thermoplastic materials. However, the general effect of a few of the more important and controversial variables was investigated in order to provide some appreciation of the sources of variability. This paper presents the results and observations from an inter-laboratory study that determined tensile modulus of stiff polypropylene geogrids. Various test parameters and procedures affecting the measured results and their potential relevance to field performance were studied. Conclusions and guidelines are provided, and recommendations are made for modifications to current test methods when tensile modulus at low strains is of particular interest.
High Strength Polyester Geotextile Testing and Material Property Evaluation
Authors: Paulson JN 
Published: March 2009

High strength woven polyester geotextiles were tested for manufacturing quality control purposes, and for project approvals.This testing included both single end breaks, and full wide width strength testing. Wide strip tensile strengths were determined using ASTM D4595, “Tensile Properties of Geotextiles by the Wide Width Strip Method”.
Results show consistency in single end breaks, with significant variability when full wide strip tensile specimens were tested. Results were variable both in ultimate strength determinations and at 5 and 10% Several laboratories also tested this material, with their results presented. A summary of the results is discussed followed by recommendations for modification to ASTM D4595 to limit results variability.
Geosynthetic Installation Damage Under Two Different Backfill Conditions
Authors: Koerner GR , Koerner RM , Elias V 
Published: March 2009

Six different geotextiles and one geogrid were placed on an angular, poorly graded gravel, backfilled with the same type of gravel,compacted in a standardized manner, and then exhumed within the same day. A visual damage assessment indicated that the exhumed geotextiles had 60 to 108 holes per square meter and the geogrids had approximately 4 damaged ribs per square meter. A large number of strength tests were performed on the exhumed samples and compared to the original (as-received) strengths to obtain an average percent retained strength. The results for the geotextiles were from 30% to 58% strength retained while the geogrid resulted in a 71% strength retained.
At a second site the entire study was repeated with new materials but now the soil was a poorly graded sand both beneath and above the geosynthetics. The same types of geotextiles and geogrids as with the first site were used in these tests. Here the results were very different, with no holes or damaged ribs, and average geotextile strengths retained from 72% to 96%. The geogrid had its full strength retained.
The data results in quantifiable values for installation damage partial factors-of-safety (the inverse of the strength retained), as well as guidance on the type of backfill soil to use with polymeric reinforcement. Clearly, angular gravel can be damaging to both geotextiles and geogrids and should only be used with considerable caution or with the addition of protection materials.
The Role of Fiber, Matrix, and Interphase in the Compressive Static and Fatigue Behavior of Polymeric Matrix Composite Laminates
Authors: Swain RE , Elmore JS , Lesko JJ , Reifsnider KL 
Published: March 2009

In the continuing effort to understand the processes involved during the compressive failure of statically and dynamically loaded composite structures, this work is concerned with the role the fiber, matrix, and interphase play in determining a composite's compressive performance. Fourteen material systems representing permutations of four carbon fiber systems, three matrix systems, percentages of fiber surface treatment, and three sizing conditions have been laminated and cut into coupons. The bond strength arising from the particular combination of fiber, surface treatment, sizing, and matrix is quantified by measuring the transverse flexural strength of each material system.
Center-holed, cross-plied specimens of each of the 14 materials were tested in quasi-static compression to determine their structural strength. An attempt was then made to correlate differences in compressive strength to differences in the properties of the three phases. A fixed percentage of each strength value was then utilized to establish the tension-compression fatigue stress level employed for each of the 14 material systems. Damage analysis revealed the mechanisms responsible for the wide variation in fatigue life witnessed. The interphase is seen to play a second-order role in determining the compressive strength of these particular notched cross-plied laminates. On the other hand, the interphase is shown to be a key variable in dictating these laminates' compression-dominated fatigue behavior.
Behavior and Microstructure of Ferritic Steels Irradiated in the Phénix Reactor
Authors: Gilbon D , Séran J-L , Cauvin R , Fissolo A , Alamo A , Le Naour F , Lévy V 
Published: March 2009

This paper deals with the irradiation behavior of three ferritic steels, namely F17 (17Cr), EM12 (9Cr-2MoNbV) and EM10 (9Cr-lMo). These alloys were irradiated up to 100 dpa in Phénix as samples or wrapper tubes. The immersion density measurements confirm their high swelling resistance, but the tensile and impact tests reveal great differences in mechanical properties. The ductile-brittle transition temperature (DBTT) of F17 is strongly increased, and compared to an aging treatment, the irradiation amplifies and shifts the embrittlement towards lower temperatures. In contrast to F17, the mechanical properties of EM10 are unaffected by irradiation, while EM12 has an intermediate behavior.
The transmission electron microscopy (TEM) examinations show that all the small density changes come from irradiation-induced voids and that the embrittlement of F17 results from α′ phase formation enhanced by irradiation. In conclusion, EM10 is by far the most attractive candidate for wrapper applications. Its fully martensitic structure provides an improved swelling resistance and its chemical composition should inhibit the microstructural instabilities that are responsible for the embrittlement of F17 and EM12.
Neutron Irradiation Damage in Ferrltic Fe-Cr Alloys
Authors: Gelles DS 
Published: March 2009

Recent work on microstructural development in a series of ferritic alloys following irradiation in the Fast Flux Test Facility (FFTF) is presented. the series includes Fe-Cr binary alloys ranging from 3 to 18 chromium, and substitutional ferritic alloys based on Fe-10Cr with minor additions of silicon, manganese, vanadium, tantalum, and zirconium. Irradiations were performed to fluences as high as 30 dpa at 425°C. the simple Fe-Cr binary alloy behavior following irradiation to 15 dpa was found to be similar to that observed following irradiation in EBR-II. All specimens contained radiation damage such as dislocation loops and voids. Swelling was highest, 0.26%, in the Fe-9Cr alloy with a corresponding dislocation network comprising equal parts of a⟨100⟩ and a/2 ⟨111⟩ Burger's vectors. Less swellings was found in other alloys with a corresponding dislocation structure composed mainly of a⟨100⟩ loops. An example of a deformation slip band containing elongated voids was found, which indicated that channel fracture may occur in ferritic alloys that contain uniform void swelling.
The behavior of substitutional Fe-10Cr ferritic alloys following irradiation to 30 dpa demonstrated that different solutes affect microstructural development. Void and dislocation development were observed in all conditions but the amount of swelling and the dislocation character (a⟨100⟩ verses a/2 ⟨111⟩) and structure (network verses individual loops) varied both with solute type and amount of solute (0.1 or 1.0 wt%). Swelling was lowest in Fe-10Cr-1Si due to delayed void nucleation; the dislocation structures were loop dominated in both Fe-10Cr-1Si and Fe-10Cr-1V. Void shape was found to vary between dodecahedral with {011} faces and {100} truncations and cubic with {100} faces and {011} truncations.
The Microstructural Evolution and Swelling Behavior of Type 316 Stainless Steel Irradiated in HFIR
Authors: Hamada S , Suzuki M , Maziasz PJ , Hishinuma A , Tanaka MP 
Published: March 2009

Solution annealed (SA) and 20% cold worked (CW) Type 316 (UNS S 31600) stainless steels were irradiated in the high flux isotope reactor (HFIR) to 55 dpa and to 3445 appm helium at 300 to 500°C. The irradiated specimens were examined by transmission electron microscopy (TEM) to evaluate microstructural evolution. At irradiation temperatures of 400°C and below, there was very little difference in the microstructural and swelling behavior between SA and CW material. A high concentration of fine bubbles was uniformly dispersed in the matrix. Swelling was very low (&lt;0.4%). High concentrations of dislocation loops were observed. No precipitates were found at 300°C. A few precipitates were observed in the matrix and along the grain boundaries at 400°C. Large differences in swelling behavior and in the formation of precipitates appeared between 400 and 500°C. Low concentrations of large dislocation loops were observed in both materials at 500°C. The cavity size distributions were broad, but clearly bimodal. Swelling values in SA and CW were 2.3 and 0.7%, respectively. Many coarse precipitates were found in the matrix of SA, which were identified as M6C type phase enriched in nickel, iron, chromium, silicon, and molybdenum. The CW material developed fewer precipitates than the SA material at 500°C.
Swelling behavior was compared in heat-to-heat variations of Type 316 stainless steel irradiated in HFIR. Significant swelling differences between heats are seen for irradiations in the temperature range of 500°C and above and at fluences beyond 30 dpa.
Irradiation-Assisted Stress Corrosion Cracking and Grain Boundary Segregation in Heat Treated Type 304 SS
Authors: Jacobs AJ , Clausing RE , Heatherly L , Kruger RM 
Published: March 2009

Evidence was obtained correlating the susceptibility of Type 304 (UNS 530400) stainless steel (SS) to irradiation-assisted stress corrosion cracking (IASCC) and grain boundary segregation. Susceptibility to IASCC was measured in constant extension rate tensile (CERT) tests, and grain boundary segregation was demonstrated by Auger electron spectroscopy and HNO3/Cr+6 corrosion tests.
A high degree of IASCC susceptibility was imparted to commercial purity Type 304 SS by solution annealing in the temperature range 2200 to 2400°F (1204 to 1316°C), and then irradiating it in the advanced test reactor to a fast neutron fluence of 2.22 to 3.08 × 1021 n/cm2 (E &gt; 1 MeV). The high temperature solution anneal effectively purged the grain boundaries of trace elements such as sulfur, phosphorus, and silicon. In the solution annealed, unirradiated condition, the stainless steel was resistant to stress corrosion cracking. Following irradiation, the material was very susceptible to IASCC. Auger analysis and corrosion testing indicated that the irradiated material was no longer free of grain boundary segregation. Sulfur, phosphorus, and silicon were found on grain boundaries in addition to an enrichment in nickel and a depletion of chromium.
Nucleation of Helium Bubbles at Grain Boundaries During Irradiation
Authors: Singh BN , Foreman AJE 
Published: March 2009

Experimental results are used to determine the dependence of bubble density, at grain boundaries as well as within the grains, on irradiation temperature and helium gen eration rate. The measured flux of helium to grain boundaries is then related to helium generation rate. Finally, the dependence of the grain boundary bubble density on helium flux is obtained. These dependencies point to a possibility that under irradiation the diffusion kinetics of helium during the bubble nucleation phase may be material independent.
Analytical calculations are made to determine these dependencies. In these calculations, the nucleation at the boundary and within the grains is considered to be coupled. The comparison of the calculated and experimental results shows that the dependence of the average flux of helium on the helium generation rate can be predicted reasonably accurately within the framework of the diatomic type nucleation. The nucleation behavior at grain boundaries has been calculated using diatomic and multi-atomic type mechanisms. Dependencies calculated in terms of the multi-atomic type nucleation are found to be consistent with the observed nucleation behavior at grain boundaries.
A Study of Cascade Cluster Formation and Interaction in Ion-Irradiated Gold by In-Situ Observation
Authors: Sekimura N , Yamanaka Y , Ishino S 
Published: March 2009

Atomic collision cascades initiated from high energy PKAs (primary knock-on atoms) produce defect clusters in metals and alloys irradiated with fast neutrons or energetic ions. They will affect not only the early stage of microstructural evolution but that at high fluence. We have performed heavy ion irradiation experiments with simultaneous electron microscopy using the 400 kV Cockcroft-Walton type accelerator/200 kV electron microscope facility of the University of Tokyo. In the present study, 99.99% pure gold is selected as a reference material for face centered cubic (fCC) metals. Thin foil specimens are irradiated with 400 keV Xe+ ions at elevated temperatures up to 770 K in the electron microscope, and cascade cluster formation and interaction processes are investigated from the video recording of TEM images.
Instantaneous formation of vacancy loops and SFTs (stacking fault tetrahedra) is observed during ion irradiation. Most of the defect clusters shrink and annihilate with very short lifetimes under irradiation compared with those during isothermal annealing without irradiation. Lifetimes of the clusters are strongly influenced by impinging ion flux, indicating that interstitials coming from other cascades annihilate the vacancy clusters. At the irradiation temperature of 470 K, we also observed that some of the vacancy loops showed sudden growth in size.
The number of subclusters at the moment of cluster formation decreases at higher temperature. The initial size distribution of observed cascade clusters is also measured between 470 and 770 K. Higher ion flux at 670 K promotes formation of larger vacancy clusters, which can be attributed to cascade overlapping taking place in a limited time scale.
The Production Rate of Freely Migrating Defects in Self-Ion Irradiated Nickel and Fe-Cr-Ni Alloys
Authors: Muller A , Macht M-P , Naundorf V 
Published: March 2009

Diffusion processes in irradiated materials are considerably promoted by the nonequilibrium mobile vacancies and interstitials introduced by irradiation. To quantify these effects as is necessary for an understanding of, for example, void swelling or phase stability, the production rate of freely migrating defects must be known for the specific irradiation conditions. This poses a considerable problem for neutron and ion irradiations, where defects are produced in cascades. Because of spontaneous recombination and clustering of defects, only a small number of freely migrating defects is expected in comparison to the calculated displacement rate.
Diffusion coefficients of nickel in nickel and in Fe-20Cr-20Ni and Fe-20Cr-60Ni were directly measured with secondary ion mass spectroscopy (SIMS) under 300-keV Ni+ irradiation in the temperature range between 650 and 1000 K. Dose rates between 10-4 and 3 × 10-2 dpa/s and doses larger than 0.2 dpa were applied. The results were analyzed by means of a rate equation model. For the self-ion irradiated nickel a value of 1.5% of the calculated displacement rate was deduced for the rate of freely migrating defects independent of temperature. Similar values were estimated for the alloys.
Helium Bubbles in Copper Studied by Positron Annihilation
Authors: Amarëndra G , Viswanathan B , Gopinathan KP 
Published: March 2009

The evolution of defect structures in copper, following (1) helium production by (n,α) reaction in boron-impregnated copper and (2) direct helium implantation, has been studied by detailed positron lifetime and line shape measurements and the results compared. In the as-irradiated Cu-B (Case 1 above), the shorter lifetime τ1 = 167 ± 2 ps of 97% intensity has been understood as due to positron trapping at small helium vacancy complexes, while in the as-irradiated state of copper (Case 2 above), τ1 = 180 ±10 ps of 92% intensity is explained as due to the combined effects of positron trapping at dislocation loops and substitutional helium-vacancy complexes. The longer lifetime τ2 = 450 ± 30 ps of 3% intensity in Cu-B and τ2 = 420 ± 30 ps of 8% intensity in copper are understood as due to helium-free voids formed during irradiation. The observed difference in the lifetime behavior in the initial stage of defect recovery in copper, as compared to that in Cu-B, is attributed to the effect of irradiation temperature on dislocation loop density. In the intermediate annealing interval, a stage has been observed in both Cu-B and copper, marked by the occurrence of a minimum in the variation of τ2, maximum in I2, and a shoulder in the line shape curve. These are explained in terms of the formation of bubble nucleus, controlled by a thermally activated migration of helium atoms to vacancy traps. A small shift in the bubble nucleation temperature is observed in α-irradiated copper as compared to that in Cu-B.
In the post nucleation growth stage, the behavior of bubble lifetime and its intensity are found to be similar for both Cu-B and copper, wherein τ2 increases towards a saturation value accompanied by a corresponding decrease in I2 towards a plateau. The observed positron lifetime for large bubbles has been analyzed by relating the annihilation rate to helium atom density and helium pressure in bubbles evaluated for both Cu-B and copper. These are found to be in fair agreement with the estimates of equilibrium pressures, supporting the mechanism of thermal vacancy condensation for bubble relaxation. Helium retention in bubbles is found to be stable in copper even close to its melting point.
Analyzing Electrochemical Impedance Corrosion Measurements by the Systematic Permutation of Data Points
Authors: Roberge PR 
Published: March 2009

The statistical validation of a resistance-capacitance (RC) model from a limited number of data points can be achieved by systematically permuting the three data points that are chosen to extrapolate the centers of semicircular impedance diagrams. An earlier version of the geometric analysis technique, which consisted of finding geometrically the center of an arc formed by the successive data points on a complex impedance diagram, had been successfully applied to the study of erosion corrosion mechanisms of some copper nickel alloys submitted to highly turbulent conditions.
A series of results obtained with a combination of alloy composition, exposure conditions, and environments seems to indicate that the nonadherence to a perfect RC model by electrochemical impedance data provides information concerning the types of corrosion processes occurring on a metallic surface. The analytical method developed to reveal these fundamental characteristics of impedance patterns will be critically detailed with particular emphasis on the parameters controlling its resolution and on its ease of implementation.
Computer Modeling of Offshore Cathodic Protection Systems: Method and Experience
Authors: Strømmen RD 
Published: March 2009

This paper offers a brief review of methods that are used and presents different applications and experience from computer modeling of offshore cathodic protection systems. This comprises state-of-the-art software based on the Finite Difference Method ( FDM ), Finite Element Method (FEM), and Boundary Element Method (BEM) adapted for the calculation of current and potential distributions on complex, cathodically protected steel structures in seawater.
The numerical discretization procedures referred to above are combined with a data base and procedures for handling the electrochemical boundary conditions. In addition, software modules are included that handle the initialization of the computer models, definition of geometry, the numerical solution of the nonlinear discretized equations, and presentation of results.
In particular, this paper presents the principles and procedures used to handle boundary conditions. The procedures are based on basic corrosion theory and general experience as well as on laboratory and field tests. The author and his company have made use of extensive amounts of data obtained by in situ measurements of current densities and potentials on offshore platforms using proprietary electrical field gradient/current density systems. Thus the modeling results and predictions have been verified by field data.
On the Effect of Some Critical Parameters in Cathodic Protection Systems: A Numerical /Experimental Study
Authors: Carvalho SLD , Telles JCF , de Miranda LRM 
Published: March 2009

The potential distribution over the surface of underwater structures depends on a series of environmental parameters in addition to the material properties of the surfaces. Among others, the water velocity, resistivity, temperature, salinity, and dissolved oxygen affect the efficiency of cathodic protection systems. The present work discusses the influence of some of these parameters. Stirring, resistivity of the medium, and geometrical distribution of anodes are particularly considered.
Three electrolytes of distinct conductivities were studied, and for each system analyzed two stirring speeds were used. The systems of cathodic protection were analyzed for three different geometrical configurations between impressed current anodes and cathodes. To assess the influence of the aforementioned parameters, the computer program PROCAT has been used to simulate the experiments. This program is a general application boundary element computer system. It is capable of analyzing three-dimensional, two-dimensional, and axisymmetric corrosion cells, including nonlinear and possibly time-dependent polarization curves. In the present computer simulation, the nonlinear polarization curves were obtained experimentally under different environmental conditions. The experiments were implemented in a rectangular reservoir that was represented as a two-dimensional problem.