bluuebunny/crossref_metadata_2025_split huggingface dataset:
Man Versus Machine: A Comparison of Visual Evaluation and Computerized Image Analysis for the Measurement of Weather-Induced Surface Cracking
Authors: Jacques LFE , Lee FH 
Published: March 2009

Many of the types of weathering-induced degradation are not measured in an accurate quantitative manner. The cracking of a coating is a good example of such a parameter. Visual scales are used that can be either a photograph or a representative drawing of the degradation. Visual evaluation of cracking is particularly susceptible to operator bias and may not produce a repeatable or precise result. It is desirable to make a more exact measurement to discriminate more easily between coatings of different performances. It is also desirable to measure quantitatively the initial stages of cracking since these give the ability to shorten test times and develop more effective pass/fail criteria.
Technology is now available to measure cracking in a precise and repeatable way using digitized photographs or other images of the coatings and image analysis software techniques. A set of cracked coatings were measured using both image analysis and multiple visual inspectors, and the results were compared. The coatings used exhibited a wide range of colours and different levels and sizes of cracking defects. The specimens were evaluated by a team of professional coatings inspectors and were rated according to several industry standard scales, such as ASTM, and TNO(Toegepast Natuuwetenschappelyk Onderzok) of Delft, Netherlands. Items of interest were precision of measurement, reduction of operator-induced bias, and the speed of repetitive measurement. The data were analyzed statistically and the results presented.
Development of a Methodology for Service Lifetime Prediction of Renewable Energy Devices
Authors: Kim H-M , Jorgensen GJ , King DE , Czanderna AW 
Published: March 2009

Emerging advanced multilayer renewable energy devices, such as reflector materials and photovoltaic modules, are expected to exhibit significantly increased service lifetimes compared to existing devices. Such devices must be capable of 20 to 30 years of operation under harsh outdoor weathering conditions. Industrial manufacturers cannot afford to wait extended periods of time to determine whether such lifetimes are realistic. Consequently, a flexible, robust, and accurate method for predicting the service lifetime of such devices is essential. Two requirements for developing such a method are first, to correlate the accelerated lifetime test methods with anticipated life under real-world operating environments; and second, to establish statistical models for predicting service lifetimes based on environmental stress factors.
The relative significance of the weathering stress factors ultraviolet light (UV), temperature (T), and relative humidity (RH) was ascertained. Optical properties of new reflector materials were measured and their loss of performance with exposure time was modelled as a function of an appropriate combination of stress factors. Then, the functional relationship between performance measurements and time in accelerated lifetime tests was investigated. The basic framework of this approach is SPt analysis because it intends to explain the bridge functions from Stresses (S) to Performance (P) and from Performance to lifetime (t) of the materials. The results show that the cumulative dosage of ultraviolet radiation between 290–320 nm (UV-B) with synergistic effects of T and RH is a very critical factor in inducing performance loss. Finally, the SPt model developed for accelerated laboratory data was verified for data obtained from outdoor sites, and excellent agreement was found.
The Use of Ranked Versus Rated Data in the Evaluation of Weathered Specimens or Material
Authors: Asher LB 
Published: March 2009

The evaluation of specimens after weathering (in natural outdoor exposures or accelerated cycles) can be handled by a number of approaches; two of these are ranking and rating. This paper will center on these two approaches and will demonstrate how ranking is often superior. Rating requires one to compare the specimens against a scale (ie. 1 through 10 with 1 being “excellent”, 5 being “good” and 10 being “poor”, etc.). Ranking on the other hand requires the direct comparison of the specimens against each other.
Since people typically do not like to be overly critical or overly generous, the rating approach of ten leads to the specimens being rated in the middle of the scale (with ratings of 4 to 7 out of a scale of 1 to 10). The specimens differentiation or discrimination is therefore greatly reduced. The ranking approach forces people to rank the specimens from best to worst. It is highly recommended that ties not be allowed; this forces the evaluators to clearly state their preferences.
Since ranking involves a direct comparison, all the specimens must be available at the same time. If this is not possible, the rating approach would be the logical choice. The use of visual examples or standards (that visually demonstrate three ratings,ie. 1,5 & 10) is strongly recommended in these situations.
The ranked and rated data from a visual comparison of six reflective sheetings for whiteness will be used to demonstrate the effectiveness of each approach. The statistical evaluation of the ranked data will be discussed. This will include both simplified and more comprehensive analysis approaches. The averages and ranges of ranked data will represent the simplified methods. Thurstone Scaling and Analysis of Variance (ANOVA) represent the more comprehensive methods.
The Effect of the Trace Impurity Uranium on PWR Aqueous Corrosion of Zircaloy-4
Authors: Peters HR , Harlow JL 
Published: March 2009

Commercial Zircaloy-4 specifications control natural uranium to &lt;3.5 ppm by weight. Long-term in-pile corrosion tests were conducted on Zircaloy-4 coupons containing 0.1, 2.1, 10.6, and 24.1 ppm by weight of natural uranium. The objective of this testing was to determine the effect of the trace impurity uranium on the in-pile corrosion of Zircaloy-4. The tests were conducted in the advanced test reactor in Idaho at test temperatures of 355, 332, 310, and 274°C and at fast-neutron (&gt;1 MeV) fluxes of &gt; 1.0 × 1014 n/cm2-s. Limited testing was also conducted at lower fluxes.
The pre-transition corrosion rates were observed to increase with increasing uranium content and flux level. The transition times were doubled at 2.1 ppm and quadrupled at 10.6 and 24.1 ppm uranium compared to the 0.1 ppm control ingot. Transition time differences were observed to diminish with decreasing fast-neutron flux. Post-transition corrosion rates also increased with uranium levels. The net effect on long-term corrosion is a reduction (X2 to X5) in corrosion film thickness for Zircaloy-4 containing uranium levels at the specification limit (3.5 ppm) compared to the 0.1 ppm control ingot. Based on the data presented, significant differences in PWR corrosion will develop as a result of varying natural uranium levels in ingots.
Properties of an Irradiated Heat-Treated Zr-2.5Nb Pressure Tube Removed From the NPD Reactor
Authors: Chow CK , Coleman CE , Koike MH , Causey AR , Ells CE , Hosbons RR , Sagat S , Urbanic VF , Rodgers DK 
Published: March 2009

Some pressure tubes in reactors moderated by heavy water have been made from heat-treated (HT) Zr-2.5Nb. One such tube was removed from the NPD nuclear reactor after 20 years of operation. An extensive program was carried out jointly by AECL and PNC to evaluate the condition and properties of this pressure tube. The investigations include irradiation creep, tensile, corrosion, delayed hydride cracking (DHC), fatigue, and fracture properties.
Results show that: (1) the in-reactor elongation rate is much lower and the transverse strain rates are slightly larger than in cold-worked (CW) Zr-2.5Nb tubes; (2) the tensile properties, hydrogen pickup, threshold stress intensity factor for DHC initiation, DHC velocity, and fatigue crack growth rates were similar to those of the CW Zr-2.5Nb material; (3) the fracture toughness of this tube, as measured by curved compact toughness specimens and burst tests, is slightly higher than the CW tubes. The results were also compared with other heat-treated Zr-2.5Nb materials irradiated in the Fugen reactor.
The tube was in excellent condition when removed from the reactor and would have been satisfactory for further service.
Influence of Processing Variables and Alloy Chemistry on the Corrosion Behavior of ZIRLO Nuclear Fuel Cladding
Authors: Comstock RJ , Schoenberger G , Sabol GP 
Published: March 2009

Variations in the thermal heat treatments used during the fabrication of ZIRLO (Zr-1Nb-1Sn-0.1Fe) fuel clad tubing and in ZIRLO alloy chemistry were explored to develop a further understanding of the relationship between processing, microstructure, and cladding corrosion performance. Heat treatment variables included intermediate tube annealing temperatures as well as a beta-phase heat treatment during the latter stages of the tube reduction schedule. Chemistry variables included deviations in niobium and tin content from the nominal composition. The effects of both heat treatment and chemistry on corrosion behavior were assessed by autoclave tests in both pure and lithiated water and high-temperature steam. Analytical electron microscopy demonstrated that the best out-reactor corrosion performance is obtained for microstructures containing a fine distribution of beta-niobium and Zr-Nb-Fe particles. Deviations from this microstructure, such as the presence of beta-zirconium phase, tend to degrade corrosion resistance.
ZIRLO fuel cladding was irradiated in four commercial reactors. In all cases, the microstructure in the cladding included beta-niobium and Zr-Nb-Fe particles. ZIRLO fuel cladding processed with a late-stage beta heat treatment to further refine the second-phase particle size exhibited inreactor corrosion behavior that was similar to reference ZIRLO cladding. Variations of the inreactor corrosion behavior of ZIRLO were correlated to tin content, with higher oxide thickness observed in the ZIRLO cladding containing higher tin. The results of these studies indicate that optimum corrosion performance of ZIRLO is achieved by maintaining a uniform distribution of fine second-phase particles and controlled levels of tin.
Corrosion Behavior of Duplex and Reference Cladding in NPP Grohnde
Authors: Besch OA , Yagnik SK , Woods KN , Eucken CM , Bradley ER 
Published: March 2009

The Nuclear Fuel Industry Research (NFIR) Group undertook a lead test assembly (LTA) program in NPP Grohnde PWR in Germany to assess the corrosion performance of duplex and reference (i.e., non-duplex) cladding. Two identical 16 by 16 LTAs, each containing 32 peripheral test rods, completed four reactor cycles, reaching a peak rod burnup of 46 MWd/kgU. The results from poolside examinations performed at the end of each cycle, together with power histories and coolant chemistry, are reported.
Five different cladding materials [three types of duplex (D1-D3) and two types of reference (R1, R2)] were characterized during fabrication. The corrosion performance of the cladding materials was tracked in long-term tests (∼900 days) in high-pressure, high-temperature autoclaves. The relative ranking of corrosion behavior in such tests corresponded well with the inreactor corrosion performance. The extent and distribution of hydriding in duplex and reference specimens during the autoclave testing has been characterized.
The in-reactor corrosion data indicate that the low-tin (1.3% Sn) Zircaloy-4 reference cladding, R2, had an improved corrosion resistance compared to high-tin (1.5% Sn) Zircaloy-4 reference cladding, R1. Two types of duplex cladding, D1 (Zr-2.5% Nb) and D2 (Zr-0.4% Fe-0.5% Sn), showed an even further improvement in corrosion resistance compared to R2 cladding. The third duplex cladding, D3 (Zr-4 + 1.0% Nb), had significantly less corrosion resistance, which was inferior to R1. The in-reactor and out-reactor corrosion performances have been ranked.
Comparison of the Long-Time Corrosion Behavior of Certain Zr Alloys in PWR, BWR, and Laboratory Tests
Authors: Garzarolli F , Broy Y , Busch RA 
Published: March 2009

Laboratory corrosion tests have always been an important tool for Zr alloy development and optimization. However, it must be known whether a test is representative for the application in-reactor. To shed more light on this question, coupons of several Zr alloys were exposed under isothermal conditions in all or most of the following environments: In-Reactor: (1) PWR core at 300 to 340°C up to six years. (2) BWR core with a low sensitivity to nodular corrosion up to four years. (3) BWR core with a high sensitivity to nodular corrosion up to two years.
Ex-Reactor (in Autoclave): (1) 350°C/pressurized water up to three years. (2) 400°C/100-bar steam up to two years. (3) 350°C/0.01 M LiOH water up to two years. (4) 500 to 515°C/high-pressure steam 16 to 24 h.
In addition, the material condition of several of the examined Zr alloys was varied over a wide range.
For evaluation of the in-PWR tests and for comparison of out-of-pile and in-pile tests, the different temperatures and times were normalized to a temperature-independent “normalized time” by assuming an activation temperature (Q/R) of 14 200 K. Comparison of in-PWR and out-of-pile corrosion behavior of Zircaloy shows that corrosion deviates to higher values in PWR if a weight gain of about 50 mg/dm2 is exceeded. In the case of the Zr2.5Nb alloy, a slight deviation of corrosion as compared to laboratory results starts in PWR only above a weight gain of 100 mg/dm2. In BWR, corrosion of Zircaloy is enhanced early in time if compared with out-of-pile. Zr2.5Nb exhibits higher corrosion results in BWR than Zircaloy-4.
Alloying chemistry and material condition affect corrosion of Zr alloys. However, several of the material parameters have shown a different ranking in the different environments. Nevertheless, several material parameters influencing in-reactor corrosion like the second phase particle (SPP) size or in-PWR behavior as the Sn and Fe content can be optimized by out-of-pile corrosion tests.
Crack Initiation Life Behavior Under Biaxial Loading Conditions: Experimental Behavior and Prediction
Authors: Nowack H , Hanschmann D , Ott W , Trautmann K-H , Maldfeld E 
Published: March 2009

An experimental program with proportional and nonproportional loading histories was performed with cruciform aluminum specimens on a biaxial testing machine. FEMFAT, a crack initiation life prediction method as originally proposed by Ott, which includes an elastic-plastic stress-strain analysis based on the finite element method (FEM) in combination with a Mróz-type material model and an event independent continuous damage (EVICD) evaluation approach on the basis of incremental plastic work was applied to predict the crack initiation life behavior as observed in the experiments. The predictions were partially extremely conservative.
Two new fatigue evaluation approaches, EVICD-J1 and EVICD-N, were developed on the basis of the original EVICD approach to account for the effect of mean stresses. They led to significant improvements in the predictions.
The new approaches do not need cycle counting and are applicable to arbitrary multiaxial loading histories in the low-cycle fatigue (LCF) and in the high-cycle fatigue (HCF) range.
Crack Propagation in Cruciform IMI 834 Specimens Under Variable Biaxial Loading
Authors: Trautmann K-H , Maldfeld E , Nowack H 
Published: March 2009

In the present study, the crack propagation behavior of cruciform IMI 834 specimens under different types of in-phase biaxial block loading histories was investigated. The test temperature was 350°C. The phenomenological crack propagation behavior and the orientation of the cracks in the biaxial tests are described. This study shows that the mean stress and the amplitude of the minor cycles in the blocks had a significant effect.
Linear crack propagation predictions were performed and indications of crack closure influences and load sequence effects were observed.
Application of a J-Q Model for Fracture in the Ductile-Brittle Transition
Authors: Landes JD 
Published: March 2009

A model to predict cleavage failure of precracked bodies in the transition region for steels was recently proposed by the author. It is based on the concept that the stress-controlled fracture of a weak link triggers the failure of the entire body. The stress that triggers fracture is predicted by a numerical crack-tip stress analysis. The model uses toughness measured at one condition as input to predict toughness at another. For example, toughness measured at one temperature can be used to predict toughness at another temperature, or toughness measured from one geometry can be used to predict toughness for another geometry.
In this paper the model is applied to predict transition toughness for some cases where the toughness is known so that the predictions from the model can be evaluated. The results show that the predictions have the same trends as many of the measured transition toughness results. The model is also applied to several component-type geometries to show that it can be used to transfer laboratory results to structural component models.
Effects of Mixed Mode I/II Loading and Grain Orientation on Crack Initiation and Stable Tearing in 2024-T3 Aluminum
Authors: Amstutz BE , Sutton MA , Dawicke DS , Boone ML 
Published: March 2009

The effects of material grain orientation and Mixed Mode I/II loading on crack initiation and stable tearing in 2.3-mm-thick, unclad 2024-T3 aluminum is experimentally investigated. Mode I experiments were performed on center-cracked specimens with the crack being oriented at various angles relative to the rolling direction. Defining θ to be the angle between the normal to the initial crack plane and the loading direction, Mode I/II experiments were performed using an Arcan test fixture for 0° ≤ θ ≤ 90° [corresponding to 90° ≥ β ≥ 0°, where β = atan (KII/KI)] with the crack oriented either along the rolling direction (T-L) or perpendicular to the rolling direction (L-T).
Results indicate that: 1. The Mode I crack tip opening displacement (CTOD) is a strong function of the orientation of the crack relative to the rolling direction; CTOD for a T-L specimen is 0.84 mm, increasing linearly with orientation angle to 1.05 mm for an L-T case. 2. The Mode I/II CTOD increases rapidly during initial increments of crack growth and then decreases towards a constant value as crack growth continues. 3. For θ &lt; 68° (β &gt; 29°), all cracks kinked and the Mode I/II plastic zones are similar to rotated Mode I plastic zones throughout the crack growth process. 4. JII = 0 reasonably predicts the direction of tension-dominated crack growth, but does not predict the transition to shear crack growth which occurs for θ ≥ 75°. 5. KII ≥ KI for θ ≈ 58° (β = 45°) does not quantitatively predict the transition to shear crack growth for θ ≥ 75° (β ≤ 22°), but does provide an indication of changing conditions in the crack tip region.
An Analytical Investigation of the Effect of Crack Depth (a) and Crack Depth to Width (a/W) Ratio on the Fracture Toughness of A533-B Steel
Authors: Smith JA , Rolfe ST 
Published: March 2009

The use of various crack depths (a) and crack-depth to specimen-width (a/W) ratios in laboratory tests to model flawed structural components has led to considerable interest in the role of both the crack depth (a) and the a/W ratio on fracture toughness. To investigate the separate roles of crack depth and the a/W ratio, three-dimensional elastic-plastic finite element analyses, (FEA) of square SE(B) specimens with a/W ratios ranging from 0.1 to 0.5 [crack depths ranging from 2.0 mm (0.08 in.) to 50.8 mm (2.0 in.)] have been conducted. The material properties used in this analysis were those for the material used in an experimental study conducted at the University of Kansas (KU) and Oak Ridge National Laboratory (ORNL). The specimen dimensions were chosen such that the results for specimens having a fixed crack depth and varying a/W ratios could be compared to the results for specimens with a fixed a/W ratio and varying crack depths.
The results of the experimental studies had indicated that both the crack depth and the a/W ratio each have a significant effect on the fracture toughness. Both the lower bound toughness and the transition temperature were affected. Three-dimensional elastic-plastic FEA were used to model each specimen geometry, and the predicted stresses, CTOD, and J-integral for the various crack depths and a/W ratios were compared. The results of the FEA support the findings of the previous experimental study. For a high-constraint geometry (a/W = 0.5), there is not a significant change in the near tip stresses for different size specimens. However, for low-constraint geometries (a/W = 0.1), the near tip stresses are significantly affected by the actual crack depth and specimen size. The findings of this study are significant in helping to understand the relative role of crack depth, a/W ratio, and specimen size on fracture toughness. Future studies are expected to extend the findings of this study to the behavior of actual structures with cracks.
Creep Crack Growth Behavior of Aluminum Alloy 2519: Part I—Experimental Analysis
Authors: Hamilton BC , Hall DE , Saxena A , McDowell DL 
Published: March 2009

The discipline of time-dependent fracture mechanics has traditionally focused on the creep crack growth behavior of high-temperature materials that display creep-ductile behavior, such as stainless steels and chromium-molybdenum steels. Elevated temperature aluminum alloys, however, have been developed that exhibit creep-brittle behavior; in this case, the creep crack growth rate correlates with the stress intensity factor, K. The fracture characteristics of aluminum alloy 2519-T87 were studied at 135°C, and the creep and creep crack growth behavior were characterized utilizing experimental and numerical methods.
The strain to failure for creep deformation specimens was limited to only 1.2 to 2.0%. Creep crack growth tests revealed a unique correlation between the creep crack growth rate and K, a result consistent with creep-brittle behavior. No experimental correlation was found between the creep crack growth rate and the Ct, parameter. Microscopy of fracture surfaces revealed distinct regions of intergranular and transgranular fracture, and the transition between the fracture regions was found to occur at a critical K-level. Experimental results also appeared to show that initiation of crack growth (incubation) is controlled by the accumulation of a critical amount of damage ahead of the crack tip and that a correlation exists between the incubation time and K. Total time to failure is viewed as a summation of the incubation period and the crack growth period, and the design importance of incubation time is discussed.
The Modelling of Irradiation-Enhanced Phosphorus Segregation in Neutron Irradiated Reactor Pressure Vessel Submerged-Arc Welds
Authors: Druce SG , English CA , Foreman AJE , McElroy RJ , Vatter IA , Bolton CJ , Buswell JT , Jones RB 
Published: March 2009

Recent results on neutron-irradiated RPV submerged-arc welds have revealed grain boundary segregation of phosphorus during irradiation, which may lead to intergranular fracture. However, the experimental database is insufficient to define the dependence of the process on variables such as dose, dose-rate and temperature. This paper describes work in which two existing models of phosphorus segregation, under thermal or irradiation conditions, have been developed to obtain predictions of these dependencies.
The critical parameters in the models have been adjusted to give consistency with the available reference data, and predictions have been made of the dependence of segregation on a number of variables.