bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of Methods to Alleviate Corrosion Fatigue in Type 135 Drill-Pipe Steel for Offshore-Drilling Applications
Authors: Pettit DE , Hoeppner DW , Hyler WS 
Published: March 2009

Various methods of modifying the drilling environment and changing the response of the material to the environment were examined as potential methods of alleviating corrosion fatigue in Type 135 drill-pipe steel for use in offshore-drilling applications. The fatigue behavior of Type 135 steel specimens in seawater and in air was compared to the results obtained in deaerated seawater, freshwater and seawater drilling mud, inhibited drilling mud, and drilling mud with an elevated pH. No improvement in fatigue life resulted for any of the modified environments examined, several actually proving detrimental. Cathodic-protection studies were then conducted on specimens subjected to various applied current densities during fatigue cycling in seawater and a range of current densities that improved the fatigue behavior determined. The half-cell potential was determined for the steel in seawater and zinc selected as the sacrificial metal coating. Zinc-electroplated specimens fatigue tested in seawater showed a marked increase in fatigue life compared to that of uncoated specimens in seawater. Bare regions up to ⅜ in. wide were tolerated with no loss of protection and regions as large as ¾ in. wide still resulted in an improved fatigue-corrosion behavior.
Thus, zinc electroplating of Type 135 drill-pipe steel resulted in a substantial improvement in fatigue behavior in a seawater environment. Alteration of the chemical environment resulted in no improvement of the fatigue behavior of uncoated specimens over that obtained in plain seawater.
Predicting Low-Cycle Fatigue Data for Low-Alloy Cast Steels
Authors: Schmieder AK 
Published: March 2009

Low-cycle fatigue tests were made on low-alloy cast steel in three conditions, as well as a few tests on wrought specimens. Specimens 1 in. in diameter with a ground surface were tested by reversed, push-pull, strain-controlled mode at room temperature. True stress-true strain, tension tests were also made on the materials.
The strain-hardening exponent for a single hysteresis loop agrees closely with that at certain portions of the tensile curve. Whether these materials will cyclic-strain harden or soften at a specified strain range could also be determined from the tension test data. Using these observations, and the work of Martin, Manson and Morrow and their colleagues, a formula was synthesized which predicted fatigue lives of all durations from tensile data and the fatigue limit of the material. When the fatigue limit was adjusted for the specimen conditions the cyclic lives were predicted with useful accuracy. For example, micro-shrink in one casting was found to reduce the cyclic life sharply without much loss in tensile fracture ductility. Use of the notched specimen fatigue limit in the formula gave a reasonably accurate prediction of cyclic life for this casting. The formula is also used to calculate cyclic life under conditions of variable stress and to calculate the reduction of fatigue limit due to cyclic pre-stressing at stresses higher than the fatigue limit.
Effect of Strength and Thickness on Notch Ductility
Authors: Gross JH 
Published: March 2009

For a number of years, standards and code-writing bodies have been attempting to specify fracture toughness in terms of the Charpy V-notch rather than the Charpy keyhole test because various investigators have shown that V-notch test results correlate much better with service experience. However, the change to V-notch specifications has been deterred by uncertainty concerning the best criterion for establishing transition temperatures and the effect of strength and thickness on transition temperatures. Therefore, five steels covering a wide range of yield and tensile strengths (ABS-C: 39/63, A302-B: 56/88, HY-80: 81/99, A517-F: 121/134, and HY-130: 140/148) were tested as quarter-, half-, single-, and double-width (QW, HW, SW, and DW) Charpy V-notch specimens in the longitudinal and transverse directions and with through-thickness and surface notches. Transition temperatures were determined for various energy-absorption, lateral-expansion, and fracture-appearance criteria.
The results showed that energy-absorption criteria for determining transition temperature should increase with strength to ensure a constant notch ductility. Thus the best method for determining transition temperature was the direct measurement of lateral expansion. Of the lateral-expansion criteria evaluated, the 15 mil value agreed best with fracture-mechanics considerations.
The average increase in transition temperature was 60 F from QW to HW specimens, 26 F from HW to SW specimens, and 2 F from SW to DW specimens. This indication of maximum constraint for the SW specimen was not consistent with the effects produced when the standard V-notch was replaced with a fatigue crack. Consequently, the size of the Charpy test specimen that should be used for evaluating thick plates has not been established and requires additional study.
The effects of strength and thickness on transition temperature were much larger than the effects of testing direction, notch location, or notch acuity.
The results indicate that, of the various criteria for evaluating the Charpy V-notch impact-test performance of structural steels, lateral expansion is the best criterion for compensating for the important effects of steel strength and plate thickness. Moreover, its validity is supported by fracture-mechanics concepts.
Materials Sensitive to Slow Rates of Straining
Authors: Hartbower CE 
Published: March 2009

In precrack Charpy slow-bend and impact tests of D6aC high-strength steel at 300 to 500 F, there was a reduction in slow-bend fracture energy as the test temperature was increased; whereas, there was an increase in impact fracture energy over the same temperature range. Thus, in high-strength steels, it is sometimes found that the precrack Charpy slow-bend and impact test results are approximately the same at room temperature, but attain a significant spread at moderately elevated temperature. In 6Al-4V titanium, the difference between slow-bend and impact was most pronounced at room temperature, again with the lowest fracture energy in slow bend; whereas, at 300 F, the slow-bend test indicated the material to be as tough or tougher than impact. In all-beta 3Al-13V-11Cr titanium in the solution-treated condition tested at room temperature, the slow-bend test result showed markedly higher toughness than impact, but, after aging, the slow-bend test result was appreciably lower than the impact value.
Differences in fracture appearance attending slow versus impact rates of loading confirm the above observations. The lower toughness in slow bending is believed to be the result of a combination of factors, including an adiabatic temperature rise in the plastic zone on impact, and a time-dependent-embrittlement mechanism occurring in slow bending. In a material with a sharply defined transition curve at or around room temperature, it is easy to see how an adiabatic temperature rise in the plastic zone ahead of the crack could markedly increase the resistance to crack propagation. At the same time, it is well known that embrittlement involving a diffusion mechanism is not detected by impact testing; for example, hydrogen embrittlement and strain aging. In 6Al-4V titanium, the difference between slow-bend and impact at room temperature is consistent with a hydrogen-embrittlement mechanism; namely, maximum embrittlement around room temperature and a decreasing embrittlement at higher (and lower) temperatures. In D6aC steel, on the other hand, the loss of toughness in slow-bend occurs at moderately elevated temperature, which is consistent with spontaneous strain aging as a time-dependent embrittling mechanism.
From these findings, it appears that the concept of strain-rate sensitivity should not be limited to the traditional interpretation that impact is the most severe test of a material. In a number of common structural metals, the situation is reversed; that is, the materials are in fact more “sensitive” to slow rates of straining.
Significance of the Drop-Weight Tear Test and Charpy V-Notch Impact Test Results
Authors: Eiber RJ , Duffy AR , McClure GM 
Published: March 2009

The results of extensive research on piping and pressure vessels of plain carbon and low-alloy materials is providing an understanding of the significance of impact test results in terms of the full-scale fracture initiation and propagation characteristics.
The impact tests employed in the research work were the Charpy V-notch impact test and the drop-weight tear test (DWTT). The impact tests have been correlated with full-size cylindrical vessel tests in which the initiation and propagation characteristics have been determined under controlled conditions.
The results of the research indicate that, for the materials studied, the impact test fracture appearances relate to the structural fracture appearance with certain limitations. Specifically, the DWTT when conducted on material of the same thickness as the structure will predict directly the fracture propagation transition temperature. The Charpy V-notch test fracture appearance can be correlated to the structural fracture propagation transition temperature but is offset generally on the temperature scale because of the difference in thickness between the Charpy specimen and the structure.
Correlations have been attempted between Charpy or DWTT energies and the fracture initiation characteristics determined from full-scale cylindrical vessel experiments. These correlations to date between the plane stress-stress intensity factor Kc and the plateau impact energies have exhibited considerable scatter, and no consistent trends are indicated. Also, correlations were attempted between the impact energies and the fracture propagation behavior, but no consistent relationship was found.
Dynamic Tear Energy—A Practical Performance Criterion for Fracture Resistance
Authors: Lange EA , Loss FJ 
Published: March 2009

The dynamic tear (DT) method of testing for fracture toughness is described. Design of specimens, impact test machines, and methods for energy measurement are presented. The relationship between DT energy and KIc values is presented for steel, and procedures for translating the energy values to design parameters such as critical flaw size and stress level are outlined.
The current need for the use of the DT test in the development and selection of high-strength structural metals is illustrated by examples of conditions where the Cv test can be shown to be inadequate. Fracture toughness criteria defined by Cv and DT tests are compared for a high-strength titanium alloy, a 180-ksi yield strength steel, a 140-ksi yield strength steel weld metal, and a quenched and tempered 2¼ Cr-1 Mo steel of 90 ksi yield strength. In all of these examples the Cv test is shown to provide information in variance to that from the DT, DWT-NDT, and Robertson tests. It is concluded that the DT test method has desirable features for general industrial use, and it can provide broad-scope characterization of the fracture resistance of steels, titanium alloys, and aluminum alloys.
Use of the Scanning Electron Microscope in the Materials Sciences
Authors: Russ JC 
Published: March 2009

The scanning electron microscope is a relatively new instrument now finding rapidly growing use in the materials sciences. It scans a fine beam of electrons across the specimen surface and displays an image of that surface on a cathode-ray tube using any of the radiations that are generated by incident electrons. The characteristics of each of the images that can be formed using the different signals available are described, as well as its particular use for different types of specimens.
Many types of materials specimens can be examined in the scanning electron microscope with no preparation, but to obtain optimum results it is often necessary or desirable to coat the surface with a thin conductive layer. This and other steps of specimen preparation and handling techniques for solid and powder samples are outlined. Finally the interpretation of the various types of images and the dynamic observation of changes produced in the specimen by heating, straining, etc., are considered.
Evaluation of a Method of Test for Plane Strain Fracture Toughness Using a Bend Specimen
Authors: Heyer RH , McCabe DE 
Published: March 2009

A task group of ASTM Committee E-24 conducted an interlaboratory test program on determination of KIc using the proposed “Recommended Practice for Plane Strain Fracture Toughness Testing of High-Strength Metallic Materials Using a Fatigue-Cracked Bend Specimen.”
Analysis of KIc data for an aluminum alloy and two high-strength alloy steels showed that laboratory mean values were within ±10 percent of grand mean values. Replication was generally satisfactory, although not as good as for smooth specimen tension tests.
Information obtained on fatigue cracking and other details of the procedure will be useful in planned revisions, leading to a standard method of test.
British Experience with Plane Strain Fracture Toughness (KIc) Testing
Authors: May MJ 
Published: March 2009

This paper reviews the background to the formation of a Working Group in the United Kingdom concerned with fracture testing of high-strength metallic materials. The results are given of two collaborative test programs designed to familiarize participants with testing techniques based on linear elastic fracture mechanics and interpretation of load-displacement curves.
Results also are presented of specific studies on the influence of fatigue precracking stress intensity and the specimen dimensions such as thickness and crack length on KIc measurement.
The current objectives of the BISRA Fracture Toughness (High Strength steels) Committee are to produce a British standard for plane strain fracture toughness (KIc) testing and prove its workability by a further collaborative test program.
The Influence of Crack Length and Thickness in Plane Strain Fracture Toughness Tests
Authors: Jones MH , Brown WF 
Published: March 2009

Results are presented from a systematic investigation of the influence of crack length and specimen thickness on the fracture properties of 4340 steel bend specimens heat treated to yield strength levels between 180 and 213 ksi. It is shown that KIc values determined in accordance with the present ASTM Tenative Method of Test for Plane Strain Fracture Toughness of Metallic Materials (E 399-70T) can vary moderately within the specimen size and geometric limitations imposed by the Test Method. The magnitude of these variations will depend on the material properties and would be increased by relaxation of the size requirements.
The possibility of employing subsized specimens for screening materials regarding their plane strain fracture toughness was explored as well as several methods for relating KIc values to uniaxial tensile data. The results indicated that use of subsized specimens with the ASTM Committee E-24 Test Method does not constitute a useful screening procedure. For steels subject to single aging or tempering reactions, it appears that the relation KIc ∼ σYS-m may be useful for estimating KIc values. However, on the basis of present knowledge, it is not possible to calculate KIc with useful accuracy from uniaxial tensile data alone.
Crack Toughness Measurements of High-Strength Steels
Authors: Steigerwald EA 
Published: March 2009

The influence on fracture toughness of relative specimen thickness in the center-precracked tension specimen and crack length in the precracked bend specimen was evaluated. The results indicated that the nature of the crack growth curve in the precracked sheet tension test could be related directly to the fracture mode transition temperature. Tests conducted below the fracture mode transition region provided only catastrophic crack extension, while testing within the transition region resulted in measurable slow growth which was initiated by a sharp discontinuity (pop-in). Above the brittle-to-ductile transition slow crack growth was observed, but no meaningful fracture toughness could be measured.
The study of the influence of crack length on the fracture toughness obtained in the notch bend test indicated that valid values of KIc were obtained when the crack size (a) was 2.5 times the (K/σy)2 ratio in accordance with ASTM recommendations. However, it appears that the crack size requirements could be reduced by a factor of 2.5 without producing variations of greater than 5 percent in the measured fracture toughness value provided that the thickness requirement was satisfied.
The available KIc values for a variety of high-strength steel types were also presented graphically as a function of both strength level and test temperature.
Review of Developments in Plane Strain Fracture Toughness Testing
Authors: Brown WF 
Published: March 2009

Description
The object of this book is to bring together a series of papers which describe recent experience obtained in the United States and in England with the application of the ASTM E24 Proposed Method of Test for Plane Strain Fracture Toughness of Metallic Materials. This information supplements that which has appeared in ASTM STP 381 on Fracture Toughness Testing and its Application and in STP 410 on Plane Strain Crack Toughness Testing of High Strength Metallic Materials. This publication is a cooperative effort of ASTM and NASA. NASA research personnel have participated in ASTM Fracture Committee activities since their inception in 1959. This participation reflects the strong interest that NASA has maintained in the development of test methods for evaluation of the fracture resistance of engineering materials. This interest arises from the necessity for the use of high-strength alloys in critical parts of aerospace structures. By cooperation with ASTM in publication of this book NASA is helping to fulfill its obligation to provide the widest practicable and appropriate dissemination of results from its activities.
Effiziente Erfüllbarkeitsalgorithmen für die Generierung von TestmusternEfficient Satisfiability Solving Algorithms for Test Pattern Generation
Authors: Drechsler Rolf , Eggersglüß Stephan , Fey Görschwin , Schlöffel Jürgen , Tille Daniel 
Published: March 2009

Zusammenfassung
Während Schaltungen noch bis vor einigen Jahren vornehmlich in Rechenanlagen Verwendung fanden, werden sie zunehmend ein Teil unserer täglichen Umgebung und finden in vielen sicherheitskritischen Bereichen Anwendung. Exemplarisch seien hier medizinische Apparaturen und die Automobilindustrie genannt. Schon heute entstehen z.B. in dem zuletzt genannten Bereich bis zu 40% der Kosten durch die Elektronik. Hinzu kommt, dass hier immer mehr sicherheitsrelevante Komponenten, wie Bremsen und Lenkung, elektronisch unterstützt bzw. gesteuert werden. Daher werden immer höhere Anforderungen an die Verfahren gestellt, die die Korrektheit dieser Schaltungen und Systeme gewährleisten sollen. In den vergangenen Jahren wurden große Fortschritte erzielt, doch durch die immer höhere Komplexität der Systeme und den Einsatz neuer Technologien müssen auch die Werkzeuge weiterentwickelt werden, die die Qualität sicher stellen. Ein wesentlicher Aspekt bei der Erstellung von Schaltungen und Systemen ist der Test. Die durch den Test entstehenden Kosten betragen bis zu 30% der Gesamtkosten der Fertigung. Eine grundlegende Methode zum Testen ist die Generierung von Testmustern ausgehend von einem System und einem betrachteten Fehlermodell. In den frühen 90er Jahren wurden Verfahren zur automatischen Testmustergenerierung (ATPG = Automatic Test Pattern Generation) basierend auf Boolescher Erfüllbarkeit (SAT = Satisfiability) vorgeschlagen. Aufgrund der Mächtigkeit moderner SAT-Beweiser sind diese Verfahren wieder in den Fokus der Forschung gerückt. In dieser Arbeit werden die grundlegenden Mechanismen der Methode vorgestellt und aktuelle Erweiterungen diskutiert. Es zeigt sich, dass es möglich ist, große industrielle Schaltungen mit diesen Verfahren effizient zu bearbeiten. Abschließend werden aktuelle Forschungsaufgaben identifiziert.
Glucagon-like peptide-1 receptor agonists in type 2 diabetes: a meta-analysis of randomized clinical trials
Authors: Monami Matteo , Marchionni Niccolò , Mannucci Edoardo 
Published: March 2009

ObjectiveThe role of glucagon-like peptide-1 (GLP-1) receptor agonists in the treatment of type 2 diabetes is debated; many recent trials, which were not included in previous meta-analyses, could add relevant information.Design and methodsAll available randomized controlled trials (RCTs), either published or unpublished, performed in type 2 diabetic patients with GLP-1 receptor agonists (exenatide and liraglutide), with a duration>12 weeks were meta-analysed for HbA1c, body mass index, hypoglycaemia and other adverse events.Results and conclusionsA total of 21 RCTs (six of which unpublished), enrolling 5429 and 3053 patients (with GLP-1 receptor agonists and active comparator or placebo respectively), was retrieved and included in the analysis. GLP-1 receptor agonists determine a significant improvement of HbA1c in comparison with placebo (−1.0 (−1.1, −0.8),P<0.001), with a low risk of hypoglycaemia. There is no evidence of increased cardiovascular risk with the use of GLP-1 receptor agonists. GLP-1 receptor agonists, which induce weight loss, are associated with gastrointestinal side effects. GLP-1 receptor agonists are effective in reducing HbA1c and postprandial glucose. In patients failing to sulphonylureas and/or metformin, GLP-1 receptor agonists are similarly effective as insulin. Available data suggest that the efficacy and tolerability of the novel agent, liraglutide, which is adequate for once-a-day administration, are comparable with those of exenatide bis in die.
Human corticotropin releasing hormone test performance in the differential diagnosis between Cushing's disease and pseudo-Cushing state is enhanced by combined ACTH and cortisol analysis
Authors: Arnaldi Giorgio , Tirabassi Giacomo , Papa Roberta , Furlani Giorgio , Trementino Laura , Cardinaletti Marina , Faloia Emanuela , Boscaro Marco 
Published: March 2009

ObjectiveCorticotropin releasing hormone (CRH) test does not reliably distinguish Cushing's disease (CD) from normality or pseudo-Cushing state (PC). We assessed whether this could be achieved with a novel approach while preserving the ability of the test to distinguish CD from ectopic ACTH syndrome (EAS).DesignRetrospective/prospective study.Subjects and methodsWe studied 51 subjects with CD, 7 with EAS, 26 with PC, and 31 controls (CT). Human CRH (hCRH) test was performed at 0830 h by measuring plasma ACTH and serum cortisol at −15, 0, 15, 30, 45, 60, 90, and 120 min.ResultsThe area under the curve–ACTH exhibited a significant negative correlation with baseline serum cortisol in CT and PC, but not in CD or EAS patients. ACTH response to hCRH was blunted in PC compared with CT, whereas peak serum cortisol was higher in PC than in CT subjects. These findings suggested that ACTH-dependent Cushing's syndrome can be diagnosed by the presence of two hCRH test parameters and excluded if either or both are absent. Application of i) basal serum cortisol >12 μg/dl and peak plasma ACTH >54 pg/ml, or ii) peak serum cortisol >21 μg/dl and peak plasma ACTH >45 pg/ml, had 91.3% (95% confidence intervals (CI) 81–97.1) and 94.8% (CI 85.6–98.9) sensitivity and 98.2% (CI 90.6–99.9) and 91.2% (CI 80.7–97) specificity respectively, in diagnosing ACTH-dependent Cushing's syndrome. The >14% serum cortisol increase from mean baseline values to the mean of 15 and 30 min values in patients who were positive for the test completely discriminated between CD and EAS.ConclusionsSimultaneous plasma ACTH and serum cortisol analysis enables the hCRH test to distinguish CD from PC and from normality, while preserving its ability to discriminate CD from EAS.