bluuebunny/crossref_metadata_2025 huggingface dataset:
Substantial 13C/12C and D/H fractionation during anaerobic oxidation of methane by marine consortia enriched in vitro
Authors: Holler Thomas , Wegener Gunter , Knittel Katrin , Boetius Antje , Brunner Benjamin , Kuypers Marcel M. M. , Widdel Friedrich
Published: September 2009

The anaerobic oxidation of methane (AOM) by methanotrophic archaea and sulfate‐reducing bacteria is the major sink of methane formed in marine sediments. The study of AOM as well as of methanogenesis in different habitats is essentially connected with the in situ analysis of stable isotope (13C/12C, D/H) signatures (δ‐values). For their kinetic interpretation, experimental (cultivation‐based) isotope fractionation factors (α‐values) are richly available in the case of methanogenesis, but are scarce in the case of AOM. Here we used batch enrichment cultures with high AOM activity and without background methanogenesis from detrital remnants to determine 13C/12C and D/H fractionation factors. The enrichment cultures which originated from three marine habitats (Hydrate Ridge, NE Pacific; Amon Mud Volcano, Mediterranean Sea; NW shelf, Black Sea) were dominated by archaeal phylotypes of anaerobic methanotrophs (ANME‐2 clade). Isotope fractionation factors calculated from the isotope signatures as a function of the residual proportion of methane were 1.012–1.039 for 13CH4/12CH4 and 1.109–1.315 for CDH3/CH4. The present values from in vitro experiments were significantly higher than values previously estimated from isotope signature distributions in marine sediment porewater, in agreement with the overlap of other processes with AOM in the natural habitat.
Grazing affects methanotroph activity and diversity in an alpine meadow soil
Authors: Abell Guy C. J. , Stralis‐Pavese Nancy , Sessitsch Angela , Bodrossy Levente
Published: September 2009

The role of methane‐oxidizing bacteria (MOB) in alpine environments is poorly understood, but is of importance given the abundance of alpine environments and the role of MOB in the global carbon cycle. Using a combination of approaches we examined both seasonal and land usage effects on the ecology of microbial methane oxidation in an alpine meadow soil. Analysis of the abundance and diversity of MOB demonstrated that the abundance and diversity of the dominant type II MOB, predominantly Metylocystis and relatives, was only influenced by season. Conversely type Ia MOB abundance was significantly affected by season and land usage, while diversity changes were effected predominantly by land use. Assessment of methane oxidation potential and soil physical properties demonstrated a strong link between type Ia MOB abundance and methane oxidation potential as well as a complex series of relationships between soil moisture, pH and MOB abundance, changing with season. The results of this study suggest that, while type II MOB, unaffected by land use, represent the dominant MOB, Methylobacter‐related type Ia MOB appear to be responsible for the majority of methane oxidation and are strongly affected by the grazing of cattle.
Yield Phenomena of Post Biaxially Strained Metals
Authors: Samanta Shyam K.
Published: September 2009

In sequential of multistep forming operations, the material which has already undergone permanent deformation is expected to behave differently in each stage of deformation than the as-received material. The effect of such changes on (i) the materials ability to distribute strain uniformly, (ii) the strain limits, and (iii) the residual ductility have been studied for a mild steel and for a dual-phase steel. Steels of both materials were balanced biaxially prestrained for different levels of strains and then uniaxial properties and forming limits were determined. Both materials were found to suffer a rapid loss of uniform strain and residual ductility. Forming limits of both steels were found to decrease with prestrain except for stretch-type deformation in the sheet plane. The prestrain produces strain softening1 in mild steel; whereas, this is observed only in 90 deg to the rolling direction in dual-phase steel. In balanced biaxially prestrained (5 percent major and minor strain) dual-phase steel, during hemispherical punch stretching, necking mostly occurs in the rolling direction as opposed to the transverse direction in the as-received material. Such effect can be explained in terms of loss of stability which is observed in uniaxial property of this material.
Fatigue of Autofrettaged Thick Tubes: Closed and Open Ended; As-Received and Honed
Authors: Findley W. N. , Reed R. M.
Published: September 2009

Results of fatigue tests are presented for thick tubes of 32.3 mm (1.27 in) ID and wall ratio of 2.5 of SAE 4333 steel. Tubes having both as-received and honed bores were autofrettaged to three different degrees. Results are given for both open-ended and closed-ended autofrettage. Autofrettage increased the fatigue strength as much as 107 percent. Over autofrettage and open-ended autofrettage produced results not much different from closed-ended normal autofrettage. Under autofrettage causing half the change in diameter of normal autofrettage produced 21 percent less fatigue strength than normal autofrettage.
Fatigue of Autofrettaged Thick Tubes: Effect of Thermal Shock, Electropolishing, and Tempering
Authors: Findley W. N. , Reed R. M.
Published: September 2009

Thick tubes of 32.3 mm (1.27 in.) ID and wall ratio of 2.5 for SAE 4333 steel were subjected to fatigue testing after the following treatments: normal autofrettage followed by thermal shock; electropolishing; electropolishing then normal autofrettage; electropolishing then normal autofrettage then thermal shock; electropolishing then open-ended autofrettage; tempering from Rc 36 down to Rc 29. Results showed a thermal shock of 600°C for 3 s reduced the fatigue strength of autofrettaged specimens 6 to 8 percent. Electropolishing reduced the fatigue strength 13 percent for as-received bores and 6 percent for autofrettaged bores. Double tempering to Rc 29 reduced the fatigue strength 57 percent compared to Rc 36.
Constraint Effects on the Prediction of Fatigue Life of Surface Flaws
Authors: Jolles M.
Published: September 2009

The effects of the variation of stress field triaxiality on the prediction of the fatigue growth of semielliptic surface flaws are investigated. The concepts of crack closure are used in a fatigue growth analysis to account for constraint variation. The analysis, together with a traditional fatigue crack growth analysis which does not account for constraint variation, is used to predict flaw growth observed in experiments. Significant improvements in predicted fatigue life, as well as predicted crack shape, are obtained by accounting for the variation in constraint.
Benchmark Cyclic Plastic Notch Strain Measurements
Authors: Sharpe William N. , Ward Michael
Published: September 2009

Plastic strains at the roots of notched specimens of Inconel 718 subjected to tension-compression cycling at 650°C are reported. These strains were measured with a laser-based technique over a gage length of 0.1 mm and are intended to serve as “benchmark” data for further development of experimental, analytical, and computational approaches. The specimens were 250 mm by 2.5 mm in the test section with double notches of 4.9 mm radius subjected to axial loading sufficient to cause yielding at the notch root on the tensile portion of the first cycle. The tests were run for 1000 cycles at 10 cpm or until cracks initiated at the notch root. The experimental techniques are described, and then representative data for the various load spectra are presented. All the data for each cycle of every test are available on floppy disks from NASA.
An Evaluation of Anisotropic Effective Stress-Strain Criteria for the Biaxial Yield and Flow of 2024 Aluminum Tubes
Authors: Stout M. G. , Hecker S. S. , Bourcier R.
Published: September 2009

2024 aluminum tubes, heat treated to a T6 and T8 temper, were tested in combinations of tension-internal pressure and tension-torsion loading. Yield loci and flow behavior were determined for both modes of loading and compared to theoretical predictions. Both tempers of 2024 aluminum exhibited crystallographic textures and anisotropic yield and flow. Hill’s quadratic yield criterion and the associated flow rule under-estimate balanced biaxial yield and flow, which is consistent with hydraulic bulge data on other face-centered cubic metals. Hill’s nonquadratic criterion, which adds one additional parameter, and Bassani’s criterion, which adds two parameters, predict the anisotropic yield behavior much more accurately. Predictions of the complete flow behavior, including strain paths, with these anisotropic criteria could be improved markedly by including provisions for planar anisotropy.
An Evaluation of the Compact Shear Specimen for Mixed Mode Fracture Studies
Authors: Riddle R. A. , Streit R. D. , Finnie I.
Published: September 2009

A compact shear specimen configuration, consisting of three legs with the outer two loaded axially in a direction opposite to the inner one, has been used for several mixed-mode fracture studies. From a detailed computer analysis of this specimen, it is shown that the loading boundary conditions play an extremely important role in determining the state of stress at the crack tip. By simply changing the flexibility of the loading fixture, the specimen can be subjected to a range of mixed mode conditions from almost all Mode I to virtually pure Mode II. Data of other researchers are reviewed in light of this finding. It is shown that by applying loads obliquely to the outer legs pure Mode I loading may also be obtained with this specimen.
Punch Press Monitoring with Acoustic Emission (AE) Part I: Signal Characterization and Stock Hardness Effects
Authors: Kim B. S.
Published: September 2009

As an integral part of the punch press monitoring research program, the Acoustic Emission (AE) signal emitted from a Minster1 #3 punch press is completely characterized in terms of signal component identification, relative timing and signal amplitude of each component. The AE signal generated during punching is found to consist of three components: initial impact, shear fracture and rupture. Effects of stock hardness are then examined in terms of relative timing and amplitude of those three components. Good correlations are found between stock hardness and the corresponding AE signals (and thus AE counts).
Punch Press Monitoring with Acoustic Emission (AE) Part II: Effects of Process Variables
Authors: Kim B. S.
Published: September 2009

In a previous paper, the acoustic emission (AE) signal emitted from a Minster1 #3 punch press was completely characterized and effects of stock hardness were examined. The AE signal emitted during punching was found to consist of three components: initial impact, shear fracture and rupture. Effects of stock hardness on the AE signal were then examined in terms of relative timing and amplitude of these three components and an excellent correlation was found between AE count and stock hardness. As a continuation, effects of stock thickness, tool size and tool wear are examined in this report. Similar to the previous study, their effects are investigated qualitatively in terms of relative timing and amplitude of the AE component and quantitatively in terms of AE count. Again good correlations are found between these process variables and the AE signals.
Fracture Toughness Evaluation of the Heterogeneous Bond Region in HT80 Steel Weldments
Authors: Mutoh Y. , Toyoda M. , Satoh K. , Doi S.
Published: September 2009

Fracture toughness tests of specimens in which the crack fronts consist of the weld metal region, the HAZ, and the base metal region have been carried out. It seems that, even in the case of the specimens, the stretched zone width can be a proper parameter of fracture toughness. It is necessary to take note of the stretched zone width in the lower toughness region in estimating the macroscopic and average value of fracture toughness of the specimen. It is satisfactory to consider that the critical COD values of the specimens used here, even though the weld metal region is away from the center of thickness, are roughly equal to those of specimens of which the crack front is completely in the weld metal.
An Analytical Rolling Model Including Through Thickness Shear Stress Distributions
Authors: Lalli L. A.
Published: September 2009

An extension of the slab method of analysis as applied to rolling is presented. The von Mises yield criterion, including shear stresses, is written in terms of the frictional boundary condition at the roll-metal interface. Utilizing simplifying assumptions, an expression results which can then be combined with the equilibrium equations so that analytical expressions for roll force, torque, and extrusion ratio result. Whereas the concept is based on the same physical principles inherent in Orowan’s analysis of rolling, the slab method of analysis used here is less rigorous but has the advantage that analytic expressions are obtainable. Therefore, the equations are applicable for mill control purposes. Furthermore, the analytic expressions can be inverted so that estimates of friction and flow stress may be obtained by roll force and extrusion ratio measurements. In hot rolling, the temperature of the sheet may then be inferred from this value of flow stress, if the material’s flow stress is a known function of temperature and strain rate. Thus, this provides the capability to eventually control sheet temperatures and lubrication conditions by adjusting coolant sprays. Theoretical verification is discussed by comparison with Orowan’s theory and finite element analysis. Accuracy is discussed in terms of hot continuous mill and laboratory reversing mill data.
Predictions of the Stress Intensity Factor for an Internal Circumferential Crack at a Butt-Weld Between Cylinders Using the Plane Strain Solution
Authors: Cheng W. , Stevick G. , Finnie I.
Published: September 2009

It is assumed that the axial bending stresses which arise from this type of weld have a linear distribution. From these stresses, axisymmetric solutions in the literature enable the stress intensity factor to be calculated for an internal circumferential crack. In this paper it is shown that the same solution may be obtained from the plane strain solution for bending of a cracked beam. This approach applies to any radius to thickness ratio for thin-walled pipe while the axisymmetric solutions apply only for the specific ratios taken in the numerical solutions. Also, the present procedure allows the radial deflection and moment on the crack plane to be determined as a function of crack depth with simple calculations.
Fatigue Crack Retardation of Low Carbon Steel in Saltwater
Authors: Tokaji K. , Ando Z. , Kojima T.
Published: September 2009

The crack propagation behavior following the application of a single tensile overload in 3 percent saltwater was examined using a low carbon steel, which has a considerably lower static strength than high strength steel used in previous report. Experiments were carried out under sinusoidally varying loads at a load ratio of 0 and a frequency of 10 Hz, and the effects of saltwater were evaluated by comparing with the result in air and result on high strength steel. A single tensile overload was found to cause delayed retardation, just as it did in air. The overload affected zone size was not affected by saltwater and showed the same value in both environments. This observed trend differed from the result on high strength steel in which the overload affected zone size was larger in 3 percent saltwater than in air, and thus it was found that the effect of saltwater on retardation behavior was different even in the similar steels. Retardation cycles were smaller in 3 percent saltwater than in air. Since the overload affected zone size was not affected by saltwater, the decrease in retardation cycles was attributed to the higher rates of fatigue crack propagation in 3 percent saltwater. Thinner specimen showed stronger retardation than thicker one. The behavior at midthickness of thicker specimen showed delayed retardation as well as the result in air. Moreover, the crack propagation behavior following the application of a single tensile overload in 3 percent saltwater was well explained by the crack closure concept.
Intermediate Temperature, Low-Cycle Fatigue Behavior of Coated and Uncoated Nickel Base Superalloys in Air and Corrosive Sulfate Environments
Authors: Whitlow G. A. , Johnson R. L. , Pridemore W. H. , Allen J. M.
Published: September 2009

Low temperature hot corrosion effects on the low cycle fatigue (LCF) life and fracture morphology of a Udimet 720 alloy and the effectiveness of a protective coating in minimizing life degradation are reported. Strain controlled, continuous cycling (1 cpm) and 1 h hold (at maximum tensile strain) tests at 1350°F (732°C) in air revealed only small changes in life that could be attributed to creep during the 1 h hold. The presence of a corrosive salt environment, however, resulted in more than an order of magnitude degradation in life. In air and salt, the fracture was initially transgranular, but in salt it quickly changed to an intergranular mode, particularly at cyclic strains above 0.65 percent. These differences are attributed to reductions of 95 and 28 percent in the respective ductility and fatigue strength coefficients in the Coffin-Manson and Basquin relationships between cyclic strain and life. At cyclic strains ≤ ± 0.5 percent, a diffusion aluminide coating was protective in 1350°F (732° C) salt, with lives equivalent to those for the coated alloy in air; but at higher strains, coating failure occurred. Insignificant differences in fatigue life in air were noted for Udimet 720 and Udimet 710 alloys.
An Investigation of the Effects of Grain Size and Hardness in Temper-Embrittled 2 1/4 Cr-1 Mo Steel
Authors: McMahon C. J. , Gentner D. H. , Ucisik A. H.
Published: September 2009

Measurements of FATT as a function of hardness, grain size, and fracture surface impurity concentration were made on a 2 1/4 Cr-1 Mo steel doped with Mn + Si + P in an effort to devise an embrittlement equation relating FATT to these variables, as done previously in NiCr and NiCrMoV steels. Observations of the hardness and grain size effects on an undoped steel were also made. The effects of variations of hardness and grain size were quite irregular, especially in the doped steel, and it was therefore not possible to develop the equation. The probable reasons for the inapplicability of this approach in the 2 1/4 Cr-1 Mo type of steel are discussed.
Evaluation of a New High Strength Austenitic Alloy for Generator Retaining Rings
Authors: Ganesh S. , Viswanathan R. , Newhouse D. L.
Published: September 2009

A new high strength, nonmagnetic, iron-base alloy has been developed for large retaining ring application. This alloy is based on the development efforts recently completed in a previous collaboration between EPRI and the University of California, but takes advantage of the fact that tantalum, whose price is subject to fluctuations, can be successfully replaced partially or fully by niobium. Among the niobium modified versions evaluated, the alloy containing 1Nb + 1Ta provided the optimum combination of desired properties. This alloy, which has the approximate composition Fe-34.5Ni-5Cr-3Ti-1Nb-1Ta-0.5A1-1.0Mo-0.3V-0.01B, has demonstrated the capability to reach yield strength levels of around 200 ksi (1379 MPa), following controlled hot working, modest cold expansion and a double aging heat treatment. Compared to the currently used 18Mn-5Cr alloy, the new alloy exhibited superior stress corrosion resistance (in humid air and 3.5 percent NaCl) and comparable toughness in air and dry hydrogen. Physical properties such as density, magnetic permeability, thermal conductivity and coefficient of thermal expansion were found to be compatible with the requirements for retaining ring application. It is anticipated that successful achievement of similar properties in large-scale heats and subsequent commercialization can result in improved generator reliability, size capability and efficiency. This paper is a progress report on this development.
Corrosion Fatigue Crack Propagation Behavior of a C-Mn-Cb Steel
Authors: Wilson A. D.
Published: September 2009

The fatigue crack propagation properties of a C-Mn-Cb plate steel (SA633 Grade C) in a 3.5 percent NaCl solution have been evaluated for loading frequencies of 10, 1.0, and 0.1 Hertz. To reveal the influence of test specimen orientation and steel cleanliness, both a conventional sulfur level and a low sulfur-calcium treated plate were examined in the three major testing orientations. In addition to other basic testing of the plates, the elastic-plastic fracture toughness properties were also established. The fatigue crack growth rates at 0.1 Hz of both steels were increased by factors of 2–5 over air data, depending on the ΔK level and specimen orientation; some increase was also noted at 1.0 Hz. The acceleration due to the salt water environment was a result of a hydrogen embrittlement mechanism which resulted in bursts of faceted, cleavage-like, transgranular fracture of ferrite grains in this ferrite-pearlite steel. At higher ΔK levels, the calcium treated steel showed slower growth rates than the conventional sulfur level steel for all testing conditions. It was found that higher oxygen contents of a salt water solution could lead to corrosion product wedging at low ΔK levels, which could retard crack growth.
Seizure Mechanism in Cold Extrusion and Forging
Authors: Kawai Nozomu , Saiki Hiroyuki , Nakamura Tamotsu
Published: September 2009

To examine the seizure mechanism in cold extrusion and forging, a bifurcating extrusion type friction testing machine has been manufactured by the authors. This friction testing method was devised to simulate the frictional surface in the process accompanied with a remarkable surface expansion which influences markedly the seizure phenomena in extrusion and forging. Using a commercially pure aluminium as the workmetal, the frictional characteristics, and in particular the seizure mechanism, have been investigated under a lubricated condition with a mineral oil of higher viscosity and a dry frictional condition. Under the lubricated condition, the frictional surface was remarkably expanded more than 26 times; nevertheless no seizure was observed throughout the extruded travel. On the other hand, under the dry frictional condition, the seizure is initiated at the region where a virgin surface is exposed or the relative slip displacement exceeds a critical value. It was observed that even in the dry frictional condition, a smooth burnished metal surface could be obtained if the surface expansion ratio and the relative slip displacement are lower than a critical value.
Correction of Distortions in Dynamic Crush Test Data Due to Load Cell Inertia Effects
Authors: Thornton P. H.
Published: September 2009

The application of deconvolution techniques to the results obtained in the dynamic collapse of tubes in axial compression is described. It is shown that low pass filtering techniques are not adequate to obtain complete information on the crush characteristics. Data distortion caused by load cell resonance can be corrected by deconvolution provided that a notch filter is used to reduce the amplitude of the resonance response prior to deconvolution.
The Effects of Material Strength, Stress Ratio, and Compressive Overload on the Threshold Behavior of a SAE1045 Steel
Authors: Yu M. T. , Topper T. H.
Published: September 2009

The fatigue crack growth rate behavior of a SAE1045 steel in the as received condition and four different quenched and tempered conditions was studied as a function of stress ratio and peak compressive overload. The threshold stress intensity behavior of the quenched and tempered conditions was not sensitive to changes of monotonic mechanical properties. The threshold decreased linearly with increasing positive stress ratio and compressive peak load level. As received ferritic-pearlitic SAE1045 steel was much more sensitive to stress ratio and compressive peak load than any of the quenched and tempered conditions studied.
A Constitutive Model of Creep Describing Creep Recovery and Material Softening Caused by Stress Reversals
Authors: Ohno N. , Murakami S. , Ueno T.
Published: September 2009

The constitutive model of creep proposed by the present authors on the basis of a creep-hardening surface in creep strain space (CHS model) is first modified to incorporate creep recovery. It is assumed that total creep strain can be divided into two parts; i.e., a part which recovers anelastically after stress removal and an irrecoverable part. These two parts are described by McVetty’s equation and the CHS model, respectively. Then, the validities of the modified and the original CHS model are discussed by performing creep tests of type 304 stainless steel under cyclic reversed torsion combined with constant tension at 600°C.
A Continuous Damage Mechanics Model for Ductile Fracture
Authors: Lemaitre Jean
Published: September 2009

A model of isotropic ductile plastic damage based on a continuum damage variable, on the effective stress concept and on thermodynamics is derived. The damage is linear with equivalent strain and shows a large influence of triaxiality by means of a damage equivalent stress. Identification for several metals is made by means of elasticity modulus change induced by damage. A comparison with the McClintock and Rice-Tracey models and with some experiments is presented for the influence of triaxiality on the strain to rupture.
Effect of Tensile-Mean-Strain on Plastic Strain Energy and Cyclic Response
Authors: Ellyin F.
Published: September 2009

Tests have been conducted to determine the effect of tensile-mean-strain on cyclic properties, low cycle fatigue, and total absorbed plastic strain energy to failure of ASTM A-516 Grade 70 carbon low alloy steel. Stable hysteresis loops at half-life are presented for different strain controlled tests. The cyclic properties were determined by a least squares fit technique. The results of tensile-mean-strain are compared with fully-reversed fatigue tests. The absorbed plastic strain energy per cycle was measured and compared with a proposed relationship for non-Masing material behavior. A relationship of the form Wf=KNfα is found to be a good representation of the data. It is observed that the material tends toward a steady-state condition independent of the level of the mean strain provided the fatigue life is greater than one thousand cycles.
Biaxial Strength of HY 80 Steel
Authors: Chan K. S. , Lindholm U. S. , Wise J.
Published: September 2009

The biaxial deformation behavior of HY 80 steel has been examined by testing thin wall tubes under combined axial tension and internal pressure. The effective stress-strain curves and the hardening response have been found to vary with the stress state. The plastic strain ratio at a given stress ratio deviates from the von Mises value except at the stress states near uniaxial tension, plane strain and equi-biaxial tension. Using Drucker theory, these deviations are eliminated and the resulting yield locus is in good agreement with both the Bishop-Hill theory and the experimental results. Influenced by the tube geometry, the instability strains at the onset of diffuse necking are decreased by an increase in hoop tension. The diffuse necking strains are reasonably predicted by the Swift and the Lankford-Saibel/Mellor criteria.
Barreling of Solid Cylinders Under Axial Compression
Authors: Banerjee J. K.
Published: September 2009

Axisymmetric compression tests of solid aluminum cylinders, over a wide range of “aspect ratios” (length/diameter) and both under dry as well as lubricated conditions, suggest that the resulting curvature of the “barrel” formed fits closely a circular arc and its radius follows a power law with the true axial compressive stress. The true compressive stress-strain curve, extrapolated from the experimental data in each test, shows that within the variety of lubricants used the Specific Forming Energy is minimum with teflon sheets as dry lubricant, and increases successively with silicon spray, motor oil, and dry friction.
A Computational Temperature Analysis for Induction Heating of Welded Pipes
Authors: Koch R. L. , Rybicki E. F. , Strattan R. D.
Published: September 2009

Recent approaches to controlling stress corrosion cracking in welded 304 stainless steel pipes have been based on various types of controlled heating procedures. When applied properly, the heating procedure introduces high compressive stresses in region of observed cracking. The compressive stresses are believed to be effective in deterring stress corrosion cracking. One procedure for applying controlled heating to the pipe employs induction heating and is called Induction Heating for Stress Improvement or IHSI. The effective utilization of induction heating requires an understanding of how the induction heating parameters are related to the resulting residual stresses. This paper describes the development of a computational model directed at evaluating the heat densities and temperature distributions for Induction Heating for Stress Improvement (IHSI). The basic mechanism of inducting differs from that of a welding arc in that induction heating produces a distribution of heat sources within the pipe wall while in weld arc heating, the heat source is confined to the surface. Thus the computational model requires two parts. The first part evaluates the induced electrical current and determines the density of heat sources in the pipe wall. The second part of the model uses these heating densities to evaluate the temperature distribution. Temperature dependent properties were found to be important in representing the induction heating phenomenon. However, including temperature dependent properties in the model leads to nonlinear equations which require iterative solution methods for each part of the model. The nonlinear characteristics of the equations also require iterations between the two parts of the model. The model includes the important parameters of the induction heating process and has shown good agreement with temperature data for two different pipe sizes. Because of the inherent nonlinearities in the model and the iterative methods required for general solutions, extensions of the model to improve the algorithimic efficiency are discussed.
Crack Growth and Instable Fracture of Rotating Disks
Authors: Sakata M. , Aoki S. , Kishimoto K. , Kanzawa M. , Ogure N.
Published: September 2009

The fracture of rotating disks that have cracks and/or notches is predicted employing the crack instability criterion based on the J-integral R-curve approach characterizing a material resistance to fracture. The J-integrals of cracked rotating disks are calculated by an elastic-plastic finite element method taking account of the thickness effects. Spin tests were carried out on disks having fatigue cracks and/or notches and the crack extensions as well as the bursting speeds of the disk specimens were measured. It is shown that the predicted values of bursting speed are in good agreement with those obtained by the experiment.
A Method for Measurement of Axisymmetric Axial Residual Stresses in Circumferentially Welded Thin-Walled Cylinders
Authors: Cheng Weili , Finnie Iain
Published: September 2009

A new method is proposed for measuring the axial component of an axisymmetric residual stress field in thin-walled cylinders. The specific application considered is determination of the stress at the centerline of a circumferential weld. The method involves strain measurements at the outside wall while a complete circumferential slit is cut to increasing depths from the inside wall. The technique is applied to the simple case of a single pass weld. Experimental results are in good agreement with predicted values.
Constraint Effect in Thermo-Mechanical Fatigue
Authors: Sehitoglu Huseyin
Published: September 2009

Many structural members in service experience fluctuating loads and temperatures. Thermal stresses devlop on a contrained element if the temperature is cycled. Constraint exists in structural components due to temperature gradient, material anisotropy, and geometry effects. The equilibrium and compatibility equations determine the degree of constraint on the critcal component of the body. A two-bar structure is employed in this study to simulate different constraint conditions encountered in practice. The constraint types are termed (a) total, (b) partial, (c) over, and (d) notch constraint. Thermo-mechanical fatigue test results indicate that the fatigue lives decrease severely with increasing constraint, increasing temperature range and with the presence of notch or a defect.
Elastic-Plastic Fracture Mechanics Analysis on Environmentally Accelerated Cracking of Stainless Steel in High Temperature Water
Authors: Kawakubo T. , Hishida M.
Published: September 2009

Stress corrosion crack growth during slow strain rate testing was investigated using elastic-plastic fracture mechanics. Thin compact and center-notched specimens of sensitized Type 304 stainless steel were examined at different extension rates in high temperature oxygenated water. The analytical results showed that the crack growth rate has a best correlation with a time differential of the J-integral, which is an estimate of a crack tip deformation rate. Based on the analysis, a new mechanistic model under both monotonic and cyclic loadings was suggested, where cracking was classified into three categories depending on the environmental acceleration, i.e., mechanical cracking, corrosion enhanced mechanical cracking, and stress corrosion cracking.
Cyclic Crack Growth Behavior of Reactor Pressure Vessel Steels in Light Water Reactor Environments
Authors: Van Der Sluys W. A. , Emanuelson R. H.
Published: September 2009

During normal operation light water reactor (LWR) pressure vessels are subjected to a variety of transients resulting in time varying stresses. Consequently, fatigue and environmentally assisted fatigue are growth mechanisms relevant to flaws in these pressure vessels. In order to provide a better understanding of the resistance of nuclear pressure vessel steels to flaw growth process, a series of fracture mechanics experiments were conducted to generate data on the rate of cyclic crack growth in SA508-2 and SA533B-1 steels in simulated 550°F Boiling Water Reactor (BWR) and 550°F Pressurized Water Reactor (PWR) environments. Areas investigated over the course of the test program included the effects of loading frequency and R ratio (Kmin/Kmax) on crack growth rate as a function of the stress intensity factor (ΔK) range. In addition, the effect of sulfur content of the test material on the cyclic crack growth rate was studied. Cyclic crack growth rates were found to be controlled by ΔK, R ratio, and loading frequency. The sulfur impurity content of the reactor pressure vessel steels studied had a significant effect on the cyclic crack growth rates. The Higher growth rates were always associated with materials of higher sulfur content. For a given level of sulfur, growth rates were higher in a 550°F simulated BWR environment than in a 550°F simulated PWR environment. In both environments cyclic crack growth rates were a strong function of the loading frequency. Further, the loading frequency at which the highest cyclic crack growth rate was observed was found to be a function of the applied ΔK level. In most cases, all cyclic crack growth rates were on or under the ASME Section XI high R water reference flaw growth line and above the Section XI air reference flaw growth line, supporting the position of these lines on the growth rate–ΔK level graph.
A Comparison of Hydrogen and Mercury Embrittlement in Monel at Room Temperature
Authors: Traylor L. B. , Price C. E.
Published: September 2009

Slow strain rate tensile tests were performed on annealed and cold drawn Monel 400 and Monel R405 at room temperature in air, mercury, and electrolyte hydrogen. Hydrogen and mercury caused embrittlement with the fractures having the same specific features. Crack initiation was largely intergranular but an increasing proportion of transgranular cracking occurred subsequently, especially in the presence of hydrogen and for Monel R405. It is believed that the decreased cohesive strength and enhanced shear models of embrittlement apply to the intergranular and transgranular crack modes respectively.
Crack Growth Behavior of Aluminum Alloys Tested in Liquid Mercury
Authors: Kapp J. A. , Duquette D. , Kamdar M. H.
Published: September 2009

Crack growth rate measurements have been made in three mercury embrittled aluminum alloys each under three loading conditions. The alloys were 1100-0, 6061-T651, and 7075-T651. The loading conditions were fixed displacement static loading, fixed load static loading, and fatigue loading at two frequencies. The results showed that mercury cracking of aluminum was not unlike other types of embrittlement (i.e. hydrogen cracking of steels). Under fixed load static conditions no crack growth was observed below a threshold stress intensity factor (KILME). At K levels greater than KILME cracks grew on the order of cm/s, while under fixed displacement loading, the crack growth rate was strongly dependent upon the strength of the alloy tested. This was attributed to crack closure. In the fatigue tests, no enhanced crack growth occurred until a critical range of stress intensity factor (ΔKth) was achieved. The ΔKth agreed well with the KILME obtained from the static tests, but the magnitude of the fatigue growth rate was substantially less than was expected based on the static loading results. Observations of the fracture surfaces in the SEM suggested a brittle intergranular fracture mode for the 6061-T651 and the 7075-T651 alloys under all loading conditions. The fractographic features of the 1100-0 alloy under fixed load and fatigue loading conditions were also brittle intergranular. Under fixed displacement loading the cracks grew via a ductile intergranular mode.
Evaluation of Crack Growth in Oxygenated High Temperature Water Using Full Size Pipe Tests
Authors: Horn R. M.
Published: September 2009

Full Size pipe tests have been conducted as part of EPRI research programs at the General Electric Company to verify IGSCC crack growth predictions made using a linear elastic fracture mechanics model. The tests on 10.16 cm (4″ pipes) were performed in oxygenated, high temperature, high purity water. The pipes were produced through standard manufacturing procedures which in turn led to characteristic field piping sensitization levels in the heat affected zones (HAZ) and characteristic through wall weld residual stresses. The tests were conducted at stresses equal to or below the yield strength under constant load with limited cycling. Ultrasonic inspection and metallography were used to characterize crack depth after several test phases and used to verify model predictions. Significant cracks were detected and radial and circumferential growth were documented. These test results support the predictions made using linear elastic fracture mechanics modeling, and are discussed in terms of crack growth data developed in CT specimens in the laboratory. The stress level and oxygen level are shown to influence the crack growth rates. Rates of circumferential crack growth are also evaluated. The paper discusses the results in the context of other stress corrosion evaluations as well.
Prevention of Fracture of Cracked Steel Bars Using Laser: Part II—Laser Welding
Authors: Kato Akira
Published: September 2009

This paper investigates the effect of laser welding on the prevention of fracture of cracked steel specimens. Precracks occurred in shaft specimens of SAE 1015 were welded by a CO2 laser, and then the rotary bending fatigue and static tensile tests were executed. Both strengths of fatigue and tensile of specimens having a diameter 11mm with a fairly large precrack 13mm long could be raised up to that of virgin specimens. It was shown that laser welding is very effective for the fracture prevention of cracked steel shafts.
Phosphorylation of Nogo Receptors Suppresses Nogo Signaling, Allowing Neurite Regeneration
Authors: Takei Yoshinori
Published: September 2009

Extracellular phosphorylation of Nogo receptors by casein kinase II blocks agonist binding.
Mechanical Signals Trigger Myosin II Redistribution and Mesoderm Invagination in
Drosophila
Embryos
Authors: Pouille Philippe-Alexandre , Ahmadi Padra , Brunet Anne-Christine , Farge Emmanuel
Published: September 2009

Mesoderm invagination during gastrulation is controlled by mechanical cues that promote Fog signaling and redistribution of a motor protein.
Neurotransmitters Drive Combinatorial Multistate Postsynaptic Density Networks
Authors: Coba Marcelo P. , Pocklington Andrew J. , Collins Mark O. , Kopanitsa Maksym V. , Uren Rachel T. , Swamy Sajani , Croning Mike D. R. , Choudhary Jyoti S. , Grant Seth G. N.
Published: September 2009

Analysis of protein phosphorylation patterns provides insight into the organization of molecular networks at the postsynaptic density.
Control of Neuronal Growth Cone Navigation by Asymmetric Inositol 1,4,5-Trisphosphate Signals
Authors: Akiyama Hiroki , Matsu-ura Toru , Mikoshiba Katsuhiko , Kamiguchi Hiroyuki
Published: September 2009

Measurements of its spatial profile reveal the crucial role of asymmetric IP3signals in growth cone navigation.
MSK2 Inhibits p53 Activity in the Absence of Stress
Authors: Llanos Susana , Cuadrado Ana , Serrano Manuel
Published: September 2009

The kinase MSK2 inhibits p53 transcriptional activity at a subset of promoters through a kinase-independent mechanism.
Bruton’s Tyrosine Kinase Revealed as a Negative Regulator of Wnt–β-Catenin Signaling
Authors: James Richard G. , Biechele Travis L. , Conrad William H. , Camp Nathan D. , Fass Daniel M. , Major Michael B. , Sommer Karen , Yi XianHua , Roberts Brian S. , Cleary Michele A. , Arthur William T. , MacCoss Michael , Rawlings David J. , Haggarty Stephen J. , Moon Randall T.
Published: September 2009

Combining an siRNA screen with a small-molecule screen reveals BTK as a nuclear inhibitor of the Wnt–β-catenin pathway.
PI3Kγ Adaptor Subunits Define Coupling to Degranulation and Cell Motility by Distinct PtdIns(3,4,5)P
3
Pools in Mast Cells
Authors: Bohnacker Thomas , Marone Romina , Collmann Emilie , Calvez Ronan , Hirsch Emilio , Wymann Matthias P.
Published: September 2009

Specific adaptor subunits, p84 or p101, of phosphoinositide 3-kinase γ dictate different cellular responses.
The VDAC2-BAK Rheostat Controls Thymocyte Survival
Authors: Ren Decheng , Kim Hyungjin , Tu Ho-Chou , Westergard Todd D. , Fisher Jill K. , Rubens Jeff A. , Korsmeyer Stanley J. , Hsieh James J.-D. , Cheng Emily H.-Y.
Published: September 2009

The relative abundance of an anion channel and a proapoptotic protein determines thymocyte responses to death signals.
Differential Interactions of FGFs with Heparan Sulfate Control Gradient Formation and Branching Morphogenesis
Authors: Makarenkova Helen P. , Hoffman Matthew P. , Beenken Andrew , Eliseenkova Anna V. , Meech Robyn , Tsau Cindy , Patel Vaishali N. , Lang Richard A. , Mohammadi Moosa
Published: September 2009

Manipulation of the interaction of a morphogen with the extracellular matrix changes its biological activities by altering its diffusion.
Inhibition of mTOR Signaling in Parkinson’s Disease Prevents
l
-DOPA–Induced Dyskinesia
Authors: Santini Emanuela , Heiman Myriam , Greengard Paul , Valjent Emmanuel , Fisone Gilberto
Published: September 2009

Dyskinetic side effects of a Parkinson’s disease medication may involve dopamine D1 receptor–mediated activation of mTORC1.
The Akt1-eNOS Axis Illustrates the Specificity of Kinase-Substrate Relationships in Vivo
Authors: Schleicher Michael , Yu Jun , Murata Takahisa , Derakhshan Berhad , Atochin Dimitriy , Qian Li , Kashiwagi Satoshi , Di Lorenzo Annarita , Harrison Kenneth D. , Huang Paul L. , Sessa William C.
Published: September 2009

Akt mediates postnatal angiogenesis through eNOS signaling.
Integrating Proteomic, Transcriptional, and Interactome Data Reveals Hidden Components of Signaling and Regulatory Networks
Authors: Huang Shao-shan Carol , Fraenkel Ernest
Published: September 2009

Analysis of multiple “omic” data sets with a prize-collecting Steiner tree algorithm reveals components of signaling networks that are not obvious by analyzing the data individually.
Tks5-Dependent, Nox-Mediated Generation of Reactive Oxygen Species Is Necessary for Invadopodia Formation
Authors: Diaz Begoña , Shani Gidon , Pass Ian , Anderson Diana , Quintavalle Manuela , Courtneidge Sara A.
Published: September 2009

Localized production of reactive oxygen species is key for cellular invasiveness and may be involved in a positive feedback loop with proteins that organize their site of production.
The Plant NADPH Oxidase RBOHD Mediates Rapid Systemic Signaling in Response to Diverse Stimuli
Authors: Miller Gad , Schlauch Karen , Tam Rachel , Cortes Diego , Torres Miguel A. , Shulaev Vladimir , Dangl Jeffery L. , Mittler Ron
Published: September 2009

Reactive oxygen species produced by RBOHD mediate rapid, long-distance stress signals in plants.
The Single Transmembrane Domains of Human Receptor Tyrosine Kinases Encode Self-Interactions
Authors: Finger Carmen , Escher Claudia , Schneider Dirk
Published: September 2009

The transmembrane domain of any of the 58 human receptor tyrosine kinases is sufficient to mediate dimerization.
An Al-LURE-ing Guidance System
Authors: Wong Wei
Published: September 2009

Chemoattractants that help guide growing pollen tubes in
Torenia fournieri
have been identified.
DBLing Your Defenses
Authors: Adler Elizabeth M.
Published: September 2009

A neuronal signal involving a noncanonical TGF-β signaling pathway induces the expression of genes encoding antifungal caenacin-family peptides.
Two-in-One Antibody
Authors: Kiberstis Paula A.
Published: September 2009

The antigen binding site of a therapeutic antibody for cancer simultaneously binds two proteins required for tumor growth.
Signal Transduction—Receptors, Mediators, and GenesA report on the 12th Joint Meeting of the Signal Transduction Society, Weimar, Germany, 28 to 31 October 2008.
Authors: Entschladen Frank , Lindquist Jonathan A. , Serfling Edgar , Thiel Gerald , Kieser Arnd , Giehl Klaudia , Ehrhardt Christina , Feller Stephan M. , Ullrich Oliver , Schaper Fred , Janssen Ottmar , Hass Ralf , Friedrich Karlheinz
Published: September 2009

Cell signaling researchers gathered in Weimar, Germany, for the annual meeting of the Signal Transduction Society.
Amyloid Goes Global
Authors: Bezprozvanny Ilya
Published: September 2009

Amyloid plaques have farther-reaching effects on astrocytes than previously suspected.
Early Events of B Cell Activation by AntigenA presentation from the 12th Joint Meeting of the Signal Transduction Society, Weimar, Germany, 29 to 31 October 2008.
Authors: Depoil David , Weber Michele , Treanor Bebhinn , Fleire Sebastian J. , Carrasco Yolanda R. , Harwood Naomi E. , Batista Facundo D.
Published: September 2009

B cells undergo membrane spreading and contraction during activation in response to antigen-presenting cells.
Brains Over Brawn
Authors: Wong Wei
Published: September 2009

A single amino acid difference accounts for the greater affinity of nicotine for the brain acetylcholine receptor compared to the muscle subtype.
Bringing Src to the Phosphatase
Authors: Gough Nancy R.
Published: September 2009

The protein RIL, which is epigenetically silenced in some cancers, serves as an adaptor to bring active Src to the phosphatase PTPL1.
Why We Need Quantitative Dynamic Models
Authors: Iyengar Ravi
Published: September 2009

Quantitative models provide insight into the mechanisms of cellular behavior and should enable personalized disease intervention.
Syndecans Shed Their Reputation as Inert Molecules
Authors: Bass Mark D. , Morgan Mark R. , Humphries Martin J.
Published: September 2009

The shedding of the extracellular domain of a transmembrane proteoglycan can be controlled by its cytoplasmic domain.
Feminizing Liver Metabolism
Authors: Gough Nancy R.
Published: September 2009

In the absence of cryptochrome function, the expression of genes encoding drug metabolism enzymes in male mice becomes like the expression in female mice.