bluuebunny/crossref_metadata_2025_split huggingface dataset:
Über den Einfluß von Eigenspannungen, Nahtgeometrie und mehrachsigen Spannungszuständen auf die Betriebsfestigkeit geschweißter Konstruktionen aus Baustählen
Authors: Sonsino C. M. 
Published: December 2004

AbstractFür eine betriebsfeste Bemessung von geschweißten Konstruktionen sind u.a. Einflüsse aus Eigenspannungen, Nahtgeometrien und mehrachsigen Spannungszuständen auf die Lebensdauer zu berücksichtigen. Erkenntnisse zum Einfluß von Eigenspannungen im Bereich der Dauerfestigkeit lassen sich, je nach von der Nahtgeometrie abhängigen Spannungskonzentration und Spannungsabbau, nicht unbedingt auf den Bereich der Zeitfestigkeit oder auf zeitlich veränderliche Belastungen mit die Dauerfestigkeit zum Teil überschreitenden Anteilen übertragen. Eine Verbesserung rung der Nahtgeometrie, z. B durch die WIG‐Behandlung, führt grundsätzlich zu einem besseren Schwingfestigkeitsverhalten, wenn Nahtübergangsradien ausreichend groß sind. Im Hinblick auf eine Übertragbarkeit von mit Proben gewonnenen Ergebnissen auf große Bauteile müssen Kriterien wie Strukturspannung oder örtliche Vergleichsspannung, Anriß und der Größeneinfluß beachtet werden. Für eine Schadensakkumulationsberechnung wird als Schadenssumme D = 0,5 empfohlen. Bezüglich einer Bewertung von mehrachsigen Spannungszuständen kann beim Vorliegen von konstanten Hauptspannungsrichtungen die Gestaltänderungsenergiehypothese sowohl auf der Basis von Struktur‐ als auch örtlichen Spannungen befriedigend angewendet werden. Falls jedoch Veränderungen von Hauptspannungsrichtungen, z. B. infolge einer Phasenverschiebung zwischen Normal‐ und Schubspannungen auftreten, versagen alle bekannten Hypothesen durch eine hohe Überschätzung der Lebensdauer. Für solche Fälle ist gegenwärtig ein experimenteller Betriebsfestigkeitsnachweis zu empfehlen.
Rechnerische Beschreibung des Kriechverhaltens ausgewählter hochwarmfester Legierungen. Teil 1: Kriechgleichungen Für einzelne Versuchswerkstoffe
Authors: Kloss K. H. , Granacher J. , Pfenning A. 
Published: December 2004

AbstractFür hochwarmfeste Werkstoffe werden Gleichungen vorgestellt, die auf den Ergebnissen von Warmzug‐, Zeitstand‐ und Glühversuchen an einzelnen Versuchswerkstoffen beruhen und die elastoplastische Verformung, das Kriechen und die Kontraktion dieser Werkstoffe im gesamten, anwendungsrelevanten Temperatur‐, Spannungs‐ und Zeitbereich beschreiben.
Rechnerische Beschreibung des Kriechverhaltens ausgewählter hochwarmfester Legierungen Teil 2: Kriechgleichung Für die Werkstoffsorte IN‐939
Authors: Kloss K. H. , Granacher J. , Pfenning A. 
Published: December 2004

AbstractZur Aufstellung einer Kriechgleichung der Werkstoffsorte IN‐939 werden aus einer umfangreichen Kriechdatensammlung mittlere Zeitdehngrenzkurven und Zeitbruchkurven gebildet und hieraus mittlere Kriechkurven abgeleitet. Auf deren Basis wird eine bereits für einen Einzelwerkstoff erstellte Kriechgleichung an das durchschnittliche Kriechverhalten der Werkstoffsorte im gesamten anwendungsrelevanten Bereich angepaßt.
Study on numerical approaches for the evaluation of J‐Integral Results in 3D problems
Authors: Grebner H. 
Published: December 2004

AbstractFor numerical analyses of fracture mechanics problems often a combination of the finite element method with a post processor program for the evaluation of J‐integral values is used. Instead of calculating a line integral as originally proposed by RICE it is reasonable to evaluate surface or volume integrals (for two or three dimensional calculations, respectively) in this case.In this paper 3D‐formulations proposed by DE LORENZI and ATLURI are considered and several possibilities of the numerical realisation of these formulations are described. While the De Lorenzi proposal is contained as subroutines in the GRS‐version of the standard finite element program ADINA, the Atluri formulation is used in separate post‐processing programs developed by GRS.As a first application three‐dimensional calculations of a compact‐tension‐shear specimen are considered.
Mathematical Model for high temperature properties of cast nickel superalloys with high content of gamma prime phase
Authors: Efimov A. 
Published: December 2004

AbstractThis investigation relates to structural cast superalloys with improved oxidation resistance in the temperature range of 1100–1200°C. It was tried to clarify the role of heavy metal elements on mechanical properties of an alloy in the system Ni‐17at% Al‐3at% Cr‐Mo‐Ta‐W. Solidus temperature, yield strength at 20°C, ultimate tensile strength at 1200°C of polycrystal alloys and creep‐rupture life at 1000°C and 1200°C of single crystals <001> were investigated by means of experimental design and regression analysis techniques, It was determined that solidus temperature do not depend from W content, yield strength at 20°C and ultimate tensile strength at 1200°C strongly depend on Ta and W contents. The properties sharply increase with simultaneous adding of Ta+W. At 1200°C Mo content is a critical factor. The influence of alloying with Ta and W on the creep resistance of single crystals was examined. With increase of test temperature dependence of creep resistance from refractory additives appears to increase, but interval of an optimum alloying narrows.
Barkhauseneigenspannungsmessungen an einem schadhaften Hydraulikzylinder mit tribotechnischer Funktionsschicht
Authors: Richter H. 
Published: December 2004

AbstractVon der Zylinderinnenfläche eines Flugzeug‐Hydraulikzylinders war ein Schwingbruch ausgegangen und hatte zu einer Leckage geführt. Hauptursache für den Schwingbruch waren Anrisse, die bei der Endbearbitung der Zylinderinnenfläche zusammen mit Zugeigenspannungen in örtlich begrenzten Bereichen der Randschicht des Grundmaterials erzeugt worden waren. Mittels Barkhausenrauschanalyse ließen sich Eigenspannungsunterschiede an der Zylinderinnenfläche messen, ohne daß die dort aufgebrachte tribotechnische Funktionsschicht aus Chrom entfernt werden mußte. Die Ergebnisse der Barkhausenspannungsmessungen wurden durch stichprobenartige röntgenografische Eigenspannungsmessungen bestätigt.
Bewertung zyklischer Verformungsvorgänge metallischer Werkstoffe mit Hilfe mechanischer, thermometrischer und elektrischer meßverfahren Characterization of cyclic deformation behaviour by mechanical, thermometrical and electrical methods
Authors: Eifler D. , Piotrowski A. 
Published: December 2004

AbstractZyklische Verformungsvorgänge verursachen mikrostrukturelle Werkstoffveränderungen, die zum Versagen führen können. Am Beispiel normalisierter und vergüteter Stähle sowie verschiedener Sinterstähle wird gezeigt, wie mechanische, thermometrische und elektrische Meßverfahren genutzt werden können, das zyklische Verformungsverhalten umfassend zu bewerten.
Numerisch ermittelter Parameter C* zur Beschreibung des Kriechrißverhaltens
Authors: Granacher J. , Tscheuschner R. , Mao T. S. , Maile K. , Bareiß J. 
Published: December 2004

AbstractIn früheren Untersuchungen gewonnene umfangreiche Kriechrißergebnisse an drei warmfesten Stählen werden mit einem Parameter C* beschrieben, der aufgrund inelastischer Finit‐Element‐Analysen berechnet wird. Die Streubänder der Kriechrißeinleitungsdauer und der Kriechrißgeschwindigkeit werden für diesen Parameter ermittelt. Außerdem werden Anwendungsgesichtspunkte zur Bauteilberechnung aufgeführt.
Mikrostrukturelle, mechanische und korrosive Eigenschaften reibrührgeschweißter Stumpfnähte in Aluminiumlegierungen
Authors: Donne C. Dalle , Braun R. , Staniek G. , Jung A. , Kaysser W. A. 
Published: December 2004

AbstractDas Reibrührschweißen (friction stir welding FSW) ist ein neues Fügeverfahren, mit dem auch die schwer schmelzschweißbaren, höherfesten Aluminiumlegierungen ohne große Festigkeitsverluste verschweißt werden können. Erste Ergebnisse von Untersuchungen an selbst hergestellten FSW‐Stumpfnähten der Aluminiumlegierungen 2024–T3 und 6013‐T4 werden vorgestellt. Zunächst wird das Gefüge der Naht und der Wärmeeinflußzone mikrostrukturell und durch Härteverläufe charakterisiert. Weiterhin wird mit Zug‐, Schwingfestigkeits‐ und Rißfortschrittsversuchen nachgewiesen, daß insbesondere die FSW‐Nähte der Legierung 2024‐T3 außerordentlich hohe mechanische Belastungen ertragen. Abschließende Korrosionsuntersuchungen der FSW‐Nähte zeigen eine gewisse Anfälligkeit der abschreckempfindlichen Legierung 2024‐T3 für interkristalline Korrosion und Schichtkorrosion.
Versagen von Keramik im Hochtemperaturbereich
Authors: Fett T. , Munz D. 
Published: December 2004

AbstractDas Versagensverhalten keramischer Werkstoffe im Hochtemperaturbereich ist sehr komplex. Neben den schon bei Raumtemperatur wirksamen Effekten der unterkritischen Rißausbreitung und der zyklischen Ermüdung müssen noch die Effekte des Kriechens an sich sowie die Materialschädigungen beim Kriechbruch und beim Kriechrißwachstum berücksichtigt werden. Der größte Teil der Arbeit ist der Beschreibung des unterkritischen Rißwachstums und des Kriechrißwachstums gewidmet. Einer der Schwerpunkte liegt dabei auf der Beschreibung und Anwendung des C*‐Konzepts.
Allurin, a 21 kD sperm chemoattractant, is rapidly released from the outermost jelly layer of the Xenopus egg by diffusion and medium convection
Authors: Xiang Xueyu , Kittelson Andrew , Olson John , Bieber Allan , Chandler Douglas 
Published: December 2004

AbstractAllurin, a 21 kD protein from Xenopus laevis egg jelly, has been demonstrated to attract sperm by video microscopy and by quantitative chemotaxis chamber assays. Here, we use immunocytochemistry to demonstrate that this sperm chemoattractant is located in the outermost layer of egg jelly (J3) and is rapidly released into the surrounding medium. SDS–PAGE analysis and Western blotting confirm the appearance of allurin in the medium within 1.5 min and separation of proteins in the medium by anion exchange FPLC, shows that nearly half of the allurin released over a 12‐hr period is discharged in the first 5 min. The kinetics of allurin release from J3 and its appearance in the medium were quantitatively accounted for, by computer simulation of mathematical diffusion and convection models. Comparison of simulation data to quantitative measurements of allurin appearance in the medium suggests that allurin, although larger than most chemoattractants, is effectively dispersed by a combination of diffusion and medium mixing at the jelly surface during spawning. Our model further predicts that the innermost jelly layer, J1, is less permeable to allurin than the other layers, allowing it to act as a “reflector” to speed up allurin discharge. Mol. Reprod. Dev. 70: 344–360, 2005. © 2005 Wiley‐Liss, Inc.
Identification of maternal mRNAs in porcine parthenotes at the 2‐cell stage: A comparison with the blastocyst stage
Authors: Hwang Kyu‐Chan , Lee Hwa‐Young , Cui Xiang‐Shun , Kim Jin‐Hoi , Kim Nam Hyung 
Published: December 2004

AbstractSuccessful embryonic development is dependent on the temporal and stage‐specific expression of appropriate genes. Currently, information on specific gene expression during early cleavage‐stage embryos before zygotic gene activation (ZGA) is limited. In the present study, we compare gene expression between porcine 2‐cell and blastocyst stage parthenotes to identify genes that are specifically or predominantly expressed by employing annealing control primer (ACP)‐based GeneFishing PCR. Using 60 ACPs, we identified and sequenced nine differentially expressed genes (DEGs). A BLAST search revealed that cloned genes or ESTs (GDI‐2, MTMR3, MKLN1, NUP88, ePAD, CIRHIM, UPF3B, ITGA2, and CGI‐140) had significant sequence similarities with known genes (78–95%) of other species in the GenBank/EMBL database. Real‐time reverse transcriptase‐polymerase chain reaction (RT‐PCR) data disclosed that these genes were regulated upstream in metaphase II (MII) oocyte, 1‐cell, and 2‐cell stage embryos during early pre‐implantation. Similarly, upregulation was observed in MII mouse oocytes and 1‐cell stage embryos before ZGA, suggesting that these nine differentially expressed orthologous genes play important roles during early cleavage before ZGA. Further analysis of the differentially expressed genes identified in this report should provide the basis for research on early cleavage and activation of the embryonic genome. Mol. Reprod. Dev. 70: 314–323, 2005. © 2005 Wiley‐Liss, Inc.
Expression of fibroblast growth factor‐8 and its cognate receptors, fibroblast growth factor receptor (FGFR)‐3c and‐4, in fetal bovine preantral follicles
Authors: Buratini J. , Glapinski V.F. , Giometti I.C. , Teixeira A.B. , Costa I.B. , Avellar M.C.W. , Barros C.M. , Price C.A. 
Published: December 2004

AbstractParacrine cell signaling is thought to be important for ovarian follicle development, and a role for some members of the fibroblast growth factor (FGF) family have been suggested. In the present study, we tested the hypothesis that FGF‐8 and its cognate receptors (FGFR‐3c and FGFR‐4) are expressed in bovine preantral follicles. Reverse transcription‐polymerase chain reaction was used to amplify bovine FGF‐8, FGFR‐3c, and FGFR‐4 from preantral follicle samples and a variety of fetal and adult tissues. All three genes were widely expressed in fetal tissues, with a restricted expression pattern in adult tissues. FGF‐8 and FGFR‐3c were expressed in secondary follicles in 70% of fetuses examined, whereas FGFR‐4 expression was significantly less frequent (20%). FGFR‐3c expression frequency was significantly lower in primordial compared to secondary follicles, and FGF‐8 expression showed a similar trend. FGFR‐4 was only observed when all follicle classes of an individual were expressing both FGF‐8 and FGFR‐3c. We conclude that FGF‐8 and its receptors are expressed in preantral follicles in a developmentally regulated manner. Mol. Reprod. Dev. 70: 255–261, 2005. © 2005 Wiley‐Liss, Inc.
Postpartum depression and related psychosocial variables in Hong Kong Chinese women: Findings from a prospective study
Authors: Leung Sharron S.K. , Martinson Ida M. , Arthur David 
Published: December 2004

AbstractResearch on predictors of postpartum depression (PPD) in Hong Kong (HK) Chinese women is scant. A prospective study with 385 HK Chinese postpartum women was conducted to identify correlations between PPD and demographic variables, and antenatal depression and psychosocial variables, and to determine which of these variables were predictors of PPD. Using the Edinburgh Postnatal Depression Scale (EPDS), we classified 19.8% of participants as postnatally depressed. Fifty‐six percent of the variance in PPD was explained by social support and stress factors. However, social support factors accounted for only a small percentage of that variance. The major predictors were antenatal depression, postnatal perceived stress, and childcare stress. HK women may benefit from a culturally appropriate intervention focused on reducing stress in the postpartum period. © 2004 Wiley Periodicals, Inc. Res Nurs Health 28:27–38, 2005
Time optimal factorizations on compact Lie groups
Authors: Dirr G. , Helmke U. , Kleinsteuber M. 
Published: December 2004

AbstractIn this paper we study the relationship between factorization problems on SU(2n) or more generally on compact Lie groups G and time optimal control problems. Both types of problems naturally arise in physics, such as in quantum computing and in controlling coupled spin systems (NMR‐spectroscopy). In the first part we show that certain factorization problems can be reformulated as time optimal control problems on G. In the second part a necessary condition for the existence of finite optimal factorizations is discussed. At the end we illustrate our results by an example on Euler angle factorizations. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Iterative Refinement Revisited
Authors: Drygalla Volker , Zielke Gerhard 
Published: December 2004

AbstractDie Verfügbarbarkeit von effektiven Algorithmen zur exakten Berechnung von Skalarprodukten ermöglicht die Nachiteration von Lösungen linearer Gleichungssysteme mit direkten wie iterativen Methoden im nichtsingulären wie überbestimmten Fall und bietet weite Anwendungsmöglichkeiten für nichtlineare Gleichungssysteme, insbesondere für die Behandlung von Eigenwertaufgaben. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Computing Interior Eigenvalues of Conservative Gyroscopic Problems
Authors: Markiewicz Marta , Voss Heinrich 
Published: December 2004

AbstractWe propose a new method for computing a large number of eigenpairs in the interior of the spectrum for conservative gyroscopic eigenproblems by the nonlinear Arnoldi method combined with a localized version of safeguarded iteration. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Generalization of a Parametric Fixed‐Point Iteration
Authors: Popova Evgenija D. 
Published: December 2004

AbstractBased on new sufficient regularity conditions, Rump's method for solving parametric interval linear systems is generalized which expands its scope of applicability over a class of co‐called column‐dependent parametric matrices. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Finite difference schemes for some types of boundary value problems with interfaces
Authors: Jovanović Boško S. , Vulkov Lubin G. 
Published: December 2004

AbstractStability and convergence of finite difference schemes approximating an elliptic partial differential equation with interface are examined. A convergence rate estimate compatible with the smoothness of the input data is obtained. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A constitutive model for non‐linear behavior of SMC accounting for linear viscoelasticity and micro‐damage
Authors: Oldenbo M. , Varna J. 
Published: December 2004

AbstractAn approach for modeling sheet molding compound (SMC) composites as viscoelastic damageable material is presented. Continuum damage mechanics theory by Chow and Wang (Int. J. Fract., 33, 3 (1987)) was used in combination with linear viscoelasticity. The model was applied to a modern SMC composite material containing both hollow glass spheres for low density and toughening additive for improved impact resistance. Tensile tests and uniaxial creep test were employed to build the constitutive model. Validation was done by comparing test data with simulations of uniaxial creep on material with different degrees of damage. The model has good accuracy at moderate damage levels under controlled time‐dependent crack propagation. Tensile testing at two different fixed strain rates was simulated using quasi‐elastic method to calculate relaxation modulus. The model predicts the stress‐strain curve with good accuracy until the region is close to failure, where new mechanisms not accounted for are taking place. Finally, a simulation of a cyclic tensile test with increasing maximum strain per cycle was performed, and since both damage and viscoelasticity are included in the model, the slope change, accumulation of residual strain, and hysteresis in the stress‐strain, loading‐unloading curve are predicted. POLYM. COMPOS., 26:84–97, 2005. © 2004 Society of Plastics Engineers
Plastic composites for electromagnetic interference shielding applications
Authors: Bigg D. M. , Stutz D. E. 
Published: December 2004

AbstractResearch in the past eight years has established the ability of polymer composites made with sufficient electrical conductivity to be suitable as shields against electromagnetic interference (EMI). A number of conductive fillers have been used to produce such composites. These include carbon black, carbon fibers, metal fibers, metal flakes, and metal‐coated glass fibers. Each filler offers its own set of advantages and disadvantages. An important aspect of developing polymeric composites for EMI shielding applications is measuring their shielding ability in areliable, easy‐to‐use test facility. Once a reliable test has been developed, basic data relating the bulk conductivity (or surface conductivity of coatings) can be generaated. The objective of this article is to discuss the relative utility of the different types of fillers commonly used, present an analysis of the utility of different testing approaches, and show data correlating volume resistivity with shielding effectiveness.
Hydrolysis and condensation of silanes in aqueous solutions
Authors: Savard S. , Blanchard L.‐P. , Léonard J. , Prud'homme R. E. 
Published: December 2004

AbstractAminosilanes hydrolyze rapidly in aqueous acidic solutions and exhibit good stability; however 1H NMR measurements indicate that γ‐MPS (γ‐methacryloxypropyltrimethoxy silane) hydrolyzes slowly and condenses rapidly under similar conditions. The rate constant of these two reactions depends upon the pH of the solution, and the rate constant of the condensation reaction also depends upon the initial γ‐MPS concentration. The hydrolysis is faster and the condensation slower at low pH's. These factors explain why an induction period is observed before the adsorption of γ‐MPS onto mica takes place and why it does not occur if the induction period is too long. Using the Lentz technique, it is also shown that the main species resulting from the condensation of a concentrated γ‐MPS solution is a cyclic trimer or tetramer, in agreement with literature results.
The effect of silica on the crystallization of isotactic poly(propylene oxide)
Authors: Kennedy M. A. , Brown G. R. , St‐pierre L. E. 
Published: December 2004

AbstractThe addition of one part, by weight, of fine particle silica to one hundred parts isotactic poly(propylene oxide) causes a retardation in the rate of radial growth of spherulites at all temperatures between 268 and 313 K. The results have been fitted empirically by use of the Hoffman‐Lauritzen equation suitably modified to account for effects due to the presence of the silica. At certain temperatures the presence of the silica also causes a change in the morphology of the spherulites.
Stress dependence of the coefficient of moisture diffusion in composite materials
Authors: Neumann Shoshana , Marom Gad 
Published: December 2004

AbstractA model for the effect of external loading on diffusion into the bulk resin matrix of unidirectional composite materials is proposed. The model attributes the effect to a change in the free volume of the resin matrix, which is equal to its volume strain. The latter is calculated by substracting the volume strain of the fibers from that of the composite. The ratio of the diffusion coefficients in the stressed and unstressed states is expressed as a function of the stress level, the volume fraction of the fibers, and the angle between the applied stress and the fiber direction. Calculations for a glass‐fiber‐reinforced epoxy composites are presented.
Processing‐property relationships in compression molding of sheet molding compounds
Authors: Oh Sang Yeol , Han Chang Dae 
Published: December 2004

AbstractAn experimental investigation was conducted into establishing relationships between the processing variables and the mechanical properties of compression‐molded parts of sheet molding compounds (SMC). Emphasis was placed on investigating the effects on the tensile properties, impact strength, and dynamic mechanical properties of composite specimens, of low‐profile additives, and of treating glass fibers (for reinforcement) with sizing chemicals. The processing variables investigated were cure time, mold temperature, and mold pressure. It was found that: (1) An optimum cure time and mold temperature exist for achieving molded SMC composites of the greatest tensile and impact strengths; (2) Of the four different types of low‐profile thermoplastic additives employed, the poly(vinyl acetate) modified with acrylic acid gives rise to molded SMC composites having the greatest tensile and impact strengths; (3) An optimum cure time and mold temperature exist for achieving the highest glass‐transition (Tg) of the low‐profile additive; (4) The values of cure time and mold temperature that have yielded the greatest tensile and impact strengths also yield molded specimens having the highest Tg of the low‐profile additive.