12 results on '"Local Concept"'
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2. Conclusion: Crafting Elastic Masculinity
- Author
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Cao, Siyang, author
- Published
- 2021
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3. Benefits of Fatigue Assessment with Local Concepts
- Author
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Schaumann, P., Wilke, F., Peinke, Joachim, editor, Schaumann, Peter, editor, and Barth, Stephan, editor
- Published
- 2007
- Full Text
- View/download PDF
4. Home Photo Categorization Based on Photographic Region Templates
- Author
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Kim, Sang-Kyun, Yang, Seungji, Seo, Kyong Sok, Ro, Yong Man, Kim, Ji-Yeon, Seo, Yang Suk, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Dough, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Lee, Gary Geunbae, editor, Yamada, Akio, editor, Meng, Helen, editor, and Myaeng, Sung Hyon, editor
- Published
- 2005
- Full Text
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5. C-OWL: Contextualizing Ontologies
- Author
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Bouquet, Paolo, Giunchiglia, Fausto, van Harmelen, Frank, Serafini, Luciano, Stuckenschmidt, Heiner, Goos, Gerhard, editor, Hartmanis, Juris, editor, van Leeuwen, Jan, editor, Fensel, Dieter, editor, Sycara, Katia, editor, and Mylopoulos, John, editor
- Published
- 2003
- Full Text
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6. Time and Physics — a Noncommutative Revolution
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Heller, Michał, Hintikka, Jaakko, editor, Van Dalen, Dirk, editor, Davidson, Donald, editor, Kuipers, Theo A. F., editor, Suppes, Patrick, editor, Woleński, Jan, editor, and Eilstein, Helena, editor
- Published
- 2002
- Full Text
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7. The use of terminological knowledge bases in software localisation
- Author
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Karkaletsis, E. A., Spyropoulos, C. D., Vouros, G., Carbonell, Jaime G., editor, Siekmann, Jörg, editor, Goos, G., editor, Hartmanis, J., editor, van Leeuwen, J., editor, and Steffens, Petra, editor
- Published
- 1995
- Full Text
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8. Structured and efficient local evaluation of the fatigue strength of threads with the help of FEM
- Author
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Strummer, Moritz
- Subjects
fatigue strength assessment ,FEM ,Örtliches Konzept ,fatigue strength ,Schädigungsparameter ,Local Concept ,Gewindeverbindungen ,Lebensdauerbewertung ,damage parameter ,Schwingfestigkeit ,threaded connections ,zyklische Belastung ,cyclic loading - Abstract
Diese Arbeit befasst sich mit der Bewertung der Lebensdauer von Gewindeverbindungen anhand des örtlichen Konzepts. Dazu werden lokale Spannungs-Dehnungs-Kurven und ihre Hysteresen mit Hilfe der Finiten-Elemente-Methode ermittelt und anschließend in eine numerische Schädigung umgerechnet. Diese Schädigung in Form eines lokalen Schädigungsparameters wird mit einer Wöhlerlinie verglichen, um letztlich eine ertragbare Lebensdauer zu kalkulieren. Am Anfang des Vorhabens werden die konkreten Aufgabenstellungen, die in der Arbeit behandelt werden, aufgelistet. Ebenso wird ein Überblick über die zu erreichenden Ziele gegeben. Im ersten Hauptabschnitt werden dem Leser grundlegende Kenntnisse aus dem Stand der Technik und Forschung vorgestellt, die im weiteren Verlauf der Arbeit benötigt werden. Es werden allgemeine Informationen zu Gewindeverbindungen und ihren Anwendungen gegeben. Nachfolgend wird eine Zusammenfassung des Ablaufs und der Funktionsweise einer Finiten-Elemente-Berechnung gegeben. Des Weiteren werden die wichtigsten Kenngrößen unter zyklischer Belastung zusammengefasst und deren Ermittlungsmöglichkeiten aufgezeigt. Zudem werden die Mechanismen der Ermüdungsfestigkeit und das Plastizitätsverhalten von Werkstoffen unter schwingender Belastung erläutert. Zuletzt erfolgt eine Vorstellung der verschiedenen Konzepte zur Lebensdauerbewertung. Im nächsten Abschnitt wird dem Leser vermittelt, wie die Spannungs-Dehnungs-Kurven für die Implementierung im FE-Programm ohne Versuche ermittelt werden können. Dabei werden verschiedene Ansätze gezeigt und miteinander verglichen. Diese Kurven werden im nachfolgenden Kapitel an einer Probengeometrie evaluiert, wobei zusätzlich die verfügbaren Materialmodelle untersucht werden. Es erfolgt eine Auswahl des geeignetsten Modells. Als nächstes wird zu einem zentralen Punkt der Arbeit übergegangen, der Finite-Elemente-Modellierung einer Gewindeverbindung. Hier werden die grundlegenden Annahmen und Daten zum Modell beschrieben. Die aufgebrachten zyklischen Lasten und Randbedingungen sowie Kontaktzustände werden detailliert aufgezeigt. Die Wahl der Elementtypen und die Vernetzung im Allgemeinen wird ebenso veranschaulicht. Zum Abschluss dieses Segments werden die relevanten Ergebnisse der numerischen Berechnungen für die nachfolgende Bewertung diskutiert. Im letzten Hauptabschnitt werden die ermittelten Ergebnisse in Form von Hysteresen in eine Schädigung umgerechnet. Davor wird die ertragbare Schädigung des Werkstoffs in Form von Wöhlerlinien ermittelt. Hier werden drei verschiedene Ansätze vorgestellt. Mit Hilfe der lokalen Schädigung erfolgt eine Gegenüberstellung der örtlichen Werte mit den globalen des Werkstoffs als Wöhlerlinien. Daraus werden für verschiedene Spannungsamplituden ertragbare Schwingspielzahlen berechnet, die letztlich eine Punktewolke liefern aus welcher eine Bauteilwöhlerlinie generiert wird. DieseWöhlerlinien werden zur Validierung mit Daten aus der Literatur verglichen. Abschließend wird eine Zusammenfassung aller Ergebnisse festgehalten und die daraus resultierenden Folgerungen aufgezeigt. Zudem wird ein Ausblick auf weitere notwendige Schritte gegeben. This thesis deals with the evaluation of the fatigue life of threaded connections based on the local concept. For this purpose, local stress-strain curves and their hystereses are determined using the finite element method, which then are converted into a numerical damage. This damage in the form of a local damage parameter is compared with a S-N curve in order to ultimately calculate a tolerable number of cycles. At the beginning of the project, the concrete tasks that are dealt with in the thesis are listed. An overview of the objectives to be achieved is also given. In the first main section, the reader is presented with basic knowledge from the state of the art and research that will be required in the further process of the work. General information on threaded connections and their applications is given. In the following, a summary of the procedure and the principle functions a finite element calculation is given. Furthermore, the most important parameters under oscillating load are summarized and their determination possibilities are shown. In addition, the mechanisms of fatigue strength and the plastic behaviour of materials under cyclic loading are explained. Finally, a presentation of the different concepts for fatigue life assessment is given. In the next section, the reader is shown how the stress-strain curves can be determined without tests for implementation in the FE program. Different approaches are shown and compared. These curves are evaluated in the following chapter on a specimen geometry, whereby the available material models are also examined. The most suitable model is selected. In the next step, one key aspect of the project, the finite element modeling of a threaded connection, is introduced. The basic assumptions and data for the model are described. The applied cyclic loads and boundary conditions as well as contact states are shown in detail. The choice of element types and meshing in general is also illustrated. At the end of this segment, the relevant results of the numerical calculations are discussed for the subsequent evaluation. In the last main section, the hystereses results obtained are converted into local damage. Before that, the tolerable damage to the material is determined in the form of a S-N curve. Three different approaches are presented in this thesis. With the help of the local damage a comparison of the local values with the global values of the material as S-N curve is carried out. For different nominal stress amplitudes a tolerable number of cycles are calculated, which finally deliver a point cloud from which a component S-N curve is generated. These S-N curves are compared with data from the literature for validation. Finally, a summary of all results is provided and the conclusions are shown. Furthermore, an outlook on further necessary steps is given.
- Published
- 2020
9. Crane runways – Fatigue evaluation of crane rail welds using local concepts
- Author
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Euler, M. and Kuhlmann, U.
- Subjects
- *
MATERIAL fatigue , *MECHANICAL loads , *RAIL fastenings , *WELDED joints , *STRAINS & stresses (Mechanics) , *GIRDERS , *SHEAR (Mechanics) - Abstract
Abstract: The introduction of the wheel loads into a crane runway with a hot rolled I-section and a block rail fastened by longitudinal fillet welds forms a multiaxial fatigue problem. At the point of wheel load application the top region of the runway girder is subjected to a stress field comprising local stress components induced by the concentrated load, i.e. local transverse pressure and local shear stress in addition to the direct and shear stress components due to global bending. The superposition of all aforementioned stress components (and stress ranges, resp.) during each single crane pass results in a so-called non-proportional cyclic stressing of the rail welds with alternating principal stress direction. Due to the variation of the principal stress direction the conventional fatigue evaluation procedures appear not to be reliable. To approach the complex issue two crane runway girders were tested under proportional multiaxial loading, i.e. under flexural bending and stationary wheel load, both simultaneously pulsating. The paper presents the fatigue evaluation of these tests using different local concepts. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
- View/download PDF
10. Recent developments in local concepts of fatigue assessment of welded joints
- Author
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Radaj, D., Sonsino, C.M., and Fricke, W.
- Subjects
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WELDING , *SEALING (Technology) , *FORGING , *METALWORK - Abstract
Abstract: Several lately proposed modifications or variants of the structural stress or strain concepts, of the notch stress or strain concepts (also termed ‘local stress or strain concepts’) and of the fracture mechanics concepts of fatigue assessment of welded joints are reviewed, whereas the wider context is presented in a recently republished and actualised standard work. The structural stress concepts described first are based on a linearisation of the stress distribution across the plate thickness or along the anticipated crack path and, alternatively, on the structural stress 1mm in depth below the weld toe. The structural stress is defined and set against design S–N curves. A further structural stress concept is presented for welded joints in thin-sheet steels and aluminium alloys. Among the elastic notch stress concepts, the variant with the reference notch radius, ρ r =1mm, recently verified also for welded joints in aluminium alloys with plate thicknesses t ⩾5mm and the variant with a small-size reference notch radius, ρ r =0.05mm, applicable to welded joints in thin-sheet materials, are outlined. The elastic–plastic notch strain concept is applied to a spot-welded tensile-shear specimen starting from a small-size keyhole notch at the nugget edge. The novel notch stress intensity factor (NSIF) approach relating to crack initiation and extrapolated to final fracture of seam-welded joints in steels and in aluminium alloys is reviewed. A more recently developed crack propagation approach for spot welds is finally described. [Copyright &y& Elsevier]
- Published
- 2009
- Full Text
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11. Influence of residual stresses and mean load on the fatigue strength of case-hardened notched specimens
- Author
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Krug, Thomas, Lang, Karl-Heinz, Fett, Theo, and Löhe, Detlef
- Subjects
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RESIDUAL stresses , *STRAINS & stresses (Mechanics) , *STRENGTH of materials , *DEFORMATIONS (Mechanics) - Abstract
Abstract: Case-hardened gear wheels, e.g., in vehicle transmissions are cyclically most stressed components. Their lifetime is determined by the interaction of loading, tooth flank load-capacity and tooth foot load-capacity. The latter is influenced by a multitude of parameters like mean loading or residual stress state appearing during operation. To evaluate the tooth-foot load-capacity, the knowledge of the mean stress and residual stress sensitivity of the fatigue strength of the material conditions at the sites critical for failure is necessary. The examinations on hand concerning means stress sensitivity and residual stress sensitivity usually deal with homogeneous materials. Systematic analyses for case-hardened conditions are missing. In this work case-hardened notched specimens with different residual stress states are investigated under cyclic bending. The results are analyzed using a local concept and an additional fracture mechanical approach. With the local concept it was possible to determine the crack initiation site which was partly at the surface and partly below the surface. The fracture mechanical approach was necessary to understand the crack stop behavior and to determine the site critical for failure. An uniform description of the lifetime behavior of unpeened and shot peened specimen could be achieved using a modified Haigh diagram which takes into account the local stress state at the site critical for failure. [Copyright &y& Elsevier]
- Published
- 2007
- Full Text
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12. Summary
- Author
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Mitter, H. and Urban, Paul, editor
- Published
- 1978
- Full Text
- View/download PDF
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