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  • 1
    Electronic Resource
    Electronic Resource
    Stress concentrations around holes in anisotropic laminated plates (1982)
    Springer
    Zeitschrift für angewandte Mathematik und Physik 33 (1982), S. 684-692 
    Details
    ISSN: 1420-9039
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Description / Table of Contents: Résumé Une méthode d'approche générale basée sur une fonction de tension représentée par deux potentiels complexes en combinaison avec l'intégrale de Cauchy a été appliquée à l'analyse de plaques perforées anisotropiques, laminées symétriquement. Des résultats sont présentés pour des plaques composites sous tension avec perforations elliptiques et rondes. On a constaté que les facteurs de concentration de tension sont très sensibles aux changements de l'anisotropie et de l'hétérogénéité des plaques ainsi qu'à la direction des tensions extérieures et à la forme des perforations.
    Notes: Abstract A general approach based on a stress function, represented by two complex potentials, in conjunction with Cauchy's integral, is applied to the analysis of perforated anisotropic symmetrically laminated plates. Results are shown for composite plates under tension with elliptic and circular openings. The stress concentration factors were found to be quite sensitive to changes in plate anisotropy and heterogeneity, direction of external tensile force and form of hole.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00944950
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  • 2
    Electronic Resource
    Electronic Resource
    Die instabile Karotisstenose – eine entzündliche Erkrankung? (2000)
    Springer
    Der Nervenarzt 71 (2000), S. 955-962 
    Details
    ISSN: 1433-0407
    Keywords: Schlüsselwörter Karotisstenose ; Mikroembolien ; T-Zellen ; Tissue-Faktor ; Matrixmetalloproteinase ; Keywords Carotid artery stenosis ; Microemboli ; T cells ; Tissue factor ; Matrixmetalloproteinase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Arterioarterial thromboembolism from extracranial internal carotid artery (ICA) stenosis is an important pathogenic mechanism of ischemic stroke. However, even a high-grade ICA stenosis carries a greatly variable annual risk of stroke, as high as 13% following a recent occurrence of transient or minor cerebral ischemia or as low as 1–2% in clinically asymptomatic patients. There is increasing evidence that inflammatory processes play a central role in atherosclerosis and particularly in plaque destabilization converting chronic atherosclerosis into an acute neurological disorder. In thromboendarterectomy specimens from patients with high-grade ICA stenoses, the extent of inflammatory infiltration and the expression of matrixmetalloproteinase-9 correlated to clinical and ultrasonic features of plaque destabilization such as cerebral microembolism. Inflammation might become a new therapeutic target in symptomatic carotid artery disease.
    Notes: Zusammenfassung Arterioarterielle Thrombembolien aus extrakraniellen Stenosen der A. carotis interna (ACI) stellen eine häufige Ursache zerebraler Ischämien dar. Dabei ist das Schlaganfallrisiko nicht ausschließlich vom Stenosegrad abhängig: Hochgradige (〉70%ige) ACI-Stenosen haben ein jährliches Schlaganfallrisiko von 13%, wenn sie innerhalb von 6 Monaten symptomatisch waren, gegenüber nur 1–2% bei zuvor asymptomatischen Stenosen. Die Pathomechanismen, die aus einem chronischen arteriosklerotischen Karotisplaque eine akute neurologische Erkrankung im Sinne der Plaquedestabilisierung machen, sind weitgehend unklar. Es gibt zunehmende Hinweise darauf, dass Entzündungsprozesse an der Entstehung der Arteriosklerose generell und der Plaquedestablisierung im Besonderen beteiligt sind. Anhand von Gefäßpräparaten nach Karotisthrombendarteriektomien konnte gezeigt werden, dass das Ausmaß der T-Zell- und Makrophageninfiltration in der Gefäßwand und die Expression von Matrixmetalloproteinasen mit klinischen und sonologischen Zeichen der Plaquedestabilisierung im Sinne von Mikroembolien korreliert. Damit ergeben sich möglicherweise neue antiinflammatorische Therapieansätze bei symptomatischen Karotisprozessen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001150050692
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  • 3
    Electronic Resource
    Electronic Resource
    Steady penetration of rigid tools through plastic media (1981)
    Springer
    Acta mechanica 40 (1981), S. 209-220 
    Details
    ISSN: 1619-6937
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Description / Table of Contents: Zusammenfassung Es werden analytische Lösungen für die Spannungs- und Geschwindigkeitsfelder um die eindringende Nase eines starren Werkzeugs hergeleitet, welches stetig in ein plastisches Material eindringt. Das Problem wird für den ebenen Verzerrungszustand mit einem halbkreisförmigen Kopf und für den axialsymmetrischen Fall für einen halbkugelförmigen Kopf hergeleitet. Das Materialverhalten wird durch die von Mises Fließregel zusammen mit einem Potenzgesetz für starr-plastische Verfestigung beschrieben. Die Lösungen zeigen, daß ein stationäres Ausbreiten freier kreisförmiger und kugelförmiger Flächen durch das Material unter einem weit draußen angreifenden Zug möglich ist.
    Notes: Summary Analytical solutions are derived for stress and velocity fields around the leading edge of a rigid tool that moves steadily through a plastic medium. The problem is formulated in a plane strain version with a semicircular head and in an axially symmetric version with a hemispherical head. Material behaviour is described by the von Mises flow rule along with a rigid/power-hardening strees-strain characteristic. The solutions show that there is a possibility of steady propagation of free circular and spherical surfaces, through the medium, under the action of a remotely applied tension.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01170432
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  • 4
    Electronic Resource
    Electronic Resource
    Plastic boundary layers induced by variable wall friction (1983)
    Springer
    Acta mechanica 47 (1983), S. 161-165 
    Details
    ISSN: 1619-6937
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01176508
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  • 5
    Electronic Resource
    Electronic Resource
    Plastic boundary layers (1982)
    Springer
    Acta mechanica 45 (1982), S. 73-89 
    Details
    ISSN: 1619-6937
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Plastic boundary layers that develop in steady rectilinear flow of rigid/linear-hardening materials, near rough walls, are investigated. The general rectilinear flow problem is reduced to two semi-coupled partial differential equations. A few exact solutions for steady flow through simple cross sections are derived and used for a detailed study of plastic boundary layers. Material behaviour is governed by the usual von-Mises flow rule. The results reveal the influence of wall friction, wall pressure and material hardening on the boundary layers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01295572
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  • 6
    Electronic Resource
    Electronic Resource
    Helical flow of plastic materials (1983)
    Springer
    Acta mechanica 50 (1983), S. 135-140 
    Details
    ISSN: 1619-6937
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary An exact closed form solution is given for steady helical flow of plastic materials. Material behaviour is governed by the von-Mises flow rule in conjunction with a rigid/linear-hardening stress-strain characteristic. A restricted version of the general solution is used, as an example, for simulating the helical motion of a rough rigid tool through a circular cylindrical tunnel which is embedded in an infinite plastic medium. It is shown that wall friction induces a plastic boundary layer into the medium. The influence of wall pressure, wall friction and material properties on the behaviour within the boundary layer is discussed. It is also pointed out that no such helical flow pattern is possible for a rigid/perfectly-plastic material.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01170447
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  • 7
    Electronic Resource
    Electronic Resource
    A phenomenological theory of damaging and Adaption Processes of Solids (1984)
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 15 (1984), S. 264-268 
    Details
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Eine phänomenologische Theorie der Schädigungs- und Adaptionsprozesse in festen KörpernIn der vorliegenden Arbeit wird versucht, ein phänomenologisches Konzept zu entwickeln, um den Tragfähigkeitsverlust belasteter Werkstoffe infolge struktureller und geometrischer Veränderungen mit Hilfe von Schädigungs- und Adaptionsparametern zu formulieren. Dabei wird die Einbuße an Tragfähigkeit, die etwa durch Wachstum struktureller und geometrischer Imperfektionen sowie durch andere Entfestigungsvorgänge, entsteht, als Schädigung schlechthin bezeichnet. Die Reaktion des Werkstoffs, bei Einwirkung äußerer Felder der auftretenden Schädigung das Gleichgewicht zu halten, erfolgt durch Adaptionsvorgänge, z. B. Verfestigung. Beide Prozesse werden durch kinetische Gleichungen beschrieben und in einfachen Beispielen besprochen.
    Notes: In the present paper the attempt is made to develop a phenomenological concept based on the assumption that the mechanical resistance of the material decreases as result of the structural and geometrical changes which take place in the solids during loading. This model is described in terms of damaging and adaptation parameters. The growth of structural and geometrical imperfections, as well as other softening processes leading to the loss of the mechanical strength of the solid regarded here as damaging processes. These damaging processes can occur simultaneously with the processes of material resistance (for example, strain-hardening) to the aggressive action of the external load. Development of the damaging and adaptation processes is described by properly kinetic equations. Several simple typical examples are discussed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mawe.19840150803
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