Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 268 (1990), S. 414-425 
    ISSN: 1435-1536
    Keywords: mesophase ; fibrouscomposites ; diffuseboundary ; polymer-polymer adjacent phases ; diffusion reaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract In this paper the mesophase developed between main phases in fibrous composites was studied assuming that it constitutes a diffuse boundary. This type of mesophase is normally developed in polymer-polymer adjacent phases and it it useful for the study of modern composites disposing a coupling agent between main phases. At the high temperature of reaction of phases during the casting process both neighboring phases are partly liquified, allowing a two-way movement of elements of either phase whose intensity and extent depends on the particular diffusion characteristics of either phase and the affinities between them. The characteristics of this diffusion reaction were studied and their influence on the development and the properties of the adhesion between phases were established, especially for fiber composites. Interesting results were derived concerning the extent of the diffusive mesophase and its mechanical properties, as well as its contribution on the global mechanical behavior of the composite. Finally, the results were found to be in agreement with previously established models.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 268 (1990), S. 1118-1130 
    ISSN: 1435-1536
    Keywords: Particulatecomposites ; Kernermodel ; Christensenfield ; mesophase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract An accurate relationship for the shear modulus of particulates is derived based on the Kerner model, but not using its approximate relations. Furthermore, the model takes into account the existence of the mesophase layer between the inclusions and the matrix, which acts as a smooth transition boundary layer between constituent materials. By applying Christensen's field to the Kerner model, modified by introducing the mesophase, the new model is liberated from any inconsistencies. Experimental evidence and application to a glass particle-epoxy resin-matrix composite indicated the superiority of the model over previous ones.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Archive of applied mechanics 61 (1991), S. 578-587 
    ISSN: 1432-0681
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Übersicht In dieser Arbeit wird der Einfluß von adhäsiven Materialien auf das Verhalten der Risse in zweidimensionalen linear-elastischen Körpern untersucht. Insbesondere werden Delaminations- und Entklebeeffekte behandelt. Es wird angenommen, daß das adhäsive Material ein nichtmonotones mehrdeutiges Gesetz einführt, das durch nichtkonvexe Superpotentiale beschreiben werden kann. Die direkte Randwertintegralmethode wird für dieses Problem erweitert. Man erhält zwei äquivalente, mehrdeutige Integralgleichungen für jeden Riß. Die Theorie wird durch numerische Beispiele erläutert, die die Berechnung der auftretenden Spannungskonzentrationsfaktoren betreffen.
    Notes: Summary The present paper studies the influence of adhesives on the behaviour of cracks in two-dimensional linear elastic bodies. Especially the delamination and debonding effects are studied. The adhesive material is assumed to introduce non-monotone, possibly multivalued laws which can be described via non-convex superpotentials. The direct boundary integral equation method is extended for this problem. It gives rise to two equivalent multivalued integral equations holding on each crack. Numerical examples concerning the resulting stress intensity factors illustrate the theory.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Archive of applied mechanics 62 (1992), S. 83-90 
    ISSN: 1432-0681
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Übersicht Die Methode reflektierender Kaustiken wurde auf Stabknick probleme angewendet. Die von der Oberfläche des Stabes reflektierten Lichtstrahlen (parallel, konvergent oder divergent) erzeugen Kaustiken, die aus zwei stark leuchtenden geraden Linien bestehen, die den leuchtenden Bereich des Stabes begrenzen. Durch Messung des Abstands zwischen den Grenzen der Kaustiken kann der Störparameters des geknickten Stabes bestimmt werden. Eine genaue experimentelle Ermittlung vons ermöglicht die Lösung der nachs entwickelten Eulerschen Gleichungen für die kritische Knicklast und der Terme höherer Ordnung im Nachknickzustand. Die Methode ist eine vielseitige und sensitive Technik, um experimentell die elastische Knickform von Stäben zu bestimmen; sie kann auf das plastische Knicken ausgedehnt werden.
    Notes: Summary The optical method of reflected caustics was applied to beam buckling problems. The reflected rays of a light beam (either parallel, or convergent, or divergent) on the flanks of the strut create caustics which consist of two strongly illuminated straight lines, confining the luminous region of the strut. By measuring the distance between the extremities of the caustics, the perturbation parameters of the buckled beam can be defined. The accurate experimental evaluation ofs allows the solution of the respective Euler expansion equations for the critical buckling load and its higher order terms in the post-buckling state of the strut. The method is a versatile and sensitive technique for experimentally defining the mode of elastic buckling of struts and can be extended to study plastic buckling cases.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Archive of applied mechanics 63 (1993), S. 242-252 
    ISSN: 1432-0681
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Zusammenfassung Das elastische Problem einer unendlichen, orthotropen Platte mit verschiedenen Wurzeln ihrer charakteristischen Gleichung wird im Falle, daß die Fasern senkrecht zu einem inneren Riß verlaufen und daß sie durch ein elliptisches Loch geschwächt sind, im Rahmen der Lekhnitskii-Theorie gelöst. Die Platte wird im Unendlichen einer vorgeschriebenen Spannung unterworfen, während die Randbedingungen an den Rißflanken, am Lochrand und im Unendlichen gegeben sind. Mit Hilfe der Methode der komplexen Variable wird die Lösung des Problems zurückgeführt auf die Berechnung von Cauchy-Integralen der analytischen Funktionen des Problems. Die numerische Lösung des Problems zeigt eine starke Abhängigkeit von Mode-I-Spannungsintensitätsfaktoren (SIF) an den Rißspitzen von der Rißlänge oder des Ligaments zwischen der Rißplatte und dem Loch. Weiterhin wurde gezeigt, daß Orthotropie starken Einfluß auf die Spannungsintensität hat. Diese Beobachtungen stehen in voller Übereinstimmung mit Resultaten aus der Arbeit [1] über ein ähnliches Problem für eine orthotrope Platte, wo allerdings die Wurzel der charakteristischen Gleichung identisch sind.
    Notes: Summary The elastic problem of an infinite orthotropic plate with different roots of its characteristic equation, when the fibers are oriented perpendicularly to an internal crack, and is weakened by an elliptic hole, is solved using Lekhnitskii's theory. The plate is subjected to prescribed stresses at infinity, while the boundary conditions are given at the flanks of the crack, at the rim of the perforation and at infinity. Using the complex-variable method, the solution of the problem is reduced to the evaluation of Cauchy-type integrals concerning the analytic functions of the problem. The numerical solution of the problem revealed an intense variation of mode-I stress intensity factors (SIF) at the crack tips due to the increase of either the crack length, or the distance of the near-by rack tip from the center of the hole. Furthermore, it was found that orthotropy strongly influences the intensity of stresses at the crack tips. These findings are in complete agreement with results given in a previous work by the authors, concerning a similar problem for an orthotropic plate, which, however, constitutes a special case, where the material presents equal roots for its characteristic equation [1].
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 28 (1993), S. 4510-4514 
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The variation of the dynamic elastic modulus in the immediate vicinity of the tip of the running crack was studied through an iterative procedure, based on the theoretical expressions for the stress-field components and the experimental relation between strain rate and elastic modulus. It was found that the elastic modulus varied strongly around the tip of the crack, both in radial and polar sense. Also it was observed that the polar distribution of the elastic modulus presented clear off-axis extrema in directions that were in good agreement with experimentally measured branching angles, thus indicating a possible relation between these two phenomena.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of radioanalytical and nuclear chemistry 188 (1994), S. 189-198 
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Two archeological ceramic sherds in a single quartz aliquot form have been dated success-fully for the first time, by the newly developed method of optical stimulated luminescence (OSL) with green light-emitting diodes (LED). Comparison with the conventional thermoluminescence (TL) method provided ages of the same order of magnitude. The ceramics come from two recently excavated sites at “Hellenikon” and “Ligourio” in Argolid, Peloponnese, Greece. One sherd dates from the end of 4th millenium B.C., while the other is classified around 7th c. B.C.. The new method of nuclear dating is described in the paper and appropriately evaluated.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 29 (1994), S. 3527-3534 
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract While it has been established that the elastic moduli and compliances of anisotropic and isotropic materials should be positive for thermodynamic reasons, no condition related to the values of Poisson's ratio has yet been established. However, it is generally accepted that for isotropic materials Poisson's ratio should vary between — 1.0 and 0.5, whereas for orthotropic materials various conditions have been introduced relating the different components of the anisotropic Poisson's ratio with the remaining elastic constants of the material. In this paper, limits for Poisson's ratio of body-centred cubic (bcc) polycrystalline materials are determined, based on the modes of deformation of a typical unit cell of the material subjected to a uniform external loading arbitrarily oriented relative to the principal axes of the crystal. It is shown that the values of Poisson's ratio thus established correlate satisfactorily with experimental values of this constant. The procedure can be readily applied to other structural units of polycrystalline bodies.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 26 (1991), S. 3575-3580 
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The phenomenon of ductile blunting under plane stress conditions in cracked polycarbonate plates was studied. Because this phenomenon is intimately connected with the amount of crack opening displacement (CTOD) and its analogous phenomenon of crack tip advance displacement (CTAD), a study was undertaken of the mechanism of the development of blunting by evaluating the mode of evolution of CTOD and CTAD in the specimens. As study by scanning electron microscopy is limited to a thin layer of the surface of the specimen, this method is most convenient for studying blunting phenomena under plane-stress conditions. Interesting results were derived from these experiments and the characteristic properties of plane-stress blunting were determined.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 26 (1991), S. 1640-1646 
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract An experimental study was undertaken concerning the propagation of a slant crack under compression. By using the equations of the deformed shape of a crack and by introducing a correction model in order to prevent the crack lips from incompatible displacements, an estimate of the stress distribution along the crack borders was achieved. It was found that an opening-mode K 1 stress intensity factor (SIF) must be introduced at the crack tips in the overall compressive stress field, in order to give the required space for the lip-slip phenomenon, due to shearing, to take place. This local dilatation in the vicinity of the crack tip, together with the lip-slip phenomenon, due to which the initial crack tip is displaced into a new position along the deformed crack borders, causes the out-of-plane propagation of the crack, either towards the largest compressive stress in the case of biaxial stress field, or towards the applied compression in a uniaxial compressive field. A series of experiments on PMMA (perspex) rectangular specimens with pre-existed cracks and slits has been executed and the type of the stress field in the front of the propagated branches is examined by using the method of caustics. It was found that the crack propagation under compression is an interactive process of two conjugate branches, which is strongly influenced by the boundary conditions of the pre-existed discontinuity.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...