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  • fracture mechanics  (2)
  • *Morphogenesis  (1)
  • 0699  (1)
  • Animals  (1)
  • 2000-2004  (4)
  • 1
    Digitale Medien
    Digitale Medien
    Effect of crack shape, inclination angle, and friction coefficient in crack surface contact problems (2000)
    Springer
    International journal of fracture 105 (2000), S. 367-389 
    Details
    ISSN: 1573-2673
    Schlagwort(e): Stress intensity factor ; tribology ; contact problem ; friction coefficient ; fracture mechanics ; rolling contact fatigue ; surface crack ; body force method.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract In rolling/sliding contact fatigue, it is known that the crack propagates at a characteristic angle θ=15–30 deg to the surface. To analyze the mechanism, however, the body force method has been widely used assuming 3D crack models for θ=45–90. In this study, therefore, the unknown body force densities are newly approximated by using fundamental density functions and polynomials. Then, a semi-elliptical crack model is analyzed for θ=15–90 under compressive residual stresses and Hertzian contact loads. The stress intensity factors K II, K III are calculated with varying the crack shape b/a, inclination crack angle θ, and crack face friction coefficient μ. The calculations show that the present method is useful for the analysis for θ=15–30 deg with high accuracy. It is seen that the K II-values when b/a→0 are larger than the ones when b/a=1 by 0–24% for both under compressive residual stress and Hertzian contact load. Regarding the maximum K II values under Hertzian contact load, the results of θ=15 deg are smaller than the ones of θ=45 deg by 23–34%. Regarding the amplitude of (K II max−K II min), the results of θ=15 deg are smaller than the ones of θ=45 deg by 4–24%. With increasing the value of friction coefficient μ for crack faces the value of K II decreases significantly. When the crack is short and the inclination angle θ is small, the value of friction coefficient f for Hertzian contact load largely affect the K II value.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1007688027669
    Standort Signatur Erwartet Verfügbarkeit
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    Artikel (Nationallizenzen)
    Volltext
  • 2
    Digitale Medien
    Digitale Medien
    Generalized stress intensity factors in the interaction between two fibers in matrix (2000)
    Springer
    International journal of fracture 103 (2000), S. 19-39 
    Details
    ISSN: 1573-2673
    Schlagwort(e): Elasticity ; composite material ; fracture mechanics ; fiber ; generalized stress intensity factor ; end effect ; interaction ; rectangular inclusions.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract To evaluate the mechanical strength of fiber reinforced composites it is necessary to consider singular stresses at the end of fibers because they cause crack initiation, propagation, and final failure. The singular stress is expressed by generalized stress intensity factors defined at the corner of fibers. As a 2D model an interaction between rectangular inclusions under longitudinal tension is treated in this paper. The body force method is used to formulate the problem as a system of singular integral equations with Cauchy-type or logarithmic-type singularities, where the unknown functions are the densities of body forces distributed in infinite plates having the same elastic constants as those of the matrix and inclusions. In order to analyze the problem accurately, the unknown functions are expressed as piecewize smooth functions using two types of fundamental densities and power series, where the fundamental densities are chosen to represent the symmetric stress singularity of 1/r 1−λ 1 and the skew-symmetric stress singularity of 1/r 1−λ 2. Then, generalized stress intensity factors at the end of inclusions are systematically calculated for various locations, spacings and elastic modulus of two rectangular inclusions in a plate subjected to longitudinal tension.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1007696723382
    Standort Signatur Erwartet Verfügbarkeit
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    Artikel (Nationallizenzen)
    Volltext
  • 3
    facet.materialart.
    Unbekannt
    Co-seismic geoelectric potential changes observed in Japan (2000)
    In:  Geophys. Res. Lett., Colorado Springs, US Air Force Academy, vol. 27, no. 10, pp. 1535-1538, pp. L12S08, (ISSN: 1340-4202)
    Details
    Publikationsdatum: 2000
    Beschreibung: Nagao et al. monitor the geoelectric potential difference between pairs of electrodes (or dipoles) buried at about 2 m depth at several stations in Japan for the purpose of observing co-seismic signals. Studying several recent earthquakes, they report that the signals commence not with the origin time of the earthquakes but with the arrival time of seismic waves. They find two types of co-seismic changes: offset/decay type, which last long after the seismic vibrations cease, and oscillatory type, which decay with the seismic vibrations. They also find that the amplitude of the co-seismic signals does not scale with the dipole length. Also in this issue, Hayakawa et al. [1531] investigate ultra low frequency (ULF) electromagnetic emissions associated with a large earthquake that occurred at Biak Island, Indonesia, in February 1996. Examining data from Biak and Darwin, they find that the ULF emissions observed about 1.5 months before the quake serve as a precursory signature of the earthquake.
    Schlagwort(e): Earthquake ; Electromagnetic methods/phenomena ; 0699 ; Electromagnetics ; General ; or ; miscellaneous ; 7223 ; Seismology ; Seismic ; hazard ; assessment ; and ; prediction ; 9320 ; Information ; related ; to ; geographic ; region ; Asia ; 9810 ; General ; or ; miscellaneous ; New ; fields ; (not ; classifiable ; under ; other ; headings) ; GRL
    Standort Signatur Erwartet Verfügbarkeit
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    BIBLIOGRAFIE SEISMOLOGIE
  • 4
    facet.materialart.
    Unbekannt
    Ventroptin: a BMP-4 antagonist expressed in a double-gradient pattern in the retina (2001)
    American Association for the Advancement of Science (AAAS)
    Details
    Publikationsdatum: 2001-07-07
    Beschreibung: In the visual system, the establishment of the anteroposterior and dorsoventral axes in the retina and tectum during development is important for topographic retinotectal projection. We identified chick Ventroptin, an antagonist of bone morphogenetic protein 4 (BMP-4), which is mainly expressed in the ventral retina, not only with a ventral high-dorsal low gradient but also with a nasal high-temporal low gradient at later stages. Misexpression of Ventroptin altered expression patterns of several topographic genes in the retina and projection of the retinal axons to the tectum along both axes. Thus, the topographic retinotectal projection appears to be specified by the double-gradient molecule Ventroptin along the two axes.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sakuta, H -- Suzuki, R -- Takahashi, H -- Kato, A -- Shintani, T -- Iemura Si -- Yamamoto, T S -- Ueno, N -- Noda, M -- New York, N.Y. -- Science. 2001 Jul 6;293(5527):111-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Molecular Neurobiology, National Institute for Basic Biology, The Graduate University for Advanced Studies, 38 Nishigonaka, Myodaiji-cho, Okazaki 444-8585, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11441185" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Alternative Splicing ; Amino Acid Sequence ; Animals ; Bone Morphogenetic Protein 4 ; Bone Morphogenetic Proteins/*antagonists & inhibitors/genetics/metabolism ; Chick Embryo ; Cloning, Molecular ; Electroporation ; Embryo, Nonmammalian/cytology/metabolism ; Eye Proteins/chemistry/genetics/*metabolism ; *Gene Expression Regulation, Developmental ; Gene Library ; Humans ; In Situ Hybridization ; Mice ; Microinjections ; Molecular Sequence Data ; *Morphogenesis ; Nerve Tissue Proteins ; Precipitin Tests ; Protein Binding ; Protein Isoforms/chemistry/genetics/metabolism ; RNA, Messenger/analysis/genetics ; Retina/*embryology/*metabolism ; Sequence Alignment ; Surface Plasmon Resonance ; Xenopus Proteins ; Xenopus laevis/embryology/metabolism
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Publiziert von American Association for the Advancement of Science (AAAS)
    Standort Signatur Erwartet Verfügbarkeit
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    AKTUELLE ARTIKEL
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