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  • 1
    Electronic Resource
    Electronic Resource
    High power failure of superconducting microwave filters: Investigation by means of thermal imaging (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 571-573 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated power handling of high-temperature superconducting microstrip filters employing highly sensitive thermal imaging. At low power, the images show small heating effects localized to areas with high current densities (ΔT〈0.5 K), consistent with the known surface resistance and simulations of the current distribution. The breakdown at high-power levels, however, is always nucleated by a frequency independent local hot spot (T(approximately-greater-than)Tc). Scanning electron microscopy analysis of this area reveals a flaw in the superconducting material, presumably reducing the local critical current. The maximum power handling of these filters is, therefore, still open to improvement. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.117790
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  • 2
    Electronic Resource
    Electronic Resource
    Large area double-sided YBa2Cu3O7−δ films grown by single-source metal-organic chemical vapor deposition (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 712-714 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Thin films of YBa2Cu3O7−δ were sequentially grown on both sides of 3 in. diameter LaAlO3 substrates by a single-source MOCVD technique to facilitate the fabrication of double-sided high temperature superconductor microwave devices. YBCO films on both sides of the LaAlO3 substrates had thicknesses greater than 4000 A(ring), Tc's of 87–88.5 K, and microwave surface resistances as low as 23 mΩ at 94 GHz and 77 K (scaling to 260 μΩ at 10 GHz). It was found that the substrate temperature, brought to the desired value by radiant heating, played a critical role in the deposition of very low surface resistance YBCO films. Microwave bandpass filters with a 19-pole forward coupled configuration were fabricated from these films. The filters showed excellent performance with dissipation losses as low as 0.5 dB. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.115283
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  • 3
    Electronic Resource
    Electronic Resource
    Cloudiness over the Eastern Equatorial Pacific for summer 1983 from geostationary satellite data
    Amsterdam : Elsevier
    Advances in Space Research 5 (1985), S. 197-201 
    Details
    ISSN: 0273-1177
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0273-1177(85)90321-7
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  • 4
    Electronic Resource
    Electronic Resource
    Elastic compliances and stress-intensity factors for side-grooved compact specimens (1977)
    Springer
    International journal of fracture 13 (1977), S. 544-548 
    Details
    ISSN: 1573-2673
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00034260
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  • 5
    Electronic Resource
    Electronic Resource
    On the use of 2D isoparametric elements for calculations in the fully plastic range (1977)
    Springer
    International journal of fracture 13 (1977), S. 507-511 
    Details
    ISSN: 1573-2673
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00034251
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  • 6
    Electronic Resource
    Electronic Resource
    Crack extension modeling with singular quadratic isoparametric elements (1976)
    Springer
    International journal of fracture 12 (1976), S. 647-651 
    Details
    ISSN: 1573-2673
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00034654
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  • 7
    Electronic Resource
    Electronic Resource
    Requirements for a one parameter characterization of crack tip fields by the HRR singularity (1981)
    Springer
    International journal of fracture 17 (1981), S. 27-43 
    Details
    ISSN: 1573-2673
    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: Résumé Lorsqu'un barreau fissuré sur ses bords est soumis à flexion, ou lorsqu'un panneau fissuré en son centre ou présentant une fissure simple est soumis à des contraintes de traction, des champs complexes de contrainte et de déformation aux extrémités des fissures considérées apparaissent. Ces champs sont comparés aux champs singuliers étudiés par Hutchinson et Rice et Rosengren pour le même niveau d'un J déterminé. Les comparaisons montrent que la dimension R de la région à l'extrémité d'une fissure sur laquelle agit de manière déterminante une singularité HRR se trouve être substantiellement plus grande dans une éprouvette de flexion que dans un panneau présentant une fissure centrale, et ce pour une plasticité contenue ou une plasticité à large échelle. Les propriétés de durcissement ont également une influence déterminante sur R. On discute les implications de ces résultats sur l'exigence de dimension minimum qui est essentielle dans le cas du critère de rupture à un paramètre basé sur une intégrale J ou dans le cas du COD.
    Notes: Abstract Detailed crack tip stress and strain fields are generated for the edge crack bar subjected to bending and the center cracked panel and single cracked panel subjected to tensile loads. These fields are compared with the singular fields, due to Hutchinson and Rice and Rosengren, at the same level of applied J. The comparisons show that the size R of the region at the crack tip dominated by the HRR singularity is substantially larger in the bend specimen than in the center-cracked panel for contained and large scale plasticity. Hardening properties also have a strong influence on R. The implications of these results on the minimum size requirement essential to a one parameter fracture criterion based on the J-integral or crack tip opening displacement are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00043119
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  • 8
    Electronic Resource
    Electronic Resource
    The geometry effects for stress intensity factor of sandwich specimen for measuring interfacial fracture toughness (1993)
    Springer
    International journal of fracture 59 (1993), S. 377-385 
    Details
    ISSN: 1573-2673
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The interfacial stress intensity factors for three types of sandwich specimens: the single edge crack tensile specimen, the three point bend specimen and the four point shear specimen were obtained by the finite element analysis and compared with the asymptotic solutions. The results show that the geometric effect for mode II specimen is larger than mode I specimen. The limit curves for geometry factor equal to 1.05 were obtained to indicate the usable range of validity of the asymptotic solution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00034565
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  • 9
    Electronic Resource
    Electronic Resource
    J-dominance under plane strain fully plastic conditions: the edge crack panel subject to combined tension and bending (1985)
    Springer
    International journal of fracture 29 (1985), S. 73-84 
    Details
    ISSN: 1573-2673
    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: Résumé On établit les solutions en état plan de déformation applicables à l'ensemble d'une zone caractérisée par une fissure semi infinie disposée normalement au bord libre d'un demi-espace semi-infini, et dont le ligament est sujet à des combinaisons arbitraires de contraintes de traction et de flexion. Pour décrire le comportement du matériau, on utilise une relation quadratique dérivée de la théorie de la déformation en conditions totalement plastique et incompressible. On se pose la question de la prédominance de J dans le voisinage de l'extrémité de l'entaille, en comparant les solutions par éléments finis couvrant l'intégralité de la région étudiée aux solutions prenant en compte les régions singulières de Hutchinson, Rice, Rosengren. Cette comparaison montre que la plage d'accord dépend largement de la proportion de la flexion sur la traction. Lorsqu'on est voisin de la flexion pure, la zone de prédominance de J représente une fraction importante du ligament, et la taille de cette zone n'est pas influencée par le comportement l'écronissage. Par contre, au voisinage de l'extension pure, la zone de prédominance de J est considérablement plus petite, et sa taille dépend fortement des caractéristiques d'écronissage. On discute également des dimensions nécessaires à une caractérisation suivant l'intégrale J des zones voisines de l'extrémité d'entailles dans des corps soumis à tension et flexion combinée.
    Notes: Abstract Full field plane-strain solutions are obtained for a semi-infinite crack aligned perpendicularly to the free-edge of a semi-infinite half space where the ligament is subject to arbitrary combinations of tension and bending. The material behavior is described by the incompressible fully plastic pure-power-law deformation theory relation. The question of J-dominance of the crack-tip region is addressed by comparing the full field finite element solutions with the Hutchinson-Rice-Rosengren singularity fields. These comparisons show that the region of agreement is strongly dependent on the relative amount of bending to tension. In the vicinity of pure bending, the zone of J-dominance is a significant fraction of the ligament, and the size of the zone does not depend on hardening behavior. In the vicinity of pure stretch, the zone of J-dominance is substantially smaller and depends strongly on hardening characteristics. Size requirements which are necessary to ensure J characterization of the near-tip fields of cracked bodies subject to combined tension and bending are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00034294
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  • 10
    Electronic Resource
    Electronic Resource
    Energy release rate along a three-dimensional crack front in a thermally stressed body (1986)
    Springer
    International journal of fracture 30 (1986), S. 79-102 
    Details
    ISSN: 1573-2673
    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: Résumé En sa basant sur une intégrale simple exprimant le taux de relaxation d'énergie afférant aux champs de contrainte à l'extrémité d'une fissure, expression applicable à la réponse d'un matériau quelconque, on a déduit une intégrale de domaine (superficielle ou volumique) décrivant l'énergie dans un corps soumis à contraintes thermiques. On fournit l'intégrale générale relative à un domaine fini tridimensionnel et á des cas particuliers bidimensionnels et axisymétriques, exprimant le taux de relaxation d'énergie. L'intégrale de domaine est naturellement compatible avec une formulation par éléments finis des équations de champ. Comme telle, elle convient idéalement pour un calcul facile et précis des valeurs ponctuelles du taux de relaxation de l'énergie le long du front d'une fissure tridimensionnelle. L'implantation d'éléments finis dans l'intégrale de domaine correspond à une technique d'extension virtuelle de la fissure. On discute des procédures de calculs du taux de relaxation de l'énergie, qui utilisent les solutions relatives au champ déterminées par voie numérique. A titre d'illustration, on présente plusieurs exemples numériques.
    Notes: Abstract Based on a line-integral expression for the energy release rate in terms of crack tip fields, which is valid for general material response, a (area/volume) domain integral expression for the energetic force in a thermally stressed body is derived. The general three-dimensional finite domain integral expression and the two-dimensional and axisymmetric specializations for the energy release rate are given. The domain expression is naturally compatible with the finite element formulation of the field equations. As such it is ideally suited for efficient and accurate calculation of the pointwise values of the energy release rate along a three-dimensional crack front. The finite element implementation of the domain integral corresponds to the virtual crack extension technique. Procedures for calculating the energy release rate using the numerically determined field solutions are discussed. For illustrative purposes several numerical examples are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00034019
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