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  • 1
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Fatigue & fracture of engineering materials & structures 17 (1994), S. 0 
    ISSN: 1460-2695
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Maschinenbau
    Notizen: Fatigue crack growth behaviour under intermittent overstressing was investigated in dry air with a low carbon steel under tension-compression and tension-tension loading with different mean stress levels. A very small number of cycles of overstress applied intermittently during a very large number of cycles of understress below threshold caused, in all cases, a significant acceleration in crack growth rate as compared to the case of steady cyclic stress. The acceleration for the case with tensile mean stresses was a little smaller than in the case without mean stress and it was related to a little higher crack closure level in the former case. Stress history in the precracking process had some effect on crack closure and, consequently, on the acceleration. A fairly good correlation was obtained between the acceleration and the effective stress intensity range. The acceleration under multi-level intermittent overstresses with different mean stresses could be predicted by linear summation from two-level intermittent overstress test data. No difference was recognized in the fracture surface morphology between the cases with different mean stress level including the cases of multi-level stresses, indicating that the micromechanism of crack growth acceleration would be the same in all cases.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 81 (1998), S. 0 
    ISSN: 1551-2916
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Maschinenbau , Physik
    Notizen: The high-temperature step that is required in a manufacturing process can contribute substantially to the cost. A technical cost framework (TCF) that allows trends in these costs to be determined as a function of the essential variables provides opportunities for their minimization. The basic variables are the furnace capacity, the operating temperature, and the furnace construction. The dependent variables are power, acquisition, and replacement. Information from thermal and process models as well as the furnace element life expectancy provides the functions needed to conduct the minimization through the TCF. The overall strategy is developed and illustrated with examples.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 81 (1998), S. 0 
    ISSN: 1551-2916
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Maschinenbau , Physik
    Notizen: A computational model has been developed to study the stress and strain histories experienced by zirconia-containing cast refractory blocks when they are cooled from the casting temperature. Incorporated into the model are strong temperature dependencies of the following material properties: elastic modulus, flow strength, thermal conductivity, and thermal expansion. The pressure-sensitive Drucker-Prager plasticity model has been used to account for the substantial difference between the tensile and compressive stress-strain behaviors found in these refractories. The temperature-induced phase transformation in the zirconia, as well as the overall thermal contraction, are united by introducing a coefficient of total dilatation. A nonuniform radial distribution of the transforming phase is also incorporated. The parameters that control the time-dependent stress and strain responses are identified by performing calculations that span the range of expected variables. Process strategies for manufacturing crack-free blocks are suggested.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 84 (2001), S. 0 
    ISSN: 1551-2916
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Maschinenbau , Physik
    Notizen: Thermal barrier coatings (TBCs) made by electron-beam physical vapor deposition (EB-PVD) exhibit a thermal conductivity strongly affected by a hierarchy of pores introduced during the deposition process. These pores are in the form of narrow gaps, aligned spheroids, and random spheres at specific sites within the coatings. Models for the effects on thermal conductivity of pores having these shapes and spatial arrangements are taken from the literature and combined with new results to provide descriptors of overall relationships between the relative density and pore morphology of a coating and its thermal conductivity. Correlations between conductivity and elastic modulus are also explored as a means for determining the viability of modulus measurements as a simple-to-use conductivity probe. For the types of pore commonly found in EB-PVD TBCs, there appears to be a tight correlation at typical porosity levels.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 368-372 (Feb. 2008), p. 1831-1834 
    ISSN: 1013-9826
    Quelle: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Thema: Maschinenbau
    Notizen: In this research, the metal and ceramic laminates Ti/Al2O3, Ni/Al2O3 were prepared by PAS.The bonding interfaces of Ti/Al2O3, Ni/Al2O3 were observed and analyzed. The microstructures oflaminates were observed by SEM. It was shown that the joints of the samples were tight and had notvisible flaws. Moreover, the comparison of Ti/Al2O3 and Ni/Al2O3 laminates showed that the joinmechanisms of them were different. Ni/Al2O3 laminates that had not apparent conversion zone werejoined by diffusion and had lower bond strength. Ti/Al2O3 laminates have obvious conversion zonebecause Ti and oxygen have strong combining power. Three-point bending test indicated that the fractureof laminates was correlated to the bond strength of the interface
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 569 (Jan. 2008), p. 265-268 
    ISSN: 1662-9752
    Quelle: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Thema: Maschinenbau
    Notizen: We used ethylene glycol as pore-forming agent to prepare porous carbon withinterconnected pores derived from phenol–formaldehyde resin. The mixture of resins and glycol wasby polymerization and pyrolysis monolithic material of porous carbon with interconnected mesoporesand a narrow pore size range. The average pore size of the porous carbon obtained was 28.2 nm. Thenitrogen adsorption isotherm for the porous carbon exhibited type IV isotherm, which correspondedto mesoporous adsorption. The method could endow porous carbon with BET surface area and porevolume about 500 m2/g and 0.607 cm3/g, respectively. The mesopores in porous carbon formed as aresult of phase separation of resin-rich phase and glycol-rich phase at polymerization and remove ofglycol-rich at subsequent pyrolysis
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 569 (Jan. 2008), p. 109-112 
    ISSN: 1662-9752
    Quelle: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Thema: Maschinenbau
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Acta mechanica solida Sinica 4 (1991), S. 189-205 
    ISSN: 0894-9166
    Schlagwort(e): literlaminar shear strength ; fiber-wound pressure vessels ; burst large strain ; finite element analysis ; resin matrix
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract The interrelationship between the burst strength of fiber-wound pressure vessels and resin properties has been investigated. Experimental results show that the effect of resin properties of the burst strength can be as large as 20–35 percent. Delamination occurring in the head region of a pressure vessel is identified as the main cause leading to the burst strength degradation, with help of the improved netting analysis. A special FORTRAN program is then developed to incorporate the spacial axisymmetric finite strain FEM approach, and the foregoing presupposition is further confirmed by numerical calculations. Interlaminar shear stresses are found to be the major cause in prompting the observed delaminations. It is argued then that the interlaminar shear strength (ILSS) of a composite should be considered as a fundamental parameter for vessel design and resin selection. Hydrostatic burst test results of glass fiber-wound pressure vessels correlate satisfactorily with this prediction. The best stress equilibrium coefficientK, being closely related to ILSS, is proposed as a proper criterion for resin matrix screening.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Journal of fusion energy 18 (1999), S. 51-55 
    ISSN: 1572-9591
    Schlagwort(e): Fusion energy ; resonant tunneling
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract Conventional quantum mechanics calculation shows that fusion energy without strong nuclear radiation is feasible, because this is the nature of sub-barrier nuclear fusion. When the Coulomb barrier is relatively thin and low, the resonant tunneling would select the fusion reaction with strong neutron and Gamma radiation. On the other hand, if the Coulomb barrier is thick and high, the resonant tunneling would select the fusion reaction without strong neutron and Gamma radiation. Thus, fusion energy with lowest radiation is predictable in terms of d + t fusion data. This is the harmony between various approaches towards fusion energy. What we lose is the assumption of compound nucleus model for light nuclei fusion, and what we gain is the fusion energy without strong neutron and Gamma radiation.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Journal of fusion energy 19 (2000), S. 163-168 
    ISSN: 1572-9591
    Schlagwort(e): d + t fusion cross section ; selective resonant tunneling ; Coulomb barrier ; muon-catalyzed fusion
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract Based on the concept of “damp matching” [1] and the famous d + t fusion data, a conventional quantum mechanics calculation shows that the plasma fusion, muon-catalyzed fusion, and the low-energy nuclear reaction are essentially same in the sense of resonant tunneling through the Coulomb barrier. The good agreement between theory and experimental data justifies the selectivity in resonant tunneling, which implies the possibility of having fusion energy with no strong neutron and gamma radiation.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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