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  • Articles  (24)
  • 1995-1999  (10)
  • 1990-1994  (13)
  • 1975-1979  (1)
  • Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics  (22)
  • Mathematics  (2)
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  • Articles  (24)
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  • 1
    ISSN: 1520-5002
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1520-5002
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Archive of applied mechanics 69 (1999), S. 765-784 
    ISSN: 1432-0681
    Keywords: Key words Finite elements, statistical equivalent linearization, component-mode synthesis, complex modal analysis, random eigenvalue problem, hysteresis, damping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Summary This paper focuses on the stochastic dynamic response of structures modeled by finite elements with a relatively large number of degrees of freedom. FE models with nonlinearities and uncertain (stochastic) system properties are discussed. It is shown that component mode synthesis can be used most advantageously to solve the issue of computational efficiency and feasibility. The stochastic response due to stochastic loading of large FE models with nonlinear elements is determined by statistical equivalent linearization (EQL). The developed component-mode synthesis allows to determine the complex modal properties of arbitrary large linearized finite element models. Nonsymmetric structural matrices, as a result of the EQL, and filters for modeling of filtered white noise can be treated by the suggested approach. Since the efficiency of the procedure is nearly independent of the number of degrees-of-freedom (DOF) involved, statistical equivalent linearization becomes applicable for arbitrary detailed FE models. Furthermore, the dynamic response of FE models with uncertain or stochastic system properties is discussed. In this case, Monte Carlo simulation is suggested as the most appropriate approach for FE models. The paper focuses on the random eigenvalue problem for large FE systems as the computationally most demanding part of the dynamic analysis. Component-mode synthesis is used to provide in an efficient manner all the eigenvalue solutions of the FE system needed by the Monte Carlo simulation.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 26 (1991), S. 3287-3291 
    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 It is well known that the microstructure of metal-matrix composite materials is significantly different from that of the unreinforced matrix. Heat treatments which optimized strength values in the matrix therefore, no longer do so in the composite. It is thus beneficial to find these variations in the heat treatment process, and to pinpoint the microstructural mechanisms responsible. It is known that, in addition to a higher dislocation density, the composite also has a very fine grain size and many whisker interfacial nucleation sites. This study has found that the time required for solutionizing appears to be much shorter in the composite primarily due to the very small grain size. It was also observed that artificial ageing was not very effective in the composite since the precipitates nucleated and grew on the whisker interfaces, therefore, only natural ageing was necessary to achieve peak tensile and yield strengths.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 29 (1994), S. 239-249 
    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 interesting cubic-shaped precipitate was observed in the matrix of a squeeze-cast Al-4.3 wt % Cu-2.0 wt % Mg/SiC composite which was heat-treated to a T7 condition. Although this phase had been observed by a few investigators in the past, it had never been examined in detail until now. This cubic phase generally had an edge length ranging from 30 to 50 nm and existed in volume fractions as high as 3.8%. Theoretical strengthening models predicted this phase to have good potential for precipitate strengthening. In addition, the cubic phase exhibited a low rate of coarsening at temperatures as high as 250 °C; apparently due to its low interfacial energy. Consequently, this cubic precipitate shows potential for increasing the useful temperature range of aluminium alloys and composites and could be of great importance to the aerospace and automotive industries.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 29 (1994), S. 424-435 
    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 Al-4.3 wt% Cu-2.0 wt% Mg alloy reinforced with 20 vol% reinforcing fibres was examined after a T7 heat treatment. The expected precipitate phase was equilibrium S′ (Al2CuMg), which was confirmed to form in the monolithic alloy. However when this Al-Cu-Mg alloy was squeeze-cast into a fibre preform and given an identical T7 heat treatment a number of other phases also nucleated; these included θ′ (Al2Cu), β′ (Mg2Si) and the cubic σ phase (Al5Cu6Mg2). These additional phases were determined to nucleate and grow rapidly during the water-quench following solution treatment. The existence of excess Si (approximately 0.5 wt%) in the matrix was determined to be responsible for nucleation of these additional phases. This extra Si entered the composite matrix during squeeze-casting through breakdown of an SiO2 layer which existed at the fibre interfaces. During quenching Si clusters rapidly form and provide nucleation sites for the σ and θ′ phases. The Si clusters apparently created a compressive strain in the matrix which attracted a high concentration of small Cu atoms to their interface. The σ phase nucleated in this high-Cu region since, on a localized scale, σ became the equilibrium phase. This type of nucleation process may also explain the enhanced precipitate nucleation which occasionally takes place in other alloy systems when trace amounts of certain elements are added.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical methods of operations research 46 (1997), S. 287-307 
    ISSN: 1432-5217
    Keywords: Reliability-based optimization ; structural reliability ; cost function ; nonlinear programming ; Monte Carlo simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract A method to carry out a Reliability-Based Optimization (RBO) of especially nonlinear structural systems is introduced. Statistical uncertainties involving both structural and loading properties are considered. The concept is based on the separation of structural reliability analyses and the optimization procedures. Two approaches are discussed, depending on the interaction of reliability analysis and mathematical programming and the way of representation of the limit state functions (LSF) of the structure. As, for cases of practical significance, the LSF is known only pointwise it is approximated by Response Surfaces (RS). For the response calculations Finite Element (FE) procedures are utilized. Failure probabilities are determined by applying variance reducing Monte Carlo simulation (MCS) techniques such as Importance Sampling (IS). Following the reliability analysis, the optimization procedure is controlled by the NLPQL algorithm. A numerical example in terms of a template ocean platform exemplifies the procedures.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Experimental mechanics 31 (1991), S. 118-121 
    ISSN: 1741-2765
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The increasing use of nonselective mechanical harvesters of fruit requires sorting the fruit on firmness. A model and computer program were developed based upon Hertzian impact theory which can predict the impact force function for a spherical fruit hitting a simply supported beam. The model was exercised to observe the effects of beam dimensions and fruit characteristics, including firmness, on the force function. Experimental work showed that measurements from a strain gage on the impacted beam can be used to determine the force function. The measured force function approximated the function predicted by the impact theory model. This work indicated that by the proper design of a sensing beam, fruit firmness may be sensed.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0935-9648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 27 (1976), S. 560-568 
    ISSN: 0947-5117
    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: Precipitation and corrosion behaviour of unstabilized and stabilized 18 10 CrNi steels after short term sensibilizing annealingThe authors have studied the precipitation behaviour of the steels X5 CrNi 18 9, X10CrNiTi 18 9 and X 10CrNiNb 18 9 after solution and sensibilization annealing, and the intercrystalline corrosion behaviour in the Straußtest. On the basis of the results obtained it was possible to determine the and carbonitrides and to define the grain segregation ranges. In the case of the unstabilized materials the behaviour is a function of the formation of chromium depleted zones. However, it is not absolute value of the depletion at the carbid/austenite interphase which controls corrosion, but the depletion in an adjacent zone of measurable thickness. Beyond that the Huey test allows the corrosion susceptibility to be determined in those regions where no continuous chromium depleted zone exists. In the case of stabilized steels the corrosion behaviour depends in addition from carbonitride precipitation, since these compounds are heavily attacked by the boiling nitride acid.
    Notes: Die Verfasser untersuchten das Ausscheidungsverhalten der Stähle X 5 CrNi 18 9, X 10CrNiTi 18 9 und X 10CrNiNb 18 9 nach Lösungs- und Sensibilisierungsglühen sowie das Verhalten gegen interkristalline Korrosion im Strauß-Versuch. Aufgrund der Ergebnisse konnte die Art der Ausscheidungen bestimmt werden (Karbid M23C6 und Karbonitride) und auch die Kornzerfallsbereiche konnten definiert werden. Im Falle des nichtstabilisierten Materials ist das Verhalten abhängig von der Bildung von chromveramten Zonen; dabei ist jedoch nicht die absolute Höhe der Verarmung an der Grenzfläche Kabid/Austenit ausschlaggebend, sondern vielmehr die Verarmung in einer Zone meßbarer Dicke. Im Huey-Versuch läßt sich außerdem die Korrosionsanfälligkeit in den Zonen ermitteln, wo keine zusammenhängende Chromverarmungszone vorliegt. Im Falle der stabilisierten Stähle ist das Korrosionsverhalten außerdem abhängig von der Karbonitridausscheidung, da diese Ausscheidungen von der siedenden Salpetersäure stark angegriffen werden.
    Additional Material: 12 Ill.
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