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  • Articles: DFG German National Licenses  (10)
  • 1990-1994  (7)
  • 1980-1984  (3)
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  • Articles: DFG German National Licenses  (10)
Material
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    The Significance of the Contributions of S. A. Korff to the Field of Cosmogenic Nuclides (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 655 (1992), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1992.tb17065.x
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Cosmic-Ray Record in Solar System Matter (1983)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Nuclear and Particle Science 33 (1983), S. 505-538 
    Details
    ISSN: 0163-8998
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.ns.33.120183.002445
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    THE EFFECT OF STRESS RATIO ON THE FATIGUE THRESHOLD CONDITION OF PHYSICALLY SMALL CRACKS (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Fatigue & fracture of engineering materials & structures 16 (1993), S. 0 
    Details
    ISSN: 1460-2695
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: An approach is proposed to predict the intrinsic threshold of physically small cracks without invoking crack closure considerations. The basic assumption invoked is that a ΔK representation is valid for short cracks, hence the lower-bound threshold value, ΔK0(s)(min) for short cracks can be numerically equated with the lower-bound threshold value of long cracks, ΔK*0(l)(min), s of the same material. Several experimental observations provide a basis for this rationalization. The approach allows a quantitative prediction of stress ratio and crack length dependence of ΔK0(S) which provides good agreement with experimental data for several low-strength steels and aluminium alloys. This alternative procedure may be found useful in design applications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-2695.1993.tb00096.x
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    THE INFLUENCE OF STRENGTH AND STRESS RATIO ON SHORT-CRACK THRESHOLDS AND NON-PROPAGATING FATIGUE CRACKS (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Fatigue & fracture of engineering materials & structures 16 (1993), S. 0 
    Details
    ISSN: 1460-2695
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Quantitative predictions of the influence of yield strength and stress ratio, R, on the physically small crack fatigue threshold stress intensity, ΔK0(s), are presented. It is shown that at R= 0 to -1, although the threshold stress Δs̀0 increases, the threshold stress intensity, ΔK0(s), decreases with increasing yield strength. Moreover, a lower bound value, ΔK0(s)(min) is shown to have a constant value, irrespective of the strength and stress ratio. For a given strength, ΔK0(s), decreases with increasing R in the range -1〈inlineGraphic alt="leqslant R: less-than-or-eq, slant" extraInfo="nonStandardEntity" href="urn:x-wiley:8756758X:FFE419:les" location="les.gif"/〉R〈inlineGraphic alt="leqslant R: less-than-or-eq, slant" extraInfo="nonStandardEntity" href="urn:x-wiley:8756758X:FFE419:les" location="les.gif"/〉0.6 and attains a constant low value for R 〉 0.6. Predicted values of ΔK0(s) are in good agreement with experimental data for steels. The formation and length of non-propagating fatigue cracks, anp, are also discussed. The methods suggested for estimating ΔK0(s) and anp may be found useful in design procedures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-2695.1993.tb00097.x
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  • 5
    Electronic Resource
    Electronic Resource
    A MODEL FOR THE COMBINED EFFECTS OF STRESS RATIO AND GRAIN SIZE ON THE LEFM FATIGUE THRESHOLD CONDITION (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Fatigue & fracture of engineering materials & structures 15 (1992), S. 0 
    Details
    ISSN: 1460-2695
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A long-crack, fatigue-threshold model which explains and predicts the commonly observed effects of stress ratio, R, and grain size, d, on δK0, is proposed. The inclusion of a grain-size-effect is an extension of a recently proposed model that examined the effect of the R ratio. The extended model is based on the hypothesis that near-threshold, crack growth involves two micro-mechanical processes of fracture; Kmax-controlled submicroscopic cleavage, which predominates when the defect concentration is small, and δK-controlled reversed shear which predominates when the defect concentration is large, both processes occurring in a critically stressed volume, Vc, ahead of the crack tip. Defect concentration in Vc is reduced by a low value of R and a coarse grain size and is increased by a high value of R and a fine grain size. Good agreement is shown to exist between predicted and experimental curves of δK0 versus R and δK0 versus grain size for several steels and aluminium alloys. In particular, δK0 is shown to have an upper and a lower bound value for a material. The model may be used as an alternative procedure for obtaining quick, approximate but conservative estimates of δK0 for practical design applications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-2695.1992.tb00056.x
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    A MODEL FOR THE EFFECT OF A GASEOUS ENVIRONMENT ON THE LEFM FATIGUE THRESHOLD CONDITION OF STEELS (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Fatigue & fracture of engineering materials & structures 15 (1992), S. 0 
    Details
    ISSN: 1460-2695
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Using a different approach to those methods involving hydrogen-embrittlement and crack-closure mechanisms a previously developed model is extended to predict the commonly observed effects of yield strength and a gaseous environment on the long-crack fatigue crack growth threshold. The model assumes the existence of two intrinsic thresholds namely an upper bound value and a lower bound value related to, respectively, Kmax-controlled cleavage and δK-controlled reversed shear mechanisms of crack growth in a critically stressed volume at the crack tip. This new development assumes that nascent hydrogen atoms, liberated from moisture in the environment, assist in reducing dislocation mobility thereby rationalizing experimental observations on low strength materials in moist laboratory air when compared to a dry inert environment. Quantitative predictions of fatigue thresholds in laboratory air and inert environments show good agreement with experimental data for several low and high strength steels. This alternative procedure may be found to be useful in practical design applications when reasonably fast and accurate estimates are required.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-2695.1992.tb00057.x
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  • 7
    Electronic Resource
    Electronic Resource
    THE COMBINED EFFECTS OF STRESS RATIO AND YIELD STRENGTH ON THE LEFM FATIGUE THRESHOLD CONDITION (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Fatigue & fracture of engineering materials & structures 15 (1992), S. 0 
    Details
    ISSN: 1460-2695
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract— Long-crack (LEFM) fatigue threshold, Δ,K0 values are predicted which include the commonly observed effects of stress ratio, R, and yield strength, σy. It is assumed that the yield strength effect on threshold is indirectly related to grain size and so is not an independent variable. Two intrinsic thresholds of a material are invoked to explain the observations of higher ΔK0 values and a higher R-ratio sensitivity of ΔK0 in low strength materials compared to high strength materials. The paper shows that ΔK0 is almost independent of both yield strength and stress ratio at high values of the stress ratio. Quantitative relations are developed to estimate curves of (i) ΔK0 versus R and (ii) ΔK0 versus σy. These curves show good agreement with experimental data for steels and aluminium alloys. A method is presented that may be used as an alternative procedure for obtaining quick and conservative estimates of ΔK0 for design applications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-2695.1992.tb01257.x
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  • 8
    Electronic Resource
    Electronic Resource
    Atmospheric P CO 2 changes recorded in lake sediments (1984)
    [s.l.] : Nature Publishing Group
    Nature 308 (1984), S. 344-346 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Using a four-box model for the global carbon cycle, including the southern ocean reservoir, Lal and Venkatavaradan5 showed that changes in the atmospheric PCo2 or in the large-scale ocean circulation can produce appreciable changes in the atmospheric d14C, of the order observed in the tree-ring ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/308344a0
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    Paper (German National Licenses)
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  • 9
    Electronic Resource
    Electronic Resource
    Polar ice ablation rates measured using in situ cosmogenic 14 C (1990)
    [s.l.] : Nature Publishing Group
    Nature 346 (1990), S. 350-352 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The ice samples were collected during the 1987-1988 field season at Allan Hills main ice field by D. Burtner. The sample locations are Cul-de-Sac (76°46' S; 159°26'E) and (76°43' S, 159°22' E), near station 10 of the triangulation chain by Nishio and Annexstad2'3. The ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/346350a0
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    Paper (German National Licenses)
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  • 10
    Electronic Resource
    Electronic Resource
    Gas-rich meteorites: Probes for particle environment and dynamical processes in the inner solar system (1984)
    Springer
    Space science reviews 37 (1984), S. 111-159 
    Details
    ISSN: 1572-9672
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The discovery in the early sixties of precompaction solar wind irradiation records in the gas-rich meteorites opened up the possibility of studying the solar activity at different epochs in the distant past. Subsequent studies in several meteorites have led to the discovery of the precompaction records of irradiation of constituent grains by solar wind, solar flare and galactic cosmic ray particles. There are also microcraters resulting from their collisions with interplanetary dust grains. Analyses of these records and their observed similarity with those found in the lunar samples led to the hypothesis that the precompaction records in individual components of these meteorites were imprinted while they were residing in the near surface region of their parent bodies, most probably the asteroids. Although the asteroids are the most plausible candidates for the parent bodies of gas-rich meteorites, there exist certain dynamical arguments which tend to favor a cometary origin in certain cases. Also, recent studies indicate that in the case of gas-rich carbonaceous chondrites solar flare irradiation of grains may have occurred prior to formation of the parent bodies. In this review we summarize the significant advances that have taken place in the multi-disciplinary studies (petrography, chemistry, and radiation effects) of the gas-rich meteorites and critically evaluate the present state of our knowledge regarding the origin and evolution of the gas-rich meteorites. The information on the spatial and temporal variations in the interplanetary radiation and particle fluxes, obtained from the analysis of precompaction irradiation records in these meteorites is presented and further studies in certain specific topics are suggested for resolving some of the unsolved problems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00213959
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    Paper (German National Licenses)
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