Ultra-slow Fatigue Crack Propagation in Metallic Alloys

AbstractThe influence of frequency (20kHz ultrasonic tests and conventional 20 to 35Hz tests) and environment (air and vacuum) on near-threshold fatigue crack propagation of three metallic alloys, Ti-6Al-4V, 2024-T351 and 12% Cr stainless steel is compared experimentally. The effective stress-intensity factor which is considered as the propagation driving force is determined from closure measurements or tests run at high R-ratio. Based on microfractographic observations, the results are discussed in terms of a preexisting model for intrinsic and environmentally assisted fatigue crack propagation

Vergleichende biomechanische und mikro-computertomographische Untersuchung des Einheilverhaltens bioresorbierbarer Magnesium-Pins und konventioneller Titan-Implantate im transkortikalen Rattenmodell

Recently, Haesevoets, Folmer, and Van Hiel (2015) strongly questioned the comparability and equivalence of different mixed–motive situations as modelled in economic games. Particularly, the authors found that different game correlated only weakly on average and loaded on two separate factors. In turn, personality traits failed to consistently account for behavioural tendencies across games. Contrary to the conclusions of Haesevoets et al., these findings are actually perfectly in line with the game–theoretic understanding of the different economic games. If one considers the variety of specific motives underlying decisions in different games, Haesevoets et al.'s findings actually support the validity of different games rather than questioning it. This, in turn, emphasizes the necessity for the plethora of different games that have been developed over decades in economics and psychology

Asthenospheric signature in fertile spinel lherzolites from the Viliga Volcanic Field in Northeast Russia

none5Mantle xenolith bearing olivine melanephelinites from the Okhotsk sector of the Okhotsk-Eolteka Volcanic Belt (OCVB), northeastern Russia, occur as small isolated volcanoes emplaced within massive late Early to Late Cretaceous subduction-related calc-alkaline rocks. The xenoliths are typical medium- to fine-grained anhydrous mainly spinel lherzolites that are strongly to weakly foliated with intensive to minor recrystallization to equigranular texture. The primitive mantle normalized whole-rock REE have flat patterns or patterns with slightly elevated light REE (LREE) ((La/y-b)N = 0.48-1.38). The REE in clinopyroxenes have systematically decreasing normalized abundances from Sm to La, implying that the LREE enrichments in the whole-rock REE patterns are attributed to circulation of minor intergranular fluids or melts. Equilibration temperatures and pressures calculated for the Viliga samples are in the range of 1050-1160 °C and 15-21 kbar, respectively. Ca diffusion rates in olivine reveal a rapid transport to the surface (2-6 days) of these peridotites. Model calculations have shown that the fertile lherzolites can be produced by 2-9% batch melting, whereas the depleted peridotites require 15% batch melting of a primitive source. The cessation of the interaction between the palaeo-Pacific plate and the NE Russian margin at c. 87 Ma apparently caused a 'piecemeal' collapse of the former followed by intrusion and ascent of olivine melanephelinitic magma, which entrained xenoliths from the asthenospheric mantle of the subducted plate during the Pliocene through the generated window(s). Moreover, clinopyroxenes that have low 87Sr/86Sr and high 143Nd/144Nd and plot in and above the mid-ocean ridge basalt (MORB) field are consistent with an upwelling asthenospheric mantle through the window(s) created by the 'piecemeal' collapse of the palaeo-Pacific plate. © The Geological Society of London 2008.noneNTAFLOS T.; TSCHEGG C.; COLTORTI M.; AKININ V.; KOSLER J.Ntaflos, T.; Tschegg, C.; Coltorti, Massimo; Akinin, V.; Kosler, J