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