Factors of Crack Initiation and Microcrack Propagation in Aluminum Lithium 2091 and in Aluminum 2024

Abstract

Initiation and microcrack propagation stages were investigated by optical microscopic observations of fatigue damage . The differerices observed at high fatigue lives on S-N curves are found to correlate with the nature of initiation sites . It is shown that microcrack growth rates are equivalent for both 2024 T351 and 2091 T8 alloys, though long crack growth rates for 2091 T8 are lower as compared to those of 2024 T351 .

Fatigue Behavior of Aluminum–Lithium Alloys

“…Some of the studies that have attempted to investigate the HCF behavior of AlÀLi alloys include an evaluation of (i) effect of lithium content, (ii) effect of prestrain before artificial aging, (iii) degree of aging, (iv) crystallographic texture, and finally (v) the role of impurity elements resulting in the presence of coarse intermetallic particles in the alloy microstructure (Bischler and Martin, 1987;Bretz et al, 1984;De et al, 2011;Di et al, 1987;Farcy et al, 1987;Peters et al, 1986). However, few studies have attempted to conduct a detailed investigation and to provide a convincing explanation of the observed behavior.…”

Thermal Structures and Materials for High-Speed Flight

“…The dynamic response is of considerable interest, and two representative examples are shown in graphical form, Figures 3 and 4, with loading given by Eqs. (35) and (36), respectively. In each figure, the "elastic" curve is the result of runs made with the constitutive model "locked" to prevent material yielding (even though such response is not possible at those temperatures) for a comparison to the viscoplastic response.…”