โ Scribed by G.E. Nordmark; J.G. Kaufman
No coin nor oath required. For personal study only.
Fatigue-crack propagation data have been obtained for a variety of aluminum alloys. tempers, and products in relatively thick sections of interest for large aircraft shapes. For the higher stress-intensity ranges. the alloys rate in about the same order with regard to resistance to fatigue crack propagation as with regard to plane-strain fractare toughness. However, for low stress intensity ranges (i.e. short cracks or low load ranges) the rate of fatigue-crack propagation was lowest for two alloys. 2020-T6S 1 and 2014-T652.
which have low plane-strain fracture toughness. The relative order for different specimen orientations was generally consistent with that based upon plane-strain fracture toughness. High humidity results in higher rates of fatigue-crack propagation. with the effect indicated to be largest for those alloys which are susceptible to stress-corrosion cracking.
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