Fatigue-life calculations on pristine and corroded open-hole specimens using small-crack theory
✍ Scribed by J.C. Newman Jr.; W. Abbott
- Publisher
- Elsevier Science
- Year
- 2009
- Tongue
- English
- Weight
- 501 KB
- Volume
- 31
- Category
- Article
- ISSN
- 0142-1123
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✦ Synopsis
This paper uses a plasticity-induced crack-closure model and small-crack theory to calculate the fatigue lives of 2024-T3 aluminum alloy sheet specimens with open holes subjected to cantilever (R = À1) bending loads. The bending specimens had three drilled holes that were either pristine or exposed to outside weather conditions at various locations for 3-12 months. The exposed specimens developed various levels of corrosion pits in and around the holes. These pre-corroded specimens were then returned to the laboratory and fatigue tested under laboratory-air conditions with cantilever bending loads. The present paper uses fatigue-crack growth with an equivalent-initial-flaw-size (EIFS) to fit the fatigue behavior of the exposed specimens. Improved stress-intensity factor equations for a corner crack at the edge of an open hole under remote bending were used to make the fatigue-life calculations. The EIFS values agreed well with the median corrosion-pit depths measured on the exposed specimens with moderate corrosion. For one case of severe corrosion, the EIFS value was much larger than the measured pit depth.