A gust spectrum representative of the load history of an under wing skin in a transport aircraft was used in flight simulation fatigue crack propagation tests on 2024-T3 and 7475-T761 aluminum alloy sheet. Tests were conducted at several design stress levels and in environments of air and air plus water spray. Results show that the fatigue crack propagation resistance of 2024-T3 sheet under gust spectrum loading is generally superior to that of 7475-T761 sheet, and that this superiority is mainly due to a greater amount of crack growth retardation during the less severe loads and flights that follow the peak loads in severe flights. The straightforward use of 7475 alloy in tension-critical structures like the under wing skin of a transport aircraft would result in decreased crack propagation resistance. In order to utilize the higher static structural efficiency and fracture toughness of 7475 alloy (in relation to 2024-T3), it may be possible to improve the relative performance by selecting an adhesive bonded laminated sheet or sandwich panel concepts.
Flight Simulation Environmental Fatigue Crack Propagation in 2024-T3 and 7475-T761 Aluminum
1980
10 pages
Report
No indication
English
ALUMINUM ALLOY SHEET 5.7Zn - 2.2Mg - 1.6Cu - 0.22Cr (7475-T761)
SAE Technical Papers | 1976
ALUMINUM ALLOY SHEET 5.7Zn - 2.2Mg - 1.6Cu - 0.22Cr (7475-T761)
SAE Technical Papers | 1978
ALUMINUM ALLOY SHEET, ALCLAD 5.7Zn - 2.2Mg - 1.6Cu - 0.22Cr (7475-T761)
SAE Technical Papers | 1979