MANOEUVRE SPECTRUM FATIGUE CRACK PROPAGATION IN ALUMINIUM ALLOY SHEET MATERIALS.

2024-T3, 2048-T851, 7075-T6 and 7475-T761 aluminum alloy sheets were compared for fatigue crack propagation resistance under maneuver spectrum and constant amplitude loading. For maneuver spectrum loading 7475-T761 was superior overall, and this superiority is most probably due to the superior fracture toughness of this alloy. In more detail, 2024-T3 was superior for lower stress levels and lower crack growth rates with maneuver spectrum loading and for lower DELTA K values with constant amplitude loading, while 7475-T T761 was superior for higher crack growth rates and higher stress levels with maneuver spectrum loading and for higher DELTA K values with constant amplitude loading.