Effect of fatigue crack length on failure mode of a center-cracked thin aluminium plate

The residual strength of a 1 m wide and 1.6 mm thick plate containing a centre crack has to be estimated in order to compare with experimental findings. The plate is made of 2024 aluminium alloy. A notch is machined and the plate is pre-fatigued to an initial crack length of 10 mm. Then the plate is subjected to a constant amplitude fatigue loading from 0 to 100 MPa \(\sqrt m \) . Evaluate the residual strength of the plate after 10000 and 80000 cycles. The 2024 aluminium alloy obeys the following fatigue crack growth rule:da/dN = 2.5 x10−12 (ΔK)4, with da/dN in m/cycle and ΔK in MPa. Yield stress: σy = 400MPa and fracture toughness for thickness of 1.6 mm: Kk = 130MPa \(\sqrt m \) .