K-R curves of thin 2195-T8 aluminium alloy plate

The dependence of the raising toughness (R-curves) of a 2195-T8 Al-Cu-Li alloy plate on the microstructure is studied. Large intermetallic particles organised in arrays along the rolling direction serve as nucleation sites of ductile fracture; crack growth occurs mainly by pop-in. The application of Rice and Johnson's criterion for ductile fracture, making appropriate use of the average inclusion spacing along the fracture path in LT and TL direction, leads to satisfactory predictions of the onset of pop-ins and of the R-curves toughness plateaus.