Three dimensional finite element prediction of crack closure and fatigue crack growth rate for a corner crack

The effect of plasticity induced crack closure on fatigue crack growth rate has been examined for the case of a 2024 aluminium alloy plate with two lateral corner cracks emanating from a central hole. The plate was subjected to constant amplitude loading and a combination of constant amplitude and single overload loading prior to the measurement of the opening load. The opening load was measured by comparing the strain ahead of the crack tips with the far field strain as the load on the specimen was cycled. Measurements were also made of the growth rate of the crack in fatigue.