Crack Paths in a Friction Stir-Welded Pad-Up for Fuselage Applications

Crack paths in friction stir-welded 2198-T8 SE(T) plates with pad-up are investigated. Fatigue tests are performed with and without a friction stir weld in a range of samples, and crack paths and fatigue crack growth rates are compared. The effects of the weld on the damage tolerance of samples are studied. A hole is drilled through the specimen to study its effects on the crack trajectory. It is shown that the crack growth rate is slower with a weld than without a weld. The position of hole can change crack path and crack trajectories. A program is developed to input the residual stress distribution into an ABAQUS finite element model, and the crack paths are predicted to understand the effects of the weld. These predictions are compared with experimental data gathered on crack deviation behavior. The predictions agree well with the experimental findings.