Damage tolerance of FSWed integral wing panel reinforced by bonded crack retarders

A total of 2195 T8 samples were designed, and the friction stir weld lines were kept in the sample center. Two kinds of crack retarders were designed and bonded onto the samples in three different positions. Fatigue tests were performed with and without crack retarders bonded on the samples. Crack growth rates and fatigue lives were measured and compared with each other. The effect of crack retarder's width and position on damage tolerance was studied. Crack paths were observed and studied. It is shown that the wider size crack retarder can improve fatigue life even two times more than the narrower one, and it can make crack paths smooth. The damage tolerance of the panel achieves the best performance when the retarder covers the weld zone completely.