Effects of bonded crack retarders on fatigue parameters of FSWed integral panel

As known, friction stir welded (FSWed) joints are mature to be applied in aircraft structure. However, the weld creates local discontinuity in property and local tensile residual stress, which harm the damage tolerance of welded panels. So crack retarders were bonded in the weld zone to improve damage tolerance. Finite element method was used to calculate stress intensity factors by ABAQUS software. Finite element models were built to simulate the function of bonded retarder. Cohesive elements were used between the substrate panel and bonded retarder. A Fortran program was made to input residual stress to finite element models. Stress intensity factors from residual stress with and without bonded retarders were calculated and compared. Effects of residual stress on stress intensity factors and redistribution of residual stress were taken into considered. Effective R ratios were calculated with crack growing through the weld. Effects of bonded retarder on stress intensity factors were calculated. The results were compared with the experimental findings.