Effect of impact damage positions on the buckling and post-buckling behaviors of stiffened composite panel

Effect of impact damage positions on the buckling and post-buckling behaviors of stiffened composite panels under axial compression were investigated in this paper. Barely visible impact damage (BVID) was introduced to three different positions on the smooth sides at impact energy 50 J. Impact crater depths and damage areas were measured and relationships between the two parameters were affirmed. Compression after impact (CAI) experiments were conducted both on the damaged and undamaged specimens to achieve the effect of impact damage on buckling and post-buckling behaviors. The results show that only local buckling in skin bay occurs without global buckling appearing for both damaged and undamaged specimens, which contains four half waves. The buckling load of damaged and undamaged specimens varies little. However, the failure loads of damaged specimens decrease to different extent according to their impact positions, with a maximum decrease of 10% compared to the undamaged specimens. Failure modes of the damaged and undamaged specimens are similar and complex, which contain the debonding of skin to stiffeners, breaking of stiffeners as well as tearing and splitting of skin.