Investigation into the effect of impact damage on compression behavior of the omega-stiffened composite panels

Abstract With superior performance and weight-saving potential, composite structures have been increasingly applied in the aerospace industry. The damage process and post-buckling deformation of composite panels under compressive load have been proven to limit the application of composite structures. For the purpose of utilizing the full potentiality of thin-walled composite structures, an experimental investigation was employed to explore the influence of impact damage on the buckling behavior and the load-carrying capacity of omega-stiffened composite panels. Pristine panels and impact-damaged panels were under compressive load until failure. The results showed that the pristine panels had higher compressive stability and ultimate strength, and the existence of impact damage led to a decline in the buckling load and the carrying capacity, which were up to 16% and 27%, respectively. Additionally, the complex stress state caused by the introduced impact damage influenced the buckling response and the damage patterns of the omega-stiffened panels. The pristine panels exhibited typical compression failure mode, with matrix crack and fiber breakage in the stringer and the skin. However, the collapse of the pre-damaged panels was dominated by the debonding of the skin-stiffener interface and the out-of-plane deformation of the skin.