Exploration of impact response and damage mechanism of discontinuous CFRP laminates subjected to low velocity impact

Carbon fiber-reinforced polymer composites (CFRPs) are widely used in many fields because of their excellent mechanical properties; however, they are very sensitive to low velocity impact. A new-type biomimetic structure, which has a "bricks-and-mortar" arrangement of nacre from mollusk shells, was designed and manufactured for enhancing the impact resistance of the CFRPs. The impact response and absorption of impact energy of this structure were also investigated. Impact damage forms of the biomimetic structure were analyzed based on the surface and internal morphologies. The results indicate that biomimetic structure can decrease the impact damage of the CFRPs. Two damage behaviors of the biomimetic structure were observed under relatively higher impact energy. The discontinuous structure reduces the damage using a smaller load for the first damage and a larger deformation for the second damage, which improves the impact resistance of the CFRPs. The discontinuous structure restrains longitudinal crack propagation to a certain extent, effectively reducing the damaged area of the CFRPs. Thus, the proposed structure can increase the strength retention rate of the material by about 5%. In addition, the compression after impact damage modes of CFRPs with three types of structure are summarized and classified originally.