Research on the damage and energy absorption characteristics of spiral gradient composite structures subjected to impact loading

Inspired by the gradient structure and spiral structure in the dense impact region and the periodic region of the chelates of the finch-tail mantis shrimp, the back surface spiral laminates (BSL) and impact surface spiral laminates (ISL) with gradient design are designed and fabricated, and compared with compared with the common full spiral laminates (FSL) and non-spiral unidirectional laminates (NSL), respectively. The damage and energy absorption of four laminates with different structural designs are compared and analyzed by impact tests at two impact speeds. Combined with the numerical simulation analysis, the damage process and energy absorption of each layer are investigated, and the damage and energy absorption characteristics of the spiral gradient structure are discussed. The results indicate that the energy absorption of the FSL, ISL and BSL are 30.89 %, 27.13 % and 24.74 % greater than that of the NSL as the impact velocity is approximately 132 m/s. The spiral structure of laminated panels significantly improves impact resistance, although the influence of gradient structures remains to be determined. When the impact velocity is approximately 220 m/s, the energy absorption of the FSL, ISL and BSL are 33.21 %, 19.92 % and 19.96 % lower than that of the NSL, respectively. Compared to the gradient structure, the spiral structure in composite laminates significantly weakens the impact resistance.