Impact behaviour and protection performance of a CFRP NPR skeleton filled with aluminum foam

• A lightweight composite material body, comprising both soft and hard phases, was prepared by filling an auxetic structure fabricated from CFRP with aluminum foam. • The impact behaviours of the representative volume element were investigated to elucidate the underlying mechanisms of wave motion, deformation and failure. • The explosion responses were divided into three stages via two limit lines, and the enhanced energy absorption characteristics and protection performance were illustrated. In order to enhance the protection capability during impact loading, a composite material body (CMB) has been constructed using aluminum foam and a negative Poisson’s ratio (NPR) structure. The re-entrant NPR structure, fabricated from carbon fiber reinforced plastic (CFRP), serves as the skeleton, while the aluminum foam acts as an enhancer. The impact behaviours of a representative volume element were tested in three characteristic directions (referring to the in-plane re-entrant and vertical directions 1 and 2, and the out-of-plane normal direction 3) using both experimental and numerical methods. The impact responses of the CMB sandwich structures under explosion impact were then numerically predicted. The experimental results demonstrate that the RVE exhibits superior damping performance in the 1 and 2 directions in comparison to the 3 direction. The results demonstrate that the displacement field of the CMB is sectioned into distinct zones by its skeleton during explosion impact, which is attributed to the differing properties of the aluminum foam and CFRP. Furthermore, a graded failure mode within the specified protection limit is observed, indicating that the incorporation of aluminum foam filler has the potential to improve the protective capability. These findings provide insights into the structural design of impact protection engineering.