A new multifunctional multi-arc enhanced cylindrical metastructure integrating stable mechanical properties, two plateau stress stages, and Poisson's ratio sign-switching

The increase in energy absorption is often accompanied by an increase in stiffness, which will exacerbate structural damage under compressive load. Based on multi-arc enhanced re-entrant honeycomb, a novel multi-arc enhanced cylindrical metastructure (MAECM) is designed in this paper to solve the conflict between stiffness and energy absorption. The new metastructure exhibits two plateau stress stages, Poisson's ratio sign-switching, and constant Poisson's ratio. Specimens with different parameters are printed, and the corresponding finite element models are established. The effects of various parameters on mechanical properties are investigated by finite element analysis and experiment. Results show that the two plateau stress stages and Poisson's ratio sign-switching can be achieved through the self-contact of the connecting rods. The constant Poisson's ratio can be achieved under specific geometric parameters to achieve stable mechanical properties of the structure. The geometric parameters can effectively adjust the Young's modulus, specific energy absorption (SEA), Poisson's ratio, contact strain, and sign-switching strain of the structure. Compared with the original structure, the Young's modulus of MAECM has decreased by 67 %, and the energy absorption has increased by 164 %. The various mechanical properties, low stiffness, and superior energy absorption capacity of MAECM make it more advantageous than other proposed structures. These outstanding mechanical properties enable MAECM to solve the conflict between stiffness and energy absorption. The lower Young's modulus and adjustable Poisson's ratio enable MAECM to be used as the internal supporting substructure of the missile skin. The deformation of the MAECM can achieve the adjustment of the missile's motion attitude. MAECM expands the application of metastructures in the aerospace field and provides a novel method for designing multifunctional metastructures.