Effective elastic modulus and energy absorption performance evaluations of a novel re-entrant chiral hybrid honeycomb

Re-entrant honeycombs are widely used in safeguard structures due to their geometric simplicity and excellent energy absorption capacities. However, traditional re-entrant honeycombs exhibit insufficient stiffness and stability owing to the lack of internal support. This paper proposes a new hybrid honeycomb by integrating a chiral component inside the re-entrant honeycomb. Since Young's modulus is a key parameter to evaluate the energy absorption performance and stiffness, an analytical model is given to predict the effective Young's modulus of the proposed hybrid honeycomb. It is found that the optimal design scheme is to directly insert a circular ring inside the re-entrant honeycomb.The normalized specific energy absorption(SEA) of the hybrid honeycomb is 95% larger than that of the traditional re-entrant honeycomb. The normalized SEA first increases to a peak value and then decreases with the cell wall thickness. The optimal thickness of the cell wall for the maximum SEA is derived in terms of the geometric configuration of the unit cell. The normalized SEA first decreases to a valley value and then increases with the re-entrant angle. A longer horizontal cell wall results in a smaller normalized SEA.This paper provides a new design method for safeguard structures with high stiffness and energy absorption performance.