Structure design and mechanical properties of a novel anti-collision system with negative Poisson's ratio core

• Novel double-arrow structures with negative Poisson's ratio are proposed. • The novel hexagonal structure has better energy absorption efficiency than the existing tetragonal structure at the same relative density. • The proposed multi-objective optimization method and robustness analysis improve the crashworthiness and the robustness of the structures. • The crash box with NPR core absorbs more impact energy than the traditional crash box under the trolley collision experiment. Novel three-dimensional double-arrow structures with negative Poisson's ratio (NPR) based on the concept of hexagonal crystal system are proposed to enhance the energy absorption for impact load cases, the corresponding prediction formulas of mechanical properties are deduced, the deformation modes, fracture characteristics, rebound characteristics and energy absorption performance of structures are studied by simulation and experiment. The influences of impact velocity characteristics and microstructure parameter characteristics on crashworthiness are further discussed. A multi-objective optimization strategy containing optimal Latin hypercube sampling, response surface method, and non-dominated genetic algorithm is developed to optimize the microstructure parameters and improve the crashworthiness of double-arrow structure. Considering a lot of uncertainty factors in practical engineering problems, an uncertainty analysis of NPR core crash box is carried out by using the 6-Sigma robustness analysis method. A comparative experiment on traditional crash box and NPR core crash box is performed to explore the crashworthiness under front bumper impact experiment. NPR core crash box shows remarkable energy absorption effects compared with traditional crash box. This study provides valuable suggestions and guidance for the design and application of structures with negative Poisson's ratio under impact load cases.