Design and impact analysis of anti-chiral porous structures with tunable Poisson's ratio and thermal expansion coefficient

With the rapid development of industrial science and technology, the demand and research for new structures and materials has become one of the important directions driving industrial development. Meanwhile, the increasingly complex service environment also puts forward higher requirements for the multifunctionality of materials. In this paper, a multifunctional metamaterial with both tunable negative thermal expansion and negative Poisson's ratio (PR) effects is designed by combining the bi-material bending rods and the anti-chiral negative Poisson's ratio (NPR) metamaterial construction method. Theoretical derivation of the effective Poisson's ratio and coefficient of thermal expansion (CTE) was conducted based on the energy method, and the influence of dimensional parameters on the effective PR and CTE was explored. Finally, the impact resistance of multifunctional metamaterials under different component material combinations was comparatively analyzed. The results show that when the component materials 1 and 2 are Invar and Al, respectively, they can have both negative thermal expansion and negative Poisson's ratio characteristics, and have good impact energy absorption properties. Their absorption energy is 1.92 times higher than that of the Al/Invar and Al/Al material combinations.