In-plane dynamics crushing of a combined auxetic honeycomb with negative Poisson's ratio and enhanced energy absorption

Abstract

In order to improve the energy absorption capacity of the honeycomb, a combined auxetic honeycomb is designed in this paper. By using the double-inclined walls replacing the horizontal walls of the star-shaped honeycomb (SSH), and introducing a thin-walled circle contacting with the four concave corners of the SSH, the star-circle honeycomb (SCH) is designed. The in-plane dynamic crushing behaviors was explored based on finite element method (FEM). There are three types of deformation modes observed with different impact velocity, including low-, medium- and high-velocity loading modes and the stress-strain curve exhibits two plateau stress stages. Based on the deformation characteristics of the representative unit, theoretical calculation models were established to estimate the plateau stress of the SCH under low- and high-velocity loading according the conservation of energy and the theoretical calculation was in keep well with the numerical simulation. A deformation modes map was summarized to investigate the effects of the impact velocity and the relative density on the deformation modes and the energy absorption capability and the dynamic Poisson's ratio were studied. The result shows that the SCH presents better energy absorption compared with SSH as well as retaining the negative Poisson's ratio property. The deformation mechanism was revealed form the structural design and plastic hinge dissipation. This work presents a different design strategy for the auxetic honeycomb, expected to guide the design of more novel auxetic with better energy absorption and mechanical property.