Dynamic impact properties of a novel auxetic metamaterial

A novel auxetic metamaterial which is organized in the lattice is presented in this paper. Dynamic uniaxial impact behavior of the auxetic lattice using experiment and finite element simulation is investigated. The corresponding results have proved that the plastic beam-based finite element model has good agreement with the experiment. To explore the rate sensitivity of the auxetic lattice metamaterial, impact simulations of auxetic metamaterials at 13.07% relative density are firstly conducted under six velocities range from 1 to 100m/s. The comparison of deformation exhibits that deformation pattern depends on impact velocities. The shock wave effect can be obviously observed in the impact procedure which results in the loss of negative Poisson’s ratio effect at high velocity. The effective impact indices including plateau stress and densification strain can be extracted from the stress-strain curves. The simplified theory model based on the rigid, perfectly-plastic, locking model is utilized to fit data from the simulation. Furthermore, the effect of relative density on impact mechanical properties is investigated. The basic theoretical model is developed by considering the relative density which accords with simulation data well in four relative densities respectively 7.35%, 13.07%, 20.42%, 29.41%. Finally, the formula of plateau stress with respect to impact velocity and relative density can be obtained. The researches herein are aiming to reveal the dynamic properties of the auxetic lattice metamaterial and provide a constitutive model for potential application.