High velocity impact response of sandwich structures with auxetic tetrachiral cores: Analytical model, finite element simulations and experiments

Abstract

This paper investigates the energy absorption and deformation characteristics of sandwich structures with auxetic tetrachiral core under high velocity projectile impact. The finite elementmodel of the structure is developed using the Johnson-Cook material model and is used to studythe effects of projectile impacts forvelocities between150 and 450 m/s. TheFE model is validated usingin-houseexperiments on 3D printed PLA sandwich with tetrachiral core under hemispherical projectile impact and also using experimental datareported in the literature. Further, a semi-analytical model is developed to estimate the residual velocities and energy absorption of sandwich structure under blunt projectile impact, which shows good agreement with the FE results with an error of less than 8%. Finally, the performance of the sandwich structure with tetrachiral cores is studied under projectile impact for velocities ranging from 150 to 350 m/s and compared with sandwich structures with re-entrant and double arrowhead cores. The results show that for velocities above the ballistic limit, the energy absorbed by the facesheets, and core are nearly constant and is greatest for blunt projectile impact, followed by hemispherical, ogive, and conical geometries. Furthermore, sandwich structures with auxetic cores exhibit better energy absorption characteristics compared to those with hexagonal honeycomb cores.