High velocity impact behaviour of additively manufactured cellular core backed Kevlar

This work investigates the effect of several parameters of a cellular core, protected by a Kevlar plate, under ballistic impact. Three core geometries, two sizes, and four relative densities are explored and their effects quantified. Overall, auxetic geometries (re-entrant and double arrowhead) result in a significant reduction in transmitted force at the cost of increasing the maximum displacement compared to a non-auxetic hexagonal structure. The cell size has no effect on the maximum displacement for any of the geometries or the transmitted force for the auxetics. A smaller cell size does, nonetheless, increase the peak transmitted force for the hexagonal structure. Increasing the relative density of the structures increases the transmitted force whilst decreasing the maximum displacement across all unit cells considered. This work provides a basis for the parameter selection when using cellular structures in an impact mitigation setting.