Impact Analysis of Auxetic Structures for Military Applications

Abstract

Abstract: Auxetic structures are special structures which tend to become wider when subjected to longitudinal tension instead of getting compressed, which implies structures having a negative poisson’s ratio. These structures are used in impact pads due to this unique property. In this comparative study were done on different types of materials and structures which are recognized for 3D printing the auxetic structures. The three stages of explicit dynamic analysis involves firstly selecting the most appropriate structures from chiral truss, re-entrant hexagon, arrow head and one non- auxetic structure which is hexagon structure. From this the structure having the least deformation at the impact point is selected which is re-entrant hexagon. Following this, keeping re-entrant hexagon as the structure, the next set of analysis is performed by varying the structure materials. Polycarbonate, polystyrene, polyvinyl chloride and high density polyethylene were studied and the analysis results showed, polyvinyl chloride as the suitable material. Lastly the limiting velocity for the impact is calculated by varying the impact velocity from 800m/s, 1000m/s and 1200m/s beyond which the structure experienced fracture. This study proposes the selection of suitable auxetic structure and material for manufacturing impact pads. Keywords: Auxetic structures, impact pads, indentation resistance, explicit dynamics, 3D printing, FDM, Poisson’s ratio