In-plane energy absorption evaluation of 3D printed polymeric honeycombs

Honeycomb structures have been widely used for impact protection and energy absorption applications. However, studies on such structures have been mainly limited to metallic honeycombs with little research done on polymeric honeycomb structures. The purpose of this paper is to study the in-plane static compressive crushing behaviour and energy absorption capacity of 3D printed polymeric honeycomb structures of different unit cell thicknesses. Uniaxial quasi-static compression tests were performed on hexagonal honeycomb structures of varying wall thicknesses printed in Nylon 12 by fused deposition modelling 3D printing. Numerical simulations using ABAQUS/Explicit finite element analysis software were performed to determine the compressive behaviour of the same honeycomb structures. Gibson and Ashby's analytical model was also used to determine the theoretical plateau stresses of the honeycombs. The experimental compressive behaviour, plateau stress and energy absorption capacity of the honeycombs were compared with numerical and analytical values. It was found that experimental results obtained are in good agreement with computational numerical solutions and with the theoretical model for all cell wall thickness to cell wall length ratios. It was also observed that the plastic deformation of hexagonal honeycombs are different in its two main in-plane directions and 3D printing can be applied to generate honeycomb structures of varying geometry and energy absorption capacity with predictable performance.