Energy absorption enhancement of additively manufactured hexagonal and re-entrant (auxetic) lattice structures by using multi-material reinforcements

The effect of using multiple materials within hexagonal and re-entrant (auxetic) cellular structures was investigated. For each topology, three different material configurations including (a) Nylon, (b) Carbon fibre reinforced Nylon and (c) Glass fibre reinforced Nylon were used. A numerical model was constituted to imitate the compressive behaviour of these multi-material cellular structures under quasi-static loading. For the validation, samples were printed with Fused Filament Fabrication (FFF) technique and experimentally tested. A good correlation was captured between numerical and experimental analyses. This study found that deploying a multi-material approach enhanced the re-entrant cellular structures specific energy absorption, compressive strength and modulus values over the single Nylon structure of 60 %, 104 % and 201 %, respectively. A similar trend with lesser improvements of 15 %, 60 % and 127 % was monitored for hexagonal cellular structure, in the same sequence.