Effects of print orientation on the design of additively manufactured bio-based flexible lattice structures

In upholstery applications, it is common to use polyurethane (PUR) foam when flexibility is desired. However, as PUR is a carbon-based material produced using toxic isocyanates, it is environmentally beneficial to replace PUR with bio-based alternatives. The challenge, however, lies in finding suitable bio-based replacement materials, capable of mimicking the foam-like functionality of PUR since many are stiff and brittle. Therefore, instead of relying on the inherent material property, this paper explores the possibility of producing flexible foam-like structures from bio-based materials with additive manufacturing (AM) employed as the manufacturing technique. As one of the key design constraints associated with AM is the intrinsic material anisotropy in the build direction, this paper focuses on the effects of print orientation on the compressive behaviour of structure which is indicative of flexibility. Three open-celled strut-based lattice structures are chosen for this purpose and the effect of these cell topologies on the compressive behaviour of structures is studied. The scope of this work includes structures printed using selective laser sintering (SLS) in a bio-based polyamide material (PA 1101). The results show that material failure and deformation behaviour are affected by print orientation, while the amount of plastic deformation is more influenced by the lattice cell topology.