Compression behaviour of TPU printed 2D lattice structures using fused filament fabrication: Characterization and applications

Lattice structures are ideal for energy absorption applications due to their unique ability to distribute and dissipate forces efficiently. This study investigates the compression and deformation behaviour of auxetic (re-entrant) and non-auxetic (hexagonal, square) 2D lattice structures of the same volume fraction fabricated through fused filament fabrication with Thermoplastic Polyurethane (TPU) material. Uniaxial quasi-static out-of-plane compression tests were performed to evaluate properties such as stiffness, yield strength, and energy absorption. The behaviour of lattice structures can be categorized into elastic, plateau, and densification regions, reflecting their deformation mechanism under quasi-static compression load. The experimental findings reveal that the re-entrant lattice exhibits greater stiffness, while the square lattice demonstrates superior energy absorption capabilities. A combination of higher energy absorption and stiffness lattice forms a blend lattice, resulting in mechanical characteristics that fall between those of individual lattice types. These lattices have a softening effect, which can be minimized in a blend lattice. To leverage these advantages, a shoe sole was designed using these lattices to improve comfort and fit.