Integrated characterization of fully 3D printed shoes using lightweight microfoamed TPU

This study evaluated the manufacturing process and mechanical performance of fully 3D-printed shoes fabricated using polylactic acid (PLA), lightweight PLA (LW-PLA), thermoplastic polyurethane (TPU), and lightweight TPU (LW-TPU). The filaments were characterized through rheological, differential scanning calorimetry (DSC), and morphological analyses, and fully 3D-printed shoes were fabricated using dual-nozzle fused deposition modeling (FDM) with three body/support material configurations: LW-PLA/PLA, TPU/LW-PLA, and LW-TPU/PLA. The printed shoes were evaluated for morphology, compressive properties, impact attenuation behavior, and preliminary plantar pressure analysis. LW filaments maintained porous structures after extrusion and printing, while TPU shoe and LW-TPU shoe showed greater deformability than the rigid LW-PLA shoe. The TPU shoe showed strong impact absorption through large deformation, whereas LW-TPU shoe exhibited a balanced response with low stiffness, high compressive deformability, controlled impact attenuation, and lightweight structure. A pilot plantar-pressure evaluation with two participants was conducted to obtain preliminary pressure distribution observations. The peak pressure results showed a tendency toward reduced pressure in selected metatarsal and heel regions for the TPU shoe and LW-TPU shoe, while LW-TPU shoe showed increased contact area in the midfoot and heel regions. Overall, LW-TPU showed potential as a promising material candidate for fully 3D-printed shoes, and this study provides foundational data for future material selection, process optimization, and standardized evaluation of fully 3D-printed footwear.