Experimental characterization of additively manufactured flexible cellular materials under different dynamic loading

Abstract

This doctoral research explores the mechanical behavior of flexible cellular materials fabricated via Fused Filament Fabrication (FFF) using thermoplastic polyurethane (TPU). Five cellular topologies—hexagonal, re-entrant, square, and their rotated variants—were designed, printed, and experimentally tested under different loading conditions. First, cyclic compression tests revealed that stiffness and deformation modes depend strongly on topology. Fatigue tests up to 100,000 cycles showed differences in durability and stiffness degradation, with re-entrant and rotated designs maintaining better mechanical performance over time. Impact tests using an open Hopkinson pressure bar (OHPB) setup were then conducted to assess dynamic response, highlighting how topology and orientation affect energy absorption and peak force. Finally, a proof-of-concept application was developed by integrating the cellular structures into the heel region of a tennis shoe sole. Fatigue testing of these inserts confirmed their potential as cushioning components in footwear. The findings demonstrate how design and topology influence the performance of FFF cellular materials, providing insights for their use in impact-resistant and energy-absorbing applications.