Energy absorption and self-sensing performance of 3D printed CF/PEEK cellular composites

We report the energy absorption and piezoresistive self-sensing performance of 3D printed discontinuous carbon fiber (CF)-reinforced polyetheretherketone (PEEK) cellular composites. Experiments conducted on three different 2D lattices with hexagonal, chiral re-entrant topologies same relative density (33%) CF loading (30 wt%) reveal that CF/PEEK hexagonal lattice (HL), due its relatively brittle response, shows about 40% 9% decrease in specific (SEA) under in-plane out-of-plane compression, respectively, compared PEEK HL. While collapse response HL is nearly insensitive to strain-rate over 43 ≤ ε̇ 106 s−1, we observe a twenty-fold increase peak stress five-fold SEA impact range strain-rates for The exhibit pronounced both compression maximum sensitivity 3.1 5.2, lattice, offering insight into damage-state. Higher damage indicates faster percolation new contacts folds forming between cell walls within compression. energy-absorbing strain- damage-sensing nature demonstrated here offers design lightweight, high-performance multifunctional lattices.