Search

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

We theoretically investigate the effects of atomic defect related short-range disorders and electron-electron interactions on Anderson type localization and the magnetic properties of hexagonal armchair graphene quantum dots using an extended mean-field Hubbard model and wave packet dynamics for the calculation of localization lengths. We observe that randomly distributed defects with concentrations between 1 and 5% of the total number of atoms leads to localization alongside magnetic puddle-like structures. Although the localization lengths are not affected by interactions, staggered magnetism and localization are found to be enhanced if the defects are distributed unevenly between the sublattices of the honeycomb lattice., TUBITAK (116F152)