Compressive behavior of age hardenable tetrahedral lattice truss structures made from aluminium

Open cell, lattice truss structures have been made by folding perforated 6061 aluminium alloy sheets. Simple air brazing is used to construct sandwich panels with cellular core relative densities between 0.02 and 0.08. Some panels were quenched and aged while others were tested in an annealed condition. The measured peak compressive strengths varied from 0.7 to 20 MPa, increasing with core relative density and parent alloy yield strength. The peak strength of the annealed lattice significantly exceeds ideal-plastic predictions. A model based on inelastic column theory incorporating strain hardening was able to predict the lattice truss core's compressive peak strength capacity in both the annealed and age hardened conditions, for all relative densities tested. Comparisons with compressive strength data for other cellular metals indicate that wrought aluminium alloy tetrahedral lattice structures outperform aluminium foams and prismatic corrugations, and compare favorably with honeycombs when the strain hardening of the parent alloy is high. Their impact energy absorption can be similarly tuned and competes well with other concepts under high intensity loading conditions. (C) 2004 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.