A more weight-efficient hierarchical hexagonal multi-cell tubular absorber

Hierarchical metallic thin-walled tubes are more weight-efficient than single-cell tubes (STs) in energy absorption. Tubes with regular hexagonal single-cell section and hierarchical section are designed, tested and analyzed. Crushing mechanisms of these structures are revealed through finite element analyses (FEAs) and axial compression experiments. It is found that for hierarchical tubes (HTs) there are three folding styles, including sub-cell folding, mixed folding and global folding. Sub-cell folding greatly increases the mean crushing force (MCF) of the tube and the MCF reaches to the apex when appears the mixed folding, which is the transition from sub-cell folding to global bending. Plastic models for these three folding styles are built and consistently predict the MCF. The research indicates that the HT is a more weight-efficient energy absorber. (C) 2018 Elsevier Ltd. All rights reserved.