In-plane compression behavior and energy absorption of hierarchical triangular lattice structures.

Hierarchical structures greatly enhance the anti-crushing behavior of thin-walled tubular structures. To reveal the hierarchical mechanism, hierarchical lattice tubes (HLTs) with lattice sandwich walls were designed and manufactured. In-plane compression experiments were carried out to reveal the progressive collapse modes and folding mechanisms. Compared with single-cell tubes (STs) and multi-cell lattice tubes (MLTs), HLTs possess much greater mean crushing forces (MCFs), three to five times higher. Two crushing mechanisms were revealed, including the hierarchical sandwich-folding mechanism and the multi-folding mechanism. Hierarchical sandwich-fold has much greater plastic bending moment while multi-fold has much shorter wave-length. Both these two mechanisms let hierarchical structure greatly improve its anti-crushing ability and weight efficiency in energy absorption. Theoretical models were proposed to predict the MCF and the specific energy absorption (SEA) of the HLT. These models are consistent with the test data and correctly reflect the energy absorbing ability of the HLT. [ABSTRACT FROM AUTHOR]