Hybrid design and energy absorption of luffa-sponge-like hierarchical cellular structures

Luffa sponge has hierarchical cellular structure with macro-pores and micro-pores. Its strength is greatly enhanced by the stiff inner-surface layer around the macro-pores. This hierarchical bio-cellular structure was mimicked to construct a hierarchical aluminum foam cylinder reinforced by stiff thin-walled carbon fiber reinforced plastic (CFRP) tubes. Compression behaviors of the luffa-sponge-like hierarchical foam cylindrical structures were revealed and it is found that the specific energy absorption (SEA) of the hierarchical structure is greatly improved compared with the pure aluminum foam cylinder. Interaction between the CFRP tube and the aluminum foam lets the SEA of the hierarchical cylinder is greater than the linear summation of the SEA of each component in the hierarchical foam. Through hybrid and hierarchical design, an ultra-light composite cellular structure with excellent energy absorption was developed. (C) 2016 Elsevier Ltd. All rights reserved.