Crashworthiness behavior of Koch fractal structures

Thin-walled structures are currently used in automotive and aerospace fields due to their excellent lightweight and crashworthiness properties. This paper describes a new crush absorber design based on the Koch fractal (KF) geometry to improve energy absorption performance. The crash performance of three Koch fractal designs, one single-wall and two hybrid (double-wall), with different Koch fractal orders and wall thicknesses are investigated by experimental testing and computational modelling. Computational models of 1st order basic Koch and hybrid Koch structures are developed, with the predictions being compared with the experimental data. The computational simulations reveal a significant synergistic effect in the hybrid Koch structure, stemming from the interaction between the inner Koch wall and the external wall. Among the three designs of Koch structures, the 2nd order hybrid Koch absorbers give the highest specific energy absorption performance. Furthermore, these 2nd order hybrid Koch absorbers outperform a wide range of multi-cell structures of the same mass. The findings of this research open up a new route of designing novel lightweight energy absorbers with improved crash characteristics. (C) 2018 Elsevier Ltd. All rights reserved.