In-plane dynamic crushing of a novel honeycomb with functionally graded fractal self-similarity

Abstract

While the separate design of functionally graded and fractal self-similarity structures had shown to be effective in improving the energy absorption capacities of honeycombs, their combined effect is still unknown. Hence, in this study, a series of novel fractal honeycombs are proposed based on the combination of functionally gradient with fractal self-similarity features, which are constructed by varying the fractal parameter in each layer of the traditional self-similar honeycombs. Two graded fractal honeycombs with symmetric gradient and another two with asymmetric gradient are presented, and their dynamic crushing behaviors are numerically investigated. The numerical approach is first validated by comparing against theoretical and experimental data. Subsequently, it is demonstrated that the SG-I honeycomb can present the best energy absorption behavior (89% higher than traditional honeycomb) for low-velocity impact, while SG-II honeycomb performs the best for specific energy absorption (17% larger than traditional honeycomb) for high-velocity impact. Furthermore, deformation patterns under dynamic crushing can be controlled through the introduction of different gradient distributions. The graded fractal honeycombs present significant improvements to the absorbed energy and mean crushing force over traditional honeycombs, offering a new route to the design and optimization of future lightweight energy absorption systems with improved safety protection performance.