Multi-objective optimization of diaphragm reinforced bamboo-inspired energy absorption systems

Traditional cellular materials cannot tune the mechanical properties after manufacture. Modular metamaterials possess desirable flexibility and tunability, while their crashworthiness is generally inadequate. To break these limits, bionic diaphragm reinforced bamboo-inspired systems are proposed in this work. The internodes and nodes are in-plane loaded, whilst the diaphragms are out-of-plane loaded to intensify membrane deformation, triggering property advantage combination under various load conditions. Based on experimental and simulation results, specific energy absorption of the proposed systems is up to 47 % larger than existing bamboo-inspired system of same mass, where long effective stroke, neglectable stress peak, self-locking robustness and mechanical tunability are observed. Surprisingly, their crashworthiness is optimum among the self-locked systems and even comparable to cellular materials under out-of-plane loads. A three level Box-Behnken design method with relative error less than 3.7 % is then implemented by Design Expert 13.3, combining response surface methodology and multi-objective optimization techniques to achieve efficient and accurate experimental design and process optimization. Three criterions have been successively selected, and the optimal system achieves specific energy absorption of 24.6 J/g. This study paves a new way for promoting carrying capacity and tunability of energy absorbers by structural design under modular strategy.