Elevated energy absorption capability oriented toughening design for brittle polymer composites

Ordered cellular materials have emerged as important energy absorption materials. However, the strength-toughness trade-off has always limited their practical applications. To enhance the toughness and energy absorption capability of 3D printed brittle cellular materials, this study employs three toughening strategies: the multi-stage strategy, the interpenetrating strategy, and their combined strategy. The experimental research under quasi-static compression is conducted to investigate the energy absorption characteristics and toughening mechanisms. Results show that multi-stage structure design improves toughness and total energy absorption (TEA) by transforming large-scale fracture into localized progressive failure through crack twist and branching. Its TEA can reach 61 times compared with the corresponding cellular material. Meanwhile, the interpenetrating structure design enhances the ductility and energy absorption of the material by mitigating stress concentrations. Its TEA can reach 33 times compared with the corresponding cellular material. After combining the advantages of both strategies, multi-stage-interpenetrating cellular composites exhibit superior overall performance and a variety of deformation mechanisms. Moreover, the toughening effects of various strategies vary among different structures, which comes from their deformation modes. This study offers a valuable approach for toughening brittle cellular materials, providing crucial insights for advancing the development and application of polymer composites.