Tailoring ideal stress plateau for impact-resistant lattices with a bionic hybrid hierarchical strategy

It is a long-standing challenge to harness ideal stress plateau with unobvious peak, large capacity and high steadiness when designing impact-resistant structures. To achieve this goal, bionic hybrid hierarchical lattices (BHHL) inspired by muscles and shells of the lobsters are proposed, which integrates high-capacity stretch-dominated and high-stability bending-dominated units. Prescribable deformation pattern and ideal stress plateau are observed from experiments and simulations. Energy absorption efficiency, force efficiency and force steadiness of BHHL respectively reach 54.8 %, 92.9 % and 84.6 % under quasi-static loads, which averagely outperforms five classical structures of same mass by 12.7 %, 32.8 % and 66.7 %. Notably, these superiorities almost remain unaffected in strong impact experiments with energies of 13.1–25.6 kJ. A plastic hinge model with relative error less than 3.8 % is developed to estimate the plateau stress, and can be used to tailor ideal target stress plateau under both quasi-static and dynamic loads. Due to integration of stretch- and bending-dominated mechanisms, specific energy absorption of BHHL is inferior to stretch-dominated but obviously superior to bending-dominated structures of same mass, whilst its other indicators are notably higher than all eight comparative models. This works provides a new pathway to quickly tailor ideal stress plateau for impact-resistant lattices based on metallic constituent material and novel structural design.