Biomimetic dual-phase Bouligand meso-structure with synergistic strength and toughness

Attaining both strength and toughness is a crucial requirement for most structural materials. Unfortunately, these two properties are generally mutually exclusive. Therefore, structural materials with balance between strength and toughness hold promises for various engineering applications. This work proposes a novel design strategy that incorporates the dual-phase design method into the biomimetic Bouligand meso-structure, aiming to provide valuable insights into the strategy of resolving the conflict between strength and toughness. Experiments and numerical simulations of quasi-static/dynamic compression, three-point bending tests and cyclic loading tests show that the innovative design harnesses multiple mechanisms to achieve a balance between strength and toughness, including remarkable interlayer coupling, effective stress transfer, twisted crack propagation, interface energy dissipation, and crack path guidance between different phases. Testing results indicate that the biomimetic dual-phase Bouligand meso-structure demonstrate a 636.16% increase in Young’s modulus and a 258.54% enhancement in specific energy absorption compared to the TPU-based single-phase Bouligand structure, while its maximum flexural strain is 73.68% higher than that of the PLA-based sample. In addition, its promising applications in the field of personnel impact protection are illustrated by two examples. Our work promotes the innovative development of design strategies for next-generation biomimetic structural materials and offers an effective solution for the combination of rigid and flexible protection.