Study on mechanical properties of polyurethane-enhanced triply periodic minimal composite structures inspired by rachis microstructure

Inspired by the micro-curved structure and microfiber filling of the feather, four novel polyurethane-enhanced triply periodic minimal composite structures are designed. Based on Euler theory and simulated annealing algorithm, the mechanical relationships of enhanced composite structures at the compression and impact stage are deduced and predicted. The polyurethane-enhanced composite structure is larger than the corresponding triply periodic minimal structure in the average load. The specific energy absorption of the polyurethane-enhanced triply periodic minimal composite structure is at least 10% better than the original. Through the energy expansion of the foam, the energy transfer path is allowed to deviate in the foam. And the load distribution is not only in the vertical direction but also in the transverse direction. All these factors (more energy dissipation and transfer path deviation) work to improve the crashworthiness of polyurethane-enhanced composite structures. The impact videos are captured by high-speed photography FASTCAM Nova R2. The reduction of normalized stress is proved in the design of polyurethane-enhanced structure, and the reduction of the impact acceleration of polyurethane-enhanced composite structure is more than 13.6%. This bio-inspired rigid-flexible coupling design of composite structure is crucial to the novel design of the next generation.