3D printing method for embedded structures of PU energy-absorbing materials and its compression mechanical behavior

When unmanned aerial vehicles (UAV) are exposed to extreme weather conditions such as strong wind and hail, alternating stress is much more likely to arise in their structures. This repeated stress will accelerate the fatigue of UAV body structures and shorten their life, thus threatening flight safety. In this paper, through Indirect methods of 3D printing, the ordeal pieces of polyurethane (PU) embedded energy-absorbing structure were designed by modifying PU and developing three kinds of flexible materials with different shore hardness. The functional relationship among hardness, curvature, and energy absorption performance of PU structures was established by static compression experiment. The results indicate that their top curvatures affect their energy absorption performance in the samples with the same shore hardness. Moreover, the shear deformation during compression may generate a hardened layer, enhancing its energy absorption performance. At the same time, shore hardness positively correlates with energy absorption performance for the test pieces with identical structures. The greater the shore hardness, the better the energy absorption performance. Therefore, the PU material-structure-function integrated design can achieve lightweight and improve economic efficiency in the real sense based on relieving the fatigue of fuselage structure and realizing optimal energy absorption performance.