Study of Ballistic Impact Performance of the Bioinspired Flexible Multilayered Filling Armor by Different Projectiles

Inspired by the unique hierarchical structure of biological carapaces, a bioinspired flexible multilayered filling armor is designed and developed for personal protective equipment. Similar to typical biological carapaces, the bioinspired flexible multilayered filling armor has a relatively hard segmented front layer, a soft layer connecting the front layer cells, and a filling layer embedded in the soft layer that can disperse concentrated deformation. The low-velocity drop weight impact tests, bullet impact tests, and ballistic limit V50 tests are carried out to evaluate the impact resistance of the bioinspired flexible multilayered filling armor. The current mainstream soft body armor slice specimens are used as a reference group during the experiments. Bioinspired flexible multilayered filling armor has been tested for its protective performance against various projectiles. A two-factor normalization evaluation method has been established, utilizing areal density and armor thickness to normalize backface deformation and ballistic limit energy absorption, respectively. This method evaluates the mass and spatial efficiency of the armor on different backing materials. Upon normalizing the results of bullet impact tests and ballistic limit V50 tests, it can be observed that the bioinspired flexible multilayered filling armor exhibits an energy absorption efficiency per unit thickness that is 125% higher and an energy absorption efficiency per unit area that is 9% higher than that of soft body armor. The research results indicate that the bioinspired flexible multilayered filling armor has a structural synergistic effect among different materials through hierarchical combination of each layer, which significantly improved the resistance efficiency of materials. This study can provide insights for designing new types of flexible armors.