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#17600, Ballistic Resistance of High Entropy Bio-Inspired 3D-Printed Alumina Shield

The ballistic resistance of personal body armor is mainly due to the strength of ceramic plates placed at or near the impact surface. The high hardness of ceramics serves to blunt, fragment, and decelerate an incoming projectile and distribute impact forces over a wider region. One of the most widely used ceramics is alumina due to its high strength and resistance to wear and temperature. However, as all ceramics, it is also characterized by low fracture toughness. In nature, there are several examples of organisms with shields, made of brittle constituent materials, that have high resistance to multiple impacts, e.g. diatom, nacre, oyster shell or armadillo. The architectures of these shields consist of very small tiles connected by collagen fibers, whose shape and dimensions play an important role in enhancing fracture toughness. Nowadays, the fabrication of these structures is very easy with Additive Manufacturing. Recently, the introduction of filaments made from fine powder (< 1.0 μm) and a thermoplastic binder, developed for FiDM/FFF printing processes, promoted the manufacturing of complex ceramic components using low-cost 3D printers.
In this study, the ballistic resistance of high entropy bio-inspired ceramic shields has been investigated. Specimens were 3D printed using a commercial filament with alumina powder. The mosaic architectures were designed to have a high entropy degree. The tiles of each layer were joined using a soft polymer with high strength. Different shapes and sizes of the tiles, as well as the stacked sequences of multilayer samples, were experimentally investigated. The impact tests were performed using a single-stage light-gas gun to fire a high-strength steel ball against the specimens. From preliminary tests, the bio-inspired architecture exhibited higher fracture toughness and impact resistance with respect to the monolithic samples. In addition, increasing the architecture entropy an increment of ballistic resistance was observed.

Alberto Pagano   University of Cassino and Southern Lazio
Nicola Bonora   University of Cassino and Southern Lazio
Gianluca Iannitti   University of Cassino and Southern Lazio
Sara Ricci   University of Cassino and Southern Lazio
Andrew Ruggiero   University of Cassino and Southern Lazio
Gabriel Testa   University of Cassino and Southern Lazio