Egg-shell structure design for stab resistant body armor

Abstract

Conventionally fabricated multi-layered Stab Resistance Body Armor (SRBA) is uncomfortable to wear, because it is too heavy and inflexible. The natural, hierarchical shelled scale outer structures found in certain animals have provided the inspiration for the design of modern SRBA. In this reported work, Laser Sintering (LS) technology combined with Polyamide (PA) 3200 was used to produce a structure that mimicked the complexity of a hierarchical shell-scale structure. To determine if residual heat stress produced during the LS preparation could affect the stab resistance performance of the novel SRBA sample, mechanical property tests were performed using tensile bars that were placed at different locations in the LS chamber. Stab resistance tests were performed on laser sintered egg-shell samples that were prepared by varying key design parameters. The results showed that the stab resistant performance increased as the long axis of the mini egg-shell structural unit was increased and the short axis was decreased. The density of the structured plate composed of the egg shell units was found to increase as the long axis of the mini egg-shell structural unit increased and the short axis decreased. The stabbing mechanism was investigated in detail by studying the characteristics of the shape and depth of the penetration point of the knife. Dynamic analysis was conducted to determine the relationship between the stab resistance and the shape of the egg-shell unit. Lastly, the SRBA assembly method that exhibited the optimum stab resistance and flexibility was determined. This method was determined from the premise that a good support from the bottom layer of the SRBA produces the best stab resistant performance. The novel SRBA that was fabricated using the optimized material and assembly parameters represented a 37% reduction in weight compared to conventional SRBA devices. The results of this research showed the promise of the proposed design for lighter and more effective SRBA.