Soft body armors have been widely used by law-enforcement and military personnel and have saved a large number of lives over the past several decades. However, the exact failure mechanisms of these armors at various size scales (fiber, yarn, fabric, pack, etc) are not precisely understood. Consequently, predictive capabilities on the critical conditions for the impact failure of these armors are still not well-developed. In this presentation, we summarize our recent experimental research efforts aiming at developing a better understanding of impact failure of soft body armors at scales ranging from shoot packs, single-plies, yarns, fibers, and within a single fiber. The experiments reveal that impact resistance of packets is dictated by axial properties and shear strength of the textile materials, as well as structural properties such as stacking sequences. At the single-ply level, the critical impact velocity depends heavily on the nose shape of the projectiles, as well as the axial and transverse properties of the yarns. A critical striking velocity divides the impact-energy absorption behavior into two distinct groups. The failure of yarns and fibers depends on the stress state, as interpreted from the effects of nose shapes of the indenters and from the application of multi-axial stress states. A critical striking velocity also exists for either of these cases, across which the material failure pattern changes suddenly. The detailed damage and failure process of a single fiber under transverse cutting is presented. The effects of aging on the impact resistance is also discussed.<br/>

Experimental studies on impact failure of soft body armors at micro to macro size scales

2019 Spring National Meeting

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