A State-of-the-Art Review on Material Innovations and Testing Methodologies for Soft Body Armor

The ballistic impact behavior of soft body armor is governed by complex interactions between material architecture and projectile characteristics. This review provides a critical overview of the evolution of textile and composite-based armor materials developed for ballistic protection. Emphasis is placed on experimental and analytical methodologies used to elucidate impact energy dissipation, deformation mechanisms, and failure modes. Key material-related parameters influencing ballistic performance including areal density, weave architecture, yarn crimp, twist, and thread density are systematically discussed, along with assembly variables such as ply orientation, layer number, and hybrid configurations. In parallel, the influence of projectile mass, velocity, and geometry on impact resistance is examined. The review also summarizes internationally adopted ballistic and stab-resistance standards employed for soft armor evaluation. Various assessment techniques, including yarn–yarn friction analysis, puncture resistance testing, ballistic limit velocity determination, and back-face signature measurement, are critically reviewed. Strategies aimed at enhancing impact performance, such as rubber or latex impregnation, fiber surface modification, and the incorporation of shear thickening fluids, are comprehensively discussed. Attention is given to shear thickening fluids due to their significant role in improving energy absorption and flexibility. The fundamental mechanisms governing shear thickening behavior and the parameters affecting their performance are analyzed. Overall, this review highlights emerging material design strategies and performance optimization approaches for next-generation soft body armor systems.