Per: LAURA SETTI DE SOUSA (INSTITUTO MILITAR DE ENGENHARIA), Bernardo Soares Avila de Cêa (INSTITUTO MILITAR DE ENGENHARIA), Édio Pereira Lima Júnior (INSTITUTO MILITAR DE ENGENHARIA), Sergio Neves Monteiro (INSTITUTO MILITAR DE ENGENHARIA), Lucio Fabio Cassiano Nascimento (INSTITUTO MILITAR DE ENGENHARIA), Fabio Da Costa Garcia Filho (CEFET/RJ)
Abstract:
The evolution of modern weapons demands the development of advanced materials for ballistic protection, especially in bulletproof vests. Formerly produced with animal skins or metals, vests have evolved into high-performance textile materials, lighter and more flexible due to advancements in the textile industry. High-performance synthetic fibers, such as Kevlar® and Dyneema®, are common in these vests but face challenges in terms of cost and environmental impact. Natural lignocellulosic fibers, as a sustainable alternative, offer unique characteristics, although their heterogeneity poses challenges in reliability, particularly in ballistic applications. Therefore, the proposal of hybrid composites arises, combining natural and synthetic fibers to balance low cost and high ballistic performance. However, analyzing the ballistic properties of these composites requires consideration of factors such as the stacking sequence of reinforcement layers. Therefore, this study aims to evaluate four different stacking sequences of sisal and aramid fiber layers in an epoxy matrix hybrid composite, analyzing their ballistic properties through residual velocity tests and fracture mechanisms of the specimens through macrograph. Statistical analysis (ANOVA) indicated that different stacking sequences proposed did not significantly influence the ballistic performance of the composites, although the 6A/6S composite absorbed the highest energy value. Therefore, the partial replacement of aramid layers with sisal did not compromise the energy absorption capacity, providing a cost reduction of up to 47%. Furthermore, macroscopic analyses evidenced post-impact structural integrity and different deformation mechanisms.
