Lucio Fabio Cassiano Nascimento

Evaluation of Ballistic Armor Behavior with Epoxy Composite Reinforced with Malva Fibers

In the present study, we used natural fibers malva (Urena lobata, Linn) in 0, 15 and 30 vol.% as reinforcement of epoxy matrix composites to ballistic application. Ballistic efficiency of these composites was assessed by measuring the energy absorbed and residual velocity after impact 9 mm FMJ ammunition projectile, aiming to compare with traditional materials, such as: aramid fabric Kevlar™ used in vests for personal protection. The results showed by visual analysis and scanning electron microscopy (SEM) that the main active failure mechanisms in composites were delamination layers and fiber rupture. In test groups can be seen that the absorbed energy and the residual velocity varies with the fiber percentage used. Compared to aramid there is both a gain in weight and cost of the ballistic armor, which makes the fiber malva a promising material applications involving personal protection against 9 mm caliber ammunition.

Limit Speed Analysis and Absorbed Energy in Multilayer Armor with Epoxy Composite Reinforced with Mallow Fibers and Mallow and Jute Hybrid Fabric

Epoxy matrix composites reinforced with up to 10, 20 and 30 vol% of continuous and aligned natural mallow fibers and 30 vol% of mallow and jute hybrid fabric were for the first time ballistic tested as personal armor against class III 7.62 mm FMJ ammunition. The ballistic efficiency of these composites was assessed by measuring the dissipated energy and residual velocity after the bullet perforation. The results were compared with that in similar tests of aramid fabric (Kevlar™) commonly used in vests for personal protections. Visual inspection and scanning electron microscopy analysis of impact-fractured samples revealed failure mechanisms associated with fiber pullout, rupture and layers delamination. When compared to Kevlar™, the mallow fiber and hybrid fabric composite displayed practically the same ballistic efficiency. However, there is a reduction in both weight and cost, which makes both, mallow fiber and hybrid fabric composites, a promising material for personal ballistic protection.

Ballistic Performance in Multilayer Armor with Epoxy Composite Reinforced with Malva Fibers

A multilayer armoring system (MAS) is commonly formed by three layers. The initial layer is normally composed by a ceramic with high compressive strength, which absorbs most of the kinetic projectile energy. The subsequent composite layer was formed by epoxy matrix reinforced with natural malva fibers (Urena lobata, Linn), in the form of pure or hybrid fabric with jute fibers, in order to absorb part of the kinetic energy, and to retain ceramic and projectile shrapnel. A third layer formed by aluminum alloy, was included as a penetration restrictor for bullet and fragments by plastic deformation. The ballistic efficiency was evaluated by penetration of the 7.62 × 51 mm ammunition into a clay witness backing the armor. The results showed a great potential by epoxy composites reinforced with malva fabric as compared to other natural fibers and materials traditionally used in personal protection, such as Kevlar™ aramid.

The Role of Sintered Al 2 O 3 -Nb 2 O 5 Front Plate on the Ballistic Performance of Multilayered Armors

The performance of multilayered armor systems (MAS), composed of a front Al2O3-Nb2O5 ceramic plate followed by either plies of aramid fabric layer or curaua fiber reinforced polyester matrix composite layer and backed by an aluminum alloy sheet, was assessed. Ballistic impact tests were performed with actual 7.62 caliber ammunitions. Indentation in a clay witness, simulating a personal body behind the back layer, attested the efficacy of the MAS as an armor component. The ballistic efficiency of the front ceramic dissipating more than 50% of the bullet impact energy was associated with its capacity of fragmentation. As for the remaining energy, the lighter and cheaper curaua fiber composites were found to present a significant advantage as a possible substitute for the usual aramid fabric intermediate layer in MAS for individual protection against high speed projectiles.

Comportamento balístico de compósito de polietileno de altíssimo peso molecular: efeito da radiação gama

The fiber reinforced polymer matrix composites (PMCs) are considered excellent engineering materials. In structural applications, when a high strength-to-weight ratio is fundamental for the design, PMCs are successfully replacing many conventional materials. Since World War II textile materials have been used as ballistic armor. Materials manufactured with ultrahigh molecular weight polyethylene (UHMWPE) fibers are used in the production of armor materials, for personnel protection and armored vehicles. As these have been developed and commercialized more recently, there is not enough information about the action of the ionizing radiation in the ballistic performance of this armor material. In the present work the ballistic behavior of composite plates manufactured with ultrahigh molecular weight polyethylene (UHMWPE) fibers were evaluated after exposure to gamma radiation. The ballistic tests results were related to the macromolecular modifications induced by the environmental degradation through mechanical (hardness, impact and flexure) and physicochemical (infrared spectroscopy, differential scanning calorimetry and thermal gravimetric analysis) tests. Our results indicate that gamma irradiation induces modifications in the UHMWPE macromolecular chains, altering the mechanical properties of the composite and decreasing, for higher radiation doses, its ballistic performance. These results are presented and discussed.