Édio Pereira Lima Júnior

Ballistic Test of Multilayered Armor with Intermediate Epoxy Composite Reinforced with Jute Fabric

Multilayered armors with a front ceramic followed by aramid fabric (Kevlar™) are currently used against high velocity ammunition. In these armors, a front ceramic layer that shatters and spalls the bullet is followed by an intermediate layer, usually plies of aramid fabric, which dissipates both the bullet and ceramic fragments energy. In the present work, the intermediate aramid fabric layer was replaced by an equal thickness layer of 30 vol% jute fabric reinforced epoxy composite. Ballistic impact test with 7.62 caliber ammunition revealed that both the plain epoxy and the jute fabric composite have a relatively similar performance of the Kevlar™ and also attended the NIJ standard for body protection. The energy dissipation mechanisms of jute fabric composite were analyzed by scanning electron microscopy and found to be the rupture of the brittle epoxy matrix as well as the interaction of the jute fibers with the post-impact fragments. This latter is the same mechanism recently disclosed for aramid fabric. However, the lightness and lower cost of the jute fabric composite are additional advantages that favor its substitution for the aramid fabric.

Giant Bamboo Fiber Reinforced Epoxy Composite in Multilayered Ballistic Armor

The ballistic performance of a multilayered armor with a front ceramic tile backed by a plate of giant bamboo fiber reinforced epoxy composite was assessed. The ceramic layer spalls the projectile, while the bamboo composite dissipates the remaining energy. Ballistic tests were performed with high velocity ammunition and the projectile penetration was evaluated by the intrusion depth in a clay witness. The average depth value of near 18 mm was found well below the limit specified by the NIJ standard of 44 mm and better than that for aramid fabric composite, about 22 mm, with the same thickness of the giant bamboo composite. The giant bamboo composite acts as an efficient barrier for the fragments originated from the ceramic brittle rupture. For practical application in portable armor for personal protection, the layer of giant bamboo composite presents not only a superior ballistic performance but also lightness and economical advantages over the conventional aramid fabric.

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.

Performance of Plain Woven Jute Fabric-Reinforced Polyester Matrix Composite in Multilayered Ballistic System

The ballistic performance of plain woven jute fabric-reinforced polyester matrix composites was investigated as the second layer in a multilayered armor system (MAS). Volume fractions of jute fabric, up to 30 vol %, were mixed with orthophthalic polyester to fabricate laminate composites. Ballistic tests were conducted using high velocity 7.62 mm ammunition. The depth of penetration caused by the bullet in a block of clay witness, simulating a human body, was used to evaluate the MAS ballistic performance according to the international standard. The fractured materials after tests were analyzed by scanning electron microscopy (SEM). The results indicated that jute fabric composites present a performance similar to that of the much stronger Kevlar™, which is an aramid fabric laminate, as MAS second layer with the same thickness. The mechanism of this similar ballistic behavior as well as the comparative advantages of the jute fabric composites over the Kevlar™ are discussed.

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.

CARACTERIZAÇÃO DE NANOCOMPÓSITOS COM PARTÍCULAS DE CARBETO DE BORO DISPERSAS EM MATRIZ DE POLIETILENO DE ULTRA ALTO PESO MOLECULAR

Flávio James Tommasini Édio Pereira Lima Junior Sergio Neves Monteiro Alaelson Vieira Gomes Marcelo H Prado da Silva Carla S Cosenza Resumo O estudo teve como objetivo a produção de corpos de prova de nanocompósitos baseados em uma matriz polimérica de polietileno de ultra alto peso molecular (UHMWPE) com carga de carbeto de boro dispersas, nas proporções de 0,0625%; 0,125%; 0,25%; 0,5%; 1% e 2%, respectivamente. As respectivas misturas entre os materiais, polímero e carga inorgânica, foram moldadas em prensa hidráulica quente à partir do estado fundido da matriz polimérica. A caracterização dos nanocompósitos com as cargas sem tratamento foi realizada pelas análises de difração de raio-x (DRX) e calorimetria diferencial de varredura (DSC), o que possibilitou a identificação dos planos cristalográficos característicos dos materiais, o grau de cristalinidade da matriz orgânica e suas respectivas temperaturas de fusão. As microestruturas dos materiais, morfologia da carga e adesão interfacial foram observadas através da microscopia eletrônica de varredura (FEGSEM). Através desse estudo foi possível o sugerir o comportamento do polímero com cargas de carbeto de boro dispersas em diversas proporções. Palavras-chave: Nanocompósitos; Carbeto de Boro, Polietileno de Ultra Alto Peso Molecular, Polímero, Estado Fundido.

DESEMPENHO DO COMPÓSITO DE MATRIZ POLIÉSTER REFORÇADO COM TECIDO DE JUTA EM UM SISTEMA DE BLINDAGEM MULTICAMADA

* Contribuição técnica ao 72o Congresso Anual da ABM – Internacional e ao 17o ENEMET Encontro Nacional de Estudantes de Engenharia Metalúrgica, de Materiais e de Minas, parte integrante da ABM Week, realizada de 02 a 06 de outubro de 2017, São Paulo, SP, Brasil. DESEMPENHO DO COMPÓSITO DE MATRIZ POLIÉSTER REFORÇADO COM TECIDO DE JUTA EM UM SISTEMA DE BLINDAGEM MULTICAMADA* Foluke Salgado de Assis Sérgio Neves Monteiro Fabio Da Costa Garcia Filho Artur Camposo Pereira Édio Pereira Júnior Carlos Luiz Ferreira Resumo O desempenho balístico de compósitos de matriz de poliéster reforçados com tecido de juta foi avaliado como segunda camada em um sistema de blindagem multicamadas (MAS – Multilayered Armor Systems). Diferentes frações volumétricas de tecido de juta, até 30% vol., foram misturadas com poliéster ortoftálica para se fabricar as placas compósitas. Estes compósitos foram ligados a uma camada cerâmica de alumina dianteira e seguidos por uma placa metálica de liga de alumínio como terceira camada do MAS, os testes balísticos foram conduzidos usando munição comercial de alta velocidade de 7,62 mm. A profundidade de penetração causada pela bala em um bloco de plastilina, que simula o corpo humano, foi usada para avaliar o desempenho balístico do MAS de acordo com o padrão internacional. Os materiais fraturados após testes foram analisados por microscopia eletrônica de varredura (MEV). Os resultados indicaram que os compósitos de tecido de juta apresentam um desempenho semelhante ao do tecido de aramida comercialmente utilizado como segunda camada para MAS com mesma espessura, o KevlarTM. O mecanismo que explica este comportamento balístico semelhante, bem como as vantagens econômicas comparativas dos compósitos de tecido de juta foram discutidos. Palavras-chave: Tecido de juta; Compósito de poliéster; Comportamento balístico; Sistema de blindagem multicamada.