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.
ResumoOs compósitos possuem dois ou mais constituintes físicos. O Brasil produz uma vasta quantidade de fibras vegetais e as utiliza como fase de reforço. A gelatina é obtida da ruptura de ligações covalentes e formam géis termoreversíveis. Sua principal característica, a gelificação, envolve a renaturação da estrutura e, diante do nosso objetivo, foi utilizada como suporte para as fibras já que a gelificação forma uma rede tridimensional. As fibras foram padronizadas em 0,355 mm. A gelatina foi gelatinizada e a solução coloidal vertida em moldes. Os provetes ensaiados conforme ASTM D412. O acréscimo da celulose microcristalina não altera os resultados da tensão de ruptura. O módulo de elasticidade respondeu de forma inversamente proporcional ao aumento do teor de fibras vegetais. O aumento da resistência à tração e do alongamento do material, porém, não na mesma proporção, faz com que haja uma diminuição de seu módulo elástico. O módulo de elasticidade tende a diminuir devido ao grande alongamento ao passo em que o teor de fibras vegetais e gelatina aumenta. A variação do teor de fibras vegetais e gelatina alterou significativamente os resultados dos ensaios de tração. A tensão de ruptura aumentou proporcionalmente ao aumento do teor de fibras vegetais. O alongamento também aumentou com o aumento do teor de gelatina, não sofrendo variações significativas em relação à variação do teor de fibras vegetais. Palavras-chave: Fibras vegetais; Gelatina; Compósitos; Resíduos. GELATIN FILMS REINFORCED WITH VEGETAL FIBERS AbstractComposites have two or more physical components. Brazil produces a vast amount of vegetal fibers and used as a reinforcing phase. Gelatin was obtained from the rupture of covalent bonds and it forms gelatinous film. Its main property, gelation, involves denaturation of the structure and it was used as a support for the fibers as the gelling form a three dimensional network, following our aim. The fibers were standardized in 0.355 mm. Gelatin was gelatinized and the colloidal solution poured into molds. The specimens was tested according to ASTM D412. The addition of microcrystalline cellulose does not modify the results of a rupture tension. The elasticity modulus is inversely proportional to the increase of fibers. There is an increase in straining and lengthening, but not to the same proportion, wich means that there is a decrease in its elastic modulus. The elastic modulus tends to decrease due to the great lengthening step while the vegetal fibers and gelatin increases. The variation of vegetal fibers and gelatin content significantly alter the results of tension tests. The rupture tension increased proportionally to the content of plant fibers. Stretching also increased to the gelatin content, not suffering significant changes in relation to the content of vegetal fibers.
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