Composites reinforced with natural lignocellulosic fibers (NLFs) are gaining relevance as the worldwide demand for renewable and sustainable materials increases. To develop novel composites satisfactory properties, less common NLFs should also be investigated. Among these, Cyperus malaccensis (CM), a type of sedge fiber, is already used in simple items like ropes, furniture, paper, but has not yet been investigated composite reinforcement possible engineering applications. Therefore, present...

Sisal fibers are among the natural lignocellulosic ones with great impact resistance for potential use in polymer composites. This work evaluates ballistic efficiency of distinct individual components a multilayered armor. These include front ceramic, back metallic sheet and intermediate layer as either conventional aramid fabric or novel sisal fiber reinforced epoxy composite. incorporated resin plates volume fraction 30% were tested using 7.62 caliber ammunition. The embedded under...

Multilayered armor systems (MAS) composed of relatively lighter materials with capacity to provide personal ballistic protection are being extensively investigated and used in vests. A typical MAS stand high impact energy 7.62 mm bullet has a front ceramic followed by an aramid fabric laminate, such as Kevlar™. Since both the army municipal police personnel might need wear vest, large number vests needs be supplied. In case Kevlar™, one most expensive material expiration time 5 years,...

Understanding the influence of thermal parameters on formation microstructure and intermetallics in alloys obtained through solidification is crucial for enhancing engineering properties both extensively studied materials new materials. This study aimed to identify formed during multicomponent alloy Al-33%Cu-1%Ni-1.2%Ta using a directional device. Characterization was conducted metallography, followed by scanning electron microscopy (SEM) analysis. Micrographs were from representative...

Firearms threat has always been a matter of personal concern, especially to soldiers in armed conflicts as well police officers and civilians involved with public security. A multilayered armor system (MAS) is intended protection against high kinetic energy ammunition, such that used rifles. MAS layers are normally composed front ceramic followed by layer must show both impact resistance low weight. Usually, synthetic fiber fabrics, aramid Kevlar® ultra-high molecular weight polyethylene...

Cements from alkali-activated reactions are unleashing opportunities for the future application of inorganic polymers, known as geopolymers. These materials eco-friendly, since their manufacturing process does not involve carbon dioxide (CO2) emission and it makes possible use industrial waste raw material. In this work, a geopolymeric cement concrete (GCC) was developed through adequate portions geopolymer components. Its characteristics were compared with Portland (PCC), establishment some...

Abstract The development of dislocation structures associated with work hardening stages and dynamic strain aging (DSA) is investigated in an AISI 301 austenitic stainless steel plastically deformed tension at 500 600 °C. In the first stage, up to 22% plastic 500 °C 18% 600 °C, incipient cells begin be formed are observed association {1 0 0} TEM diffraction pattern. At transition point from second well consolidated a maximum density typical DSA steels. sharp decrease rate after discloses...

Due to increasing improvement of weaponry and ammunition, attention is being given the development new materials that could more effectively resist ballistic impact. In order stop high energy bullets, with speed above 800 m/s, a strength material necessary. However, if just one used, then relatively thick piece required, which might affect negatively wearer mobility. The objective this work investigate effect thickness on behavior aramid fabric laminates, Kevlar®, hit by bullet. purpose find...

Woven fabrics made of a natural lignocellulosic mallow fiber have been used for long time in common clothes. Recently, these are being considered as reinforcement engineering composites. This work investigates the basic mechanical behavior polyester composites reinforced with up to 40 vol% fabric. Room temperature tensile tests allow evaluation properties, such ultimate strength, elastic modulus, resilience and total strain. An improvement properties was found increasing amount fabric...

The mechanical behavior and the strengthening mechanism of stainless steel welded joints at 600 °C have been investigated. welds were composed AISI 304 steel, as base metal, niobium containing 347 weld metal. investigation was conducted by means creep tests. specimens subjected to both high temperature (600 °C) long periods (up 2000 h) under constant load, properties microstructural changes in material monitored. It found that exposure load contributes a effect on weld. phenomenon might be...

Al 2 O 3 -Nb 5 has been widely explored as one of the most used material for sintering mixing in literature, due to its excellent hardness properties, armor. In this study, and Y powders were prepared, with 50% mole fraction each oxide. The mixtures subjected high energy milling an eccentric ball mill h, dried sieved a sieve vibrator. green bodies compacted at 70 MPa sintered from 1250 1650 °C 100 steps. materials characterized by quantitative X-Ray diffraction (XRD) using Rietveld method...

LA IDENTIFICACION DE TODOS LOS PUNTOS DISENO ES SUMA IMPORTANCIA EN EL ANALISIS CONFIABILIDAD ESTRUCTURAS REALES. ESTE ARTICULO SE PROPONE UNA METODOLOGIA BASADA ALGORITMO NUMERICO LAS ESTRATEGIAS EVOLUTIVAS (ES) PARA LLEVAR A CABO CON FIABILIDAD ESTRUCTURAL FUNCIONES ESTADO LIMITE MULTIPLES DISENO. INICIALMENTE, UN METODO OPTIMIZACION MULTIDIMENSIONAL UTILIZANDO APLICA OBTENER POSICION APROXIMA DA (MAXIMOS LOCALES). COORDENADAS ESTOS SON UTILIZADOS COMO PARTIDA BIEN CONOCIDO HL-RF (HASOFER...

O compósito Al2O3-YAG possui alta resistência à corrosão e fluência em ambientes agressivos, o que permite vislumbrar aplicações bastante atrativas, tais como aletas de motores a jato turbinas gás. Este também apresenta elevada dureza abrasão possibilitando seu emprego blindagens balísticas. Nesse estudo os pós precursores Al2O3, Y2O3 Nb2O5 foram homogeneizados moinho bolas planetário por 4 h, secados estufa 120 ºC 48 desaglomerados peneirados. foi produzido partir das misturas Al2O3-Y2O3...

This work analysed the effect of addition rare-earth mixed oxide (RE2O3), a solid solution Y2O3 and other rare earths benefited from Brazilian natural ore called Xenotime, on sintering properties commercial nanopowder composed Ce-tetragonal polycrystal zirconia (TZP) + 15 wt.% Al2O3. Powder mixtures were prepared, adding 10 or RE2O3 in Ce-TZP/Al2O3 powder, which compacted sintered at 1500 °C for 2 h. Sintered samples characterized by X-ray diffraction, scanning electron microscopy, relative...

O compósito Al2O3-YAG possui alta resistência a fluência em elevadas temperaturas, o que permite vislumbrar aplicações no campo da engenharia aeronáutica e espacial, tais como motores jato turbinas gás de alto desempenho. Este também apresenta algumas propriedades favoráveis seu emprego na área blindagem balísticas, por exemplo elevada dureza à abrasão. Nesse estudo foram produzidas amostras com Nb2O5 Al2O3 Nb2O5. Os pós precursores homogeneizados moinho planetário bolas 4 h, secos estufa...

The interval of existence dynamic strain aging (DSA) in AISI type 304 austenitic stainless steel subjected to quasi-static tension tests, under rates from 3.5 x 10-2 10-4 s-1, the temperature range 25 800ºC was investigated. It found that DSA occurs extending around 200 700ºC. Plastic instabilities associated with serrations, Portevin-Chatelier effect, allowed activation energies be calculated and a possible mechanism dislocation interaction interstitial carbon atoms proposed. Significant...

This study carried out the microstructural characterization, by light microscopy, of sintered SiC in presence liquid phase at temperatures 1800, 1850 and 1900 ºC, added with Al2O3 Y2O3 as well Al2O3-YAG composite proportions 5, 10 15% weight. It was possible to observe formation patterns resulting from heterogeneous segregation additives, such observation is associated pulling additives during initial stage ceramography. Two ceramographic paths were followed: method I - surface grinding...