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In this paper, the influence of nanoclay Closite 30B on ballistic impact behavior of 2D woven E- Glass/Epoxy laminated composite has been investigated experimentally. The glass/epoxy/nanoclay laminate nanocomposites have 12 layers and 60% fiber volume fraction is manufactured by VRTM method. Fibers have a plain weave configuration with density of 200gr/m2, while The epoxy resin system is made of a diglycidyl ether of bisphenol A (DGEBA), Epon 828, as the epoxy prepolymer and a polyoxypropylene diamine with average molecular weight of 400 gr/mol, Jeffamine D-400, as the curing agent. The nanoclay Closite 30B is dispersed into the epoxy system in a 0%, 1%, 2%, 3%, 5% and 7% ratio in weight with respect to the matrix. Morphological studies using XRD revealed that nanostructures are mostly in intercalated form rather than exfoliated form. In additional to tensile test, ballistic impact test is carried out on the samples by flat-ended projectile with 14gr mass and 9.77mm diameter in 130m/s, 142m/s and 155m/s velocities. The results have shown that not only the mechanical properties, but also ballistic impact resistance can be improved with adding nanoclay.

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In this paper an analytical model for investigating of the ballistic impact behavior of two dimensional woven E-glass/epoxy composites is presented on the basis dividing the impact duration to several time intervals and calculating the energy absorbed during each time interval. The major components of energy lost by projectile during ballistic impact are identified, namely the cone kinetic energy formed on the back face of the target, the secondary yarns deformation energy, the tensile failure energy of primary yarns, the delamination and matrix cracking energy. It is assumed that the shear plug formation is not observed for glass reinforced composites and the energy lost in overcoming the frictional force between projectile and composite is negligible. Analytical formulations have been presented for calculating energy absorbed by each mechanism in each time interval. Finally, a good correlation has been observed, comparing the analytical model presented in this paper to the experimental results presented by others investigators.

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Aluminum foam structure is of great importance in aerospace, naval and automotive industries due to light weight and energy absorption characteristics. In this article several aluminum foam having different densities and thickness were designed and tested using light gas gun device. A series of ballistic test were defined in order to determine the effects of density, foam thickness and projectile velocity on energy absorption aluminum foam structures. The results of the experimental testes, it is shown that the amount of energy absorption of aluminum foam structures is increased as density, foam thickness and velocity of the projectile is increased.

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In this paper, the influence of nanoclay Closite 30B on ballistic impact behavior of 2D woven E- Glass/Epoxy laminated composite has been investigated experimentally. The glass/epoxy/nanoclay hybrid laminate nanocomposites are manufactured by layup method under pressure. The nanoclay particles are Closite 30B and are dispersed into the epoxy system in a 0%, 3%, 5%, 7% and 7% ratio in weight with respect to the matrix. In additional to tensile test, ballistic impact test is carried out on the samples by flat-ended projectile with 8.9gr mass and 10mm diameter in 134m/s and 169m/s velocities. The results have shown that not only the mechanical properties, but also ballistic impact resistance can be improved with adding nanoclay.

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Sandwich panels(structures) of metal surface having aluminum foam core are of great importance in aerospace, naval and automotive industries due to high strength to weight ratio and high energy absorption characteristics. In this article several aluminum sandwich panels with aluminum foam core having different densities and thickness were designed and tested using light gas gun device. A series of ballistic test were defined in order to determine the effects of density, foam thickness and projectile velocity on energy absorption and ballistic limit velocity of sandwich structures. The material model used for metal foam was Deshpande- Fleck-Foam and coefficients were determined experimentally using foam and Matlab capabilities. Also, numerical simulation using LSDYNA software were performed. The results of the experiment and numerical simulation were compared and there was a good agreement between experimental investigation and numerical results. Using experimental testes and parametric studies,it is shown that the amount of energy absorption of sandwich structures is increased as density, foam thickness and velocity of the projectile is increased.

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In this paper, the influence of nanoclay Closite 30B on ballistic impact behavior of 2D woven E- Glass/Epoxy laminated composite has been investigated Theoretical and experimentally. The structure of the hybrid nanocomposite is glass/epoxy/nanoclay laminate and is manufactured by hand layup method under pressure. The nanoclay is dispersed into the epoxy system in a 0%, 3%, 5%, 7% and 7% ratio in weight with respect to the matrix. Comparison of theoretical results and results of the ballistic impact test are shown a good correlation. The results have shown that optimal to increase in energy absorption is 10% in 3% nanoclay content. Howevere, in the impact velocities far than ballistic impact, maximum increasing in energy absorption is 20% in 10% nanoclay content.

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In this study, factors affecting ballistic performance of fabrics used, including material properties, projectile geometry, boundary conditions, fabric dimensions, multiple plies of fabric armors and friction, has been studied. Ballistic limit was obtained as a criterion of ballistic performance of fabric to identify and compare the effect of the mentioned factor. To obtain the ballistic limit, ballistic tests were performed on the fabric. Also, a finite element model was created using LS-DYNA software and the results of the the simulation of this model show an acceptable agreement between the experimental and numerical analysis. Due to limitation in experimental tests,many of factors affecting performance of armors can be evaluated using this model.

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In this paper, the experimental behavior of grid cylindrical composite structures which are used widely in engineering structures under ballistic impact is investigated. In the present study, the grid cylindrical composites were manufactured by the filament winding process with fiber placement procedure and perforated by projectile using the ballistic gas gun. Input and output velocities of projectile were recorded. The results show that presence of discrete ribs prevents spread damage from one cell to it’s adjacent cells and structure behaves differently against projectile with velocity near ballistic limit velocity and higher velocities. With approach to the ribs location ballistic limit has been increased. However due to reduce fracture area, overall and local deformations after impact in velocity which is higher than ballistic limit velocity, projectile has been came out from grid samples with higher velocity than simple composite shells. In this paper, delamination in outer composite shell and ribs, debonding between shell and ribs, residual velocity of projectile, fracture area of the grid specimens and the effects of curvature in two deferent velocities were reported and commented upon as results.

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this paper, ballistic impact on sandwich panel with composite facesheet made of Glass/Epoxy and aluminum honeycomb core has been investigated experimentally. Ballistic impact test also carried out on Honeycomb and composite and the effect absorption energy by adding composite on two sides honeycomb is studied. By this model the influence of the components on the behavior of the sandwich panel under impact load was evaluated. Ballistic impact tests is carried out on the samples by flat-ended projectile with 8/5 gr mass and 10 mm diameter in difference velocities. Also, the contribution of the failure mechanisms to the energy absorption of the projectile kinetic energy was determined. The results show that honeycomb sandwich has more energy than when alone ballistic tests conducted on has absorbed and front cover compared with back cover sandwich structure has lower energy absorption. Also bigger than ballistic limit velocity absorbed the maximum amount of energy.

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This paper investigated experimentally and numerically the effect of nanoclay on ballistic impact behavior of GLARE. The prepared GlARE is made of two Aluminum 2024 facing sheets and E glass/ epoxy/nanoclay as nano composite core. Nano composite section has been composed of undirectional E glass 409 g/m2, resin CY 219, hardner HY 5161 and nanoclay closite 30B dispersed into the epoxy system in a 0%, 4%, 7% and 10% ratio in weight with respect to the matrix. All panels fabricated using laid-up method in fiber weight fraction of 60%. Ballistic tests were conducted using Gas gun at the velocity of 205 and 225 m/s. The results of the ballistic impact experiments show that the amount of Specific energy absorption variations in 4% of nanoclay content is insignificant. However, in nanoclay contents of 7% and 10%, the Specific energy absorption increases. In other words, it be concluded that nanoclay has positive effect on higher percentage on the ballistic impact. The 3D finite element (FE) code, LS-DYNA, is used to model and validate the experimentally obtained results. A noticeable correlation was found between experimental and numerical results.

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Due to the extreme increase in computational power over the recent years, numerical methods have gained the most proportion in analyzing composite structures and components because of the consideration complicated failure mechanisms such as delamination, fiber buckling and fiber breakage, matrix cracking, debonding ribs of skin and a combination of mentioned failure mechanisms. However exact three - dimensional modeling damages caused by impact phenomena is still a challenge. In present numerical work, the most advanced modeling techniques have been used to predict the behavior of composite structure under high velocity impact. The ribs and layers have been modeled using solid elements and a user defined material model with modified puck and Hashin (3D) failure criteria was implemented. Because these failure criteria do not exist in Commercial version of the Abaqus software, we have used Fortran software for writing these criteria so this capability was added to the software. Figures of velocity variations and force variations of projectile, damaged area, different mechanisms of fracture were reported as results and commented upon. In this study, The numerical results have been validated with experimental data and show very good agreement.

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In this study, experimental tests were performed to evaluate the effects of axisymmetric cylindrical projectile nose shapes and initial velocities on ballistic performance of laminated woven glass epoxy composites. Projectile initial velocity and nose sharpness changes, absorbed energy, delamination area, etc. are investigated by six blunt, hemispherical, conical and ogival projectiles. Hand lay-up method has been used to manufacture composite targets with 18 layers of 2D woven glass fibers of 45% fiber volume fraction. The epoxy system is made of epon 828 resin with jeffamine D400 as the curing agent. The results show that the maximum influence of projectile geometry on target behavior, occurs in ballistic limit area. In this range of initial velocity, ogival (CRH=2.5) and Blunt projectiles show the best and the worst ballistic performance. The delamination area decreases as the projectile nose sharpness increases or its initial velocity decreases. Ballistic curves for different projectiles show that the difference between projectiles behavior decreases in higher impact velocities. Because of target shear failure in blunt projectile impact, the amount of target absorbed energy for this projectile is less than other projectiles in higher impact velocities away from ballistic limit velocity.

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Due to high hardness, low density and heat resistance, ceramics are widely used in armor applications and industry, thus, in this study, perforation process of projectile into ceramic targets is investigated analytically and numerically and a modified model is developed. In the analytical section, Woodward’s theory, one of the important theories in perforation process of projectile into ceramic targets, is investigated and some modifications are applied in Woodward’s model, hence the ballistic results of analytical method are improved and the modified model shows good agreement with the experimental results that in the analytical section, the modified model is based on Woodward’s model and modification of semi-angle of ceramic fracture cone, erosion, mushrooming and rigid from of projectile and also changes in yield strength of ceramic during perforation process, damage, are considered. In the numerical section, a finite element model is created using Ls-Dyna software and perforation process of projectile into Ceramic-Aluminum target is simulated. The results of the analytical method and numerical simulation are compared to the results of the other investigators and results of modified model show improvement in prediction of ballistic results.

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In this paper, the interaction between aluminum facing and honeycomb structure in the quasi-static and the impact loading has been investigated experimentally. The structural elements used in this research were aluminum plate, aluminum 5052 honeycomb structure. The quasi-static penetration tests and ballistic impact experiments were performed on aluminum plate, honeycomb structure and sandwich panel by flat ended penetrator and flat ended projectile respectively. The failure mechanisms, the ballistic limit velocities, the absorbed energies due to penetration, the damage modes and some structural responses were studied. Also, the effect of interaction between aluminum facing and honeycomb structure in the quasi-static penetration and the ballistic impact response in this honeycomb sandwich panel was discussed and commented upon. Comparing energy absorption in these structures showed that the amount of absorbed energy by the sandwich panel with honeycomb core is more than the absorbed energy by the aluminum plate and honeycomb structure in the quasi-static penetration. These results indicated, when the honeycomb structure was used as the core of sandwich panel, resulted in increasing of the stiffness and the strength of the sandwich panel. The ballistic impact results showed that the absorbed energy and the ballistic limit velocity in the sandwich panel compared with the individual components was increased. Therefor the sandwich structure can be used as a suitable energy absorber.

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Recently shear thickening fluids (STF) are applied more and more to improve the penetration resistance of fabrics. In this research, at first, the performance of the neat and STF impregnated fabric subjected to the impact of 8.7 mm diameter steel spherical projectile is investigated experimentally. Then, the numerical analysis is done to study the effective parameters such as fabric density, static and dynamic coefficients of friction between yarns and between projectile and fabric, boundary conditions and number of layers of fabric by using commercial tool LS-DYNA software. Previous studies expressed that the major factor that improves the energy absorption capacity of STF impregnated fabrics is the friction between the impact projectile, fabric, and yarns within the fabric, however here the investigations showed that in addition to the friction, the mass of added STF is effective in the results. Increasing the mass of the fabric by adding STF, is considered as the increasing density of the fabric. Empirical investigations showed that STF-impregnated fabrics exhibited a significant enhancement in penetration resistance performance as compared to neat fabric such that the projectile penetration subjected to the fabric with 44% wt STF decreased 63% compared to neat fabric. The simulation results showed that, if the STF effects just assign to increased friction, the projectile penetration decreased 43% compared to neat fabric. But if in addition to friction, the mass of the STF is considered as the effective parameter, the penetration decreased 58% which have good agreement with experimental data.

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In this paper, a 2D analytical model is introduced for predicting the ballistic behavior of the thin laminated composite plate based on tsai-hill and maximum strain criterions. At first, try to determine the moment deformation along with the expansion of transverse wave from impact point and the nonlinear strains and stresses in the composite plate. Then, the energy absorbed due to failure modes and deflection of composite plate such as elastic deformation energy, longitudinal and lateral fracture energy, kinetic energy of local movement, delamination and matrix cracking energy is calculated. For investigation of the various failed layers is used of tsai-hill and maximum strain criterions. In addition to the effects of strain rate on the mechanical properties of the composite layers is applied momentarily during Penetration process. Finally, the present analytical model based on tsai-hill and maximum strain criterions is compared with experimental results. The maximum strain criterion respect to tsai-hill criterion has shown a good agreement with experimental results in the calculation of ballistic limit velocity. According to the obtained results the share of fracture energy compared to the elastic deformation energy by increasing the thickness becomes more and more. And also, the kinetic energy of the local movement, delamination and matrix cracking energy have lower share in the process of energy absorption.

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One of the recent techniques which has attracted attention from researchers is the use of Nano particles to reinforce composites. While the technique does not make any changes in the weight of the structure, it improves its mechanical and physical properties. One form of Nano particles includes Carbonic Nano Tubes (CNT). Since its discovery, CNT has found wide application in industryIn this article, the response of aluminum hybrid panels and composites made from epoxy-Kevlar and aluminum hybrid panels and Nano-composites made from epoxy-Kevlar to ballistic impact was studied. Four groups of the panels were constructed using 0, 0.5, 1 and 1.5 percent of carbon nanotubes (CNT)s. The hybrid samples constructed and tried out in this experiment has been done using manual layer-making and heated press.The thickness of the panels constructed from two aluminum plates and ten Kevlar 29 plates was consistent. The ballistic impact test using gas gun was implementated by conical bullet 7.6 gr shooting in two avrege velocities (220 m/s and 275 m/s). input and output velocity with each sample was assessed using a laser speedometer. The amount of energy absorption and special energy absorption of passing of the rocket was determined as the criteria for the comparison of the efficiency of ballistic of different panels. The results indicated that among the four samples examined, the panel made up of 1 percent CNTs had the most amount of energy absorption and ballistic resistance.

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