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: This paper investigated experimentally 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 volume 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. To analyze the results of the ballistic impact on the GLARE, the effect of nanoclay on the longitudinal and transversal mechanical properties of the composite was investigated. A noticeable correlation was found between ballistic impact results and Changes of toughness in longitudinal and transversal direction.

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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 research, effect of adding silica nano-particles on the mode II interlaminar fracture toughness of epoxy matrix composites reinforced with glass fibers was experimentally studied. Hand lay-up method has been used to manufacture nanocomposites with18 layers of 2D woven glass fibers with 40% fiber volume fraction. The nano-epoxy resin system is made of diglycidyl ether of bisphenol A (epon 828) resin with jeffamine D400 as the curing agent. Nanosilica particles are dispersed with 0, 0.5, 1 and 3 wt.% (of epoxy resin) to study the effect of nanosilica content on fracture toughness. Also a series of nanocomposites with 1 wt.% nanosilica content and contained 55 vol.% glass fibers were fabricated to investigate the effect of fiber volume fraction on results. End notch flexure (ENF) test was adopted for the measurement of mode II interlaminar fracture toughness. The results show that high loading of nanosilica has no significant effect on the interlaminar fracture toughness of nanocomposites while the addition of 0.5 wt% nanosilica enhanced the interlaminar fracture toughness about 36% compared to the neat composites. Decreasing fiber volume fraction improved interlaminar fracture energy.

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In this paper, an analytical model has been developed for modeling high velocity impact on ceramic/nanocomposite targets. In this model, penetration resistance of ceramic is determined based on cavity expansion analysis and variables during perforation of projectile onto ceramic are considered. Also the force of ceramic-composite interface is modified. Ballistic performance of the ceramic/composite target is investigated with adding and dispersing of nano particles of zirconia (ZrO2) in the matrix of back up composite. Ballistic impact tests were performed to validate the analytical predictions. These tests were performed by firing 10 mm steel flat ended projectile onto ceramic/composite target. Front layer is alumina ceramic and composite laminates of back up made of E-glass/epoxy with and without nano-zirconia particle of 5 wt%. The effect of nano-zirconia dispersion in the matrix for different failure modes is discussed. Experimental results revealed an improvement in the ballistic performance of samples with nano-zirconia particle. The analytical predictions of ballistic limit velocity and residual velocity of projectile are found to be in good agreement with the experimental results.

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In this paper, concentrated and distributed compressive loading quasi-static tests were conducted on sandwich structures with empty and foam filled honeycomb core. The sandwich structure used in this research were formed by aluminum plate and aluminum 5052 honeycomb structure. Foam used to fill the honeycomb structure was polyurethane foam with a density of 137.13 kg / m3.Concentrated loading quasi-static tests were performed by flat ended penetrator with a diameter of 10 mm and universal machine. Also distributed loading quasi-static tests were carried out by universal machine. In distributed loading, force is applied uniformly to the entire structure surface. Displacement rate was 2 mm/min for both types of loading. The purpose of this paper was to study the filler material effect on energy absorption and destruction shape of sandwich structure, as well as comparison of the two types of loading in unfilled and foam filled honeycomb core sandwich panels. The results of quasi-static tests showed that filler material has positive effects on increasing energy absorption in both concentrated and distributed loading. Polyurethane foam as filler material of honeycomb structure used in sandwich panel core increase specific absorbed energy of sandwich panel with foam filled core proportion to empty honeycomb core sandwich panel structure in concentrated and distributed loading by 6% and 29% respectively.

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In this paper, static analysis of transversely anisotropic laminate is investigated using improved zig-zag theory. Variation of in-plane displacement is assumed to be sinusoidal while transverse displacement is assumed to remains constant through the thickness. This piece-wise continuous sinusoidal function satisfies transverse shear stresses continuity in interfaces. The Hamilton principle is utilized to derive governing equations and related boundary conditions. The Navier-type solution is presented for simply-supported boundary conditions. The theory has the same unknown variable field as Euler Bernoulli beam although it predicts stresses high accurately. The validity of solutions is confirmed by comparing present model results with that of reported in the literature. Numerical results are given to study the influences the transverse anisotropy on displacement, strain and stress fields through the thickness. The piece-wise continuous sinusoidal function offers more accurate transverse stress distribution in comparison with the piece-wise polynomial function. The present theory provide more slightly accurate stress field through the thickness compared to high order shear deformation theory, which in turn is more accurate than Euler-Bernouli theory. The results shows the continuity of normal strain through thickness predicted by Euler-Bernouli theory has not physical basis. Furthermore, the improved zig-zag theory is capable of capturing precise stress field through the thickness in transversely anisotropic laminate