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Ballistic impact (BI) is a study that deals with a projectile hitting a target and observing its effects in terms of deformation and fragmentation of the target. The Discrete Element Method (DEM) is a powerful numerical technique used to model solid and particulate media. Here, an attempt is made to simulate the BI process using DEM. 1-D DEM for BI is developed and depth of penetration (DOP) is obtained. The DOP is compared with results obtained from 2-D DEM. DEM results are found to match empirical results. Effects of strain rate sensitivity of the material response on DOP are also simulated. [ABSTRACT FROM PUBLISHER]

This study compares some analytical models on high velocity impact behaviour of composite materials with that of experimental results from high velocity impact of hemispherical nose projectiles on nanoclay-filled composite plates in particular, assessing current models to account for the presence of nanoclay in polymer composites under such loading. Nanocomposites were prepared in 0, 1.5 and 3 wt%. The nanoclay-filled polyester resin was then utilised to manufacture laminated composite panels in four, eight and 12 layers using 400 g/m2 glass fibre woven roving via hand lay-up method. Transmission electron microscopy and X-ray diffraction confirmed intercalation and exfoliation of the nanoclay in the polyester resin system. Five models were selected for assessment. Comparison of predicted ballistic limit velocity (velocity at which the projectile remains in the composite target) with that of experimental results showed close correlation in all thickness for models that incorporated projectile nose geometry. A simple empirical equation is derived as a function of polymer laminate thickness and flexural modulus of polymer nanocomposite laminates, which varies with nanoclay content in polymer composite laminates for predicting ballistic limit velocity. [ABSTRACT FROM PUBLISHER]

In this study, aramid, Heracron®, which was purchased from Kolon Inc., Korea, and phenol composites were prepared by plasma treatment and the influence of this plasma treatment on their mechanical properties and ballistic behavior were ascertained. By measurement of water contact angle and XPS analysis, we find that the plasma treatment may help the incorporation of functional oxygen groups on the surface of the Heracron® fabrics. Additionally, the surface roughness of Heracron® fiber may be proportional to the plasma treatment times. By SEM and mechanical tests, it was shown that plasma-treated Heracron®/phenol composites exhibited higher mechanical properties compared with plasma-untreated Heracron®/phenol composites. Based on this finding, we can conclude that plasma-treatment can promote the interfacial adhesion between Heracron® and phenol, resulting in the superior mechanical properties of their composites. However, the ballistic behavior conflicted with the mechanical properties. That is to say, a helmet, manufactured from the plasma-treated Heracron®/phenol composites, exhibited lower ballistic properties than that of the plasma-untreated Heracron®/phenol composites. As a result, we demonstrated that for ballistic application, somewhat weak fiber-matrix adhesion leads to the improved ballistic behavior. However, it becomes apparent that the optimum strength condition for the composite interphase depends on the particular application, thus increased fiber-matrix adhesion may be more appropriate. [ABSTRACT FROM AUTHOR]

This study evaluates the energy absorption, perforation and damage evolution created by cylindrical projectile of different nose geometries in woven roving mat/epoxy laminates with 0.45° orientation. A series of ballistic impact tests have been carried out on the laminate with projectile nose geometries representing hemispherical, conical, and conical with round nose and truncated tip. A gas gun projectile launcher set-up was employed to impact the target at different speeds. The damage pattern, perforation mechanism and ballistic limit for each type of projectiles have been studied. Truncated-nose projectile shows the highest ballistic limit while sharp-nose shows the lowest. A quasi-static punch test was carried out on targets with projectiles of above-mentioned nose geometries to assess the damage evolution at a constant strain rate. The maximum load required to cause perforation during punch test was noted for hemispherical-nose projectile. An in-depth layerwise analysis was carried out to analyse the damage in each layer. [ABSTRACT FROM AUTHOR]