Showing papers on "Ballistic impact published in 2003"

The ballistic impact characteristics of Kevlar® woven fabrics impregnated with a colloidal shear thickening fluid

Abstract: This study reports the ballistic penetration performance of a composite material composed of woven Kevlar® fabric impregnated with a colloidal shear thickening fluid (silica particles (450 nm) dispersed in ethylene glycol). The impregnated Kevlar fabric yields a flexible, yet penetration resistant composite material. Fragment simulation projectile (FSP) ballistic penetration measurements at ∼244 m/s have been performed to demonstrate the efficacy of the novel composite material. The results demonstrate a significant enhancement in ballistic penetration resistance due to the addition of shear thickening fluid to the fabric, without any loss in material flexibility. Furthermore, under these ballistic test conditions, the impregnated fabric targets perform equivalently to neat fabric targets of equal areal density, while offering significantly less thickness and more material flexibility. The enhancement in ballistic performance is shown to be associated with the shear thickening response, and possible mechanisms of fabric-fluid interaction during ballistic impact are identified.

Failure and tribological behaviour of the AA5083 and AA6063 composites reinforced by SiC particles under ballistic impact

Abstract: The wear behaviour of two different MMCs, namely AA5083 and AA6063 reinforced by 45, 30 and 15% SiCp, respectively, are investigated under condition of high-velocity impact. The tests are carry out by firing 7.62 armour piercing rounds into these composite materials. The wear and failure mechanisms are evaluated by examining the projectile tips and the hole surfaces produced by high-velocity impact using SEM and optical microscopy. The hardness differences of the two regions on the hole surfaces, i.e. the plastically compressed regions surrounding the projectile hole is higher than unaffected matrix. The wear mechanisms on the friction surfaces of the matrix are predominantly abrasion and melt wear. It is observed that the projectile nose is plastically deformed when it impacts the armour. The projectile surface is also scratched by the SiC particles on the hole surface produced by the impact. The wear mechanism on the projectile surface is predominantly abrasive.

Anti spalling glass construction

Abstract: There are disclosed glazing cross section constructions and the relevant concept for an transportation armoured ballistic construction having improved durability, anti spalling and ballistic performances. These constructions comprise one or more than one thin chemically strengthened glass plies that can be soda-lime, borosilicate or aluminosilicate. Said chemically strengthened glass ply will be manufactured with a suitable residual stress profile that prevent or limits the effect of splinters projection in case of ballistic impact and improve the overall ballistic performances of the glazing.

Damage Tolerance of Thick-Section S-2 Glass Fabric Composites Subjected to Ballistic Impact Loading

Abstract: The damage tolerance of thick S-2 glass-fabric reinforced polyester, vinylester, and epoxy matrix composite panels subjected to ballistic impact loading has been examined. The damage shape and size was examined using ultrasonic NDE. After inspection of the damage, residual compression strength of the impacted panels was measured. The hand laid-up glass-polyester composite suffered from a large damage size, and low strength in compression after ballistic impact (CABI). The glass-vinylester and glass-epoxy panels manufactured using the SCRIMP process showed small damage sizes and high residual strengths. Through-thickness stitching of glass-vinylester and glass-epoxy panels was found to reduce the impact damage size, but the difference was quite small and did not translate into a substantial strength increase. The performance of panels with a ceramic tile bonded at the impact site was also examined. Model predictions of the CABI strength based on compression failure at the net section are compared to measur...

Impact resistance of lightweight hybrid structures for gas turbine engine fan containment applications

Abstract: The ballistic impact resistance of hybrid composite sandwich structures was evaluated with the ultimate goal of developing new materials or structures for potential gas turbine engine, fan containment applications. The sandwich structures investigated consisted of GLARE-5 (Aviation Equipment, Inc., Costa Mesa, CA) laminates as face sheets with lightweight cellular metallic materials such as honeycomb, foam, and lattice block as a core material. The impact resistance of these hybrid sandwich structures was compared with GLARE-5 laminates and 2024-T3 Al sheets, which were tested as a function of areal weight (material thickness). The GLARE-5 laminates exhibited comparable impact properties to that of 2024-T3 Al at low areal weights, even though there were significant differences in the static tensile properties of these materials. The GLARE-5, however, did have a greater ballistic limit than straight aluminum sheet at higher areal weights. Furthermore, there is up to a 25% advantage in ballistic limit for the GLARE-5/foam sandwich structures compared with straight 2024-T3 Al. But no advantage in ballistic limit was observed between any of the hybrid sandwich structures and thicker versions of GLARE-5. Recommendations for future work are provided, based on these preliminary data.

Digital speckle radiography—a new ballistic measurement technique

Abstract: Digital speckle radiography is a measurement technique which is capable of visualizing internal flow fields within an opaque material undergoing a ballistic impact. This recent development has been...

Superior Ballistic Impact Resistance Achieved by the Co-Base Alloy Haynes 25

Abstract: The fan case in a jet engine is required to contain a fan blade in the rare event of a blade loss during operation. Because of its function, the fan case is the largest structural component in high-bypass-ratio turbofan engines used in commercial aircraft. Therefore, the use of lighter and stronger materials would be advantageous in most engines and is practically a necessity in the latest generation of high-bypass engines. Small panels, 7 in. wide by 7 in. long, of a number of metallic alloys were impact tested at room temperature with a 0.50-caliber blunt-nose titanium alloy projectile at the NASA Glenn Research Center (ref. 1). These metallic systems included several high-strength aluminum (Al) alloys, Al-based laminates, aluminum metal matrix composites (Al-MMCs), nickel-base superalloys (Inconel 718 and 625), several titanium (Ti) alloys in different heat treated conditions, 304L stainless steel, a stainless-steel-based laminate, and a high strength steel (Nitronic 60). It was determined that a simple Co-base alloy (Haynes 25) had the best impact resistance on an areal weight basis. Haynes 25 was at least 10 percent better than IMI 550, the best titanium alloy tested to date, and it was far superior to other metals, especially at higher impact velocities (greater than 1100 ft/sec). Because this material could be ideal for fan containment applications in supersonic aircraft as a replacement for titanium, impact tests were also conducted at 371 oC and compared with results from alloys tested at elevated temperature under previous programs (i.e., Inconel 718, Ti-6242, M-152, Timetal 21S, and Aeromet 100). Although cobalt-base alloys are used in some high-temperature engine applications, to our knowledge they are not used in any containment systems. Advantages of cobalt over titanium include lower cost, easier processing, better high-temperature strength, and no fire hazard if tip rub occurs. Future plans include testing of lightweight sandwich panels with Haynes 25 as a core material in the form of a foam or lattice block structure and scaling up the current tests by using blade-simulating projectiles impacting large plates and half rings.

1-D and 2-D modeling of U-Ti alloy response in impact experiments

Abstract: Dynamic response of a U-0.75wt%Ti alloy has been studied in planar (disk-on-disk), reverse (disk-on-rod) and symmetric (rod-on-rod) ballistic impact experiments performed with a 25 mm light-gas gun. The impact velocities ranged between 100 and 500 m/sec and the samples were softly recovered for further examination, revealing different degrees of spall fracture (planar impact) and of adiabatic shear bands (ballistic experiments). The back (planar experiments) and the lateral (ballistic experiments) surface velocities were continuously monitored by VISAR. The velocity profiles and the damage maps were simulated using a 2-D AUTODYN Lagrangian finite differences code. Simulations of the planar experiments were performed with special attention to the compressive path of the loading cycle in order to calibrate a modified Steinberg-Cochran-Guinan (SCG) constitutive model. The Bauschinger effect and a single-parameter spall model were added to describe the unloading and tensile paths. The calibrated SCG model was then employed to simulate the ballistic experiments. An erosion AUTODYN built-in subroutine with a threshold value of plastic strain was chosen to describe the failure in the ballistic impact experiments. The results of the suggested experimental-numerical technique can be taken into account in estimating the different contributions to the shock-induced plastic deformation and failure.

The developments of fibre-reinforced composite laminates under ballistic impact

Abstract: In recent twenty years, the fibre-reinforced composite laminates have been used for structural protection widely However, the energy-absorbing and damaging mechanisms of laminates under ballistic penetration are intricate, due to the complexity of geometrical structures and material characteristics of fibre-reinforced laminates The influencing factors include the target's dimension, the structure geometry the materials properties and the properties of interlaminates, the shape and velocity of the projectiles and so on In this paper, the researches and developments in recent ten years are reviewed especially, the experimental technology, the static and dynamic mechanics of laminates, the impact force, the experical equations and the analysis models At the same time, the applications and developments of numerical methods are also discussed briefly