Abstract
This paper presents an experimental study to determine the behaviour of composite panels, made of polyurea sprayed on Kevlar or Dyneema support layers, under blast and fragments produced by an improvised explosive device (IED). The fragments used for tests were steel bearing balls of 8 and 10 mm propelled by a plastic explosive charge and bullets cal. 7.62 mm, type Full Metal Jacketed Armor Piercing (FMJ AP) and Hollow Point Boat Tail (HPBT), with impact velocity greater than 500 m/s. To determine the fragments attenuation, their velocities before and after the impact with the composite panel were measured and compared. In order to assess the blast attenuation, the reflected pressures measured by two face-on sensors, one of which was covered by the composite panel, were compared. Also, to explain the behaviour of composite panels under blast, the shock polars of materials in the panel�s composition were plotted. The results have shown that the composite panels have a low rate of attenuation of fragment velocities but a very good ability to attenuate the pressure and impulse associated with the shock wave.
Highlights
The increasing number of recent terrorist attacks, on soft targets and in public places, requires a continuous concern from national safety authorities
The use of multi-layered ballistic panels to mitigate the effects of improvised explosive devices in large openings is in line with the current trend to increase the protection of soft targets
The panels were designed to consist of two layers of porous materials arranged externally, with the main purpose of attenuating the fragments, and a central composite panel with a primary role in the attenuation of the shock wave
Summary
The increasing number of recent terrorist attacks, on soft targets (unprotected objectives) and in public places, requires a continuous concern from national safety authorities. The most common targets are the civil airports Their protection against attacks with improvised explosive devices (IED) is imperative when considering their very large spaces, very large number of passengers and airport staff. If a ballistic multi-layered panel is placed between different crowded areas, it would be possible to partition these spaces and stop/mitigate the spread of the shock waves and fragments. This ballistic panel has been designed to consist of two symmetrical layers of porous material in order to mitigate the fragments and a central composite panel capable of attenuating in particular the shock wave. Research has shown that a 4 mm thick polyurea pad can reduce the normalized peak pressure and impulse by about 74% and 49%, respectively [7]
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