Laboratory scale technology for a ballistic protection panel and preliminary results

This paper presents a laboratory scale technology for manufacturing a composite with ballistic protection characteristics for a certain level of threat. The composite is made of quadriaxial fabrics, with four oriented substrates (0°/+45°/90°/-45°), which assumes from the start that the fabric will have a quasi-isotropic behavior. The selected resin to bind the layers is made of two-component resin Biresin® CR82, with hardener CH80-2 (supplied by Sika Group). This technology implies cutting, a laying-up process, a maintenance in press, under load, for at least 8 hours, a natural aging during 7 days, and a heat treatment, in two stages, taking into account the software of the used oven, of 3 hours each, at 60 °C. There were manufactured sets of 8-layer panels and 16-layer panels, checking to have a narrow tolerance of the thickness for the set of panels with the same number of layers. The process has repeatability, precision and robustness. The recipe for making panels and the laboratory technology are original. The manufacturing process was made in compliance with the norms of safety and health at work, with adequate protective equipment. The test campaign aimed to evaluate the behavior of ballistic protection panels, at the action of bullets of 9 mm FMJ, by firing in a specialized laboratory, the method being the one recommended in the standard EN 1522/2004. The bullet has the average initial speed of 373 m/s, at a distance of 5 m (normal conditions). Only the dimensions of the test samples, which were 300 mm x 300 mm, are smaller than those required by the standard (500 mm x 500 mm). The obtained results and the mechanisms of target failure (at full penetration for 8-layer panels and partial penetration for 16-layer panels) are discussed in order to improve the response of the target, by changing parameters, such as the number of layers of the panel, that influenced weight.