Ballistic Impact Resistance of UHPC Plates Made with Hybrid Fibers and Low Binder Content

This study assesses the ballistic impact strength of thin plates made of ultra-high-performance concrete (UHPC) with low cement content (250 kg/m3) and volumes of 80% steel and 20% polypropylene (PP) hybrid fibers. The plates were prepared with thicknesses of 30, 50, and 70 mm and fiber volume ratios of 1.5% and 3.0%. Compressive strength, flexural tensile strength, residual strength, and ballistic impact strength were determined using experimental methods. Test results showed that regardless of fiber content, the UHPC specimens prepared with the hybrid fibers showed similar performance against ballistic impact, exerting relatively low impact energy below 1000 J. The UHPC3.0 mixture made with 3.0% hybrid fiber content exhibited the best performance in terms of energy absorption and spalling resistance at impact energy levels greater than 4000 J. Plate sections with thicknesses of 7 mm showed class III performance (highest level), as recommended for military-based applications.

Ballistic characterization of fiber elastomer metal laminate composites and effect of positioning of fiber reinforced elastomer

The present study aims at investigating the ballistic impact response of jute, natural rubber and aluminium based tri-layer composites with two different configurations, namely Aluminium-Jute-Rubber-Jute and Jute-Rubber-Jute-Aluminium. The proposed composites were fabricated using the compression moulding technique and subjected to ballistic impact testing at impact velocities of 75 m/s, 105 m/s, 154 m/s and 183 m/s. The energy absorption and damage mitigation characteristics of the proposed fibre metal elastomer tri-layer composites were assessed. Results showed that among the two proposed composites, the composite with rubber facing the impact side exhibits better energy absorption and also helps in damage mitigation compared to the composite having aluminium on the impact side. In addition, a parametric study was carried out by varying the thickness of the rubber layer. It was observed that the impact response of the proposed tri-layer composites improved with increasing thickness of the rubber layer, especially in the case of the Jute-Rubber-Jute-Aluminium configuration.