Experimental investigation of hybridization effects on the mechanical performance of Kevlar/UHMWPE reinforced epoxy composite structures

Abstract

In recent decades, composite materials have established themselves as some of the most effective choices for body armour due to their excellent stiffness-to-weight ratio. By combining different fiber metal laminate (FML) hybrid composites, for armour body is fabricated to enhance ballistic impact resistance. In this research, the hybridization effect on ballistic impact, flexural strength and tensile strength of FML hybrid composites is analyzed. The proposed FML hybrid composites consist of an Al6063 sheet of 0.5 mm, an ultra-high molecular weight poly-ethylene (UHMWPE) sheet of 1 mm and a Kevlar (K-29)/epoxy resin layer of 0.29 mm. The FML samples were created using the hand layup method combined with vacuum bagging techniques, and they were cured at room temperature under a vacuum pressure of 760 mmHg. Ballistic impact testing was conducted to assess energy absorption characteristics using a flat-nosed projectile. The results revealed an average energy absorption of 32.04% and the specific energy absorption (SEA) of 15.62 J-m²/kg, along with a tensile strength of 85.17 ± 1.24 MPa at a peak load of 4.68 ± 0.07 kN and a maximum deformation of 4.56 ± 0.07 mm. These findings indicate that the proposed FML hybrid composite exhibits improved impact strength while remaining lightweight at just 152 g and having a thickness of 2.2 mm. A morphological analysis was also performed to examine the fractured and split surfaces of the tested specimens, revealing various fracture modes such as delamination, matrix cracking, fiber breakage, and fiber splitting.