Experimental and numerical simulation of high density polyethylene–Kevlar trauma liner–polycarbonate hybrid composites for National Institute of Justice Level II stab-resistant of lightweight body armour

The advancement of stab-resistant body armour is critical for law enforcement and military personnel operating in high-risk environments. Conventional armour systems, while effective, often impose excessive weight and restrict mobility, compromising wearer comfort and operational efficiency. This study evaluated the stab-resistant performance of novel composite configurations integrating high-density polyethylene (HDPE), Kevlar trauma liner, and polycarbonate, with the objective of meeting National Institute of Justice (NIJ) Standard 0115.00 Level II protection requirements. Five stacking sequences (A to E) were fabricated and tested against single-edged (P1) and double-edged (S1) knives under two impact energy levels: 33 J (E1) and 50 J (E2). Experimental trials were conducted using the Stab Apparatus and Measurement System at the Science and Technology Research Institute for Defence Ballistic Laboratory, Batu Arang, Selangor, Malaysia. Results demonstrated that Sequence E which comprising HDPE type II, polycarbonate, HDPE type II, Kevlar trauma liner, HDPE type I, and HDPE type II had successfully satisfied NIJ Level II criteria. Penetration depths were 6 mm at E1 and 10 mm at E2, both within NIJ limits (≤6 mm for E1 and ≤20 mm for E2). Finite Element Analysis (FEA) predictions closely aligned with experimental outcomes, with error values ranging from 5% to 10%, thereby validating the model’s reliability. The optimized hybrid configuration exhibited superior stab resistance and notable weight reduction compared to conventional titanium O-ring armour. These findings highlight the potential of multi-material composites to deliver lightweight, agile, and effective stab-resistant armour for urban patrol and high-risk security operations.