Mechanical Performance and Impact Resistance of Sisal-Kenaf Hybrid Natural Fiber GFRP Composites

This paper examines the mechanical and impact performance of hybrid GFRP laminates in which glass fiber plies are partially replaced by alkali-treated sisal (Agave sisalana) and kenaf (Hibiscus cannabinus) natural fibers. Five five-layer sandwich configurations were fabricated by hand layup with plug-mould compression curing and tested for tensile strength, flexural strength, and Charpy impact energy. The GSKSG (Glass/Sisal/Kenaf/Sisal/Glass) arrangement achieved a 41.5% improvement in impact energy over the all-glass control while retaining 82.4% of its tensile strength — demonstrating that judicious fiber selection and stacking sequence can shift GFRP failure from brittle to progressive energy-absorbing fracture. The study provides practical fabrication guidance for natural-fiber hybrid composites and identifies GSKSG as a viable candidate for impact-tolerant, weight-sensitive structural applications.