Comprehensive Analysis of Bolted Joint Performance in Natural Fiber-Reinforced Polymer Composites: Effects of Fiber Type, Orientation, Hybridization, and Environmental Conditions

Natural fiber-reinforced polymer (NFRP) composites are increasingly considered as sustainable alternatives to conventional synthetic composites. Their low density, renewable origin, and adequate mechanical performance make them attractive for applications in automotive, construction, and marine industries. Mechanical fastening through bolted joints is widely used for assembling composite structures because it allows easy inspection, replacement, and maintenance. However, introducing bolt holes creates stress concentrations that may lead to premature failure. This study investigates the mechanical performance of bolted joints in NFRP composites, focusing on fiber type, fiber orientation, hybridization, and environmental effects such as moisture and temperature. Failure mechanisms including bearing, net-tension, and shear-out are analyzed. Findings indicate that optimized fiber orientation, hybrid reinforcement, and controlled environmental conditions significantly improve joint strength and reliability.