Enhanced Crack Resistance Using Bamboo Fiber-Reinforced Polymer (FRP) Composite for Lightweight Structural Applications

Unsaturated polyester (UP) composites are widely utilized in engineering applications, including vehicle body structures, due to their ease of processing and good interfacial compatibility with natural fibers. However, the inherent brittleness of UP limits its performance under impact or tensile loading, as it exhibits minimal plastic deformation and is prone to crack initiation and propagation. In this study, bamboo fiber was incorporated into the UP matrix at various mixing ratios to enhance its crack resistance. After achieving uniform dispersion, the composites were subjected to a splitting tensile test to evaluate their crack resistance behavior. The results indicate that the composite containing 80% polyester exhibits the highest fracture toughness, with a crack resistance value of K1C = 1.396 MPa·m0.5. This value represents a 192.03% improvement compared with neat polyester (K1C = 0.713 MPa·m0.5). The enhanced crack resistance is attributed to the fiber bridging and energy-absorption mechanisms introduced by the bamboo fibers. These findings demonstrate the effectiveness of bamboo fiber reinforcement in improving the fracture performance of UP-based composites, highlighting their potential for use in lightweight structural applications.