Mechanical properties of woven flax/carbon hybrid composites subjected to flexural loads

The integration of natural fibers with high-performance synthetic fibers in composite laminates is essential for developing sustainable, eco-friendly structures without sacrificing mechanical performance. However, achieving positive hybrid effects, particularly under flexural loading compared to conventional carbon fiber-reinforced polymers (CFRP), remains a significant challenge. This study presents a novel design approach involving precise adjustments during the dry fiber placement stage of the vacuum-assisted resin transfer molding (VARTM) process to optimize hybrid laminate performance. Selected hybrid laminates underwent mechanical characterization and fracture analysis using optical microscopy, informing a linear static numerical analysis to identify the optimal stacking sequence. The optimum hybrid laminate was subsequently manufactured and evaluated through flexural, short beam, and dynamic mechanical analysis tests. Compared to CFRP, the hybrid laminate exhibited a notable 5% increase in flexural strength, while flexural modulus and short beam strength remained within 8% of CFRP benchmarks. Notably, incorporating flax fibers increased the hybrid composite’s damping capacity (loss factor) by 22%. Fracture morphology analyses highlighted the influence of fiber stacking sequences, offering critical insights into maximizing positive hybrid effects. Non-linear numerical modeling using Puck’s failure criteria confirmed experimental findings, emphasizing the critical role of fiber modulus differences and their distribution in hybrid laminates. A small change in VARTM process results in four hybrid layups at once Flexural test and optical analysis of hybrids help identify the hybrid mechanism Based on the mechanism, optimum hybrid with aid of numerical analysis is identified Optimum hybrid shows improved flexural strength and loss factor reference to CFRP Non-linear FEA closely predicts the mechanical response and hybrid behavior