PSI - Issue 70

Karthick Rasu et al. / Procedia Structural Integrity 70 (2025) 619–626

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3.3. Impact Strength

Fig. 4. Impact strength Impact energy of the composites is presented in Fig. 4. The impact strength values of the samples, ranging from 4.21 J (Sample 1) to 9.46 J (Sample 4), demonstrate significant variation in the composites' ability to absorb and dissipate energy during impact. Sample 4, composed of 40% banana fiber, 30% coir fiber, and 30% jute fiber, exhibits the highest impact strength, suggesting that the balanced combination of three fibers provides superior energy absorption and crack resistance. This optimal fiber synergy likely enhances toughness by effectively distributing and resisting sudden impact forces within the epoxy resin matrix. In contrast, Sample 1, with 50% banana fiber and 50% coir fiber, shows the lowest impact strength, possibly due to limited interaction between the fibers or suboptimal energy dissipation pathways. The impact strength increases progressively from Sample 1 to Sample 4, reflecting the beneficial effect of incorporating multiple fiber types with complementary properties. However, Sample 5 (33% banana, 33% coir, and 34% jute) shows a slight decrease in impact strength to 8.34 J compared to Sample 4, likely due to marginally reduced fiber-matrix bonding or higher void content. These results emphasize the critical role of fiber combination, distribution, and fabrication quality in enhancing the impact resistance of composites. The findings suggest that optimizing fiber proportions and processing conditions can significantly improve the toughness and durability of natural fiber-reinforced composites. 3.4. Hardness Hardness value of the composites is illustrated in Fig. 5. The hardness values of the samples, ranging from 66.71 (Sample 1) to 74.74 (Sample 4), show a clear variation in the composites' resistance to surface deformation. Sample 4, composed of 40% banana fiber, 30% coir fiber, and 30% jute fiber, exhibits the highest hardness, indicating that its well-balanced fiber combination provides superior reinforcement and load distribution in the epoxy resin matrix. This optimal mix likely reduces localized deformation under applied pressure, enhancing the overall surface strength. Sample 1, with 50% banana fiber and 50% coir fiber, has the lowest hardness, suggesting that this fiber combination might not provide adequate reinforcement for resisting surface wear or indentation. The progressive increase in hardness from Sample 1 to Sample 4 demonstrates the beneficial effect of incorporating diverse fiber types, which enhance structural integrity. However, Sample 5 (33% banana, 33% coir, and 34% jute) shows a slight reduction in hardness (68.73) compared to Sample 4, possibly due to less effective fiber-matrix bonding or increased void content. These results highlight the influence of fiber composition, distribution, and processing conditions on the surface properties of the composites. Enhancing the uniformity of fiber distribution and selecting optimal fiber combinations can substantially improve the hardness of natural fiber-reinforced composites, thereby increasing their effectiveness in applications that demand high resistance to surface wear and deformation.