Effect of cellulose nanocrystals on the mechanical and free vibration behavior of hybrid glass/kenaf fiber reinforced polyurethane core-based sandwich structures

Engineering applications widely use foam-core-based sandwich structures. The study incorporated cellulose nanocrystals (CNC) into a hybrid glass/kenaf fiber-based polymeric sandwich structure with a 65 kg/m3 polyurethane foam core. Four unique face sheets (S1, S2, S3, and S4) were made using glass, kenaf, and CNC. Three-point bending, Charpy impact testing, and free vibration testing were used to characterize sandwich structures. The inclusion of CNC in the matrix of face sheets improved the hybrid composite’s bending strength and impact resistance. One layer of Kenaf fabric and two layers of glass make up the hybrid composite, which is stronger in both flexural strength and impact resistance, with 14.56 MPa and 8.1 J, respectively. These improvements are 44.84% and 57.49% compared to the pure glass/epoxy composite face plate. Nevertheless, the incorporation of Computer Numerical Control (CNC) failed to result in a substantial enhancement in vibration characteristics. Both matrix modification and natural fiber (kenaf) can effectively substitute glass fabric in sandwich structures