Experimental investigation of hybrid carbon-glass fiber / vinyl ester composite sandwich panels with Divinycell core for bending performance analysis with variation on bonding method

•Vacuum Assisted Resin Infusion used to fabricate hybrid sandwich composite.•The bonding method was compared between co-curing and co-bonding.•The specific maximum load of co-curing is 19 % higher compared to co-bonding under flexural test.•SEM analysis reveals the failure mode phenomena on its microstructure. Composite sandwich panels have significant durability with a high strength-over-weight ratio. However, the sandwich composites are subjected to bond failure, affecting the overall structural integrity. Considering this, the present study experimentally investigates the influence of bonding techniques, including vacuum-assisted resin infusion (VARI) with adhesive bonding and VARI without adhesive bonding (co-curing). The specimens are hybrid carbon-glass fiber-reinforced vinyl ester sandwich composites with Divinycell core. Three-point bending tests were conducted to assess the flexural performance in relation to weight. Results indicate that the VARI with adhesive bonding exhibits a lower performance compared to VARI with co-curing bonding. The specific bending stress of VARI with co-curing is 0.12 MPa/g, while VARI with adhesive bonding is 0.08 MPa/g. The specific maximum load of VARI with co-curing is 19 % higher than the adhesively bonded method. Detailed failure mechanism observations were performed using a Scanning Electron Microscope (SEM). SEM analysis reveals significant differences in fracture surface morphology, explaining the variation in mechanical performance.